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Diffstat (limited to 'test/btyacc_demo.y')
| -rw-r--r-- | test/btyacc_demo.y | 226 |
1 files changed, 226 insertions, 0 deletions
diff --git a/test/btyacc_demo.y b/test/btyacc_demo.y new file mode 100644 index 000000000000..892434c8b158 --- /dev/null +++ b/test/btyacc_demo.y @@ -0,0 +1,226 @@ +/* + * demonstrate enhancements derived from btyacc: + * backtracking to resolve conflicts + * semantic disambiguation via []-actions invoking YYVALID & YYERROR + * %locations + * @$ & @N to refer to lhs & rhs symbol location + * %destructor + * syntactic suger for inherited attributes + * extension to %type to define inherited attribute type + */ + +%LOCATIONS + +%{ +/* dummy types just for compile check */ +typedef int Code; +typedef int Decl_List; +typedef int Expr; +typedef int Expr_List; +typedef int Scope; +typedef int Type; +enum Operator { ADD, SUB, MUL, MOD, DIV, DEREF }; + +typedef unsigned char bool; +typedef struct Decl { + Scope *scope; + Type *type; + bool (*istype)(void); +} Decl; + +#include "btyacc_demo.tab.h" +#include <stdlib.h> +#include <stdio.h> +%} + +%union { + Scope *scope; + Expr *expr; + Expr_List *elist; + Type *type; + Decl *decl; + Decl_List *dlist; + Code *code; + char *id; + }; + +%left '+' '-' +%left '*' '/' '%' +%nonassoc PREFIX +%nonassoc POSTFIX '(' '[' '.' + +%token <id> ID +%token <expr> CONSTANT +%token EXTERN REGISTER STATIC CONST VOLATILE IF THEN ELSE CLCL + +%type <expr> expr(<scope>) +%type decl(<scope>) declarator_list(<scope>, <type>) + decl_list(<scope>) +%type <code> statement(<scope>) statement_list(<scope>) + block_statement(<scope>) +%type <decl> declarator(<scope>, <type>) formal_arg(<scope>) +%type <type> decl_specs(<scope>) decl_spec(<scope>) typename(<scope>) + cv_quals cv_qual +%type <scope> opt_scope(<scope>) +%type <dlist> formal_arg_list(<scope>) nonempty_formal_arg_list(<scope>) + +%destructor { // 'msg' is a 'char *' indicating the context of destructor invocation + printf("%s accessed by symbol \"decl\" (case s.b. 273) @ position[%d,%d..%d,%d]\n", + msg, + @$.first_line, @$.first_column, + @$.last_line, @$.last_column); + free($<decl>$->scope); free($<decl>$->type); } decl +%destructor { printf("%s accessed by symbol with type <decl> (case s.b. 279 & 280) @ position[%d,%d..%d,%d]\n", + msg, + @$.first_line, @$.first_column, + @$.last_line, @$.last_column); + free($$); } <decl> +%destructor { printf("%s accessed by symbol of any type other than <decl> @ position[%d,%d..%d,%d]\n", + msg, + @$.first_line, @$.first_column, + @$.last_line, @$.last_column); + free($$); } <*> +%destructor { printf("%s accessed by symbol with no type @ position[%d,%d..%d,%d]\n", + msg, + @$.first_line, @$.first_column, + @$.last_line, @$.last_column); + /* in this example, we don't know what to do here */ } <> + +%start input + +%% + +opt_scope($e): [ $$ = $e; ] + | CLCL [ $$ = global_scope; ] + | opt_scope ID CLCL [ Decl *d = lookup($1, $2); + if (!d || !d->scope) YYERROR; + $$ = d->scope; ] + ; + +typename($e): opt_scope ID + [ Decl *d = lookup($1, $2); + if (d == NULL || d->istype() == 0) YYERROR; + $$ = d->type; ] + ; + +input: decl_list(global_scope = new_scope(0)) ; +decl_list($e): | decl_list decl($e) ; +decl($e): + decl_specs declarator_list($e,$1) ';' [YYVALID;] + | decl_specs declarator($e,$1) block_statement(start_fn_def($e, $2)) + { /* demonstrate use of @$ & @N, although this is just the + default computation and so is not necessary */ + @$.first_line = @1.first_line; + @$.first_column = @1.first_column; + @$.last_line = @3.last_line; + @$.last_column = @3.last_column; + finish_fn_def($2, $3); } + ; + +decl_specs($e): + decl_spec [ $$ = $1; ] + | decl_specs decl_spec($e) [ $$ = type_combine($1, $2); ] + ; + +cv_quals: [ $$ = 0; ] + | cv_quals cv_qual [ $$ = type_combine($1, $2); ] + ; + +decl_spec($e): + cv_qual [ $$ = $1; ] + | typename [ $$ = $1; ] + | EXTERN [ $$ = bare_extern(); ] + | REGISTER [ $$ = bare_register(); ] + | STATIC [ $$ = bare_static(); ] + ; + +cv_qual: + CONST [ $$ = bare_const(); ] + | VOLATILE [ $$ = bare_volatile(); ] + ; + +declarator_list($e, $t): + declarator_list ',' declarator($e, $t) + | declarator + ; + +declarator($e, $t): + /* empty */ [ if (!$t) YYERROR; ] + { $$ = declare($e, 0, $t); } + | ID { $$ = declare($e, $1, $t); } + | '(' declarator($e, $t) ')' { $$ = $2; } + | '*' cv_quals declarator($e, $t) %prec PREFIX + { $$ = make_pointer($3, $2); } + | declarator '[' expr($e) ']' + { $$ = make_array($1->type, $3); } + | declarator '(' formal_arg_list($e) ')' cv_quals + { $$ = build_function($1, $3, $5); } + ; + +formal_arg_list($e): { $$ = 0; } + | nonempty_formal_arg_list { $$ = $1; } + ; +nonempty_formal_arg_list($e): + nonempty_formal_arg_list ',' formal_arg($e) { $$ = append_dlist($1, $3); } + | formal_arg { $$ = build_dlist($1); } + ; +formal_arg($e): + decl_specs declarator($e,$1) { $$ = $2; } + ; + +expr($e): + expr '+' expr($e) { $$ = build_expr($1, ADD, $3); } + | expr '-' expr($e) { $$ = build_expr($1, SUB, $3); } + | expr '*' expr($e) { $$ = build_expr($1, MUL, $3); } + | expr '%' expr($e) { $$ = build_expr($1, MOD, $3); } + | expr '/' expr($e) { $$ = build_expr($1, DIV, $3); } + | '*' expr($e) %prec PREFIX { $$ = build_expr(0, DEREF, $2); } + | ID { $$ = var_expr($e, $1); } + | CONSTANT { $$ = $1; } + ; + +statement($e): + decl { $$ = 0; } + | expr($e) ';' [YYVALID;] { $$ = build_expr_code($1); } + | IF '(' expr($e) ')' THEN statement($e) ELSE statement($e) [YYVALID;] + { $$ = build_if($3, $6, $8); } + | IF '(' expr($e) ')' THEN statement($e) [YYVALID;] + { $$ = build_if($3, $6, 0); } + | block_statement(new_scope($e)) [YYVALID;]{ $$ = $1; } + ; + +statement_list($e): { $$ = 0; } + | statement_list statement($e) { $$ = code_append($1, $2); } + ; + +block_statement($e): + '{' statement_list($e) '}' { $$ = $2; } + ; +%% + +extern int YYLEX_DECL(); +extern void YYERROR_DECL(); + +extern Scope *global_scope; + +extern Decl * lookup(Scope *scope, char *id); +extern Scope * new_scope(Scope *outer_scope); +extern Scope * start_fn_def(Scope *scope, Decl *fn_decl); +extern void finish_fn_def(Decl *fn_decl, Code *block); +extern Type * type_combine(Type *specs, Type *spec); +extern Type * bare_extern(void); +extern Type * bare_register(void); +extern Type * bare_static(void); +extern Type * bare_const(void); +extern Type * bare_volatile(void); +extern Decl * declare(Scope *scope, char *id, Type *type); +extern Decl * make_pointer(Decl *decl, Type *type); +extern Decl * make_array(Type *type, Expr *expr); +extern Decl * build_function(Decl *decl, Decl_List *dlist, Type *type); +extern Decl_List * append_dlist(Decl_List *dlist, Decl *decl); +extern Decl_List * build_dlist(Decl *decl); +extern Expr * build_expr(Expr *left, enum Operator op, Expr *right); +extern Expr * var_expr(Scope *scope, char *id); +extern Code * build_expr_code(Expr *expr); +extern Code * build_if(Expr *cond_expr, Code *then_stmt, Code *else_stmt); +extern Code * code_append(Code *stmt_list, Code *stmt); |