prototype.js string.gsub example

prototype.js中String.gsub源码学习。

// Ruby String.gsub
// In the block form, the current match is passed in as a parameter,
// and variables such as $1, $2, $`, $&, and $' will be set appropriately.
// The value returned by the block will be substituted for the match on each call.
Object.extend(String.prototype, {
    gsub: function(pattern, replacement) {
        var result = '',
            source = this,
            match;
        replacement = arguments.callee.prepareReplacement(replacement);
        console.log(replacement);
        while (source.length > 0) {
            if (match = source.match(pattern)) {
                result += source.slice(0, match.index);
                result += String.interpret(replacement(match));
                // pass match (object) to replacement(function),
                // return value replace match[0]...
                // origin Template.evaluate function recursive invoke String.gsub function
                source = source.slice(match.index + match[0].length);
            } else {
                result += source, source = '';
            }
        }
        return result;
    },

    sub: function(pattern, replacement, count) {
        replacement = this.gsub.prepareReplacement(replacement);
        count = count === undefined ? 1 : count;

        return this.gsub(pattern, function(match) {
            //alert(match.index);
            //alert(match[0]);
            if (--count < 0) return match[0];
            return replacement(match);
        });
    }
});

String.prototype.gsub.prepareReplacement = function(replacement) {
    if (typeof replacement == 'function') return replacement;
    var template = new Template(replacement);
    return function(match) {
        return template.evaluate(match)
    };
}

example

var Template = Class.create();
Template.prototype = {
    initialize: function(template, pattern) {
        alert(template.toString());
        this.template = template.toString();
    },

    evaluate: function(match_object) {
        return '<font color="red">' + this.template + '</font>';
    }
}

var str = 'ThereAreTest1AndTest2AndTest3.';
var txt = str.gsub(/test/i, 'Text');
console.log(txt);

var txt2 = str.sub(/test/i, 'Text', 2);
console.log(txt2);