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diff --git a/share/doc/psd/15.yacc/ssb b/share/doc/psd/15.yacc/ssb new file mode 100644 index 000000000000..2dba020cd015 --- /dev/null +++ b/share/doc/psd/15.yacc/ssb @@ -0,0 +1,147 @@ +.\" Copyright (C) Caldera International Inc. 2001-2002. All rights reserved. +.\" +.\" Redistribution and use in source and binary forms, with or without +.\" modification, are permitted provided that the following conditions are +.\" met: +.\" +.\" Redistributions of source code and documentation must retain the above +.\" copyright notice, this list of conditions and the following +.\" disclaimer. +.\" +.\" Redistributions in binary form must reproduce the above copyright +.\" notice, this list of conditions and the following disclaimer in the +.\" documentation and/or other materials provided with the distribution. +.\" +.\" All advertising materials mentioning features or use of this software +.\" must display the following acknowledgement: +.\" +.\" This product includes software developed or owned by Caldera +.\" International, Inc. Neither the name of Caldera International, Inc. +.\" nor the names of other contributors may be used to endorse or promote +.\" products derived from this software without specific prior written +.\" permission. +.\" +.\" USE OF THE SOFTWARE PROVIDED FOR UNDER THIS LICENSE BY CALDERA +.\" INTERNATIONAL, INC. AND CONTRIBUTORS ``AS IS'' AND ANY EXPRESS OR +.\" IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED +.\" WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +.\" DISCLAIMED. IN NO EVENT SHALL CALDERA INTERNATIONAL, INC. BE LIABLE +.\" FOR ANY DIRECT, INDIRECT INCIDENTAL, SPECIAL, EXEMPLARY, OR +.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF +.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR +.\" BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, +.\" WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE +.\" OR OTHERWISE) RISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN +.\" IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. +.\" +.\" @(#)ssb 8.1 (Berkeley) 6/8/93 +.\" +.\" $FreeBSD$ +.SH +Appendix B: Yacc Input Syntax +.PP +This Appendix has a description of the Yacc input syntax, as a Yacc specification. +Context dependencies, etc., are not considered. +Ironically, the Yacc input specification language +is most naturally specified as an LR(2) grammar; the sticky +part comes when an identifier is seen in a rule, immediately +following an action. +If this identifier is followed by a colon, it is the start of the +next rule; otherwise +it is a continuation of the current rule, which just happens to have +an action embedded in it. +As implemented, the lexical analyzer looks +ahead after seeing an identifier, and +decide whether the next token (skipping blanks, newlines, comments, etc.) +is a colon. +If so, it returns the token C_IDENTIFIER. +Otherwise, it returns IDENTIFIER. +Literals (quoted strings) are also returned as IDENTIFIERS, +but never as part of C_IDENTIFIERs. +.sp +.nf +.ta .6i 1.2i 1.8i 2.4i 3i 3.6i + + /* grammar for the input to Yacc */ + + /* basic entities */ +%token IDENTIFIER /* includes identifiers and literals */ +%token C_IDENTIFIER /* identifier (but not literal) followed by colon */ +%token NUMBER /* [0-9]+ */ + + /* reserved words: %type => TYPE, %left => LEFT, etc. */ + +%token LEFT RIGHT NONASSOC TOKEN PREC TYPE START UNION + +%token MARK /* the %% mark */ +%token LCURL /* the %{ mark */ +%token RCURL /* the %} mark */ + + /* ascii character literals stand for themselves */ + +%start spec + +%% + +spec : defs MARK rules tail + ; + +tail : MARK { \fIIn this action, eat up the rest of the file\fR } + | /* empty: the second MARK is optional */ + ; + +defs : /* empty */ + | defs def + ; + +def : START IDENTIFIER + | UNION { \fICopy union definition to output\fR } + | LCURL { \fICopy C code to output file\fR } RCURL + | ndefs rword tag nlist + ; + +rword : TOKEN + | LEFT + | RIGHT + | NONASSOC + | TYPE + ; + +tag : /* empty: union tag is optional */ + | \'<\' IDENTIFIER \'>\' + ; + +nlist : nmno + | nlist nmno + | nlist \',\' nmno + ; + +nmno : IDENTIFIER /* NOTE: literal illegal with %type */ + | IDENTIFIER NUMBER /* NOTE: illegal with %type */ + ; + + /* rules section */ + +rules : C_IDENTIFIER rbody prec + | rules rule + ; + +rule : C_IDENTIFIER rbody prec + | '|' rbody prec + ; + +rbody : /* empty */ + | rbody IDENTIFIER + | rbody act + ; + +act : \'{\' { \fICopy action, translate $$, etc.\fR } \'}\' + ; + +prec : /* empty */ + | PREC IDENTIFIER + | PREC IDENTIFIER act + | prec \';\' + ; +.fi +.bp |