V3: Utility functions

[Frederico Caldeira Knabben]

The CKEditor prototype defines the CKEDITOR.tools object, which holds several utility functions using all around our code.

Function under this object must be totally generic, independent of other objects and classes.

[Frederico Caldeira Knabben]

The function defined in that object should be reviewed.

[Martin Kou]

Is there any reason the *trim functions are written like this?

        trim : (function()
        {
                // We are not using \s because we don't want "non-breaking spaces" to be caught.
                var trimRegex = /(?:^[ \t\n\r]+)|(?:[ \t\n\r]+$)/g;
                return function( str )
                {
                        return str.replace( trimRegex, '' ) ;
                };
        })(),

        /**
         * Remove spaces from the start (left) of a string. The following
         * characters are removed: space, tab, line break, line feed.
         * @param {String} str The text from which remove the spaces.
         * @returns {String} The modified string excluding the removed spaces.
         * @example
         * alert( CKEDITOR.tools.ltrim( '  example ' );  // "example "
         */
        ltrim : (function()
        {
                // We are not using \s because we don't want "non-breaking spaces" to be caught.
                var trimRegex = /(?:^[ \t\n\r]+)/g;
                return function( str )
                {
                        return str.replace( trimRegex, '' ) ;
                };
        })(),

        /**
         * Remove spaces from the end (right) of a string. The following
         * characters are removed: space, tab, line break, line feed.
         * @param {String} str The text from which remove the spaces.
         * @returns {String} The modified string excluding the removed spaces.
         * @example
         * alert( CKEDITOR.tools.ltrim( '  example ' );  // "  example"
         */
        rtrim : (function()
        {
                // We are not using \s because we don't want "non-breaking spaces" to be caught.
                var trimRegex = /(?:[ \t\n\r]+$)/g;
                return function( str )
                {
                        return str.replace( trimRegex, '' ) ;
                };
        })()

There's no question it works, but they can certainly be simplified.

[Frederico Caldeira Knabben]

Replying to martinkou:

Is there any reason the *trim functions are written like this?

This is just a micro-optimization...

At runtime, regular expressions are parsed and compiled before run. Defining them as private variables in a closure make it work like a "cache" as the parsing and compilation is done only once.

Also, looking at your comment, just came to my eyes that th ltrim and rtrim regexes have extra stuff copied from trim that is not needed. I've fixed it with [2347].

[Frederico Caldeira Knabben]

Replying to fredck:

This is just a micro-optimization...

Another note on this.

It doesn't mean that we should always do such optimizations. We must consider the benefits of it, over code simplification.

In the case of the string trimming functions, they participate (a lot) in the HTML ouput generation. I wanted to have as much performance as possible there, so I've considered all kinds of optimizations.

Of course, we would not have much benefit from it if those functions would be called just a few times. In that case, simpler code would be more important than such minimal performance enhancement.

[Martin Kou]

Alright, the optimization makes sense since *trim() gets called a lot. Thanks for the clarification.