ycmm.y

使用yacc和lex编写的cmm语言的词法分析和语法分析程序.

%{

#include <stdio.h>

%}

%token IDENTIFIER CONSTANT
%token GE_OP LE_OP EQ_OP NE_OP AND_OP OR_OP
%token INT REAL
%token WHILE WRITE READ IF ELSE

%nonassoc IF
%nonassoc ELSE
%right '='
%left OR_OP
%left AND_OP
%left '>' '<' EQ_OP NE_OP LE_OP GE_OP
%left '+' '-'
%left '*' '/' '%'
%right UNARY
%left '.' '(' '['
%start program

%%

program
      : decls xstmts
      | xstmts
      ;

unop
      : '-'
      | '+'
      | '~'
      | '!'

expr
      : nonnull_exprlist
      ;

nonnull_exprlist
      : expr_no_commas
      | nonnull_exprlist ',' expr_no_commas
      ;

unary_expr
      : primary 
      | unop cast_expr %prec UNARY 
      ;

cast_expr
      : unary_expr 
      ;

expr_no_commas
      : cast_expr
      | expr_no_commas '+' expr_no_commas
      | expr_no_commas '-' expr_no_commas
      | expr_no_commas '*' expr_no_commas
      | expr_no_commas '/' expr_no_commas
      | expr_no_commas '%' expr_no_commas
      | expr_no_commas '=' expr_no_commas
      | expr_no_commas '<' expr_no_commas
      | expr_no_commas '>' expr_no_commas
      | expr_no_commas EQ_OP expr_no_commas
      | expr_no_commas NE_OP expr_no_commas
      | expr_no_commas LE_OP expr_no_commas
      | expr_no_commas GE_OP expr_no_commas
      | expr_no_commas AND_OP expr_no_commas
      | expr_no_commas OR_OP expr_no_commas

primary
      : IDENTIFIER 
      | CONSTANT  
      | '(' expr ')'
      | primary '[' expr ']'
      ;

lineno_decl
      :save_filename save_lineno decl
      ;

decls
      : lineno_decl
      | decls lineno_decl
      ;

setspecs:
        ;
decl
      : typed_declspecs setspecs initdecls ';'
      ;

typed_declspecs
      : typespec
      ;

typespec
      : INT
      | REAL
      ;

initdecls
      : initdcl
      | initdecls ',' initdcl
      ;

initdcl
      : declarator '=' init
      | declarator
      ;

init
      : expr_no_commas
      | '{' '}'
      | '{' initlist '}'
      | '{' initlist ',' '}'

initlist
      : init
      | initlist ',' init
      ;

declarator
      : notype_declarator
      ;

notype_declarator
      : IDENTIFIER
      | notype_declarator '[' expr ']'
      | notype_declarator '[' ']'
      ;

stmts
      : lineno_stmt_or_label
      | stmts lineno_stmt_or_label
      ;

lineno_stmt_or_label
      : save_filename save_lineno stmt_or_label
      ;

stmt_or_label
      : stmt
      | label
      ;

label
      : IDENTIFIER ':'
      ;

xstmts
      : 
      | stmts
      ;

compstmt
      : '{' decls xstmts '}'
      | '{' xstmts '}'
      ;

simple_if
      : if_prefix lineno_labeled_stmt
      ;

if_prefix
      : IF '(' expr ')'
      ;

save_filename
      :
      ;

save_lineno
      :
      ;

lineno_labeled_stmt
      : save_filename save_lineno stmt
      ;

stmt
      : compstmt                                
      | expr ';'                                
      | simple_if ELSE lineno_labeled_stmt      
      | simple_if %prec IF                      
      | WHILE '(' expr ')' lineno_labeled_stmt  
      | WRITE '(' expr ')' ';'                 
      | READ '(' identifiers ')' ';'          

identifiers
      : IDENTIFIER
      | identifiers ',' IDENTIFIER
      ;
%%

int main () {
      yyparse();
}