C语言代码的语法分析的具体实现代码
时间: 2023-07-10 12:09:37 浏览: 99
对于C语言代码的语法分析,可以使用词法分析器和语法分析器来实现。以下是一个简单的基于Flex和Bison的C语言语法分析器的实现代码示例:
首先是使用Flex生成的词法分析器代码:
```c
%{
#include "y.tab.h"
%}
%%
"auto" { return AUTO; }
"break" { return BREAK; }
"case" { return CASE; }
// ...
[0-9]+ { yylval.num = atoi(yytext); return NUM; }
[a-zA-Z_][a-zA-Z0-9_]* { yylval.str = strdup(yytext); return ID; }
";" { return SEMICOLON; }
"," { return COMMA; }
"+" { return PLUS; }
"-" { return MINUS; }
"*" { return TIMES; }
"/" { return DIVIDE; }
"(" { return LPAREN; }
")" { return RPAREN; }
"{" { return LBRACE; }
"}" { return RBRACE; }
"=" { return ASSIGN; }
"==" { return EQ; }
"!=" { return NEQ; }
"<" { return LT; }
">" { return GT; }
"<=" { return LTE; }
">=" { return GTE; }
"if" { return IF; }
"else" { return ELSE; }
"while" { return WHILE; }
"return" { return RETURN; }
"int" { return INT; }
"float" { return FLOAT; }
"double" { return DOUBLE; }
"char" { return CHAR; }
"void" { return VOID; }
[ \t\n] /* ignore whitespace */
. { yyerror("Unknown character"); }
%%
int yywrap() {
return 1;
}
```
然后是使用Bison生成的语法分析器代码:
```c
%{
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
int yylex();
void yyerror(const char*);
%}
%token AUTO BREAK CASE CHAR CONTINUE DEFAULT DO DOUBLE ELSE ENUM
%token EXTERN FLOAT FOR GOTO IF INT LONG REGISTER RETURN SHORT
%token SIGNED SIZEOF STATIC STRUCT SWITCH TYPEDEF UNION UNSIGNED
%token VOID VOLATILE WHILE
%token NUM ID
%token PLUS MINUS TIMES DIVIDE ASSIGN SEMICOLON COMMA LPAREN RPAREN LBRACE RBRACE EQ NEQ LT GT LTE GTE
%left PLUS MINUS
%left TIMES DIVIDE
%right UMINUS
%start program
%%
program: declaration_list {
printf("Syntax analysis completed successfully!\n");
exit(0);
}
declaration_list: declaration
| declaration_list declaration
;
declaration: type_specifier ID SEMICOLON
| type_specifier ID LBRACE RBRACE SEMICOLON
| type_specifier ID LBRACE parameter_list RBRACE SEMICOLON
| type_specifier ID LPAREN RPAREN LBRACE RBRACE
| type_specifier ID LPAREN parameter_list RPAREN LBRACE RBRACE
| type_specifier ID LPAREN RPAREN SEMICOLON
| type_specifier ID LPAREN parameter_list RPAREN SEMICOLON
;
type_specifier: INT
| FLOAT
| DOUBLE
| CHAR
| VOID
;
parameter_list: parameter_declaration
| parameter_list COMMA parameter_declaration
;
parameter_declaration: type_specifier ID
| type_specifier TIMES ID
;
%%
void yyerror(const char* msg) {
printf("Error: %s\n", msg);
exit(1);
}
int main() {
yyparse();
return 0;
}
```
这里的例子只是一个简单的示例,实际上C语言的语法非常复杂,需要更复杂的语法分析器来进行处理。此外,使用Flex和Bison生成的代码仅仅是语法分析器的一部分,还需要添加符号表、类型检查、中间代码生成等步骤来实现一个完整的编译器。
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