* Start work on TextBuffer version of MLTEV

core/text_buffer.js

@@ -0,0 +1,188 @@
+
+var _		= require('lodash');
+
+exports.TextBuffer	= TextBuffer;
+
+/*
+* gap buffer of objects
+* Single buffer for actual/render
+* Preserve original line endings if possible
+* object has text
+* standard whitespace are just objects
+* tabs are special objects
+* hard line feeds are recorded
+* cursor always at currentSpan / object
+
+
+*/
+
+function TextBuferFragment(options) {
+	if(_.isString(options)) {
+		this.text = options;
+	} else {
+		this.text = options.text || '';
+	}
+
+	var self = this;
+
+	this.isTab = function() {
+		return '\t' === self.text;
+	};
+
+	this.isWhitespace = function() {
+		return self.text.match(/\s+/g) ? true : false;
+	};
+
+	Object.defineProperty(this, 'length', {
+		enumerable : true,
+		get : function() {
+			return this.text.length;
+		},
+	});
+}
+
+function TextBuffer(options) {
+	
+	this.gapSize	= options.gapSize || 64;
+	this.buffer		= new Array(this.gapSize);
+	this.gapStart	= 0;
+	this.gapEnd		= this.gapSize;
+	this.spliceArgs	= new Array(this.gapSize + 2);
+
+
+	var self		= this;
+
+	Object.defineProperty(this, 'length', {
+		enumerable : true,
+		get : function() {
+			return this.buffer.length - (this.gapEnd - this.gapSize);
+		},
+	});
+
+	this.adjustGap = function(index) {
+		var gapSize	= (self.gapEnd - self.gapStart);
+		var delta;
+		var i;
+
+		if(index < self.gapStart) {
+			delta = self.gapStart - index;	
+
+			for(i = delta - 1; i >= 0; --i) {
+				self.buffer[self.gapEnd - delta + i] = self.buffer[index + i];
+			}
+
+			self.gapStart	-= delta;
+			self.gapEnd		-= delta;
+		} else if(index > self.gapStart) {
+			delta = index - self.gapStart;
+
+			for(i = 0; i < delta; ++i) {
+				self.buffer[self.gapStart + i] = self.buffer[self.gapEnd + i];
+			}
+
+			self.gapStart	+= delta;
+			self.gapEnd		+= delta;
+		}
+	};
+}
+
+TextBuffer.prototype.get = function(index) {
+	if(index >= this.length) {
+		return undefined;
+	}
+
+	if(index >= this.gapStart) {
+		index += (this.gapEnd - this.gapStart);
+	}
+
+	return this.buffer[index];
+};
+
+TextBuffer.prototype.insertFragment = function(index, fragment) {
+	if(index < 0) {
+		throw new RangeError('Index must be >= 0');
+	}
+
+	if(index > this.length) {
+		throw new RangeError('Index must be <= length');
+	}
+
+	if(this.gapStart === this.gapEnd) {
+		this.spliceArgs[0] = index;
+		this.spliceArgs[1] = 0;
+
+		Array.prototype.splice.apply(this.buffer, this.spliceArgs);
+
+		this.gapStart	= index;
+		this.gapEnd		= index + this.gapSize;
+	} else {
+		this.adjustGap(index);
+	}
+
+	this.buffer[this.gapStart++] = fragment;
+};
+
+TextBuffer.prototype.insertText = function(index, text) {
+	//
+	//	Create fragments from text. Each fragment is:
+	//	*	A series of whitespace(s)
+	//	*	A tab
+	//	*	Printable characters
+	//
+	//	A fragment may also have various flags set
+	//	for eol markers. These are always normalized
+	//	to a single *nix style \n
+	//
+	if(0 === text.length) {
+		return;
+	}
+
+	var re = /\s+|\r\n|\n|\r/g;
+	var m;
+	var i = index;
+	var from;
+	do {		
+		from	= re.lastIndex + (_.isObject(m) ? m[0].length - 1 : 0);		
+		m		= re.exec(text);
+		if(null !== m) {
+
+			this.insertFragment(i++, new TextBuferFragment({
+				text : text.substring(from, re.lastIndex)
+			}));
+
+			switch(m[0].charAt(0)) {
+				case '\t' :
+					for(var j = 0; j < m[0].length; ++j) {
+						this.insertFragment(i++, new TextBuffer({
+							text : m[0].charAt(j)
+						}));
+					}
+				break;
+
+				case '\r' :
+				case '\n' :
+					var count = m[0].split(/\r\n|\n|\r/g).length;
+					for(var j = 0; j < count; ++j) {
+						this.insertFragment(i++, new TextBuffer({
+							text : '\n'	//	always normalized
+						}));
+					}
+				break;
+
+				case ' ' :
+					this.insertFragment(i++, new TextBuffer({
+						text : m[0],
+					}));
+				break;
+			}		
+		}
+	} while(0 !== re.lastIndex);
+};
+
+TextBuffer.prototype.getArray = function() {
+	return this.buffer.slice(0, this.gapStart).concat(this.buffer.slice(this.gapEnd));
+};
+
+TextBuffer.prototype.getText = function(range) {
+
+};