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/**
*    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/>.
*/

/* builder.h

*/

#pragma once

#include "../stdafx.h"

namespace mongo {

class BufBuilder {
public:
    BufBuilder(int initsize = 512) : size(initsize) {
        data = (char *) malloc(size);
        assert(data);
        l = 0;
    }
    ~BufBuilder() {
        kill();
    }

    void kill() {
        if ( data ) {
            free(data);
            data = 0;
        }
    }

    /* leave room for some stuff later */
    void skip(int n) {
        grow(n);
    }

    /* note this may be deallocated (realloced) if you keep writing. */
    char* buf() {
        return data;
    }

    /* assume ownership of the buffer - you must then free it */
    void decouple() {
        data = 0;
    }

    template<class T> void append(T j) {
        *((T*)grow(sizeof(T))) = j;
    }
    void append(short j) {
        append<short>(j);
    }
    void append(int j) {
        append<int>(j);
    }
    void append(unsigned j) {
        append<unsigned>(j);
    }
    void append(bool j) {
        append<bool>(j);
    }
    void append(double j) {
        append<double>(j);
    }

    void append(void *src, int len) {
        memcpy(grow(len), src, len);
    }

    void append(const char *str) {
        append((void*) str, strlen(str)+1);
    }

    int len() {
        return l;
    }

private:
    /* returns the pre-grow write position */
    char* grow(int by) {
        int oldlen = l;
        l += by;
        if ( l > size ) {
            int a = size * 2;
            if ( l > a )
                a = l + 16 * 1024;
            assert( a < 64 * 1024 * 1024 );
            data = (char *) realloc(data, a);
            size= a;
        }
        return data + oldlen;
    }

    char *data;
    int l;
    int size;
};

} // namespace mongo