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

#include <pcrecpp.h>

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();

    /* deep - means we looked into arrays for a match
    */
    bool matches(BSONObj& j, 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;
};