Added wikitext image support

We’ve added a parser to recognise the `[img[URL or tiddler title]]`
format, and an associated image widget.

core/modules/parsers/wikiparser/rules/image.js

@@ -0,0 +1,137 @@
+/*\
+title: $:/core/modules/parsers/wikiparser/rules/image.js
+type: application/javascript
+module-type: wikirule
+
+Wiki text inline rule for embedding images. For example:
+
+```
+[img[http://tiddlywiki.com/fractalveg.jpg]]
+[img width=23 height=24 [http://tiddlywiki.com/fractalveg.jpg]]
+[img 23x24 [http://tiddlywiki.com/fractalveg.jpg]]
+[img width={{!!width}} height={{!!height}} [http://tiddlywiki.com/fractalveg.jpg]]
+[img {{!!width}}x{{!!height}} [http://tiddlywiki.com/fractalveg.jpg]]
+[img[Description of image|http://tiddlywiki.com/fractalveg.jpg]]
+[img[TiddlerTitle]]
+[img[Description of image|TiddlerTitle]]
+```
+
+Generates the `<$image>` widget.
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+exports.name = "image";
+exports.types = {inline: true};
+
+exports.init = function(parser) {
+	this.parser = parser;
+};
+
+exports.findNextMatch = function(startPos) {
+	// Find the next tag
+	this.nextImage = this.findNextImage(this.parser.source,startPos);
+	return this.nextImage ? this.nextImage.start : undefined;
+};
+
+exports.parse = function() {
+	// Move past the match
+	this.parser.pos = this.nextImage.end;
+	var node = {
+		type: "element",
+		tag: "$image",
+		attributes: this.nextImage.attributes
+	};
+	return [node];
+};
+
+/*
+Find the next image from the current position
+*/
+exports.findNextImage = function(source,pos) {
+	// A regexp for finding candidate HTML tags
+	var reLookahead = /(\[img)/g;
+	// Find the next candidate
+	reLookahead.lastIndex = pos;
+	var match = reLookahead.exec(source);
+	while(match) {
+		// Try to parse the candidate as a tag
+		var tag = this.parseImage(source,match.index);
+		// Return success
+		if(tag) {
+			return tag;
+		}
+		// Look for the next match
+		reLookahead.lastIndex = match.index + 1;
+		match = reLookahead.exec(source);
+	}
+	// Failed
+	return null;
+};
+
+/*
+Look for an image at the specified position. Returns null if not found, otherwise returns {type: "element", name: "$image", attributes: [], isSelfClosing:, start:, end:,}
+*/
+exports.parseImage = function(source,pos) {
+	var token,
+		node = {
+			type: "element",
+			name: "$image",
+			start: pos,
+			attributes: {}
+		};
+	// Skip whitespace
+	pos = $tw.utils.skipWhiteSpace(source,pos);
+	// Look for the `[img`
+	token = $tw.utils.parseTokenString(source,pos,"[img");
+	if(!token) {
+		return null;
+	}
+	pos = token.end;
+	// Skip whitespace
+	pos = $tw.utils.skipWhiteSpace(source,pos);
+	// Process attributes
+	if(source.charAt(pos) !== "[") {
+		var attribute = $tw.utils.parseAttribute(source,pos);
+		while(attribute) {
+			node.attributes[attribute.name] = attribute;
+			pos = attribute.end;
+			pos = $tw.utils.skipWhiteSpace(source,pos);
+			if(source.charAt(pos) !== "[") {
+				// Get the next attribute
+				attribute = $tw.utils.parseAttribute(source,pos);
+			} else {
+				attribute = null;
+			}
+		}
+	}
+	// Skip whitespace
+	pos = $tw.utils.skipWhiteSpace(source,pos);
+	// Look for the `[` after the attributes
+	token = $tw.utils.parseTokenString(source,pos,"[");
+	if(!token) {
+		return null;
+	}
+	pos = token.end;
+	// Skip whitespace
+	pos = $tw.utils.skipWhiteSpace(source,pos);
+	// Get the source up to the terminating `]]`
+	token = $tw.utils.parseTokenRegExp(source,pos,/(?:([^|\]]*?)\|)?([^\]]+?)\]\]/g);
+	if(!token) {
+		return null;
+	}
+	pos = token.end;
+	if(token.match[1]) {
+		node.attributes.tooltip = {type: "string", value: token.match[1].trim()};
+	}
+	node.attributes.source = {type: "string", value: (token.match[2] || "").trim()};
+	// Update the end position
+	node.end = pos;
+	return node;
+};
+
+})();