CommonTokenFactory.js

//
/* Copyright (c) 2012-2017 The ANTLR Project. All rights reserved.
 * Use of this file is governed by the BSD 3-clause license that
 * can be found in the LICENSE.txt file in the project root.
 */
//

//
// This default implementation of {@link TokenFactory} creates
// {@link CommonToken} objects.
//

var CommonToken = require('./Token').CommonToken;

function TokenFactory() {
	return this;
}

function CommonTokenFactory(copyText) {
	TokenFactory.call(this);
    // Indicates whether {@link CommonToken//setText} should be called after
    // constructing tokens to explicitly set the text. This is useful for cases
    // where the input stream might not be able to provide arbitrary substrings
    // of text from the input after the lexer creates a token (e.g. the
    // implementation of {@link CharStream//getText} in
    // {@link UnbufferedCharStream} throws an
    // {@link UnsupportedOperationException}). Explicitly setting the token text
    // allows {@link Token//getText} to be called at any time regardless of the
    // input stream implementation.
    //
    // <p>
    // The default value is {@code false} to avoid the performance and memory
    // overhead of copying text for every token unless explicitly requested.</p>
    //
    this.copyText = copyText===undefined ? false : copyText;
	return this;
}

CommonTokenFactory.prototype = Object.create(TokenFactory.prototype);
CommonTokenFactory.prototype.constructor = CommonTokenFactory;

//
// The default {@link CommonTokenFactory} instance.
//
// <p>
// This token factory does not explicitly copy token text when constructing
// tokens.</p>
//
CommonTokenFactory.DEFAULT = new CommonTokenFactory();

CommonTokenFactory.prototype.create = function(source, type, text, channel, start, stop, line, column) {
    var t = new CommonToken(source, type, channel, start, stop);
    t.line = line;
    t.column = column;
    if (text !==null) {
        t.text = text;
    } else if (this.copyText && source[1] !==null) {
        t.text = source[1].getText(start,stop);
    }
    return t;
};

CommonTokenFactory.prototype.createThin = function(type, text) {
    var t = new CommonToken(null, type);
    t.text = text;
    return t;
};

exports.CommonTokenFactory = CommonTokenFactory;