mongodb/db/minilex.h

// minilex.h
// mini js lexical analyzer.  idea is to be dumb and fast.

/**
*    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/>.
*/

namespace mongo {

#if defined(_WIN32)
    
} // namespace mongo

#include <hash_map>
using namespace stdext;

namespace mongo {
    
    typedef const char * MyStr;
    struct less_str {
        bool operator()(const MyStr & x, const MyStr & y) const {
            if ( strcmp(x, y) > 0)
                return true;
            
            return false;
        }
    };
    
    typedef hash_map<const char*, int, hash_compare<const char *, less_str> > strhashmap;
    
#else
    
} // namespace mongo

#include <ext/hash_map>

namespace mongo {
    
    using namespace __gnu_cxx;

    typedef const char * MyStr;
    struct eq_str {
        bool operator()(const MyStr & x, const MyStr & y) const {
            if ( strcmp(x, y) == 0)
                return true;
            
            return false;
        }
    };
    
    typedef hash_map<const char*, int, hash<const char *>, eq_str > strhashmap;
    
#endif
    
    struct MiniLex {
        strhashmap reserved;
        bool ic[256]; // ic=Identifier Character
        bool starter[256];

        // dm: very dumb about comments and escaped quotes -- but we are faster then at least,
        // albeit returning too much (which is ok for jsbobj current usage).
        void grabVariables(char *code /*modified and must stay in scope*/, strhashmap& vars) {
            char *p = code;
            char last = 0;
            while ( *p ) {
                if ( starter[*p] ) {
                    char *q = p+1;
                    while ( *q && ic[*q] ) q++;
                    const char *identifier = p;
                    bool done = *q == 0;
                    *q = 0;
                    if ( !reserved.count(identifier) ) {
                        // we try to be smart about 'obj' but have to be careful as obj.obj
                        // can happen; this is so that nFields is right for simplistic where cases
                        // so we can stop scanning in jsobj when we find the field of interest.
                        if ( strcmp(identifier,"obj")==0 && p>code && p[-1] != '.' )
                            ;
                        else
                            vars[identifier] = 1;
                    }
                    if ( done )
                        break;
                    p = q + 1;
                    continue;
                }

                if ( *p == '\'' ) {
                    p++;
                    while ( *p && *p != '\'' ) p++;
                }
                else if ( *p == '"' ) {
                    p++;
                    while ( *p && *p != '"' ) p++;
                }
                p++;
            }
        }

        MiniLex() {
            strhashmap atest;
            atest["foo"] = 3;
            assert( atest.count("bar") == 0 );
            assert( atest.count("foo") == 1 );
            assert( atest["foo"] == 3 );

            for ( int i = 0; i < 256; i++ ) {
                ic[i] = starter[i] = false;
            }
            for ( int i = 'a'; i <= 'z'; i++ )
                ic[i] = starter[i] = true;
            for ( int i = 'A'; i <= 'Z'; i++ )
                ic[i] = starter[i] = true;
            for ( int i = '0'; i <= '9'; i++ )
                ic[i] = true;
            for ( int i = 128; i < 256; i++ )
                ic[i] = starter[i] = true;
            ic['$'] = starter['$'] = true;
            ic['_'] = starter['_'] = true;

            reserved["break"] = true;
            reserved["case"] = true;
            reserved["catch"] = true;
            reserved["continue"] = true;
            reserved["default"] = true;
            reserved["delete"] = true;
            reserved["do"] = true;
            reserved["else"] = true;
            reserved["finally"] = true;
            reserved["for"] = true;
            reserved["function"] = true;
            reserved["if"] = true;
            reserved["in"] = true;
            reserved["instanceof"] = true;
            reserved["new"] = true;
            reserved["return"] = true;
            reserved["switch"] = true;
            reserved["this"] = true;
            reserved["throw"] = true;
            reserved["try"] = true;
            reserved["typeof"] = true;
            reserved["var"] = true;
            reserved["void"] = true;
            reserved["while"] = true;
            reserved["with "] = true;
        }
    };

} // namespace mongo