GopherProxy

	tforgot this - plan9port - [fork] Plan 9 from user space
	git clone git://src.adamsgaard.dk/plan9port
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	---
	commit e72e360a1a5a74d85a721b8405790593b033277b
	parent 3f6a501b4d661acb8dba53d8a857e963aad2fe6b
	Author: rsc <devnull@localhost>
	Date: Fri, 30 Dec 2005 15:56:36 +0000

	forgot this

	Diffstat:
	A src/cmd/ip/snoopy/filter.y \| 107 +++++++++++++++++++++++++++++…

	1 file changed, 107 insertions(+), 0 deletions(-)
	---
	diff --git a/src/cmd/ip/snoopy/filter.y b/src/cmd/ip/snoopy/filter.y
	t@@ -0,0 +1,107 @@
	+%{
	+#include <u.h>
	+#include <libc.h>
	+#include <ctype.h>
	+#include "dat.h"
	+
	+char yylp; / next character to be lex'd */
	+char *yybuffer;
	+char yyend; / end of buffer to be parsed */
	+%}
	+
	+%term LOR
	+%term LAND
	+%term WORD
	+%right '!'
	+%left '\|'
	+%left '&'
	+%left LOR
	+%left LAND
	+%start filter
	+%%
	+
	+filter : expr
	+ { filter = $$; }
	+ ;
	+expr : WORD
	+ { $$ = $1; }
	+ \| WORD '=' WORD
	+ { $2->l = $1; $2->r = $3; $$ = $2; }
	+ \| WORD '(' expr ')'
	+ { $1->l = $3; free($2); free($4); $$ = $1; }
	+ \| '(' expr ')'
	+ { free($1); free($3); $$ = $2; }
	+ \| expr LOR expr
	+ { $2->l = $1; $2->r = $3; $$ = $2; }
	+ \| expr LAND expr
	+ { $2->l = $1; $2->r = $3; $$ = $2; }
	+ \| '!' expr
	+ { $1->l = $2; $$ = $1; }
	+ ;
	+%%
	+
	+/*
	+ * Initialize the parsing. Done once for each header field.
	+ */
	+void
	+yyinit(char *p)
	+{
	+ yylp = p;
	+}
	+
	+int
	+yylex(void)
	+{
	+ char *p;
	+ int c;
	+
	+ if(yylp == nil \|\| *yylp == 0)
	+ return 0;
	+ while(isspace(*yylp))
	+ yylp++;
	+
	+ yylval = newfilter();
	+
	+ p = strpbrk(yylp, "!\|&()= ");
	+ if(p == 0){
	+ yylval->op = WORD;
	+ yylval->s = strdup(yylp);
	+ if(yylval->s == nil)
	+ sysfatal("parsing filter: %r");
	+ yylp = nil;
	+ return WORD;
	+ }
	+ c = *p;
	+ if(p != yylp){
	+ yylval->op = WORD;
	+ *p = 0;
	+ yylval->s = strdup(yylp);
	+ if(yylval->s == nil)
	+ sysfatal("parsing filter: %r");
	+ *p = c;
	+ yylp = p;
	+ return WORD;
	+ }
	+
	+ yylp++;
	+ if(*yylp == c)
	+ switch(c){
	+ case '&':
	+ c = LAND;
	+ yylp++;
	+ break;
	+ case '\|':
	+ c = LOR;
	+ yylp++;
	+ break;
	+ }
	+ yylval->op = c;
	+ return c;
	+}
	+
	+void
	+yyerror(char *e)
	+{
	+ USED(e);
	+ sysfatal("error parsing filter");
	+}