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diff --git a/gnu/lib/libregex/doc/regex.info b/gnu/lib/libregex/doc/regex.info deleted file mode 100644 index 90deedeaf44f..000000000000 --- a/gnu/lib/libregex/doc/regex.info +++ /dev/null @@ -1,2836 +0,0 @@ -This is Info file regex.info, produced by Makeinfo-1.52 from the input -file .././doc/regex.texi. - - This file documents the GNU regular expression library. - - Copyright (C) 1992, 1993 Free Software Foundation, Inc. - - Permission is granted to make and distribute verbatim copies of this -manual provided the copyright notice and this permission notice are -preserved on all copies. - - Permission is granted to copy and distribute modified versions of this -manual under the conditions for verbatim copying, provided also that the -section entitled "GNU General Public License" is included exactly as in -the original, and provided that the entire resulting derived work is -distributed under the terms of a permission notice identical to this -one. - - Permission is granted to copy and distribute translations of this -manual into another language, under the above conditions for modified -versions, except that the section entitled "GNU General Public License" -may be included in a translation approved by the Free Software -Foundation instead of in the original English. - - -File: regex.info, Node: Top, Next: Overview, Prev: (dir), Up: (dir) - -Regular Expression Library -************************** - - This manual documents how to program with the GNU regular expression -library. This is edition 0.12a of the manual, 19 September 1992. - - The first part of this master menu lists the major nodes in this Info -document, including the index. The rest of the menu lists all the -lower level nodes in the document. - -* Menu: - -* Overview:: -* Regular Expression Syntax:: -* Common Operators:: -* GNU Operators:: -* GNU Emacs Operators:: -* What Gets Matched?:: -* Programming with Regex:: -* Copying:: Copying and sharing Regex. -* Index:: General index. - -- The Detailed Node Listing -- - -Regular Expression Syntax - -* Syntax Bits:: -* Predefined Syntaxes:: -* Collating Elements vs. Characters:: -* The Backslash Character:: - -Common Operators - -* Match-self Operator:: Ordinary characters. -* Match-any-character Operator:: . -* Concatenation Operator:: Juxtaposition. -* Repetition Operators:: * + ? {} -* Alternation Operator:: | -* List Operators:: [...] [^...] -* Grouping Operators:: (...) -* Back-reference Operator:: \digit -* Anchoring Operators:: ^ $ - -Repetition Operators - -* Match-zero-or-more Operator:: * -* Match-one-or-more Operator:: + -* Match-zero-or-one Operator:: ? -* Interval Operators:: {} - -List Operators (`[' ... `]' and `[^' ... `]') - -* Character Class Operators:: [:class:] -* Range Operator:: start-end - -Anchoring Operators - -* Match-beginning-of-line Operator:: ^ -* Match-end-of-line Operator:: $ - -GNU Operators - -* Word Operators:: -* Buffer Operators:: - -Word Operators - -* Non-Emacs Syntax Tables:: -* Match-word-boundary Operator:: \b -* Match-within-word Operator:: \B -* Match-beginning-of-word Operator:: \< -* Match-end-of-word Operator:: \> -* Match-word-constituent Operator:: \w -* Match-non-word-constituent Operator:: \W - -Buffer Operators - -* Match-beginning-of-buffer Operator:: \` -* Match-end-of-buffer Operator:: \' - -GNU Emacs Operators - -* Syntactic Class Operators:: - -Syntactic Class Operators - -* Emacs Syntax Tables:: -* Match-syntactic-class Operator:: \sCLASS -* Match-not-syntactic-class Operator:: \SCLASS - -Programming with Regex - -* GNU Regex Functions:: -* POSIX Regex Functions:: -* BSD Regex Functions:: - -GNU Regex Functions - -* GNU Pattern Buffers:: The re_pattern_buffer type. -* GNU Regular Expression Compiling:: re_compile_pattern () -* GNU Matching:: re_match () -* GNU Searching:: re_search () -* Matching/Searching with Split Data:: re_match_2 (), re_search_2 () -* Searching with Fastmaps:: re_compile_fastmap () -* GNU Translate Tables:: The `translate' field. -* Using Registers:: The re_registers type and related fns. -* Freeing GNU Pattern Buffers:: regfree () - -POSIX Regex Functions - -* POSIX Pattern Buffers:: The regex_t type. -* POSIX Regular Expression Compiling:: regcomp () -* POSIX Matching:: regexec () -* Reporting Errors:: regerror () -* Using Byte Offsets:: The regmatch_t type. -* Freeing POSIX Pattern Buffers:: regfree () - -BSD Regex Functions - -* BSD Regular Expression Compiling:: re_comp () -* BSD Searching:: re_exec () - - -File: regex.info, Node: Overview, Next: Regular Expression Syntax, Prev: Top, Up: Top - -Overview -******** - - A "regular expression" (or "regexp", or "pattern") is a text string -that describes some (mathematical) set of strings. A regexp R -"matches" a string S if S is in the set of strings described by R. - - Using the Regex library, you can: - - * see if a string matches a specified pattern as a whole, and - - * search within a string for a substring matching a specified - pattern. - - Some regular expressions match only one string, i.e., the set they -describe has only one member. For example, the regular expression -`foo' matches the string `foo' and no others. Other regular -expressions match more than one string, i.e., the set they describe has -more than one member. For example, the regular expression `f*' matches -the set of strings made up of any number (including zero) of `f's. As -you can see, some characters in regular expressions match themselves -(such as `f') and some don't (such as `*'); the ones that don't match -themselves instead let you specify patterns that describe many -different strings. - - To either match or search for a regular expression with the Regex -library functions, you must first compile it with a Regex pattern -compiling function. A "compiled pattern" is a regular expression -converted to the internal format used by the library functions. Once -you've compiled a pattern, you can use it for matching or searching any -number of times. - - The Regex library consists of two source files: `regex.h' and -`regex.c'. Regex provides three groups of functions with which you can -operate on regular expressions. One group--the GNU group--is more -powerful but not completely compatible with the other two, namely the -POSIX and Berkeley UNIX groups; its interface was designed specifically -for GNU. The other groups have the same interfaces as do the regular -expression functions in POSIX and Berkeley UNIX. - - We wrote this chapter with programmers in mind, not users of -programs--such as Emacs--that use Regex. We describe the Regex library -in its entirety, not how to write regular expressions that a particular -program understands. - - -File: regex.info, Node: Regular Expression Syntax, Next: Common Operators, Prev: Overview, Up: Top - -Regular Expression Syntax -************************* - - "Characters" are things you can type. "Operators" are things in a -regular expression that match one or more characters. You compose -regular expressions from operators, which in turn you specify using one -or more characters. - - Most characters represent what we call the match-self operator, i.e., -they match themselves; we call these characters "ordinary". Other -characters represent either all or parts of fancier operators; e.g., -`.' represents what we call the match-any-character operator (which, no -surprise, matches (almost) any character); we call these characters -"special". Two different things determine what characters represent -what operators: - - 1. the regular expression syntax your program has told the Regex - library to recognize, and - - 2. the context of the character in the regular expression. - - In the following sections, we describe these things in more detail. - -* Menu: - -* Syntax Bits:: -* Predefined Syntaxes:: -* Collating Elements vs. Characters:: -* The Backslash Character:: - - -File: regex.info, Node: Syntax Bits, Next: Predefined Syntaxes, Up: Regular Expression Syntax - -Syntax Bits -=========== - - In any particular syntax for regular expressions, some characters are -always special, others are sometimes special, and others are never -special. The particular syntax that Regex recognizes for a given -regular expression depends on the value in the `syntax' field of the -pattern buffer of that regular expression. - - You get a pattern buffer by compiling a regular expression. *Note -GNU Pattern Buffers::, and *Note POSIX Pattern Buffers::, for more -information on pattern buffers. *Note GNU Regular Expression -Compiling::, *Note POSIX Regular Expression Compiling::, and *Note BSD -Regular Expression Compiling::, for more information on compiling. - - Regex considers the value of the `syntax' field to be a collection of -bits; we refer to these bits as "syntax bits". In most cases, they -affect what characters represent what operators. We describe the -meanings of the operators to which we refer in *Note Common Operators::, -*Note GNU Operators::, and *Note GNU Emacs Operators::. - - For reference, here is the complete list of syntax bits, in -alphabetical order: - -`RE_BACKSLASH_ESCAPE_IN_LISTS' - If this bit is set, then `\' inside a list (*note List Operators::. - quotes (makes ordinary, if it's special) the following character; - if this bit isn't set, then `\' is an ordinary character inside - lists. (*Note The Backslash Character::, for what `\' does - outside of lists.) - -`RE_BK_PLUS_QM' - If this bit is set, then `\+' represents the match-one-or-more - operator and `\?' represents the match-zero-or-more operator; if - this bit isn't set, then `+' represents the match-one-or-more - operator and `?' represents the match-zero-or-one operator. This - bit is irrelevant if `RE_LIMITED_OPS' is set. - -`RE_CHAR_CLASSES' - If this bit is set, then you can use character classes in lists; - if this bit isn't set, then you can't. - -`RE_CONTEXT_INDEP_ANCHORS' - If this bit is set, then `^' and `$' are special anywhere outside - a list; if this bit isn't set, then these characters are special - only in certain contexts. *Note Match-beginning-of-line - Operator::, and *Note Match-end-of-line Operator::. - -`RE_CONTEXT_INDEP_OPS' - If this bit is set, then certain characters are special anywhere - outside a list; if this bit isn't set, then those characters are - special only in some contexts and are ordinary elsewhere. - Specifically, if this bit isn't set then `*', and (if the syntax - bit `RE_LIMITED_OPS' isn't set) `+' and `?' (or `\+' and `\?', - depending on the syntax bit `RE_BK_PLUS_QM') represent repetition - operators only if they're not first in a regular expression or - just after an open-group or alternation operator. The same holds - for `{' (or `\{', depending on the syntax bit `RE_NO_BK_BRACES') if - it is the beginning of a valid interval and the syntax bit - `RE_INTERVALS' is set. - -`RE_CONTEXT_INVALID_OPS' - If this bit is set, then repetition and alternation operators - can't be in certain positions within a regular expression. - Specifically, the regular expression is invalid if it has: - - * a repetition operator first in the regular expression or just - after a match-beginning-of-line, open-group, or alternation - operator; or - - * an alternation operator first or last in the regular - expression, just before a match-end-of-line operator, or just - after an alternation or open-group operator. - - If this bit isn't set, then you can put the characters - representing the repetition and alternation characters anywhere in - a regular expression. Whether or not they will in fact be - operators in certain positions depends on other syntax bits. - -`RE_DOT_NEWLINE' - If this bit is set, then the match-any-character operator matches - a newline; if this bit isn't set, then it doesn't. - -`RE_DOT_NOT_NULL' - If this bit is set, then the match-any-character operator doesn't - match a null character; if this bit isn't set, then it does. - -`RE_INTERVALS' - If this bit is set, then Regex recognizes interval operators; if - this bit isn't set, then it doesn't. - -`RE_LIMITED_OPS' - If this bit is set, then Regex doesn't recognize the - match-one-or-more, match-zero-or-one or alternation operators; if - this bit isn't set, then it does. - -`RE_NEWLINE_ALT' - If this bit is set, then newline represents the alternation - operator; if this bit isn't set, then newline is ordinary. - -`RE_NO_BK_BRACES' - If this bit is set, then `{' represents the open-interval operator - and `}' represents the close-interval operator; if this bit isn't - set, then `\{' represents the open-interval operator and `\}' - represents the close-interval operator. This bit is relevant only - if `RE_INTERVALS' is set. - -`RE_NO_BK_PARENS' - If this bit is set, then `(' represents the open-group operator and - `)' represents the close-group operator; if this bit isn't set, - then `\(' represents the open-group operator and `\)' represents - the close-group operator. - -`RE_NO_BK_REFS' - If this bit is set, then Regex doesn't recognize `\'DIGIT as the - back reference operator; if this bit isn't set, then it does. - -`RE_NO_BK_VBAR' - If this bit is set, then `|' represents the alternation operator; - if this bit isn't set, then `\|' represents the alternation - operator. This bit is irrelevant if `RE_LIMITED_OPS' is set. - -`RE_NO_EMPTY_RANGES' - If this bit is set, then a regular expression with a range whose - ending point collates lower than its starting point is invalid; if - this bit isn't set, then Regex considers such a range to be empty. - -`RE_UNMATCHED_RIGHT_PAREN_ORD' - If this bit is set and the regular expression has no matching - open-group operator, then Regex considers what would otherwise be - a close-group operator (based on how `RE_NO_BK_PARENS' is set) to - match `)'. - - -File: regex.info, Node: Predefined Syntaxes, Next: Collating Elements vs. Characters, Prev: Syntax Bits, Up: Regular Expression Syntax - -Predefined Syntaxes -=================== - - If you're programming with Regex, you can set a pattern buffer's -(*note GNU Pattern Buffers::., and *Note POSIX Pattern Buffers::) -`syntax' field either to an arbitrary combination of syntax bits (*note -Syntax Bits::.) or else to the configurations defined by Regex. These -configurations define the syntaxes used by certain programs--GNU Emacs, -POSIX Awk, traditional Awk, Grep, Egrep--in addition to syntaxes for -POSIX basic and extended regular expressions. - - The predefined syntaxes-taken directly from `regex.h'--are: - - #define RE_SYNTAX_EMACS 0 - - #define RE_SYNTAX_AWK \ - (RE_BACKSLASH_ESCAPE_IN_LISTS | RE_DOT_NOT_NULL \ - | RE_NO_BK_PARENS | RE_NO_BK_REFS \ - | RE_NO_BK_VBAR | RE_NO_EMPTY_RANGES \ - | RE_UNMATCHED_RIGHT_PAREN_ORD) - - #define RE_SYNTAX_POSIX_AWK \ - (RE_SYNTAX_POSIX_EXTENDED | RE_BACKSLASH_ESCAPE_IN_LISTS) - - #define RE_SYNTAX_GREP \ - (RE_BK_PLUS_QM | RE_CHAR_CLASSES \ - | RE_HAT_LISTS_NOT_NEWLINE | RE_INTERVALS \ - | RE_NEWLINE_ALT) - - #define RE_SYNTAX_EGREP \ - (RE_CHAR_CLASSES | RE_CONTEXT_INDEP_ANCHORS \ - | RE_CONTEXT_INDEP_OPS | RE_HAT_LISTS_NOT_NEWLINE \ - | RE_NEWLINE_ALT | RE_NO_BK_PARENS \ - | RE_NO_BK_VBAR) - - #define RE_SYNTAX_POSIX_EGREP \ - (RE_SYNTAX_EGREP | RE_INTERVALS | RE_NO_BK_BRACES) - - /* P1003.2/D11.2, section 4.20.7.1, lines 5078ff. */ - #define RE_SYNTAX_ED RE_SYNTAX_POSIX_BASIC - - #define RE_SYNTAX_SED RE_SYNTAX_POSIX_BASIC - - /* Syntax bits common to both basic and extended POSIX regex syntax. */ - #define _RE_SYNTAX_POSIX_COMMON \ - (RE_CHAR_CLASSES | RE_DOT_NEWLINE | RE_DOT_NOT_NULL \ - | RE_INTERVALS | RE_NO_EMPTY_RANGES) - - #define RE_SYNTAX_POSIX_BASIC \ - (_RE_SYNTAX_POSIX_COMMON | RE_BK_PLUS_QM) - - /* Differs from ..._POSIX_BASIC only in that RE_BK_PLUS_QM becomes - RE_LIMITED_OPS, i.e., \? \+ \| are not recognized. Actually, this - isn't minimal, since other operators, such as \`, aren't disabled. */ - #define RE_SYNTAX_POSIX_MINIMAL_BASIC \ - (_RE_SYNTAX_POSIX_COMMON | RE_LIMITED_OPS) - - #define RE_SYNTAX_POSIX_EXTENDED \ - (_RE_SYNTAX_POSIX_COMMON | RE_CONTEXT_INDEP_ANCHORS \ - | RE_CONTEXT_INDEP_OPS | RE_NO_BK_BRACES \ - | RE_NO_BK_PARENS | RE_NO_BK_VBAR \ - | RE_UNMATCHED_RIGHT_PAREN_ORD) - - /* Differs from ..._POSIX_EXTENDED in that RE_CONTEXT_INVALID_OPS - replaces RE_CONTEXT_INDEP_OPS and RE_NO_BK_REFS is added. */ - #define RE_SYNTAX_POSIX_MINIMAL_EXTENDED \ - (_RE_SYNTAX_POSIX_COMMON | RE_CONTEXT_INDEP_ANCHORS \ - | RE_CONTEXT_INVALID_OPS | RE_NO_BK_BRACES \ - | RE_NO_BK_PARENS | RE_NO_BK_REFS \ - | RE_NO_BK_VBAR | RE_UNMATCHED_RIGHT_PAREN_ORD) - - -File: regex.info, Node: Collating Elements vs. Characters, Next: The Backslash Character, Prev: Predefined Syntaxes, Up: Regular Expression Syntax - -Collating Elements vs. Characters -================================= - - POSIX generalizes the notion of a character to that of a collating -element. It defines a "collating element" to be "a sequence of one or -more bytes defined in the current collating sequence as a unit of -collation." - - This generalizes the notion of a character in two ways. First, a -single character can map into two or more collating elements. For -example, the German "es-zet" collates as the collating element `s' -followed by another collating element `s'. Second, two or more -characters can map into one collating element. For example, the -Spanish `ll' collates after `l' and before `m'. - - Since POSIX's "collating element" preserves the essential idea of a -"character," we use the latter, more familiar, term in this document. - - -File: regex.info, Node: The Backslash Character, Prev: Collating Elements vs. Characters, Up: Regular Expression Syntax - -The Backslash Character -======================= - - The `\' character has one of four different meanings, depending on -the context in which you use it and what syntax bits are set (*note -Syntax Bits::.). It can: 1) stand for itself, 2) quote the next -character, 3) introduce an operator, or 4) do nothing. - - 1. It stands for itself inside a list (*note List Operators::.) if - the syntax bit `RE_BACKSLASH_ESCAPE_IN_LISTS' is not set. For - example, `[\]' would match `\'. - - 2. It quotes (makes ordinary, if it's special) the next character - when you use it either: - - * outside a list,(1) or - - * inside a list and the syntax bit - `RE_BACKSLASH_ESCAPE_IN_LISTS' is set. - - 3. It introduces an operator when followed by certain ordinary - characters--sometimes only when certain syntax bits are set. See - the cases `RE_BK_PLUS_QM', `RE_NO_BK_BRACES', `RE_NO_BK_VAR', - `RE_NO_BK_PARENS', `RE_NO_BK_REF' in *Note Syntax Bits::. Also: - - * `\b' represents the match-word-boundary operator (*note - Match-word-boundary Operator::.). - - * `\B' represents the match-within-word operator (*note - Match-within-word Operator::.). - - * `\<' represents the match-beginning-of-word operator - (*note Match-beginning-of-word Operator::.). - - * `\>' represents the match-end-of-word operator (*note - Match-end-of-word Operator::.). - - * `\w' represents the match-word-constituent operator (*note - Match-word-constituent Operator::.). - - * `\W' represents the match-non-word-constituent operator - (*note Match-non-word-constituent Operator::.). - - * `\`' represents the match-beginning-of-buffer operator and - `\'' represents the match-end-of-buffer operator (*note - Buffer Operators::.). - - * If Regex was compiled with the C preprocessor symbol `emacs' - defined, then `\sCLASS' represents the match-syntactic-class - operator and `\SCLASS' represents the - match-not-syntactic-class operator (*note Syntactic Class - Operators::.). - - 4. In all other cases, Regex ignores `\'. For example, `\n' matches - `n'. - - - ---------- Footnotes ---------- - - (1) Sometimes you don't have to explicitly quote special characters -to make them ordinary. For instance, most characters lose any special -meaning inside a list (*note List Operators::.). In addition, if the -syntax bits `RE_CONTEXT_INVALID_OPS' and `RE_CONTEXT_INDEP_OPS' aren't -set, then (for historical reasons) the matcher considers special -characters ordinary if they are in contexts where the operations they -represent make no sense; for example, then the match-zero-or-more -operator (represented by `*') matches itself in the regular expression -`*foo' because there is no preceding expression on which it can -operate. It is poor practice, however, to depend on this behavior; if -you want a special character to be ordinary outside a list, it's better -to always quote it, regardless. - - -File: regex.info, Node: Common Operators, Next: GNU Operators, Prev: Regular Expression Syntax, Up: Top - -Common Operators -**************** - - You compose regular expressions from operators. In the following -sections, we describe the regular expression operators specified by -POSIX; GNU also uses these. Most operators have more than one -representation as characters. *Note Regular Expression Syntax::, for -what characters represent what operators under what circumstances. - - For most operators that can be represented in two ways, one -representation is a single character and the other is that character -preceded by `\'. For example, either `(' or `\(' represents the -open-group operator. Which one does depends on the setting of a syntax -bit, in this case `RE_NO_BK_PARENS'. Why is this so? Historical -reasons dictate some of the varying representations, while POSIX -dictates others. - - Finally, almost all characters lose any special meaning inside a list -(*note List Operators::.). - -* Menu: - -* Match-self Operator:: Ordinary characters. -* Match-any-character Operator:: . -* Concatenation Operator:: Juxtaposition. -* Repetition Operators:: * + ? {} -* Alternation Operator:: | -* List Operators:: [...] [^...] -* Grouping Operators:: (...) -* Back-reference Operator:: \digit -* Anchoring Operators:: ^ $ - - -File: regex.info, Node: Match-self Operator, Next: Match-any-character Operator, Up: Common Operators - -The Match-self Operator (ORDINARY CHARACTER) -============================================ - - This operator matches the character itself. All ordinary characters -(*note Regular Expression Syntax::.) represent this operator. For -example, `f' is always an ordinary character, so the regular expression -`f' matches only the string `f'. In particular, it does *not* match -the string `ff'. - - -File: regex.info, Node: Match-any-character Operator, Next: Concatenation Operator, Prev: Match-self Operator, Up: Common Operators - -The Match-any-character Operator (`.') -====================================== - - This operator matches any single printing or nonprinting character -except it won't match a: - -newline - if the syntax bit `RE_DOT_NEWLINE' isn't set. - -null - if the syntax bit `RE_DOT_NOT_NULL' is set. - - The `.' (period) character represents this operator. For example, -`a.b' matches any three-character string beginning with `a' and ending -with `b'. - - -File: regex.info, Node: Concatenation Operator, Next: Repetition Operators, Prev: Match-any-character Operator, Up: Common Operators - -The Concatenation Operator -========================== - - This operator concatenates two regular expressions A and B. No -character represents this operator; you simply put B after A. The -result is a regular expression that will match a string if A matches -its first part and B matches the rest. For example, `xy' (two -match-self operators) matches `xy'. - - -File: regex.info, Node: Repetition Operators, Next: Alternation Operator, Prev: Concatenation Operator, Up: Common Operators - -Repetition Operators -==================== - - Repetition operators repeat the preceding regular expression a -specified number of times. - -* Menu: - -* Match-zero-or-more Operator:: * -* Match-one-or-more Operator:: + -* Match-zero-or-one Operator:: ? -* Interval Operators:: {} - - -File: regex.info, Node: Match-zero-or-more Operator, Next: Match-one-or-more Operator, Up: Repetition Operators - -The Match-zero-or-more Operator (`*') -------------------------------------- - - This operator repeats the smallest possible preceding regular -expression as many times as necessary (including zero) to match the -pattern. `*' represents this operator. For example, `o*' matches any -string made up of zero or more `o's. Since this operator operates on -the smallest preceding regular expression, `fo*' has a repeating `o', -not a repeating `fo'. So, `fo*' matches `f', `fo', `foo', and so on. - - Since the match-zero-or-more operator is a suffix operator, it may be -useless as such when no regular expression precedes it. This is the -case when it: - - * is first in a regular expression, or - - * follows a match-beginning-of-line, open-group, or alternation - operator. - -Three different things can happen in these cases: - - 1. If the syntax bit `RE_CONTEXT_INVALID_OPS' is set, then the - regular expression is invalid. - - 2. If `RE_CONTEXT_INVALID_OPS' isn't set, but `RE_CONTEXT_INDEP_OPS' - is, then `*' represents the match-zero-or-more operator (which - then operates on the empty string). - - 3. Otherwise, `*' is ordinary. - - - The matcher processes a match-zero-or-more operator by first matching -as many repetitions of the smallest preceding regular expression as it -can. Then it continues to match the rest of the pattern. - - If it can't match the rest of the pattern, it backtracks (as many -times as necessary), each time discarding one of the matches until it -can either match the entire pattern or be certain that it cannot get a -match. For example, when matching `ca*ar' against `caaar', the matcher -first matches all three `a's of the string with the `a*' of the regular -expression. However, it cannot then match the final `ar' of the -regular expression against the final `r' of the string. So it -backtracks, discarding the match of the last `a' in the string. It can -then match the remaining `ar'. - - -File: regex.info, Node: Match-one-or-more Operator, Next: Match-zero-or-one Operator, Prev: Match-zero-or-more Operator, Up: Repetition Operators - -The Match-one-or-more Operator (`+' or `\+') --------------------------------------------- - - If the syntax bit `RE_LIMITED_OPS' is set, then Regex doesn't -recognize this operator. Otherwise, if the syntax bit `RE_BK_PLUS_QM' -isn't set, then `+' represents this operator; if it is, then `\+' does. - - This operator is similar to the match-zero-or-more operator except -that it repeats the preceding regular expression at least once; *note -Match-zero-or-more Operator::., for what it operates on, how some -syntax bits affect it, and how Regex backtracks to match it. - - For example, supposing that `+' represents the match-one-or-more -operator; then `ca+r' matches, e.g., `car' and `caaaar', but not `cr'. - - -File: regex.info, Node: Match-zero-or-one Operator, Next: Interval Operators, Prev: Match-one-or-more Operator, Up: Repetition Operators - -The Match-zero-or-one Operator (`?' or `\?') --------------------------------------------- - - If the syntax bit `RE_LIMITED_OPS' is set, then Regex doesn't -recognize this operator. Otherwise, if the syntax bit `RE_BK_PLUS_QM' -isn't set, then `?' represents this operator; if it is, then `\?' does. - - This operator is similar to the match-zero-or-more operator except -that it repeats the preceding regular expression once or not at all; -*note Match-zero-or-more Operator::., to see what it operates on, how -some syntax bits affect it, and how Regex backtracks to match it. - - For example, supposing that `?' represents the match-zero-or-one -operator; then `ca?r' matches both `car' and `cr', but nothing else. - - -File: regex.info, Node: Interval Operators, Prev: Match-zero-or-one Operator, Up: Repetition Operators - -Interval Operators (`{' ... `}' or `\{' ... `\}') -------------------------------------------------- - - If the syntax bit `RE_INTERVALS' is set, then Regex recognizes -"interval expressions". They repeat the smallest possible preceding -regular expression a specified number of times. - - If the syntax bit `RE_NO_BK_BRACES' is set, `{' represents the -"open-interval operator" and `}' represents the "close-interval -operator" ; otherwise, `\{' and `\}' do. - - Specifically, supposing that `{' and `}' represent the open-interval -and close-interval operators; then: - -`{COUNT}' - matches exactly COUNT occurrences of the preceding regular - expression. - -`{MIN,}' - matches MIN or more occurrences of the preceding regular - expression. - -`{MIN, MAX}' - matches at least MIN but no more than MAX occurrences of the - preceding regular expression. - - The interval expression (but not necessarily the regular expression -that contains it) is invalid if: - - * MIN is greater than MAX, or - - * any of COUNT, MIN, or MAX are outside the range zero to - `RE_DUP_MAX' (which symbol `regex.h' defines). - - If the interval expression is invalid and the syntax bit -`RE_NO_BK_BRACES' is set, then Regex considers all the characters in -the would-be interval to be ordinary. If that bit isn't set, then the -regular expression is invalid. - - If the interval expression is valid but there is no preceding regular -expression on which to operate, then if the syntax bit -`RE_CONTEXT_INVALID_OPS' is set, the regular expression is invalid. If -that bit isn't set, then Regex considers all the characters--other than -backslashes, which it ignores--in the would-be interval to be ordinary. - - -File: regex.info, Node: Alternation Operator, Next: List Operators, Prev: Repetition Operators, Up: Common Operators - -The Alternation Operator (`|' or `\|') -====================================== - - If the syntax bit `RE_LIMITED_OPS' is set, then Regex doesn't -recognize this operator. Otherwise, if the syntax bit `RE_NO_BK_VBAR' -is set, then `|' represents this operator; otherwise, `\|' does. - - Alternatives match one of a choice of regular expressions: if you put -the character(s) representing the alternation operator between any two -regular expressions A and B, the result matches the union of the -strings that A and B match. For example, supposing that `|' is the -alternation operator, then `foo|bar|quux' would match any of `foo', -`bar' or `quux'. - - The alternation operator operates on the *largest* possible -surrounding regular expressions. (Put another way, it has the lowest -precedence of any regular expression operator.) Thus, the only way you -can delimit its arguments is to use grouping. For example, if `(' and -`)' are the open and close-group operators, then `fo(o|b)ar' would -match either `fooar' or `fobar'. (`foo|bar' would match `foo' or -`bar'.) - - The matcher usually tries all combinations of alternatives so as to -match the longest possible string. For example, when matching -`(fooq|foo)*(qbarquux|bar)' against `fooqbarquux', it cannot take, say, -the first ("depth-first") combination it could match, since then it -would be content to match just `fooqbar'. - - -File: regex.info, Node: List Operators, Next: Grouping Operators, Prev: Alternation Operator, Up: Common Operators - -List Operators (`[' ... `]' and `[^' ... `]') -============================================= - - "Lists", also called "bracket expressions", are a set of one or more -items. An "item" is a character, a character class expression, or a -range expression. The syntax bits affect which kinds of items you can -put in a list. We explain the last two items in subsections below. -Empty lists are invalid. - - A "matching list" matches a single character represented by one of -the list items. You form a matching list by enclosing one or more items -within an "open-matching-list operator" (represented by `[') and a -"close-list operator" (represented by `]'). - - For example, `[ab]' matches either `a' or `b'. `[ad]*' matches the -empty string and any string composed of just `a's and `d's in any -order. Regex considers invalid a regular expression with a `[' but no -matching `]'. - - "Nonmatching lists" are similar to matching lists except that they -match a single character *not* represented by one of the list items. -You use an "open-nonmatching-list operator" (represented by `[^'(1)) -instead of an open-matching-list operator to start a nonmatching list. - - For example, `[^ab]' matches any character except `a' or `b'. - - If the `posix_newline' field in the pattern buffer (*note GNU Pattern -Buffers::. is set, then nonmatching lists do not match a newline. - - Most characters lose any special meaning inside a list. The special -characters inside a list follow. - -`]' - ends the list if it's not the first list item. So, if you want to - make the `]' character a list item, you must put it first. - -`\' - quotes the next character if the syntax bit - `RE_BACKSLASH_ESCAPE_IN_LISTS' is set. - -`[:' - represents the open-character-class operator (*note Character - Class Operators::.) if the syntax bit `RE_CHAR_CLASSES' is set and - what follows is a valid character class expression. - -`:]' - represents the close-character-class operator if the syntax bit - `RE_CHAR_CLASSES' is set and what precedes it is an - open-character-class operator followed by a valid character class - name. - -`-' - represents the range operator (*note Range Operator::.) if it's - not first or last in a list or the ending point of a range. - -All other characters are ordinary. For example, `[.*]' matches `.' and -`*'. - -* Menu: - -* Character Class Operators:: [:class:] -* Range Operator:: start-end - - ---------- Footnotes ---------- - - (1) Regex therefore doesn't consider the `^' to be the first -character in the list. If you put a `^' character first in (what you -think is) a matching list, you'll turn it into a nonmatching list. - - -File: regex.info, Node: Character Class Operators, Next: Range Operator, Up: List Operators - -Character Class Operators (`[:' ... `:]') ------------------------------------------ - - If the syntax bit `RE_CHARACTER_CLASSES' is set, then Regex -recognizes character class expressions inside lists. A "character -class expression" matches one character from a given class. You form a -character class expression by putting a character class name between an -"open-character-class operator" (represented by `[:') and a -"close-character-class operator" (represented by `:]'). The character -class names and their meanings are: - -`alnum' - letters and digits - -`alpha' - letters - -`blank' - system-dependent; for GNU, a space or tab - -`cntrl' - control characters (in the ASCII encoding, code 0177 and codes - less than 040) - -`digit' - digits - -`graph' - same as `print' except omits space - -`lower' - lowercase letters - -`print' - printable characters (in the ASCII encoding, space tilde--codes - 040 through 0176) - -`punct' - neither control nor alphanumeric characters - -`space' - space, carriage return, newline, vertical tab, and form feed - -`upper' - uppercase letters - -`xdigit' - hexadecimal digits: `0'-`9', `a'-`f', `A'-`F' - -These correspond to the definitions in the C library's `<ctype.h>' -facility. For example, `[:alpha:]' corresponds to the standard -facility `isalpha'. Regex recognizes character class expressions only -inside of lists; so `[[:alpha:]]' matches any letter, but `[:alpha:]' -outside of a bracket expression and not followed by a repetition -operator matches just itself. - - -File: regex.info, Node: Range Operator, Prev: Character Class Operators, Up: List Operators - -The Range Operator (`-') ------------------------- - - Regex recognizes "range expressions" inside a list. They represent -those characters that fall between two elements in the current -collating sequence. You form a range expression by putting a "range -operator" between two characters.(1) `-' represents the range operator. -For example, `a-f' within a list represents all the characters from `a' -through `f' inclusively. - - If the syntax bit `RE_NO_EMPTY_RANGES' is set, then if the range's -ending point collates less than its starting point, the range (and the -regular expression containing it) is invalid. For example, the regular -expression `[z-a]' would be invalid. If this bit isn't set, then Regex -considers such a range to be empty. - - Since `-' represents the range operator, if you want to make a `-' -character itself a list item, you must do one of the following: - - * Put the `-' either first or last in the list. - - * Include a range whose starting point collates strictly lower than - `-' and whose ending point collates equal or higher. Unless a - range is the first item in a list, a `-' can't be its starting - point, but *can* be its ending point. That is because Regex - considers `-' to be the range operator unless it is preceded by - another `-'. For example, in the ASCII encoding, `)', `*', `+', - `,', `-', `.', and `/' are contiguous characters in the collating - sequence. You might think that `[)-+--/]' has two ranges: `)-+' - and `--/'. Rather, it has the ranges `)-+' and `+--', plus the - character `/', so it matches, e.g., `,', not `.'. - - * Put a range whose starting point is `-' first in the list. - - For example, `[-a-z]' matches a lowercase letter or a hyphen (in -English, in ASCII). - - ---------- Footnotes ---------- - - (1) You can't use a character class for the starting or ending point -of a range, since a character class is not a single character. - - -File: regex.info, Node: Grouping Operators, Next: Back-reference Operator, Prev: List Operators, Up: Common Operators - -Grouping Operators (`(' ... `)' or `\(' ... `\)') -================================================= - - A "group", also known as a "subexpression", consists of an -"open-group operator", any number of other operators, and a -"close-group operator". Regex treats this sequence as a unit, just as -mathematics and programming languages treat a parenthesized expression -as a unit. - - Therefore, using "groups", you can: - - * delimit the argument(s) to an alternation operator (*note - Alternation Operator::.) or a repetition operator (*note - Repetition Operators::.). - - * keep track of the indices of the substring that matched a given - group. *Note Using Registers::, for a precise explanation. This - lets you: - - * use the back-reference operator (*note Back-reference - Operator::.). - - * use registers (*note Using Registers::.). - - If the syntax bit `RE_NO_BK_PARENS' is set, then `(' represents the -open-group operator and `)' represents the close-group operator; -otherwise, `\(' and `\)' do. - - If the syntax bit `RE_UNMATCHED_RIGHT_PAREN_ORD' is set and a -close-group operator has no matching open-group operator, then Regex -considers it to match `)'. - - -File: regex.info, Node: Back-reference Operator, Next: Anchoring Operators, Prev: Grouping Operators, Up: Common Operators - -The Back-reference Operator ("\"DIGIT) -====================================== - - If the syntax bit `RE_NO_BK_REF' isn't set, then Regex recognizes -back references. A back reference matches a specified preceding group. -The back reference operator is represented by `\DIGIT' anywhere after -the end of a regular expression's DIGIT-th group (*note Grouping -Operators::.). - - DIGIT must be between `1' and `9'. The matcher assigns numbers 1 -through 9 to the first nine groups it encounters. By using one of `\1' -through `\9' after the corresponding group's close-group operator, you -can match a substring identical to the one that the group does. - - Back references match according to the following (in all examples -below, `(' represents the open-group, `)' the close-group, `{' the -open-interval and `}' the close-interval operator): - - * If the group matches a substring, the back reference matches an - identical substring. For example, `(a)\1' matches `aa' and - `(bana)na\1bo\1' matches `bananabanabobana'. Likewise, `(.*)\1' - matches any (newline-free if the syntax bit `RE_DOT_NEWLINE' isn't - set) string that is composed of two identical halves; the `(.*)' - matches the first half and the `\1' matches the second half. - - * If the group matches more than once (as it might if followed by, - e.g., a repetition operator), then the back reference matches the - substring the group *last* matched. For example, `((a*)b)*\1\2' - matches `aabababa'; first group 1 (the outer one) matches `aab' - and group 2 (the inner one) matches `aa'. Then group 1 matches - `ab' and group 2 matches `a'. So, `\1' matches `ab' and `\2' - matches `a'. - - * If the group doesn't participate in a match, i.e., it is part of an - alternative not taken or a repetition operator allows zero - repetitions of it, then the back reference makes the whole match - fail. For example, `(one()|two())-and-(three\2|four\3)' matches - `one-and-three' and `two-and-four', but not `one-and-four' or - `two-and-three'. For example, if the pattern matches `one-and-', - then its group 2 matches the empty string and its group 3 doesn't - participate in the match. So, if it then matches `four', then - when it tries to back reference group 3--which it will attempt to - do because `\3' follows the `four'--the match will fail because - group 3 didn't participate in the match. - - You can use a back reference as an argument to a repetition operator. -For example, `(a(b))\2*' matches `a' followed by two or more `b's. -Similarly, `(a(b))\2{3}' matches `abbbb'. - - If there is no preceding DIGIT-th subexpression, the regular -expression is invalid. - - -File: regex.info, Node: Anchoring Operators, Prev: Back-reference Operator, Up: Common Operators - -Anchoring Operators -=================== - - These operators can constrain a pattern to match only at the -beginning or end of the entire string or at the beginning or end of a -line. - -* Menu: - -* Match-beginning-of-line Operator:: ^ -* Match-end-of-line Operator:: $ - - -File: regex.info, Node: Match-beginning-of-line Operator, Next: Match-end-of-line Operator, Up: Anchoring Operators - -The Match-beginning-of-line Operator (`^') ------------------------------------------- - - This operator can match the empty string either at the beginning of -the string or after a newline character. Thus, it is said to "anchor" -the pattern to the beginning of a line. - - In the cases following, `^' represents this operator. (Otherwise, -`^' is ordinary.) - - * It (the `^') is first in the pattern, as in `^foo'. - - * The syntax bit `RE_CONTEXT_INDEP_ANCHORS' is set, and it is outside - a bracket expression. - - * It follows an open-group or alternation operator, as in `a\(^b\)' - and `a\|^b'. *Note Grouping Operators::, and *Note Alternation - Operator::. - - These rules imply that some valid patterns containing `^' cannot be -matched; for example, `foo^bar' if `RE_CONTEXT_INDEP_ANCHORS' is set. - - If the `not_bol' field is set in the pattern buffer (*note GNU -Pattern Buffers::.), then `^' fails to match at the beginning of the -string. *Note POSIX Matching::, for when you might find this useful. - - If the `newline_anchor' field is set in the pattern buffer, then `^' -fails to match after a newline. This is useful when you do not regard -the string to be matched as broken into lines. - - -File: regex.info, Node: Match-end-of-line Operator, Prev: Match-beginning-of-line Operator, Up: Anchoring Operators - -The Match-end-of-line Operator (`$') ------------------------------------- - - This operator can match the empty string either at the end of the -string or before a newline character in the string. Thus, it is said -to "anchor" the pattern to the end of a line. - - It is always represented by `$'. For example, `foo$' usually -matches, e.g., `foo' and, e.g., the first three characters of -`foo\nbar'. - - Its interaction with the syntax bits and pattern buffer fields is -exactly the dual of `^''s; see the previous section. (That is, -"beginning" becomes "end", "next" becomes "previous", and "after" -becomes "before".) - - -File: regex.info, Node: GNU Operators, Next: GNU Emacs Operators, Prev: Common Operators, Up: Top - -GNU Operators -************* - - Following are operators that GNU defines (and POSIX doesn't). - -* Menu: - -* Word Operators:: -* Buffer Operators:: - - -File: regex.info, Node: Word Operators, Next: Buffer Operators, Up: GNU Operators - -Word Operators -============== - - The operators in this section require Regex to recognize parts of -words. Regex uses a syntax table to determine whether or not a -character is part of a word, i.e., whether or not it is -"word-constituent". - -* Menu: - -* Non-Emacs Syntax Tables:: -* Match-word-boundary Operator:: \b -* Match-within-word Operator:: \B -* Match-beginning-of-word Operator:: \< -* Match-end-of-word Operator:: \> -* Match-word-constituent Operator:: \w -* Match-non-word-constituent Operator:: \W - - -File: regex.info, Node: Non-Emacs Syntax Tables, Next: Match-word-boundary Operator, Up: Word Operators - -Non-Emacs Syntax Tables ------------------------ - - A "syntax table" is an array indexed by the characters in your -character set. In the ASCII encoding, therefore, a syntax table has -256 elements. Regex always uses a `char *' variable `re_syntax_table' -as its syntax table. In some cases, it initializes this variable and -in others it expects you to initialize it. - - * If Regex is compiled with the preprocessor symbols `emacs' and - `SYNTAX_TABLE' both undefined, then Regex allocates - `re_syntax_table' and initializes an element I either to `Sword' - (which it defines) if I is a letter, number, or `_', or to zero if - it's not. - - * If Regex is compiled with `emacs' undefined but `SYNTAX_TABLE' - defined, then Regex expects you to define a `char *' variable - `re_syntax_table' to be a valid syntax table. - - * *Note Emacs Syntax Tables::, for what happens when Regex is - compiled with the preprocessor symbol `emacs' defined. - - -File: regex.info, Node: Match-word-boundary Operator, Next: Match-within-word Operator, Prev: Non-Emacs Syntax Tables, Up: Word Operators - -The Match-word-boundary Operator (`\b') ---------------------------------------- - - This operator (represented by `\b') matches the empty string at -either the beginning or the end of a word. For example, `\brat\b' -matches the separate word `rat'. - - -File: regex.info, Node: Match-within-word Operator, Next: Match-beginning-of-word Operator, Prev: Match-word-boundary Operator, Up: Word Operators - -The Match-within-word Operator (`\B') -------------------------------------- - - This operator (represented by `\B') matches the empty string within a -word. For example, `c\Brat\Be' matches `crate', but `dirty \Brat' -doesn't match `dirty rat'. - - -File: regex.info, Node: Match-beginning-of-word Operator, Next: Match-end-of-word Operator, Prev: Match-within-word Operator, Up: Word Operators - -The Match-beginning-of-word Operator (`\<') -------------------------------------------- - - This operator (represented by `\<') matches the empty string at the -beginning of a word. - - -File: regex.info, Node: Match-end-of-word Operator, Next: Match-word-constituent Operator, Prev: Match-beginning-of-word Operator, Up: Word Operators - -The Match-end-of-word Operator (`\>') -------------------------------------- - - This operator (represented by `\>') matches the empty string at the -end of a word. - - -File: regex.info, Node: Match-word-constituent Operator, Next: Match-non-word-constituent Operator, Prev: Match-end-of-word Operator, Up: Word Operators - -The Match-word-constituent Operator (`\w') ------------------------------------------- - - This operator (represented by `\w') matches any word-constituent -character. - - -File: regex.info, Node: Match-non-word-constituent Operator, Prev: Match-word-constituent Operator, Up: Word Operators - -The Match-non-word-constituent Operator (`\W') ----------------------------------------------- - - This operator (represented by `\W') matches any character that is not -word-constituent. - - -File: regex.info, Node: Buffer Operators, Prev: Word Operators, Up: GNU Operators - -Buffer Operators -================ - - Following are operators which work on buffers. In Emacs, a "buffer" -is, naturally, an Emacs buffer. For other programs, Regex considers the -entire string to be matched as the buffer. - -* Menu: - -* Match-beginning-of-buffer Operator:: \` -* Match-end-of-buffer Operator:: \' - - -File: regex.info, Node: Match-beginning-of-buffer Operator, Next: Match-end-of-buffer Operator, Up: Buffer Operators - -The Match-beginning-of-buffer Operator (`\`') ---------------------------------------------- - - This operator (represented by `\`') matches the empty string at the -beginning of the buffer. - - -File: regex.info, Node: Match-end-of-buffer Operator, Prev: Match-beginning-of-buffer Operator, Up: Buffer Operators - -The Match-end-of-buffer Operator (`\'') ---------------------------------------- - - This operator (represented by `\'') matches the empty string at the -end of the buffer. - - -File: regex.info, Node: GNU Emacs Operators, Next: What Gets Matched?, Prev: GNU Operators, Up: Top - -GNU Emacs Operators -******************* - - Following are operators that GNU defines (and POSIX doesn't) that you -can use only when Regex is compiled with the preprocessor symbol -`emacs' defined. - -* Menu: - -* Syntactic Class Operators:: - - -File: regex.info, Node: Syntactic Class Operators, Up: GNU Emacs Operators - -Syntactic Class Operators -========================= - - The operators in this section require Regex to recognize the syntactic -classes of characters. Regex uses a syntax table to determine this. - -* Menu: - -* Emacs Syntax Tables:: -* Match-syntactic-class Operator:: \sCLASS -* Match-not-syntactic-class Operator:: \SCLASS - - -File: regex.info, Node: Emacs Syntax Tables, Next: Match-syntactic-class Operator, Up: Syntactic Class Operators - -Emacs Syntax Tables -------------------- - - A "syntax table" is an array indexed by the characters in your -character set. In the ASCII encoding, therefore, a syntax table has -256 elements. - - If Regex is compiled with the preprocessor symbol `emacs' defined, -then Regex expects you to define and initialize the variable -`re_syntax_table' to be an Emacs syntax table. Emacs' syntax tables -are more complicated than Regex's own (*note Non-Emacs Syntax -Tables::.). *Note Syntax: (emacs)Syntax, for a description of Emacs' -syntax tables. - - -File: regex.info, Node: Match-syntactic-class Operator, Next: Match-not-syntactic-class Operator, Prev: Emacs Syntax Tables, Up: Syntactic Class Operators - -The Match-syntactic-class Operator (`\s'CLASS) ----------------------------------------------- - - This operator matches any character whose syntactic class is -represented by a specified character. `\sCLASS' represents this -operator where CLASS is the character representing the syntactic class -you want. For example, `w' represents the syntactic class of -word-constituent characters, so `\sw' matches any word-constituent -character. - - -File: regex.info, Node: Match-not-syntactic-class Operator, Prev: Match-syntactic-class Operator, Up: Syntactic Class Operators - -The Match-not-syntactic-class Operator (`\S'CLASS) --------------------------------------------------- - - This operator is similar to the match-syntactic-class operator except -that it matches any character whose syntactic class is *not* -represented by the specified character. `\SCLASS' represents this -operator. For example, `w' represents the syntactic class of -word-constituent characters, so `\Sw' matches any character that is not -word-constituent. - - -File: regex.info, Node: What Gets Matched?, Next: Programming with Regex, Prev: GNU Emacs Operators, Up: Top - -What Gets Matched? -****************** - - Regex usually matches strings according to the "leftmost longest" -rule; that is, it chooses the longest of the leftmost matches. This -does not mean that for a regular expression containing subexpressions -that it simply chooses the longest match for each subexpression, left to -right; the overall match must also be the longest possible one. - - For example, `(ac*)(c*d[ac]*)\1' matches `acdacaaa', not `acdac', as -it would if it were to choose the longest match for the first -subexpression. - - -File: regex.info, Node: Programming with Regex, Next: Copying, Prev: What Gets Matched?, Up: Top - -Programming with Regex -********************** - - Here we describe how you use the Regex data structures and functions -in C programs. Regex has three interfaces: one designed for GNU, one -compatible with POSIX and one compatible with Berkeley UNIX. - -* Menu: - -* GNU Regex Functions:: -* POSIX Regex Functions:: -* BSD Regex Functions:: - - -File: regex.info, Node: GNU Regex Functions, Next: POSIX Regex Functions, Up: Programming with Regex - -GNU Regex Functions -=================== - - If you're writing code that doesn't need to be compatible with either -POSIX or Berkeley UNIX, you can use these functions. They provide more -options than the other interfaces. - -* Menu: - -* GNU Pattern Buffers:: The re_pattern_buffer type. -* GNU Regular Expression Compiling:: re_compile_pattern () -* GNU Matching:: re_match () -* GNU Searching:: re_search () -* Matching/Searching with Split Data:: re_match_2 (), re_search_2 () -* Searching with Fastmaps:: re_compile_fastmap () -* GNU Translate Tables:: The `translate' field. -* Using Registers:: The re_registers type and related fns. -* Freeing GNU Pattern Buffers:: regfree () - - -File: regex.info, Node: GNU Pattern Buffers, Next: GNU Regular Expression Compiling, Up: GNU Regex Functions - -GNU Pattern Buffers -------------------- - - To compile, match, or search for a given regular expression, you must -supply a pattern buffer. A "pattern buffer" holds one compiled regular -expression.(1) - - You can have several different pattern buffers simultaneously, each -holding a compiled pattern for a different regular expression. - - `regex.h' defines the pattern buffer `struct' as follows: - - /* Space that holds the compiled pattern. It is declared as - `unsigned char *' because its elements are - sometimes used as array indexes. */ - unsigned char *buffer; - - /* Number of bytes to which `buffer' points. */ - unsigned long allocated; - - /* Number of bytes actually used in `buffer'. */ - unsigned long used; - - /* Syntax setting with which the pattern was compiled. */ - reg_syntax_t syntax; - - /* Pointer to a fastmap, if any, otherwise zero. re_search uses - the fastmap, if there is one, to skip over impossible - starting points for matches. */ - char *fastmap; - - /* Either a translate table to apply to all characters before - comparing them, or zero for no translation. The translation - is applied to a pattern when it is compiled and to a string - when it is matched. */ - char *translate; - - /* Number of subexpressions found by the compiler. */ - size_t re_nsub; - - /* Zero if this pattern cannot match the empty string, one else. - Well, in truth it's used only in `re_search_2', to see - whether or not we should use the fastmap, so we don't set - this absolutely perfectly; see `re_compile_fastmap' (the - `duplicate' case). */ - unsigned can_be_null : 1; - - /* If REGS_UNALLOCATED, allocate space in the `regs' structure - for `max (RE_NREGS, re_nsub + 1)' groups. - If REGS_REALLOCATE, reallocate space if necessary. - If REGS_FIXED, use what's there. */ - #define REGS_UNALLOCATED 0 - #define REGS_REALLOCATE 1 - #define REGS_FIXED 2 - unsigned regs_allocated : 2; - - /* Set to zero when `regex_compile' compiles a pattern; set to one - by `re_compile_fastmap' if it updates the fastmap. */ - unsigned fastmap_accurate : 1; - - /* If set, `re_match_2' does not return information about - subexpressions. */ - unsigned no_sub : 1; - - /* If set, a beginning-of-line anchor doesn't match at the - beginning of the string. */ - unsigned not_bol : 1; - - /* Similarly for an end-of-line anchor. */ - unsigned not_eol : 1; - - /* If true, an anchor at a newline matches. */ - unsigned newline_anchor : 1; - - ---------- Footnotes ---------- - - (1) Regular expressions are also referred to as "patterns," hence -the name "pattern buffer." - - -File: regex.info, Node: GNU Regular Expression Compiling, Next: GNU Matching, Prev: GNU Pattern Buffers, Up: GNU Regex Functions - -GNU Regular Expression Compiling --------------------------------- - - In GNU, you can both match and search for a given regular expression. -To do either, you must first compile it in a pattern buffer (*note GNU -Pattern Buffers::.). - - Regular expressions match according to the syntax with which they were -compiled; with GNU, you indicate what syntax you want by setting the -variable `re_syntax_options' (declared in `regex.h' and defined in -`regex.c') before calling the compiling function, `re_compile_pattern' -(see below). *Note Syntax Bits::, and *Note Predefined Syntaxes::. - - You can change the value of `re_syntax_options' at any time. -Usually, however, you set its value once and then never change it. - - `re_compile_pattern' takes a pattern buffer as an argument. You must -initialize the following fields: - -`translate initialization' -`translate' - Initialize this to point to a translate table if you want one, or - to zero if you don't. We explain translate tables in *Note GNU - Translate Tables::. - -`fastmap' - Initialize this to nonzero if you want a fastmap, or to zero if you - don't. - -`buffer' -`allocated' - If you want `re_compile_pattern' to allocate memory for the - compiled pattern, set both of these to zero. If you have an - existing block of memory (allocated with `malloc') you want Regex - to use, set `buffer' to its address and `allocated' to its size (in - bytes). - - `re_compile_pattern' uses `realloc' to extend the space for the - compiled pattern as necessary. - - To compile a pattern buffer, use: - - char * - re_compile_pattern (const char *REGEX, const int REGEX_SIZE, - struct re_pattern_buffer *PATTERN_BUFFER) - -REGEX is the regular expression's address, REGEX_SIZE is its length, -and PATTERN_BUFFER is the pattern buffer's address. - - If `re_compile_pattern' successfully compiles the regular expression, -it returns zero and sets `*PATTERN_BUFFER' to the compiled pattern. It -sets the pattern buffer's fields as follows: - -`buffer' - to the compiled pattern. - -`used' - to the number of bytes the compiled pattern in `buffer' occupies. - -`syntax' - to the current value of `re_syntax_options'. - -`re_nsub' - to the number of subexpressions in REGEX. - -`fastmap_accurate' - to zero on the theory that the pattern you're compiling is - different than the one previously compiled into `buffer'; in that - case (since you can't make a fastmap without a compiled pattern), - `fastmap' would either contain an incompatible fastmap, or nothing - at all. - - If `re_compile_pattern' can't compile REGEX, it returns an error -string corresponding to one of the errors listed in *Note POSIX Regular -Expression Compiling::. - - -File: regex.info, Node: GNU Matching, Next: GNU Searching, Prev: GNU Regular Expression Compiling, Up: GNU Regex Functions - -GNU Matching ------------- - - Matching the GNU way means trying to match as much of a string as -possible starting at a position within it you specify. Once you've -compiled a pattern into a pattern buffer (*note GNU Regular Expression -Compiling::.), you can ask the matcher to match that pattern against a -string using: - - int - re_match (struct re_pattern_buffer *PATTERN_BUFFER, - const char *STRING, const int SIZE, - const int START, struct re_registers *REGS) - -PATTERN_BUFFER is the address of a pattern buffer containing a compiled -pattern. STRING is the string you want to match; it can contain -newline and null characters. SIZE is the length of that string. START -is the string index at which you want to begin matching; the first -character of STRING is at index zero. *Note Using Registers::, for a -explanation of REGS; you can safely pass zero. - - `re_match' matches the regular expression in PATTERN_BUFFER against -the string STRING according to the syntax in PATTERN_BUFFERS's `syntax' -field. (*Note GNU Regular Expression Compiling::, for how to set it.) -The function returns -1 if the compiled pattern does not match any part -of STRING and -2 if an internal error happens; otherwise, it returns -how many (possibly zero) characters of STRING the pattern matched. - - An example: suppose PATTERN_BUFFER points to a pattern buffer -containing the compiled pattern for `a*', and STRING points to `aaaaab' -(whereupon SIZE should be 6). Then if START is 2, `re_match' returns 3, -i.e., `a*' would have matched the last three `a's in STRING. If START -is 0, `re_match' returns 5, i.e., `a*' would have matched all the `a's -in STRING. If START is either 5 or 6, it returns zero. - - If START is not between zero and SIZE, then `re_match' returns -1. - - -File: regex.info, Node: GNU Searching, Next: Matching/Searching with Split Data, Prev: GNU Matching, Up: GNU Regex Functions - -GNU Searching -------------- - - "Searching" means trying to match starting at successive positions -within a string. The function `re_search' does this. - - Before calling `re_search', you must compile your regular expression. -*Note GNU Regular Expression Compiling::. - - Here is the function declaration: - - int - re_search (struct re_pattern_buffer *PATTERN_BUFFER, - const char *STRING, const int SIZE, - const int START, const int RANGE, - struct re_registers *REGS) - -whose arguments are the same as those to `re_match' (*note GNU -Matching::.) except that the two arguments START and RANGE replace -`re_match''s argument START. - - If RANGE is positive, then `re_search' attempts a match starting -first at index START, then at START + 1 if that fails, and so on, up to -START + RANGE; if RANGE is negative, then it attempts a match starting -first at index START, then at START -1 if that fails, and so on. - - If START is not between zero and SIZE, then `re_search' returns -1. -When RANGE is positive, `re_search' adjusts RANGE so that START + RANGE -- 1 is between zero and SIZE, if necessary; that way it won't search -outside of STRING. Similarly, when RANGE is negative, `re_search' -adjusts RANGE so that START + RANGE + 1 is between zero and SIZE, if -necessary. - - If the `fastmap' field of PATTERN_BUFFER is zero, `re_search' matches -starting at consecutive positions; otherwise, it uses `fastmap' to make -the search more efficient. *Note Searching with Fastmaps::. - - If no match is found, `re_search' returns -1. If a match is found, -it returns the index where the match began. If an internal error -happens, it returns -2. - - -File: regex.info, Node: Matching/Searching with Split Data, Next: Searching with Fastmaps, Prev: GNU Searching, Up: GNU Regex Functions - -Matching and Searching with Split Data --------------------------------------- - - Using the functions `re_match_2' and `re_search_2', you can match or -search in data that is divided into two strings. - - The function: - - int - re_match_2 (struct re_pattern_buffer *BUFFER, - const char *STRING1, const int SIZE1, - const char *STRING2, const int SIZE2, - const int START, - struct re_registers *REGS, - const int STOP) - -is similar to `re_match' (*note GNU Matching::.) except that you pass -*two* data strings and sizes, and an index STOP beyond which you don't -want the matcher to try matching. As with `re_match', if it succeeds, -`re_match_2' returns how many characters of STRING it matched. Regard -STRING1 and STRING2 as concatenated when you set the arguments START and -STOP and use the contents of REGS; `re_match_2' never returns a value -larger than SIZE1 + SIZE2. - - The function: - - int - re_search_2 (struct re_pattern_buffer *BUFFER, - const char *STRING1, const int SIZE1, - const char *STRING2, const int SIZE2, - const int START, const int RANGE, - struct re_registers *REGS, - const int STOP) - -is similarly related to `re_search'. - - -File: regex.info, Node: Searching with Fastmaps, Next: GNU Translate Tables, Prev: Matching/Searching with Split Data, Up: GNU Regex Functions - -Searching with Fastmaps ------------------------ - - If you're searching through a long string, you should use a fastmap. -Without one, the searcher tries to match at consecutive positions in the -string. Generally, most of the characters in the string could not start -a match. It takes much longer to try matching at a given position in -the string than it does to check in a table whether or not the -character at that position could start a match. A "fastmap" is such a -table. - - More specifically, a fastmap is an array indexed by the characters in -your character set. Under the ASCII encoding, therefore, a fastmap has -256 elements. If you want the searcher to use a fastmap with a given -pattern buffer, you must allocate the array and assign the array's -address to the pattern buffer's `fastmap' field. You either can -compile the fastmap yourself or have `re_search' do it for you; when -`fastmap' is nonzero, it automatically compiles a fastmap the first -time you search using a particular compiled pattern. - - To compile a fastmap yourself, use: - - int - re_compile_fastmap (struct re_pattern_buffer *PATTERN_BUFFER) - -PATTERN_BUFFER is the address of a pattern buffer. If the character C -could start a match for the pattern, `re_compile_fastmap' makes -`PATTERN_BUFFER->fastmap[C]' nonzero. It returns 0 if it can compile a -fastmap and -2 if there is an internal error. For example, if `|' is -the alternation operator and PATTERN_BUFFER holds the compiled pattern -for `a|b', then `re_compile_fastmap' sets `fastmap['a']' and -`fastmap['b']' (and no others). - - `re_search' uses a fastmap as it moves along in the string: it checks -the string's characters until it finds one that's in the fastmap. Then -it tries matching at that character. If the match fails, it repeats -the process. So, by using a fastmap, `re_search' doesn't waste time -trying to match at positions in the string that couldn't start a match. - - If you don't want `re_search' to use a fastmap, store zero in the -`fastmap' field of the pattern buffer before calling `re_search'. - - Once you've initialized a pattern buffer's `fastmap' field, you need -never do so again--even if you compile a new pattern in it--provided -the way the field is set still reflects whether or not you want a -fastmap. `re_search' will still either do nothing if `fastmap' is null -or, if it isn't, compile a new fastmap for the new pattern. - - -File: regex.info, Node: GNU Translate Tables, Next: Using Registers, Prev: Searching with Fastmaps, Up: GNU Regex Functions - -GNU Translate Tables --------------------- - - If you set the `translate' field of a pattern buffer to a translate -table, then the GNU Regex functions to which you've passed that pattern -buffer use it to apply a simple transformation to all the regular -expression and string characters at which they look. - - A "translate table" is an array indexed by the characters in your -character set. Under the ASCII encoding, therefore, a translate table -has 256 elements. The array's elements are also characters in your -character set. When the Regex functions see a character C, they use -`translate[C]' in its place, with one exception: the character after a -`\' is not translated. (This ensures that, the operators, e.g., `\B' -and `\b', are always distinguishable.) - - For example, a table that maps all lowercase letters to the -corresponding uppercase ones would cause the matcher to ignore -differences in case.(1) Such a table would map all characters except -lowercase letters to themselves, and lowercase letters to the -corresponding uppercase ones. Under the ASCII encoding, here's how you -could initialize such a table (we'll call it `case_fold'): - - for (i = 0; i < 256; i++) - case_fold[i] = i; - for (i = 'a'; i <= 'z'; i++) - case_fold[i] = i - ('a' - 'A'); - - You tell Regex to use a translate table on a given pattern buffer by -assigning that table's address to the `translate' field of that buffer. -If you don't want Regex to do any translation, put zero into this -field. You'll get weird results if you change the table's contents -anytime between compiling the pattern buffer, compiling its fastmap, and -matching or searching with the pattern buffer. - - ---------- Footnotes ---------- - - (1) A table that maps all uppercase letters to the corresponding -lowercase ones would work just as well for this purpose. - - -File: regex.info, Node: Using Registers, Next: Freeing GNU Pattern Buffers, Prev: GNU Translate Tables, Up: GNU Regex Functions - -Using Registers ---------------- - - A group in a regular expression can match a (posssibly empty) -substring of the string that regular expression as a whole matched. -The matcher remembers the beginning and end of the substring matched by -each group. - - To find out what they matched, pass a nonzero REGS argument to a GNU -matching or searching function (*note GNU Matching::. and *Note GNU -Searching::), i.e., the address of a structure of this type, as defined -in `regex.h': - - struct re_registers - { - unsigned num_regs; - regoff_t *start; - regoff_t *end; - }; - - Except for (possibly) the NUM_REGS'th element (see below), the Ith -element of the `start' and `end' arrays records information about the -Ith group in the pattern. (They're declared as C pointers, but this is -only because not all C compilers accept zero-length arrays; -conceptually, it is simplest to think of them as arrays.) - - The `start' and `end' arrays are allocated in various ways, depending -on the value of the `regs_allocated' field in the pattern buffer passed -to the matcher. - - The simplest and perhaps most useful is to let the matcher -(re)allocate enough space to record information for all the groups in -the regular expression. If `regs_allocated' is `REGS_UNALLOCATED', the -matcher allocates 1 + RE_NSUB (another field in the pattern buffer; -*note GNU Pattern Buffers::.). The extra element is set to -1, and -sets `regs_allocated' to `REGS_REALLOCATE'. Then on subsequent calls -with the same pattern buffer and REGS arguments, the matcher -reallocates more space if necessary. - - It would perhaps be more logical to make the `regs_allocated' field -part of the `re_registers' structure, instead of part of the pattern -buffer. But in that case the caller would be forced to initialize the -structure before passing it. Much existing code doesn't do this -initialization, and it's arguably better to avoid it anyway. - - `re_compile_pattern' sets `regs_allocated' to `REGS_UNALLOCATED', so -if you use the GNU regular expression functions, you get this behavior -by default. - - xx document re_set_registers - - POSIX, on the other hand, requires a different interface: the caller -is supposed to pass in a fixed-length array which the matcher fills. -Therefore, if `regs_allocated' is `REGS_FIXED' the matcher simply fills -that array. - - The following examples illustrate the information recorded in the -`re_registers' structure. (In all of them, `(' represents the -open-group and `)' the close-group operator. The first character in -the string STRING is at index 0.) - - * If the regular expression has an I-th group not contained within - another group that matches a substring of STRING, then the - function sets `REGS->start[I]' to the index in STRING where the - substring matched by the I-th group begins, and `REGS->end[I]' to - the index just beyond that substring's end. The function sets - `REGS->start[0]' and `REGS->end[0]' to analogous information about - the entire pattern. - - For example, when you match `((a)(b))' against `ab', you get: - - * 0 in `REGS->start[0]' and 2 in `REGS->end[0]' - - * 0 in `REGS->start[1]' and 2 in `REGS->end[1]' - - * 0 in `REGS->start[2]' and 1 in `REGS->end[2]' - - * 1 in `REGS->start[3]' and 2 in `REGS->end[3]' - - * If a group matches more than once (as it might if followed by, - e.g., a repetition operator), then the function reports the - information about what the group *last* matched. - - For example, when you match the pattern `(a)*' against the string - `aa', you get: - - * 0 in `REGS->start[0]' and 2 in `REGS->end[0]' - - * 1 in `REGS->start[1]' and 2 in `REGS->end[1]' - - * If the I-th group does not participate in a successful match, - e.g., it is an alternative not taken or a repetition operator - allows zero repetitions of it, then the function sets - `REGS->start[I]' and `REGS->end[I]' to -1. - - For example, when you match the pattern `(a)*b' against the string - `b', you get: - - * 0 in `REGS->start[0]' and 1 in `REGS->end[0]' - - * -1 in `REGS->start[1]' and -1 in `REGS->end[1]' - - * If the I-th group matches a zero-length string, then the function - sets `REGS->start[I]' and `REGS->end[I]' to the index just beyond - that zero-length string. - - For example, when you match the pattern `(a*)b' against the string - `b', you get: - - * 0 in `REGS->start[0]' and 1 in `REGS->end[0]' - - * 0 in `REGS->start[1]' and 0 in `REGS->end[1]' - - * If an I-th group contains a J-th group in turn not contained - within any other group within group I and the function reports a - match of the I-th group, then it records in `REGS->start[J]' and - `REGS->end[J]' the last match (if it matched) of the J-th group. - - For example, when you match the pattern `((a*)b)*' against the - string `abb', group 2 last matches the empty string, so you get - what it previously matched: - - * 0 in `REGS->start[0]' and 3 in `REGS->end[0]' - - * 2 in `REGS->start[1]' and 3 in `REGS->end[1]' - - * 2 in `REGS->start[2]' and 2 in `REGS->end[2]' - - When you match the pattern `((a)*b)*' against the string `abb', - group 2 doesn't participate in the last match, so you get: - - * 0 in `REGS->start[0]' and 3 in `REGS->end[0]' - - * 2 in `REGS->start[1]' and 3 in `REGS->end[1]' - - * 0 in `REGS->start[2]' and 1 in `REGS->end[2]' - - * If an I-th group contains a J-th group in turn not contained - within any other group within group I and the function sets - `REGS->start[I]' and `REGS->end[I]' to -1, then it also sets - `REGS->start[J]' and `REGS->end[J]' to -1. - - For example, when you match the pattern `((a)*b)*c' against the - string `c', you get: - - * 0 in `REGS->start[0]' and 1 in `REGS->end[0]' - - * -1 in `REGS->start[1]' and -1 in `REGS->end[1]' - - * -1 in `REGS->start[2]' and -1 in `REGS->end[2]' - - -File: regex.info, Node: Freeing GNU Pattern Buffers, Prev: Using Registers, Up: GNU Regex Functions - -Freeing GNU Pattern Buffers ---------------------------- - - To free any allocated fields of a pattern buffer, you can use the -POSIX function described in *Note Freeing POSIX Pattern Buffers::, -since the type `regex_t'--the type for POSIX pattern buffers--is -equivalent to the type `re_pattern_buffer'. After freeing a pattern -buffer, you need to again compile a regular expression in it (*note GNU -Regular Expression Compiling::.) before passing it to a matching or -searching function. - - -File: regex.info, Node: POSIX Regex Functions, Next: BSD Regex Functions, Prev: GNU Regex Functions, Up: Programming with Regex - -POSIX Regex Functions -===================== - - If you're writing code that has to be POSIX compatible, you'll need -to use these functions. Their interfaces are as specified by POSIX, -draft 1003.2/D11.2. - -* Menu: - -* POSIX Pattern Buffers:: The regex_t type. -* POSIX Regular Expression Compiling:: regcomp () -* POSIX Matching:: regexec () -* Reporting Errors:: regerror () -* Using Byte Offsets:: The regmatch_t type. -* Freeing POSIX Pattern Buffers:: regfree () - - -File: regex.info, Node: POSIX Pattern Buffers, Next: POSIX Regular Expression Compiling, Up: POSIX Regex Functions - -POSIX Pattern Buffers ---------------------- - - To compile or match a given regular expression the POSIX way, you -must supply a pattern buffer exactly the way you do for GNU (*note GNU -Pattern Buffers::.). POSIX pattern buffers have type `regex_t', which -is equivalent to the GNU pattern buffer type `re_pattern_buffer'. - - -File: regex.info, Node: POSIX Regular Expression Compiling, Next: POSIX Matching, Prev: POSIX Pattern Buffers, Up: POSIX Regex Functions - -POSIX Regular Expression Compiling ----------------------------------- - - With POSIX, you can only search for a given regular expression; you -can't match it. To do this, you must first compile it in a pattern -buffer, using `regcomp'. - - To compile a pattern buffer, use: - - int - regcomp (regex_t *PREG, const char *REGEX, int CFLAGS) - -PREG is the initialized pattern buffer's address, REGEX is the regular -expression's address, and CFLAGS is the compilation flags, which Regex -considers as a collection of bits. Here are the valid bits, as defined -in `regex.h': - -`REG_EXTENDED' - says to use POSIX Extended Regular Expression syntax; if this isn't - set, then says to use POSIX Basic Regular Expression syntax. - `regcomp' sets PREG's `syntax' field accordingly. - -`REG_ICASE' - says to ignore case; `regcomp' sets PREG's `translate' field to a - translate table which ignores case, replacing anything you've put - there before. - -`REG_NOSUB' - says to set PREG's `no_sub' field; *note POSIX Matching::., for - what this means. - -`REG_NEWLINE' - says that a: - - * match-any-character operator (*note Match-any-character - Operator::.) doesn't match a newline. - - * nonmatching list not containing a newline (*note List - Operators::.) matches a newline. - - * match-beginning-of-line operator (*note - Match-beginning-of-line Operator::.) matches the empty string - immediately after a newline, regardless of how `REG_NOTBOL' - is set (*note POSIX Matching::., for an explanation of - `REG_NOTBOL'). - - * match-end-of-line operator (*note Match-beginning-of-line - Operator::.) matches the empty string immediately before a - newline, regardless of how `REG_NOTEOL' is set (*note POSIX - Matching::., for an explanation of `REG_NOTEOL'). - - If `regcomp' successfully compiles the regular expression, it returns -zero and sets `*PATTERN_BUFFER' to the compiled pattern. Except for -`syntax' (which it sets as explained above), it also sets the same -fields the same way as does the GNU compiling function (*note GNU -Regular Expression Compiling::.). - - If `regcomp' can't compile the regular expression, it returns one of -the error codes listed here. (Except when noted differently, the -syntax of in all examples below is basic regular expression syntax.) - -`REG_BADRPT' - For example, the consecutive repetition operators `**' in `a**' - are invalid. As another example, if the syntax is extended - regular expression syntax, then the repetition operator `*' with - nothing on which to operate in `*' is invalid. - -`REG_BADBR' - For example, the COUNT `-1' in `a\{-1' is invalid. - -`REG_EBRACE' - For example, `a\{1' is missing a close-interval operator. - -`REG_EBRACK' - For example, `[a' is missing a close-list operator. - -`REG_ERANGE' - For example, the range ending point `z' that collates lower than - does its starting point `a' in `[z-a]' is invalid. Also, the - range with the character class `[:alpha:]' as its starting point in - `[[:alpha:]-|]'. - -`REG_ECTYPE' - For example, the character class name `foo' in `[[:foo:]' is - invalid. - -`REG_EPAREN' - For example, `a\)' is missing an open-group operator and `\(a' is - missing a close-group operator. - -`REG_ESUBREG' - For example, the back reference `\2' that refers to a nonexistent - subexpression in `\(a\)\2' is invalid. - -`REG_EEND' - Returned when a regular expression causes no other more specific - error. - -`REG_EESCAPE' - For example, the trailing backslash `\' in `a\' is invalid, as is - the one in `\'. - -`REG_BADPAT' - For example, in the extended regular expression syntax, the empty - group `()' in `a()b' is invalid. - -`REG_ESIZE' - Returned when a regular expression needs a pattern buffer larger - than 65536 bytes. - -`REG_ESPACE' - Returned when a regular expression makes Regex to run out of - memory. - - -File: regex.info, Node: POSIX Matching, Next: Reporting Errors, Prev: POSIX Regular Expression Compiling, Up: POSIX Regex Functions - -POSIX Matching --------------- - - Matching the POSIX way means trying to match a null-terminated string -starting at its first character. Once you've compiled a pattern into a -pattern buffer (*note POSIX Regular Expression Compiling::.), you can -ask the matcher to match that pattern against a string using: - - int - regexec (const regex_t *PREG, const char *STRING, - size_t NMATCH, regmatch_t PMATCH[], int EFLAGS) - -PREG is the address of a pattern buffer for a compiled pattern. STRING -is the string you want to match. - - *Note Using Byte Offsets::, for an explanation of PMATCH. If you -pass zero for NMATCH or you compiled PREG with the compilation flag -`REG_NOSUB' set, then `regexec' will ignore PMATCH; otherwise, you must -allocate it to have at least NMATCH elements. `regexec' will record -NMATCH byte offsets in PMATCH, and set to -1 any unused elements up to -PMATCH`[NMATCH]' - 1. - - EFLAGS specifies "execution flags"--namely, the two bits `REG_NOTBOL' -and `REG_NOTEOL' (defined in `regex.h'). If you set `REG_NOTBOL', then -the match-beginning-of-line operator (*note Match-beginning-of-line -Operator::.) always fails to match. This lets you match against pieces -of a line, as you would need to if, say, searching for repeated -instances of a given pattern in a line; it would work correctly for -patterns both with and without match-beginning-of-line operators. -`REG_NOTEOL' works analogously for the match-end-of-line operator -(*note Match-end-of-line Operator::.); it exists for symmetry. - - `regexec' tries to find a match for PREG in STRING according to the -syntax in PREG's `syntax' field. (*Note POSIX Regular Expression -Compiling::, for how to set it.) The function returns zero if the -compiled pattern matches STRING and `REG_NOMATCH' (defined in -`regex.h') if it doesn't. - - -File: regex.info, Node: Reporting Errors, Next: Using Byte Offsets, Prev: POSIX Matching, Up: POSIX Regex Functions - -Reporting Errors ----------------- - - If either `regcomp' or `regexec' fail, they return a nonzero error -code, the possibilities for which are defined in `regex.h'. *Note -POSIX Regular Expression Compiling::, and *Note POSIX Matching::, for -what these codes mean. To get an error string corresponding to these -codes, you can use: - - size_t - regerror (int ERRCODE, - const regex_t *PREG, - char *ERRBUF, - size_t ERRBUF_SIZE) - -ERRCODE is an error code, PREG is the address of the pattern buffer -which provoked the error, ERRBUF is the error buffer, and ERRBUF_SIZE -is ERRBUF's size. - - `regerror' returns the size in bytes of the error string -corresponding to ERRCODE (including its terminating null). If ERRBUF -and ERRBUF_SIZE are nonzero, it also returns in ERRBUF the first -ERRBUF_SIZE - 1 characters of the error string, followed by a null. -eRRBUF_SIZE must be a nonnegative number less than or equal to the size -in bytes of ERRBUF. - - You can call `regerror' with a null ERRBUF and a zero ERRBUF_SIZE to -determine how large ERRBUF need be to accommodate `regerror''s error -string. - - -File: regex.info, Node: Using Byte Offsets, Next: Freeing POSIX Pattern Buffers, Prev: Reporting Errors, Up: POSIX Regex Functions - -Using Byte Offsets ------------------- - - In POSIX, variables of type `regmatch_t' hold analogous information, -but are not identical to, GNU's registers (*note Using Registers::.). -To get information about registers in POSIX, pass to `regexec' a -nonzero PMATCH of type `regmatch_t', i.e., the address of a structure -of this type, defined in `regex.h': - - typedef struct - { - regoff_t rm_so; - regoff_t rm_eo; - } regmatch_t; - - When reading in *Note Using Registers::, about how the matching -function stores the information into the registers, substitute PMATCH -for REGS, `PMATCH[I]->rm_so' for `REGS->start[I]' and -`PMATCH[I]->rm_eo' for `REGS->end[I]'. - - -File: regex.info, Node: Freeing POSIX Pattern Buffers, Prev: Using Byte Offsets, Up: POSIX Regex Functions - -Freeing POSIX Pattern Buffers ------------------------------ - - To free any allocated fields of a pattern buffer, use: - - void - regfree (regex_t *PREG) - -PREG is the pattern buffer whose allocated fields you want freed. -`regfree' also sets PREG's `allocated' and `used' fields to zero. -After freeing a pattern buffer, you need to again compile a regular -expression in it (*note POSIX Regular Expression Compiling::.) before -passing it to the matching function (*note POSIX Matching::.). - - -File: regex.info, Node: BSD Regex Functions, Prev: POSIX Regex Functions, Up: Programming with Regex - -BSD Regex Functions -=================== - - If you're writing code that has to be Berkeley UNIX compatible, -you'll need to use these functions whose interfaces are the same as -those in Berkeley UNIX. - -* Menu: - -* BSD Regular Expression Compiling:: re_comp () -* BSD Searching:: re_exec () - - -File: regex.info, Node: BSD Regular Expression Compiling, Next: BSD Searching, Up: BSD Regex Functions - -BSD Regular Expression Compiling --------------------------------- - - With Berkeley UNIX, you can only search for a given regular -expression; you can't match one. To search for it, you must first -compile it. Before you compile it, you must indicate the regular -expression syntax you want it compiled according to by setting the -variable `re_syntax_options' (declared in `regex.h' to some syntax -(*note Regular Expression Syntax::.). - - To compile a regular expression use: - - char * - re_comp (char *REGEX) - -REGEX is the address of a null-terminated regular expression. -`re_comp' uses an internal pattern buffer, so you can use only the most -recently compiled pattern buffer. This means that if you want to use a -given regular expression that you've already compiled--but it isn't the -latest one you've compiled--you'll have to recompile it. If you call -`re_comp' with the null string (*not* the empty string) as the -argument, it doesn't change the contents of the pattern buffer. - - If `re_comp' successfully compiles the regular expression, it returns -zero. If it can't compile the regular expression, it returns an error -string. `re_comp''s error messages are identical to those of -`re_compile_pattern' (*note GNU Regular Expression Compiling::.). - - -File: regex.info, Node: BSD Searching, Prev: BSD Regular Expression Compiling, Up: BSD Regex Functions - -BSD Searching -------------- - - Searching the Berkeley UNIX way means searching in a string starting -at its first character and trying successive positions within it to -find a match. Once you've compiled a pattern using `re_comp' (*note -BSD Regular Expression Compiling::.), you can ask Regex to search for -that pattern in a string using: - - int - re_exec (char *STRING) - -STRING is the address of the null-terminated string in which you want -to search. - - `re_exec' returns either 1 for success or 0 for failure. It -automatically uses a GNU fastmap (*note Searching with Fastmaps::.). - - -File: regex.info, Node: Copying, Next: Index, Prev: Programming with Regex, Up: Top - -GNU GENERAL PUBLIC LICENSE -************************** - - Version 2, June 1991 - - Copyright (C) 1989, 1991 Free Software Foundation, Inc. - 675 Mass Ave, Cambridge, MA 02139, USA - - Everyone is permitted to copy and distribute verbatim copies - of this license document, but changing it is not allowed. - -Preamble -======== - - The licenses for most software are designed to take away your freedom -to share and change it. By contrast, the GNU General Public License is -intended to guarantee your freedom to share and change free -software--to make sure the software is free for all its users. This -General Public License applies to most of the Free Software -Foundation's software and to any other program whose authors commit to -using it. (Some other Free Software Foundation software is covered by -the GNU Library General Public License instead.) You can apply it to -your programs, too. - - When we speak of free software, we are referring to freedom, not -price. Our General Public Licenses are designed to make sure that you -have the freedom to distribute copies of free software (and charge for -this service if you wish), that you receive source code or can get it -if you want it, that you can change the software or use pieces of it in -new free programs; and that you know you can do these things. - - To protect your rights, we need to make restrictions that forbid -anyone to deny you these rights or to ask you to surrender the rights. -These restrictions translate to certain responsibilities for you if you -distribute copies of the software, or if you modify it. - - For example, if you distribute copies of such a program, whether -gratis or for a fee, you must give the recipients all the rights that -you have. You must make sure that they, too, receive or can get the -source code. And you must show them these terms so they know their -rights. - - We protect your rights with two steps: (1) copyright the software, and -(2) offer you this license which gives you legal permission to copy, -distribute and/or modify the software. - - Also, for each author's protection and ours, we want to make certain -that everyone understands that there is no warranty for this free -software. If the software is modified by someone else and passed on, we -want its recipients to know that what they have is not the original, so -that any problems introduced by others will not reflect on the original -authors' reputations. - - Finally, any free program is threatened constantly by software -patents. We wish to avoid the danger that redistributors of a free -program will individually obtain patent licenses, in effect making the -program proprietary. To prevent this, we have made it clear that any -patent must be licensed for everyone's free use or not licensed at all. - - The precise terms and conditions for copying, distribution and -modification follow. - - TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION - - 1. This License applies to any program or other work which contains a - notice placed by the copyright holder saying it may be distributed - under the terms of this General Public License. The "Program", - below, refers to any such program or work, and a "work based on - the Program" means either the Program or any derivative work under - copyright law: that is to say, a work containing the Program or a - portion of it, either verbatim or with modifications and/or - translated into another language. (Hereinafter, translation is - included without limitation in the term "modification".) Each - licensee is addressed as "you". - - Activities other than copying, distribution and modification are - not covered by this License; they are outside its scope. The act - of running the Program is not restricted, and the output from the - Program is covered only if its contents constitute a work based on - the Program (independent of having been made by running the - Program). Whether that is true depends on what the Program does. - - 2. You may copy and distribute verbatim copies of the Program's - source code as you receive it, in any medium, provided that you - conspicuously and appropriately publish on each copy an appropriate - copyright notice and disclaimer of warranty; keep intact all the - notices that refer to this License and to the absence of any - warranty; and give any other recipients of the Program a copy of - this License along with the Program. - - You may charge a fee for the physical act of transferring a copy, - and you may at your option offer warranty protection in exchange - for a fee. - - 3. You may modify your copy or copies of the Program or any portion - of it, thus forming a work based on the Program, and copy and - distribute such modifications or work under the terms of Section 1 - above, provided that you also meet all of these conditions: - - a. You must cause the modified files to carry prominent notices - stating that you changed the files and the date of any change. - - b. You must cause any work that you distribute or publish, that - in whole or in part contains or is derived from the Program - or any part thereof, to be licensed as a whole at no charge - to all third parties under the terms of this License. - - c. If the modified program normally reads commands interactively - when run, you must cause it, when started running for such - interactive use in the most ordinary way, to print or display - an announcement including an appropriate copyright notice and - a notice that there is no warranty (or else, saying that you - provide a warranty) and that users may redistribute the - program under these conditions, and telling the user how to - view a copy of this License. (Exception: if the Program - itself is interactive but does not normally print such an - announcement, your work based on the Program is not required - to print an announcement.) - - These requirements apply to the modified work as a whole. If - identifiable sections of that work are not derived from the - Program, and can be reasonably considered independent and separate - works in themselves, then this License, and its terms, do not - apply to those sections when you distribute them as separate - works. But when you distribute the same sections as part of a - whole which is a work based on the Program, the distribution of - the whole must be on the terms of this License, whose permissions - for other licensees extend to the entire whole, and thus to each - and every part regardless of who wrote it. - - Thus, it is not the intent of this section to claim rights or - contest your rights to work written entirely by you; rather, the - intent is to exercise the right to control the distribution of - derivative or collective works based on the Program. - - In addition, mere aggregation of another work not based on the - Program with the Program (or with a work based on the Program) on - a volume of a storage or distribution medium does not bring the - other work under the scope of this License. - - 4. You may copy and distribute the Program (or a work based on it, - under Section 2) in object code or executable form under the terms - of Sections 1 and 2 above provided that you also do one of the - following: - - a. Accompany it with the complete corresponding machine-readable - source code, which must be distributed under the terms of - Sections 1 and 2 above on a medium customarily used for - software interchange; or, - - b. Accompany it with a written offer, valid for at least three - years, to give any third party, for a charge no more than your - cost of physically performing source distribution, a complete - machine-readable copy of the corresponding source code, to be - distributed under the terms of Sections 1 and 2 above on a - medium customarily used for software interchange; or, - - c. Accompany it with the information you received as to the offer - to distribute corresponding source code. (This alternative is - allowed only for noncommercial distribution and only if you - received the program in object code or executable form with - such an offer, in accord with Subsection b above.) - - The source code for a work means the preferred form of the work for - making modifications to it. For an executable work, complete - source code means all the source code for all modules it contains, - plus any associated interface definition files, plus the scripts - used to control compilation and installation of the executable. - However, as a special exception, the source code distributed need - not include anything that is normally distributed (in either - source or binary form) with the major components (compiler, - kernel, and so on) of the operating system on which the executable - runs, unless that component itself accompanies the executable. - - If distribution of executable or object code is made by offering - access to copy from a designated place, then offering equivalent - access to copy the source code from the same place counts as - distribution of the source code, even though third parties are not - compelled to copy the source along with the object code. - - 5. You may not copy, modify, sublicense, or distribute the Program - except as expressly provided under this License. Any attempt - otherwise to copy, modify, sublicense or distribute the Program is - void, and will automatically terminate your rights under this - License. However, parties who have received copies, or rights, - from you under this License will not have their licenses - terminated so long as such parties remain in full compliance. - - 6. You are not required to accept this License, since you have not - signed it. However, nothing else grants you permission to modify - or distribute the Program or its derivative works. These actions - are prohibited by law if you do not accept this License. - Therefore, by modifying or distributing the Program (or any work - based on the Program), you indicate your acceptance of this - License to do so, and all its terms and conditions for copying, - distributing or modifying the Program or works based on it. - - 7. Each time you redistribute the Program (or any work based on the - Program), the recipient automatically receives a license from the - original licensor to copy, distribute or modify the Program - subject to these terms and conditions. You may not impose any - further restrictions on the recipients' exercise of the rights - granted herein. You are not responsible for enforcing compliance - by third parties to this License. - - 8. If, as a consequence of a court judgment or allegation of patent - infringement or for any other reason (not limited to patent - issues), conditions are imposed on you (whether by court order, - agreement or otherwise) that contradict the conditions of this - License, they do not excuse you from the conditions of this - License. If you cannot distribute so as to satisfy simultaneously - your obligations under this License and any other pertinent - obligations, then as a consequence you may not distribute the - Program at all. For example, if a patent license would not permit - royalty-free redistribution of the Program by all those who - receive copies directly or indirectly through you, then the only - way you could satisfy both it and this License would be to refrain - entirely from distribution of the Program. - - If any portion of this section is held invalid or unenforceable - under any particular circumstance, the balance of the section is - intended to apply and the section as a whole is intended to apply - in other circumstances. - - It is not the purpose of this section to induce you to infringe any - patents or other property right claims or to contest validity of - any such claims; this section has the sole purpose of protecting - the integrity of the free software distribution system, which is - implemented by public license practices. Many people have made - generous contributions to the wide range of software distributed - through that system in reliance on consistent application of that - system; it is up to the author/donor to decide if he or she is - willing to distribute software through any other system and a - licensee cannot impose that choice. - - This section is intended to make thoroughly clear what is believed - to be a consequence of the rest of this License. - - 9. If the distribution and/or use of the Program is restricted in - certain countries either by patents or by copyrighted interfaces, - the original copyright holder who places the Program under this - License may add an explicit geographical distribution limitation - excluding those countries, so that distribution is permitted only - in or among countries not thus excluded. In such case, this - License incorporates the limitation as if written in the body of - this License. - - 10. The Free Software Foundation may publish revised and/or new - versions of the General Public License from time to time. Such - new versions will be similar in spirit to the present version, but - may differ in detail to address new problems or concerns. - - Each version is given a distinguishing version number. If the - Program specifies a version number of this License which applies - to it and "any later version", you have the option of following - the terms and conditions either of that version or of any later - version published by the Free Software Foundation. If the Program - does not specify a version number of this License, you may choose - any version ever published by the Free Software Foundation. - - 11. If you wish to incorporate parts of the Program into other free - programs whose distribution conditions are different, write to the - author to ask for permission. For software which is copyrighted - by the Free Software Foundation, write to the Free Software - Foundation; we sometimes make exceptions for this. Our decision - will be guided by the two goals of preserving the free status of - all derivatives of our free software and of promoting the sharing - and reuse of software generally. - - NO WARRANTY - - 12. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO - WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE - LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT - HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT - WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT - NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND - FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE - QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE - PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY - SERVICING, REPAIR OR CORRECTION. - - 13. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN - WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY - MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE - LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, - INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR - INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF - DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU - OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY - OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN - ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. - - END OF TERMS AND CONDITIONS - -Appendix: How to Apply These Terms to Your New Programs -======================================================= - - If you develop a new program, and you want it to be of the greatest -possible use to the public, the best way to achieve this is to make it -free software which everyone can redistribute and change under these -terms. - - To do so, attach the following notices to the program. It is safest -to attach them to the start of each source file to most effectively -convey the exclusion of warranty; and each file should have at least -the "copyright" line and a pointer to where the full notice is found. - - ONE LINE TO GIVE THE PROGRAM'S NAME AND A BRIEF IDEA OF WHAT IT DOES. - Copyright (C) 19YY NAME OF AUTHOR - - This program is free software; you can redistribute it and/or modify - it under the terms of the GNU General Public License as published by - the Free Software Foundation; either version 2 of the License, or - (at your option) any later version. - - This program is distributed in the hope that it will be useful, - but WITHOUT ANY WARRANTY; without even the implied warranty of - MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the - GNU General Public License for more details. - - You should have received a copy of the GNU General Public License - along with this program; if not, write to the Free Software - Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. - - Also add information on how to contact you by electronic and paper -mail. - - If the program is interactive, make it output a short notice like this -when it starts in an interactive mode: - - Gnomovision version 69, Copyright (C) 19YY NAME OF AUTHOR - Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. - This is free software, and you are welcome to redistribute it - under certain conditions; type `show c' for details. - - The hypothetical commands `show w' and `show c' should show the -appropriate parts of the General Public License. Of course, the -commands you use may be called something other than `show w' and `show -c'; they could even be mouse-clicks or menu items--whatever suits your -program. - - You should also get your employer (if you work as a programmer) or -your school, if any, to sign a "copyright disclaimer" for the program, -if necessary. Here is a sample; alter the names: - - Yoyodyne, Inc., hereby disclaims all copyright interest in the program - `Gnomovision' (which makes passes at compilers) written by James Hacker. - - SIGNATURE OF TY COON, 1 April 1989 - Ty Coon, President of Vice - - This General Public License does not permit incorporating your -program into proprietary programs. If your program is a subroutine -library, you may consider it more useful to permit linking proprietary -applications with the library. If this is what you want to do, use the -GNU Library General Public License instead of this License. - - -File: regex.info, Node: Index, Prev: Copying, Up: Top - -Index -***** - -* Menu: - -* $: Match-end-of-line Operator. -* (: Grouping Operators. -* ): Grouping Operators. -* *: Match-zero-or-more Operator. -* +: Match-one-or-more Operator. -* -: List Operators. -* .: Match-any-character Operator. -* :] in regex: Character Class Operators. -* ?: Match-zero-or-one Operator. -* {: Interval Operators. -* }: Interval Operators. -* [: in regex: Character Class Operators. -* [^: List Operators. -* [: List Operators. -* \': Match-end-of-buffer Operator. -* \<: Match-beginning-of-word Operator. -* \>: Match-end-of-word Operator. -* \{: Interval Operators. -* \}: Interval Operators. -* \b: Match-word-boundary Operator. -* \B: Match-within-word Operator. -* \s: Match-syntactic-class Operator. -* \S: Match-not-syntactic-class Operator. -* \w: Match-word-constituent Operator. -* \W: Match-non-word-constituent Operator. -* \`: Match-beginning-of-buffer Operator. -* \: List Operators. -* ]: List Operators. -* ^: List Operators. -* allocated initialization: GNU Regular Expression Compiling. -* alternation operator: Alternation Operator. -* alternation operator and ^: Match-beginning-of-line Operator. -* anchoring: Anchoring Operators. -* anchors: Match-end-of-line Operator. -* anchors: Match-beginning-of-line Operator. -* Awk: Predefined Syntaxes. -* back references: Back-reference Operator. -* backtracking: Match-zero-or-more Operator. -* backtracking: Alternation Operator. -* beginning-of-line operator: Match-beginning-of-line Operator. -* bracket expression: List Operators. -* buffer field, set by re_compile_pattern: GNU Regular Expression Compiling. -* buffer initialization: GNU Regular Expression Compiling. -* character classes: Character Class Operators. -* Egrep: Predefined Syntaxes. -* Emacs: Predefined Syntaxes. -* end in struct re_registers: Using Registers. -* end-of-line operator: Match-end-of-line Operator. -* fastmap initialization: GNU Regular Expression Compiling. -* fastmaps: Searching with Fastmaps. -* fastmap_accurate field, set by re_compile_pattern: GNU Regular Expression Compiling. -* Grep: Predefined Syntaxes. -* grouping: Grouping Operators. -* ignoring case: POSIX Regular Expression Compiling. -* interval expression: Interval Operators. -* matching list: List Operators. -* matching newline: List Operators. -* matching with GNU functions: GNU Matching. -* newline_anchor field in pattern buffer: Match-beginning-of-line Operator. -* nonmatching list: List Operators. -* not_bol field in pattern buffer: Match-beginning-of-line Operator. -* num_regs in struct re_registers: Using Registers. -* open-group operator and ^: Match-beginning-of-line Operator. -* or operator: Alternation Operator. -* parenthesizing: Grouping Operators. -* pattern buffer initialization: GNU Regular Expression Compiling. -* pattern buffer, definition of: GNU Pattern Buffers. -* POSIX Awk: Predefined Syntaxes. -* range argument to re_search: GNU Searching. -* regex.c: Overview. -* regex.h: Overview. -* regexp anchoring: Anchoring Operators. -* regmatch_t: Using Byte Offsets. -* regs_allocated: Using Registers. -* REGS_FIXED: Using Registers. -* REGS_REALLOCATE: Using Registers. -* REGS_UNALLOCATED: Using Registers. -* regular expressions, syntax of: Regular Expression Syntax. -* REG_EXTENDED: POSIX Regular Expression Compiling. -* REG_ICASE: POSIX Regular Expression Compiling. -* REG_NEWLINE: POSIX Regular Expression Compiling. -* REG_NOSUB: POSIX Regular Expression Compiling. -* RE_BACKSLASH_ESCAPE_IN_LIST: Syntax Bits. -* RE_BK_PLUS_QM: Syntax Bits. -* RE_CHAR_CLASSES: Syntax Bits. -* RE_CONTEXT_INDEP_ANCHORS: Syntax Bits. -* RE_CONTEXT_INDEP_ANCHORS (and ^): Match-beginning-of-line Operator. -* RE_CONTEXT_INDEP_OPS: Syntax Bits. -* RE_CONTEXT_INVALID_OPS: Syntax Bits. -* RE_DOT_NEWLINE: Syntax Bits. -* RE_DOT_NOT_NULL: Syntax Bits. -* RE_INTERVALS: Syntax Bits. -* RE_LIMITED_OPS: Syntax Bits. -* RE_NEWLINE_ALT: Syntax Bits. -* RE_NO_BK_BRACES: Syntax Bits. -* RE_NO_BK_PARENS: Syntax Bits. -* RE_NO_BK_REFS: Syntax Bits. -* RE_NO_BK_VBAR: Syntax Bits. -* RE_NO_EMPTY_RANGES: Syntax Bits. -* re_nsub field, set by re_compile_pattern: GNU Regular Expression Compiling. -* re_pattern_buffer definition: GNU Pattern Buffers. -* re_registers: Using Registers. -* re_syntax_options initialization: GNU Regular Expression Compiling. -* RE_UNMATCHED_RIGHT_PAREN_ORD: Syntax Bits. -* searching with GNU functions: GNU Searching. -* start argument to re_search: GNU Searching. -* start in struct re_registers: Using Registers. -* struct re_pattern_buffer definition: GNU Pattern Buffers. -* subexpressions: Grouping Operators. -* syntax field, set by re_compile_pattern: GNU Regular Expression Compiling. -* syntax bits: Syntax Bits. -* syntax initialization: GNU Regular Expression Compiling. -* syntax of regular expressions: Regular Expression Syntax. -* translate initialization: GNU Regular Expression Compiling. -* used field, set by re_compile_pattern: GNU Regular Expression Compiling. -* word boundaries, matching: Match-word-boundary Operator. -* \: The Backslash Character. -* \(: Grouping Operators. -* \): Grouping Operators. -* \|: Alternation Operator. -* ^: Match-beginning-of-line Operator. -* |: Alternation Operator. - - - -Tag Table: -Node: Top1064 -Node: Overview4562 -Node: Regular Expression Syntax6746 -Node: Syntax Bits7916 -Node: Predefined Syntaxes14018 -Node: Collating Elements vs. Characters17872 -Node: The Backslash Character18835 -Node: Common Operators21992 -Node: Match-self Operator23445 -Node: Match-any-character Operator23941 -Node: Concatenation Operator24520 -Node: Repetition Operators25017 -Node: Match-zero-or-more Operator25436 -Node: Match-one-or-more Operator27483 -Node: Match-zero-or-one Operator28341 -Node: Interval Operators29196 -Node: Alternation Operator30991 -Node: List Operators32489 -Node: Character Class Operators35272 -Node: Range Operator36901 -Node: Grouping Operators38930 -Node: Back-reference Operator40251 -Node: Anchoring Operators43073 -Node: Match-beginning-of-line Operator43447 -Node: Match-end-of-line Operator44779 -Node: GNU Operators45518 -Node: Word Operators45767 -Node: Non-Emacs Syntax Tables46391 -Node: Match-word-boundary Operator47465 -Node: Match-within-word Operator47858 -Node: Match-beginning-of-word Operator48255 -Node: Match-end-of-word Operator48588 -Node: Match-word-constituent Operator48908 -Node: Match-non-word-constituent Operator49234 -Node: Buffer Operators49545 -Node: Match-beginning-of-buffer Operator49952 -Node: Match-end-of-buffer Operator50264 -Node: GNU Emacs Operators50558 -Node: Syntactic Class Operators50901 -Node: Emacs Syntax Tables51307 -Node: Match-syntactic-class Operator51963 -Node: Match-not-syntactic-class Operator52560 -Node: What Gets Matched?53150 -Node: Programming with Regex53799 -Node: GNU Regex Functions54237 -Node: GNU Pattern Buffers55078 -Node: GNU Regular Expression Compiling58303 -Node: GNU Matching61181 -Node: GNU Searching63101 -Node: Matching/Searching with Split Data64913 -Node: Searching with Fastmaps66369 -Node: GNU Translate Tables68921 -Node: Using Registers70892 -Node: Freeing GNU Pattern Buffers77000 -Node: POSIX Regex Functions77593 -Node: POSIX Pattern Buffers78266 -Node: POSIX Regular Expression Compiling78709 -Node: POSIX Matching82836 -Node: Reporting Errors84791 -Node: Using Byte Offsets86048 -Node: Freeing POSIX Pattern Buffers86861 -Node: BSD Regex Functions87467 -Node: BSD Regular Expression Compiling87886 -Node: BSD Searching89258 -Node: Copying89960 -Node: Index109122 - -End Tag Table |