exceljs/lib/utils/string-buf.js

Excel Workbook Manager - Read and Write xlsx and csv Files.

/**
 * Copyright (c) 2015 Guyon Roche
 * 
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * 
 */
"use strict";

var utils = require("./utils");

// StringBuf - a way to keep string memory operations to a minimum
// while building the strings for the xml files
var StringBuf = module.exports = function(options) {
    this._buf = new Buffer((options && options.size) || 16384);
    this._encoding = (options && options.encoding) || 'utf8';
    
    // where in the buffer we are at
    this._inPos = 0;
    
    // for use by toBuffer()
    this._buffer = undefined;
}

StringBuf.prototype = {
    
    get length() {
        return this._inPos;
    },
    get capacity() {
        return this._buf.length;
    },
    get buffer() {
        return this._buf;
    },
    
    toBuffer: function() {
        // return the current data as a single enclosing buffer
        if (!this._buffer) {
            this._buffer = new Buffer(this.length);
            this._buf.copy(this._buffer, 0, 0, this.length);
        }
        return this._buffer;
    },
    
    reset: function(position) {
        position = position || 0;
        this._buffer = undefined;
        this._inPos = position;
    },
    
    _grow: function(min) {
        for (var size = this._buf.length * 2; size < min; size *= 2);
        //console.log("Grow: min="+min + ", size="+size);
        var buf = new Buffer(size);
        this._buf.copy(buf, 0);
        this._buf = buf;
    },
    
    addText: function(text) {
        this._buffer = undefined;
        
        //console.log("addText: writing " + text.length + " at " + this._inPos + ", size= "+ this._buf.length);
        var inPos = this._inPos + this._buf.write(text, this._inPos, this._encoding);
        
        // if we've hit (or nearing capacity), grow the buf
        while (inPos >= this._buf.length - 4) {
            this._grow(this._inPos + text.length);
            
            // keep trying to write until we've completely written the text
            inPos = this._inPos + this._buf.write(text, this._inPos, this._encoding);
        }
        
        this._inPos = inPos;
    },
    
    addStringBuf: function(inBuf) {
        if (inBuf.length) {
            this._buffer = undefined;
            
            if (this.length + inBuf.length > this.capacity) {
                this._grow(this.length + inBuf.length);
            }
            inBuf._buf.copy(this._buf, this._inPos, 0, inBuf.length);
            this._inPos += inBuf.length;
        }
    }
};