alasql/src/422where.js

AlaSQL.js - JavaScript SQL database library for relational and graph data manipulation with support of localStorage, IndexedDB, and Excel

yy.Select.prototype.compileWhere = function(query) {
	if(this.where) {
		if(typeof this.where == "function") {
			return this.where;
		} else {
			s = this.where.toJavaScript('p',query.defaultTableid,query.defcols);
			query.wherefns = s;
//		console.log(s);
			return new Function('p,params,alasql','return '+s);
		}
	} else return function(){return true};
};



yy.Select.prototype.compileWhereJoins = function(query) {
	return;

	// TODO Fix Where optimization
	//console.log(query);

	optimizeWhereJoin(query, this.where.expression);

	//for sources compile wherefs
	query.sources.forEach(function(source) {
		if(source.srcwherefns) {
			source.srcwherefn = new Function('p,params,alasql','return '+source.srcwherefns);
		};
		if(source.wxleftfns) {
			source.wxleftfn = new Function('p,params,alasql','return '+source.wxleftfns);
		};
		if(source.wxrightfns) {
			source.wxrightfn = new Function('p,params,alasql','return '+source.wxrightfns);
		};
//		console.log(source.alias, source.wherefns)
//		console.log(source);
	});
};

function optimizeWhereJoin (query, ast) {
	if(!ast) return false;
	if(!(ast instanceof yy.Op)) return;
	if(ast.op != '=' && ast.op != 'AND') return;
	if(ast.allsome) return;

	var s = ast.toJavaScript('p',query.defaultTableid,query.defcols);
	var fsrc = [];
	query.sources.forEach(function(source,idx) {
		// Optimization allowed only for tables only
		if(source.tableid) {
			// This is a good place to remove all unnecessary optimizations
			if(s.indexOf('p[\''+source.alias+'\']')>-1) fsrc.push(source);
		};
	});
//console.log(fsrc.length);
//	if(fsrc.length < query.sources.length) return;
//	console.log(ast);
//	console.log(s);
//	console.log(fsrc.length);
	if(fsrc.length == 0) {
//		console.log('no optimization, can remove this part of ast');
		return;
	} else if (fsrc.length == 1) {

		if(!(s.match(/p\[\'.*?\'\]/g)||[])
			.every(function(s){ 
						return s == "p['"+fsrc[0].alias+"']"})) { 
			return; 
			// This is means, that we have column from parent query
			// So we return without optimization
		} 

		var src = fsrc[0]; // optmiization source
		src.srcwherefns = src.srcwherefns ? src.srcwherefns+'&&'+s : s;

		if((ast instanceof yy.Op) && (ast.op == '=' && !ast.allsome)) {
			if(ast.left instanceof yy.Column) {
				var ls = ast.left.toJavaScript('p',query.defaultTableid,query.defcols);
				var rs = ast.right.toJavaScript('p',query.defaultTableid,query.defcols);
				if(rs.indexOf('p[\''+fsrc[0].alias+'\']') == -1) {
					fsrc[0].wxleftfns = ls; 
					fsrc[0].wxrightfns = rs; 
				} 
			} if(ast.right instanceof yy.Column) {
				var ls = ast.left.toJavaScript('p',query.defaultTableid,query.defcols);
				var rs = ast.right.toJavaScript('p',query.defaultTableid,query.defcols);
				if(ls.indexOf('p[\''+fsrc[0].alias+'\']') == -1) {
					fsrc[0].wxleftfns = rs; 
					fsrc[0].wxrightfns = ls; 
				} 
			}
		}
		ast.reduced = true;  // To do not duplicate wherefn and srcwherefn
		return;
	} else {
		if(ast.op = 'AND') {
			optimizeWhereJoin(query,ast.left);
			optimizeWhereJoin(query,ast.right);
		} 
	}

};