mongodb/db/matcher.h

// matcher.h

/* JSMatcher is our boolean expression evaluator for "where" clauses */

/**
*    Copyright (C) 2008 10gen Inc.
*  
*    This program is free software: you can redistribute it and/or  modify
*    it under the terms of the GNU Affero General Public License, version 3,
*    as published by the Free Software Foundation.
*  
*    This program is distributed in the hope that it will be useful,
*    but WITHOUT ANY WARRANTY; without even the implied warranty of
*    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
*    GNU Affero General Public License for more details.
*  
*    You should have received a copy of the GNU Affero General Public License
*    along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#pragma once

class RegexMatcher { 
public:
	const char *fieldName;
	pcrecpp::RE *re;
    bool inIndex;
	RegexMatcher() { re = 0; inIndex = false; }
	~RegexMatcher() { delete re; }
};

class BasicMatcher { 
public:
    BSONElement toMatch;
	int compareOp;
    bool inIndex;
};

// SQL where clause equivalent
class Where; 

/* Match BSON objects against a query pattern.

   e.g.
       db.foo.find( { a : 3 } );

   { a : 3 } is the pattern object.

   GT/LT:
   { a : { $gt : 3 } } 

   Not equal:
   { a : { $ne : 3 } } 

   TODO: we should rewrite the matcher to be more an AST style.
*/
class JSMatcher : boost::noncopyable { 
	int matchesDotted(
		const char *fieldName, 
		BSONElement& toMatch, BSONObj& obj, 
		int compareOp, bool *deep, bool isArr = false);

	struct element_lt
	{
		bool operator()(const BSONElement& l, const BSONElement& r) const
		{
			int x = (int) l.type() - (int) r.type();
			if( x < 0 ) return true;
			if( x > 0 ) return false;
			return compareElementValues(l,r) < 0;
		}
	};
public:
	enum { 
		Equality = 0,
		LT = 0x1,
		LTE = 0x3,
		GTE = 0x6,
		GT = 0x4, 
		opIN = 0x8, // { x : { $in : [1,2,3] } }
        NE = 0x9
	};

	static int opDirection(int op) { 
		return op <= LTE ? -1 : 1;
	}

	JSMatcher(BSONObj& pattern, BSONObj indexKeyPattern);

	~JSMatcher();

	/* indexMatches - true if indexKeyPattern matched ok.
       deep - means we looked into arrays for a match 
    */
	bool matches(BSONObj& j, bool& indexMatches, bool *deep = 0);

	int getN() { return n; }

private:
    void addBasic(BSONElement e, int c, BSONObj& indexKeyPattern) {
        BasicMatcher bm;
        bm.toMatch = e;
        bm.compareOp = c;
        bm.inIndex = indexKeyPattern.hasElement(e.fieldName());
        basics.push_back(bm);
        n++;
    }

	int valuesMatch(BSONElement& l, BSONElement& r, int op);

	set<BSONElement,element_lt> *in; // set if query uses $in
	Where *where;                    // set if query uses $where
	BSONObj& jsobj;                  // the query pattern.  e.g., { name: "joe" }

    vector<BasicMatcher> basics;
	int n;                           // # of basicmatcher items

	RegexMatcher regexs[4];
	int nRegex;

	// so we delete the mem when we're done:
	BSONObjBuilder *builders[8];
	int nBuilders;

    bool checkInIndex;
};