rockbox/apps/plugins/searchengine/parser.c

/***************************************************************************
 *             __________               __   ___.
 *   Open      \______   \ ____   ____ |  | _\_ |__   _______  ___
 *   Source     |       _//  _ \_/ ___\|  |/ /| __ \ /  _ \  \/  /
 *   Jukebox    |    |   (  <_> )  \___|    < | \_\ (  <_> > <  <
 *   Firmware   |____|_  /\____/ \___  >__|_ \|___  /\____/__/\_ \
 *                     \/            \/     \/    \/            \/
 * $Id$
 *
 * Copyright (C) 2005 by Michiel van der Kolk 
 *
 * All files in this archive are subject to the GNU General Public License.
 * See the file COPYING in the source tree root for full license agreement.
 *
 * This software is distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY
 * KIND, either express or implied.
 *
 ****************************************************************************/
#include "searchengine.h"
#include "token.h"
#include "dbinterface.h"
#include "parser.h"

struct token *tokenbuffer,*currentToken;
int currentindex;
int syntaxerror;
char errormsg[250];

unsigned char *parse(struct token *tokenbuf) {
	unsigned char *ret=0;
	currentindex=0;
	syntaxerror=0;
	tokenbuffer=tokenbuf;
	database_init();
	currentToken=&tokenbuffer[currentindex];
	PUTS("parse");
	ret=parseMExpr();
	if(syntaxerror) {
		PUTS("Syntaxerror");
		rb->splash(HZ*3,true,errormsg);
	}
	parser_accept(TOKEN_EOF);
	return ret;
}

void parser_acceptIt(void) {
        if(syntaxerror) return;
	currentToken=&tokenbuffer[++currentindex];
}

int parser_accept(unsigned char kind) {
	if(currentToken->kind!=kind) {
	   syntaxerror=1;
	   rb->snprintf(errormsg,250,"'%d' found where '%d' expected\n",currentToken->kind,kind);
	   return 0;
	}
	else {
	  parser_acceptIt();
	  return 1;
	}
}

unsigned char *parseCompareNum() {
	struct token *number1,*number2;
	unsigned char *ret;
	int i,n1=-1,n2=-1;
	int op;
        if(syntaxerror) return 0;
        PUTS("parseCompareNum");
        if(currentToken->kind==TOKEN_NUM ||
		currentToken->kind==TOKEN_NUMIDENTIFIER) {
	   number1=currentToken;	
	   parser_acceptIt();
	}
	else {
  	   syntaxerror=1;
	   rb->snprintf(errormsg,250,"'%d' found where NUM/NUMID expected\n",currentToken->kind);
           return 0;
	}
	if(currentToken->kind>=TOKEN_GT && currentToken->kind <= TOKEN_NE) {
		op=currentToken->kind;
		parser_acceptIt();
	}
	else {
	   syntaxerror=1;
	   rb->snprintf(errormsg,250,"'%d' found where NUMOP expected\n",currentToken->kind);
	   return 0;
	}
        if(currentToken->kind==TOKEN_NUM ||
                currentToken->kind==TOKEN_NUMIDENTIFIER) {
           number2=currentToken;
           parser_acceptIt();
        }
        else {
           syntaxerror=1;
	   rb->snprintf(errormsg,250,"'%d' found where NUM/NUMID expected\n",currentToken->kind);
	   return 0;
	}
	ret=my_malloc(sizeof(unsigned char)*rb->tagdbheader->filecount);
	if(number1->kind==TOKEN_NUM)
		n1=getvalue(number1);
	if(number2->kind==TOKEN_NUM)
		n2=getvalue(number2);
	for(i=0;i<rb->tagdbheader->filecount;i++) {
		loadentry(i);
		if(number1->kind==TOKEN_NUMIDENTIFIER)
		  n1=getvalue(number1);
		if(number2->kind==TOKEN_NUMIDENTIFIER)
		  n2=getvalue(number2);
		switch(op) {
			case TOKEN_GT:
				ret[i]=n1 > n2;
				break;
			case TOKEN_GTE:
				ret[i]=n1 >= n2;
				break;
			case TOKEN_LT:
				ret[i]=n1 < n2;
				break;
			case TOKEN_LTE:
				ret[i]=n1 <= n2;
				break;
			case TOKEN_EQ:
				ret[i]=n1 == n2;
				break;
			case TOKEN_NE:
				ret[i]=n1 != n2;
				break;
		}
	}
	return ret;
}

unsigned char *parseCompareString() {
        struct token *string1,*string2;
        unsigned char *ret;
	char *s1=NULL,*s2=NULL;
        int i,contains;
        if(syntaxerror) return 0;
        PUTS("parseCompareString");
        if(currentToken->kind==TOKEN_STRING ||
                currentToken->kind==TOKEN_STRINGIDENTIFIER) {
           string1=currentToken;
           parser_acceptIt();
        }
        else {
	   syntaxerror=1;
	   rb->snprintf(errormsg,250,"'%d' found where STRING/STRINGID expected\n",currentToken->kind);
	   return 0;
        }
	
	contains=currentToken->kind==TOKEN_CONTAINS;
        if(currentToken->kind==TOKEN_CONTAINS ||
               currentToken->kind==TOKEN_EQUALS)
	  parser_acceptIt();
	else {
           syntaxerror=1;
	   rb->snprintf(errormsg,250,"'%d' found where CONTAINS/EQUALS expected\n",currentToken->kind);
           return 0;
	}
	
        if(currentToken->kind==TOKEN_STRING ||
                currentToken->kind==TOKEN_STRINGIDENTIFIER) {
           string2=currentToken;
           parser_acceptIt();
        }
        else {
	   syntaxerror=1;
	   rb->snprintf(errormsg,250,"'%d' found where STRING/STRINGID expected\n",currentToken->kind);
	   return 0;
        }
        ret=my_malloc(sizeof(unsigned char)*rb->tagdbheader->filecount);
	if(string1->kind==TOKEN_STRING)
		s1=getstring(string1);
	if(string2->kind==TOKEN_STRING)
		s2=getstring(string2);
        for(i=0;i<rb->tagdbheader->filecount;i++) {
                loadentry(i);
		if(string1->kind==TOKEN_STRINGIDENTIFIER)
                  s1=getstring(string1);
		if(string2->kind==TOKEN_STRINGIDENTIFIER)
                  s2=getstring(string2);
		if(contains)
	          ret[i]=rb->strcasestr(s1,s2)!=0;
		else
		  ret[i]=rb->strcasecmp(s1,s2)==0;
        }
        return ret;
}

unsigned char *parseExpr() {
	unsigned char *ret;
	int i;
	if(syntaxerror) return 0;
	PUTS("parseExpr");       
	switch(currentToken->kind) {
	    case TOKEN_NOT:
		        parser_accept(TOKEN_NOT);
			PUTS("parseNot");
 	                ret = parseExpr();
			if(ret==NULL) return 0;
 	                for(i=0;i<rb->tagdbheader->filecount;i++)
		          ret[i]=!ret[i];
			break;
	    case TOKEN_LPAREN:
			parser_accept(TOKEN_LPAREN);
			ret = parseMExpr();
			if(ret==NULL) return 0;
			parser_accept(TOKEN_RPAREN);
			break;
	    case TOKEN_NUM:
	    case TOKEN_NUMIDENTIFIER:
			ret = parseCompareNum();
                        if(ret==NULL) return 0;
			break;
	    case TOKEN_STRING:
	    case TOKEN_STRINGIDENTIFIER:
			ret = parseCompareString();
                        if(ret==NULL) return 0;
 			break;
	    default:
			// error, unexpected symbol
			syntaxerror=1;
			rb->snprintf(errormsg,250,"unexpected '%d' found at parseExpr\n",currentToken->kind);
			ret=0;
			break;
	}
	return ret;
}

unsigned char *parseMExpr() {
	unsigned char *ret,*ret2;
	int i;
        if(syntaxerror) return 0;
	PUTS("parseMExpr");       
	ret=parseExpr();
	while(currentToken->kind==TOKEN_AND||currentToken->kind==TOKEN_OR) {
		switch(currentToken->kind) {
			case TOKEN_AND:
				parser_accept(TOKEN_AND);
				PUTS("parseAnd");
				ret2 = parseExpr();
				if(ret2==NULL) return 0;
                        	for(i=0;i<rb->tagdbheader->filecount;i++)
				    ret[i]=ret[i] && ret2[i];
				break;
			case TOKEN_OR:
				parser_accept(TOKEN_OR);
				PUTS("parseOr");
				ret2 = parseExpr();
				if(ret2==NULL) return 0;
				for(i=0;i<rb->tagdbheader->filecount;i++)
				    ret[i]=ret[i] || ret2[i];
				break;
		}
	}
	return ret;
}