codenothing/StringIterator

/*
 * String Iterator v0.0.2pre
 * Corey Hart @ http://www.codenothing.com
 * MIT License
 */
(function( global, undefined ) {

var Slice = Array.prototype.slice,
    toString = Object.prototype.toString,
    rnewline = /\r\n|\r|\n/;


function StringIterator( string ) {
    var self = this, i = -1, line = [], length, c;

    if ( ! ( self instanceof StringIterator ) ) {
        return new StringIterator( string );
    }
    else if ( ! StringIterator.isString( string ) ) {
        throw new Error( "No string found" );
    }

    // Meta
    self.string = string;
    self.index = -1;
    self.length = -1;
    self.character = 1;
    self.line = 1;
    self.c = "";
    self.next = "";
    self.prev = "";
    self.chars = [];
    self.lines = [ line ];

    // Break down each individual character, and seperate newlines
    for ( length = self.string.length; ++i < length; ) {
        c = self.string[ i ];
        if ( c == "\r" && self.string[ i + 1 ] == "\n" ) {
            c = "\r\n";
            i++;
        }

        self.chars.push( c );
        if ( rnewline.exec( c ) ) {
            self.lines.push( line = [] );
        }
        else {
            line.push( c );
        }
    }

    // Length should represent number of characters
    self.length = self.chars.length;
}

StringIterator.prototype = {

    // Skip to specific index
    goto: function( n ) {
        var self = this, count = 0, i = -1, line;

        if ( ! StringIterator.isNumber( n ) ) {
            throw new Error( "Expecting a number for goto" );
        }
        else if ( n < 0 ) {
            throw new Error( "Number too small for goto" );
        }
        else if ( n >= self.length ) {
            throw new Error( "Number too large for goto" );
        }

        self.index = n;
        self.c = self.chars[ n ];
        self.next = self.chars[ n + 1 ] || "";
        self.prev = self.chars[ n - 1 ] || "";

        while ( ( line = self.lines[ ++i ] ) ) {
            if ( self.index < ( count + line.length ) ) {
                self.line = i + 1;
                self.character = self.index - count + 1;
                break;
            }
            else {
                count += line.length + 1;
            }
        }

        return self;
    },

    // Forward iteration
    each: function( callback ) {
        var self = this, substr = "";

        // Test for function
        if ( ! StringIterator.isFunction( callback ) ) {
            throw new Error( "No function found" );
        }

        // Iterate
        for ( ; ++self.index < self.length; ) {
            self.goto( self.index );
            substr += self.c;

            if ( callback( self.c, self ) === false ) {
                break;
            }
        }

        if ( self.index >= self.length ) {
            self.index = self.length - 1;
        }

        return substr;
    },

    // Find a character while compiling a sub string
    seek: function( match ) {
        var self = this,
            regex = StringIterator.isRegExp( match ) ? match : null,
            endChar = StringIterator.isString( match ) ? match : null;

        // Make sure there is an end matcher
        if ( regex === null && endChar === null ) {
            throw new Error( "No seek found" );
        }

        // Iterate until we find the match
        return self.each(function( c ) {
            if ( self.prev == "\\" ) {
                return;
            }
            else if ( ( endChar && c === endChar ) || ( regex && regex.exec( c ) ) ) {
                return false;
            }
        });
    },

    // Skipping n string iterations
    skip: function( n ) {
        var self = this, count = 0;

        // No number means a single skip
        if ( n === undefined ) {
            n = 1;
        }
        // Make sure a number is passed
        else if ( ! StringIterator.isNumber( n ) ) {
            throw new Error( "Expecting a number for skip" );
        }

        // Iterate until count is matched
        return self.each(function( c ) {
            if ( ++count >= n ) {
                return false;
            }
        });
    },

    // Going back n string iterations
    reverse: function( value ) {
        var self = this,
            isFunction = StringIterator.isFunction( value ),
            substr = "",
            count = 0;

        // Number of iterations
        if ( value === undefined ) {
            value = 1;
        }
        // Make sure a number or function is passed
        else if ( ! isFunction && ! StringIterator.isNumber( value ) ) {
            throw new Error( "Expecting a number or function for reverse" );
        }

        // Reverse iterate until wall is hit
        for ( ; --self.index > 0; ) {
            self.goto( self.index );
            substr = self.c + substr;

            // Check to see if thresholds have been met
            if ( ( isFunction && value( self.c, self ) === false ) || ( ! isFunction && ++count >= value ) ) {
                break;
            }
        }

        return substr;
    },

    // Restarting iteration
    restart: function(){
        var self = this;

        self.index = -1;
        self.character = 1;
        self.line = 1;
        self.c = "";
        self.next = "";
        self.prev = "";

        return self;
    },

};


// Version
StringIterator.version = "0.0.2pre";


// Type tests
"Boolean Number String Function Array Date RegExp Object".split(' ').forEach(function( method ) {
    if ( method == 'Array' && Array.isArray ) {
        return ( StringIterator.isArray = Array.isArray );
    }

    var match = '[object ' + method + ']';
    StringIterator[ 'is' + method ] = function( object ) {
        return object !== undefined && object !== null && toString.call( object ) == match;
    };
});


// Expose
if ( typeof module == 'object' && typeof module.exports == 'object' ) {
    module.exports = StringIterator;
}
else {
    global.StringIterator = StringIterator;
}

})( this );