overleaf/services/web/public/js/ace/edit_session/bracket_match.js

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 * Distributed under the BSD license:
 *
 * Copyright (c) 2010, Ajax.org B.V.
 * All rights reserved.
 * 
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 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
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 *       notice, this list of conditions and the following disclaimer in the
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 *       names of its contributors may be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
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define(function(require, exports, module) {
"use strict";

var TokenIterator = require("../token_iterator").TokenIterator;
var Range = require("../range").Range;


function BracketMatch() {

    this.findMatchingBracket = function(position, chr) {
        if (position.column == 0) return null;

        var charBeforeCursor = chr || this.getLine(position.row).charAt(position.column-1);
        if (charBeforeCursor == "") return null;

        var match = charBeforeCursor.match(/([\(\[\{])|([\)\]\}])/);
        if (!match)
            return null;

        if (match[1])
            return this.$findClosingBracket(match[1], position);
        else
            return this.$findOpeningBracket(match[2], position);
    };
    
    this.getBracketRange = function(pos) {
        var line = this.getLine(pos.row);
        var before = true, range;

        var chr = line.charAt(pos.column-1);
        var match = chr && chr.match(/([\(\[\{])|([\)\]\}])/);
        if (!match) {
            chr = line.charAt(pos.column);
            pos = {row: pos.row, column: pos.column + 1};
            match = chr && chr.match(/([\(\[\{])|([\)\]\}])/);
            before = false;
        }
        if (!match)
            return null;

        if (match[1]) {
            var bracketPos = this.$findClosingBracket(match[1], pos);
            if (!bracketPos)
                return null;
            range = Range.fromPoints(pos, bracketPos);
            if (!before) {
                range.end.column++;
                range.start.column--;
            }
            range.cursor = range.end;
        } else {
            var bracketPos = this.$findOpeningBracket(match[2], pos);
            if (!bracketPos)
                return null;
            range = Range.fromPoints(bracketPos, pos);
            if (!before) {
                range.start.column++;
                range.end.column--;
            }
            range.cursor = range.start;
        }
        
        return range;
    };

    this.$brackets = {
        ")": "(",
        "(": ")",
        "]": "[",
        "[": "]",
        "{": "}",
        "}": "{"
    };

    this.$findOpeningBracket = function(bracket, position, typeRe) {
        var openBracket = this.$brackets[bracket];
        var depth = 1;

        var iterator = new TokenIterator(this, position.row, position.column);
        var token = iterator.getCurrentToken();
        if (!token)
            token = iterator.stepForward();
        if (!token)
            return;
        
         if (!typeRe){
            typeRe = new RegExp(
                "(\\.?" +
                token.type.replace(".", "\\.").replace("rparen", ".paren")
                + ")+"
            );
        }
        
        // Start searching in token, just before the character at position.column
        var valueIndex = position.column - iterator.getCurrentTokenColumn() - 2;
        var value = token.value;
        
        while (true) {
        
            while (valueIndex >= 0) {
                var chr = value.charAt(valueIndex);
                if (chr == openBracket) {
                    depth -= 1;
                    if (depth == 0) {
                        return {row: iterator.getCurrentTokenRow(),
                            column: valueIndex + iterator.getCurrentTokenColumn()};
                    }
                }
                else if (chr == bracket) {
                    depth += 1;
                }
                valueIndex -= 1;
            }

            // Scan backward through the document, looking for the next token
            // whose type matches typeRe
            do {
                token = iterator.stepBackward();
            } while (token && !typeRe.test(token.type));

            if (token == null)
                break;
                
            value = token.value;
            valueIndex = value.length - 1;
        }
        
        return null;
    };

    this.$findClosingBracket = function(bracket, position, typeRe) {
        var closingBracket = this.$brackets[bracket];
        var depth = 1;

        var iterator = new TokenIterator(this, position.row, position.column);
        var token = iterator.getCurrentToken();
        if (!token)
            token = iterator.stepForward();
        if (!token)
            return;

        if (!typeRe){
            typeRe = new RegExp(
                "(\\.?" +
                token.type.replace(".", "\\.").replace("lparen", ".paren")
                + ")+"
            );
        }

        // Start searching in token, after the character at position.column
        var valueIndex = position.column - iterator.getCurrentTokenColumn();

        while (true) {

            var value = token.value;
            var valueLength = value.length;
            while (valueIndex < valueLength) {
                var chr = value.charAt(valueIndex);
                if (chr == closingBracket) {
                    depth -= 1;
                    if (depth == 0) {
                        return {row: iterator.getCurrentTokenRow(),
                            column: valueIndex + iterator.getCurrentTokenColumn()};
                    }
                }
                else if (chr == bracket) {
                    depth += 1;
                }
                valueIndex += 1;
            }

            // Scan forward through the document, looking for the next token
            // whose type matches typeRe
            do {
                token = iterator.stepForward();
            } while (token && !typeRe.test(token.type));

            if (token == null)
                break;

            valueIndex = 0;
        }
        
        return null;
    };
}
exports.BracketMatch = BracketMatch;

});