bison对SysY语⾔进行语法分析 实现代码

以下是一个简单的使用Bison对SysY语言进行语法分析的示例代码：

%{
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
%}

%token INT ID IF ELSE WHILE RETURN
%token <int> NUM

%%

program:
    function_list
    ;

function_list:
    function
    | function_list function
    ;

function:
    type_specifier ID '(' parameter_list ')' compound_stmt
    ;

type_specifier:
    INT
    ;

parameter_list:
    parameter_decl
    | parameter_list ',' parameter_decl
    ;

parameter_decl:
    type_specifier ID
    ;

compound_stmt:
    '{' local_declarations statement_list '}'
    ;

local_declarations:
    /* empty */
    | local_declarations var_declaration
    ;

var_declaration:
    type_specifier ID ';'
    ;

statement_list:
    /* empty */
    | statement_list statement
    ;

statement:
    expression_stmt
    | compound_stmt
    | selection_stmt
    | iteration_stmt
    | return_stmt
    ;

expression_stmt:
    expression ';'
    | ';'
    ;

selection_stmt:
    IF '(' expression ')' statement
    | IF '(' expression ')' statement ELSE statement
    ;

iteration_stmt:
    WHILE '(' expression ')' statement
    ;

return_stmt:
    RETURN ';'
    | RETURN expression ';'
    ;

expression:
    assignment_expression
    ;

assignment_expression:
    logical_or_expression
    | unary_expression '=' assignment_expression
    ;

logical_or_expression:
    logical_and_expression
    | logical_or_expression OR_OP logical_and_expression
    ;

logical_and_expression:
    equality_expression
    | logical_and_expression AND_OP equality_expression
    ;

equality_expression:
    relational_expression
    | equality_expression EQ_OP relational_expression
    | equality_expression NE_OP relational_expression
    ;

relational_expression:
    additive_expression
    | relational_expression '<' additive_expression
    | relational_expression '>' additive_expression
    | relational_expression LE_OP additive_expression
    | relational_expression GE_OP additive_expression
    ;

additive_expression:
    multiplicative_expression
    | additive_expression '+' multiplicative_expression
    | additive_expression '-' multiplicative_expression
    ;

multiplicative_expression:
    unary_expression
    | multiplicative_expression '*' unary_expression
    | multiplicative_expression '/' unary_expression
    ;

unary_expression:
    postfix_expression
    | '-' unary_expression
    | '!' unary_expression
    ;

postfix_expression:
    primary_expression
    | ID '(' argument_list ')'
    ;

primary_expression:
    ID
    | NUM
    | '(' expression ')'
    ;

argument_list:
    /* empty */
    | expression
    | argument_list ',' expression
    ;

%%

int main(int argc, char **argv) {
    yyparse();
    return 0;
}

void yyerror(const char *msg) {
    fprintf(stderr, "Syntax error: %s\n", msg);
    exit(1);
}

这段代码定义了SysY语言的语法规则，并通过Bison的语法规则定义语言的语法结构。通过在main函数中调用yyparse函数，可以启动语法分析器进行语法分析。当语法分析器遇到错误时，会通过yyerror函数输出错误信息并退出程序。