秋梦无痕

from: http://www.lysator.liu.se/c/ANSI-C-grammar-l.html

In 1985, Jeff Lee published this Lex specification together with a Yacc grammar for the April 30, 1985 ANSI C draft. Tom Stockfisch reposted both to net.sources in 1987; that original, as mentioned in the answer to question 17.25 of the comp.lang.c FAQ, can be ftp'ed from ftp.uu.net, file usenet/net.sources/ansi.c.grammar.Z.
I intend to keep this version as close to the current C Standard grammar as possible; please let me know if you discover discrepancies.

[url=mailto:jutta@pobox.com]Jutta Degener[/url], 1995

D [0-9]
L [a-zA-Z_]
H [a-fA-F0-9]
E [Ee][+-]?{D}+
FS (f|F|l|L)
IS (u|U|l|L)*

%{
#include <stdio.h>
#include "y.tab.h"

void count();
%}

%%
"/*" { comment(); }

"auto" { count(); return(AUTO); }
"break" { count(); return(BREAK); }
"case" { count(); return(CASE); }
"char" { count(); return(CHAR); }
"const" { count(); return(CONST); }
"continue" { count(); return(CONTINUE); }
"default" { count(); return(DEFAULT); }
"do" { count(); return(DO); }
"double" { count(); return(DOUBLE); }
"else" { count(); return(ELSE); }
"enum" { count(); return(ENUM); }
"extern" { count(); return(EXTERN); }
"float" { count(); return(FLOAT); }
"for" { count(); return(FOR); }
"goto" { count(); return(GOTO); }
"if" { count(); return(IF); }
"int" { count(); return(INT); }
"long" { count(); return(LONG); }
"register" { count(); return(REGISTER); }
"return" { count(); return(RETURN); }
"short" { count(); return(SHORT); }
"signed" { count(); return(SIGNED); }
"sizeof" { count(); return(SIZEOF); }
"static" { count(); return(STATIC); }
"struct" { count(); return(STRUCT); }
"switch" { count(); return(SWITCH); }
"typedef" { count(); return(TYPEDEF); }
"union" { count(); return(UNION); }
"unsigned" { count(); return(UNSIGNED); }
"void" { count(); return(VOID); }
"volatile" { count(); return(VOLATILE); }
"while" { count(); return(WHILE); }

{L}({L}|{D})* { count(); return(check_type()); }

0[xX]{H}+{IS}? { count(); return(CONSTANT); }
0{D}+{IS}? { count(); return(CONSTANT); }
{D}+{IS}? { count(); return(CONSTANT); }
L?'(\\.|[^\\'])+' { count(); return(CONSTANT); }

{D}+{E}{FS}? { count(); return(CONSTANT); }
{D}*"."{D}+({E})?{FS}? { count(); return(CONSTANT); }
{D}+"."{D}*({E})?{FS}? { count(); return(CONSTANT); }

L?\"(\\.|[^\\"])*\" { count(); return(STRING_LITERAL); }

"..." { count(); return(ELLIPSIS); }
">>=" { count(); return(RIGHT_ASSIGN); }
"<<=" { count(); return(LEFT_ASSIGN); }
"+=" { count(); return(ADD_ASSIGN); }
"-=" { count(); return(SUB_ASSIGN); }
"*=" { count(); return(MUL_ASSIGN); }
"/=" { count(); return(DIV_ASSIGN); }
"%=" { count(); return(MOD_ASSIGN); }
"&=" { count(); return(AND_ASSIGN); }
"^=" { count(); return(XOR_ASSIGN); }
"|=" { count(); return(OR_ASSIGN); }
">>" { count(); return(RIGHT_OP); }
"<<" { count(); return(LEFT_OP); }
"++" { count(); return(INC_OP); }
"--" { count(); return(DEC_OP); }
"->" { count(); return(PTR_OP); }
"&&" { count(); return(AND_OP); }
"||" { count(); return(OR_OP); }
"<=" { count(); return(LE_OP); }
">=" { count(); return(GE_OP); }
"==" { count(); return(EQ_OP); }
"!=" { count(); return(NE_OP); }
";" { count(); return(';'); }
("{"|"<%") { count(); return('{'); }
("}"|"%>") { count(); return('}'); }
"," { count(); return(','); }
":" { count(); return(':'); }
"=" { count(); return('='); }
"(" { count(); return('('); }
")" { count(); return(')'); }
("["|"<:") { count(); return('['); }
("]"|":>") { count(); return(']'); }
"." { count(); return('.'); }
"&" { count(); return('&'); }
"!" { count(); return('!'); }
"~" { count(); return('~'); }
"-" { count(); return('-'); }
"+" { count(); return('+'); }
"*" { count(); return('*'); }
"/" { count(); return('/'); }
"%" { count(); return('%'); }
"<" { count(); return('<'); }
">" { count(); return('>'); }
"^" { count(); return('^'); }
"|" { count(); return('|'); }
"?" { count(); return('?'); }

[ \t\v\n\f] { count(); }
. { /* ignore bad characters */ }

%%

yywrap()
{
return(1);
}

comment()
{
char c, c1;

loop:
while ((c = input()) != '*' && c != 0)
putchar(c);

if ((c1 = input()) != '/' && c != 0)
{
unput(c1);
goto loop;
}

if (c != 0)
putchar(c1);
}

int column = 0;

void count()
{
int i;

for (i = 0; yytext[i] != '\0'; i++)
if (yytext[i] == '\n')
column = 0;
else if (yytext[i] == '\t')
column += 8 - (column % 8);
else
column++;

ECHO;
}

int check_type()
{
/*
* pseudo code --- this is what it should check
*
* if (yytext == type_name)
* return(TYPE_NAME);
*
* return(IDENTIFIER);
*/

/*
* it actually will only return IDENTIFIER
*/

return(IDENTIFIER);
}