args.c

来自「compiler」· C语言 代码 · 共 89 行

/*@A (C) 1992 Allen I. Holub                                                */
#include <stdio.h>
#include "lex.h"

void    factor     ( char *tempvar );
void    term       ( char *tempvar );
void    expression ( char *tempvar );

extern char *newname( void       );
extern void freename( char *name );

statements()
{
    /*  statements -> expression SEMI  |  expression SEMI statements    */

    char *tempvar;

    while( !match(EOI) )
    {
        expression( tempvar = newname() );
        freename( tempvar );

        if( match( SEMI ) )
            advance();
        else
            fprintf( stderr, "%d: Inserting missing semicolon\n", yylineno );
    }
}

void    expression( tempvar )
char    *tempvar;
{
    /* expression  -> term expression'
     * expression' -> PLUS term expression'  |  epsilon
     */

    char  *tempvar2;

    term( tempvar );
    while( match( PLUS ) )
    {
        advance();

        term( tempvar2 = newname() );

        printf("    %s += %s\n", tempvar, tempvar2 );
        freename( tempvar2 );
    }
}

void    term( tempvar )
char    *tempvar;
{
    char  *tempvar2 ;

    factor( tempvar );
    while( match( TIMES ) )
    {
        advance();

        factor( tempvar2 = newname() );

        printf("    %s *= %s\n", tempvar, tempvar2 );
        freename( tempvar2 );
    }
}

void    factor( tempvar )
char    *tempvar;
{
    if( match(NUM_OR_ID) )
    {
        printf("    %s = %0.*s\n", tempvar, yyleng, yytext );
        advance();
    }
    else if( match(LP) )
    {
        advance();
        expression( tempvar );
        if( match(RP) )
            advance();
        else
            fprintf( stderr, "%d: Mismatched parenthesis\n", yylineno );
    }
    else
	fprintf( stderr, "%d: Number or identifier expected\n", yylineno );
}