hgweb: add docFromHTML javascript function

It takes a string with HTML markup and creates DOM document from it.
The implementation is a part of code from
https://developer.mozilla.org/en-US/docs/Web/API/DOMParser#DOMParser_HTML_extension_for_other_browsers

mercurial/templates/static/mercurial.js

@@ -1,330 +1,336
 // mercurial.js - JavaScript utility functions
 //
 // Rendering of branch DAGs on the client side
 // Display of elapsed time
 // Show or hide diffstat
 //
 // Copyright 2008 Dirkjan Ochtman <dirkjan AT ochtman DOT nl>
 // Copyright 2006 Alexander Schremmer <alex AT alexanderweb DOT de>
 //
 // derived from code written by Scott James Remnant <[e-mail]>
 // Copyright 2005 Canonical Ltd.
 //
 // This software may be used and distributed according to the terms
 // of the GNU General Public License, incorporated herein by reference.
 
 var colors = [
 	[ 1.0, 0.0, 0.0 ],
 	[ 1.0, 1.0, 0.0 ],
 	[ 0.0, 1.0, 0.0 ],
 	[ 0.0, 1.0, 1.0 ],
 	[ 0.0, 0.0, 1.0 ],
 	[ 1.0, 0.0, 1.0 ]
 ];
 
 function Graph() {
 
 	this.canvas = document.getElementById('graph');
 	if (window.G_vmlCanvasManager) this.canvas = window.G_vmlCanvasManager.initElement(this.canvas);
 	this.ctx = this.canvas.getContext('2d');
 	this.ctx.strokeStyle = 'rgb(0, 0, 0)';
 	this.ctx.fillStyle = 'rgb(0, 0, 0)';
 	this.cur = [0, 0];
 	this.line_width = 3;
 	this.bg = [0, 4];
 	this.cell = [2, 0];
 	this.columns = 0;
 	this.revlink = '';
 
 	this.scale = function(height) {
 		this.bg_height = height;
 		this.box_size = Math.floor(this.bg_height / 1.2);
 		this.cell_height = this.box_size;
 	}
 
 	function colorPart(num) {
 		num *= 255
 		num = num < 0 ? 0 : num;
 		num = num > 255 ? 255 : num;
 		var digits = Math.round(num).toString(16);
 		if (num < 16) {
 			return '0' + digits;
 		} else {
 			return digits;
 		}
 	}
 
 	this.setColor = function(color, bg, fg) {
 
 		// Set the colour.
 		//
 		// If color is a string, expect an hexadecimal RGB
 		// value and apply it unchanged. If color is a number,
 		// pick a distinct colour based on an internal wheel;
 		// the bg parameter provides the value that should be
 		// assigned to the 'zero' colours and the fg parameter
 		// provides the multiplier that should be applied to
 		// the foreground colours.
 		var s;
 		if(typeof color == "string") {
 			s = "#" + color;
 		} else { //typeof color == "number"
 			color %= colors.length;
 			var red = (colors[color][0] * fg) || bg;
 			var green = (colors[color][1] * fg) || bg;
 			var blue = (colors[color][2] * fg) || bg;
 			red = Math.round(red * 255);
 			green = Math.round(green * 255);
 			blue = Math.round(blue * 255);
 			s = 'rgb(' + red + ', ' + green + ', ' + blue + ')';
 		}
 		this.ctx.strokeStyle = s;
 		this.ctx.fillStyle = s;
 		return s;
 
 	}
 
 	this.edge = function(x0, y0, x1, y1, color, width) {
 
 		this.setColor(color, 0.0, 0.65);
 		if(width >= 0)
 			 this.ctx.lineWidth = width;
 		this.ctx.beginPath();
 		this.ctx.moveTo(x0, y0);
 		this.ctx.lineTo(x1, y1);
 		this.ctx.stroke();
 
 	}
 
 	this.render = function(data) {
 
 		var backgrounds = '';
 		var nodedata = '';
 
 		for (var i in data) {
 
 			var parity = i % 2;
 			this.cell[1] += this.bg_height;
 			this.bg[1] += this.bg_height;
 
 			var cur = data[i];
 			var node = cur[1];
 			var edges = cur[2];
 			var fold = false;
 
 			var prevWidth = this.ctx.lineWidth;
 			for (var j in edges) {
 
 				line = edges[j];
 				start = line[0];
 				end = line[1];
 				color = line[2];
 				var width = line[3];
 				if(width < 0)
 					 width = prevWidth;
 				var branchcolor = line[4];
 				if(branchcolor)
 					color = branchcolor;
 
 				if (end > this.columns || start > this.columns) {
 					this.columns += 1;
 				}
 
 				if (start == this.columns && start > end) {
 					var fold = true;
 				}
 
 				x0 = this.cell[0] + this.box_size * start + this.box_size / 2;
 				y0 = this.bg[1] - this.bg_height / 2;
 				x1 = this.cell[0] + this.box_size * end + this.box_size / 2;
 				y1 = this.bg[1] + this.bg_height / 2;
 
 				this.edge(x0, y0, x1, y1, color, width);
 
 			}
 			this.ctx.lineWidth = prevWidth;
 
 			// Draw the revision node in the right column
 
 			column = node[0]
 			color = node[1]
 
 			radius = this.box_size / 8;
 			x = this.cell[0] + this.box_size * column + this.box_size / 2;
 			y = this.bg[1] - this.bg_height / 2;
 			var add = this.vertex(x, y, color, parity, cur);
 			backgrounds += add[0];
 			nodedata += add[1];
 
 			if (fold) this.columns -= 1;
 
 		}
 
 		document.getElementById('nodebgs').innerHTML += backgrounds;
 		document.getElementById('graphnodes').innerHTML += nodedata;
 
 	}
 
 }
 
 
 process_dates = (function(document, RegExp, Math, isNaN, Date, _false, _true){
 
 	// derived from code from mercurial/templatefilter.py
 
 	var scales = {
 		'year':  365 * 24 * 60 * 60,
 		'month':  30 * 24 * 60 * 60,
 		'week':    7 * 24 * 60 * 60,
 		'day':    24 * 60 * 60,
 		'hour':   60 * 60,
 		'minute': 60,
 		'second': 1
 	};
 
 	function format(count, string){
 		var ret = count + ' ' + string;
 		if (count > 1){
 			ret = ret + 's';
 		}
  		return ret;
  	}
 
 	function shortdate(date){
 		var ret = date.getFullYear() + '-';
 		// getMonth() gives a 0-11 result
 		var month = date.getMonth() + 1;
 		if (month <= 9){
 			ret += '0' + month;
 		} else {
 			ret += month;
 		}
 		ret += '-';
 		var day = date.getDate();
 		if (day <= 9){
 			ret += '0' + day;
 		} else {
 			ret += day;
 		}
 		return ret;
 	}
 
  	function age(datestr){
  		var now = new Date();
  		var once = new Date(datestr);
 		if (isNaN(once.getTime())){
 			// parsing error
 			return datestr;
 		}
 
 		var delta = Math.floor((now.getTime() - once.getTime()) / 1000);
 
 		var future = _false;
 		if (delta < 0){
 			future = _true;
 			delta = -delta;
 			if (delta > (30 * scales.year)){
 				return "in the distant future";
 			}
 		}
 
 		if (delta > (2 * scales.year)){
 			return shortdate(once);
 		}
 
 		for (unit in scales){
 			var s = scales[unit];
 			var n = Math.floor(delta / s);
 			if ((n >= 2) || (s == 1)){
 				if (future){
 					return format(n, unit) + ' from now';
 				} else {
 					return format(n, unit) + ' ago';
 				}
 			}
 		}
 	}
 
 	return function(){
 		var nodes = document.getElementsByTagName('*');
 		var ageclass = new RegExp('\\bage\\b');
 		var dateclass = new RegExp('\\bdate\\b');
 		for (var i=0; i<nodes.length; ++i){
 			var node = nodes[i];
 			var classes = node.className;
 			if (ageclass.test(classes)){
 				var agevalue = age(node.textContent);
 				if (dateclass.test(classes)){
 					// We want both: date + (age)
 					node.textContent += ' ('+agevalue+')';
 				} else {
 					node.title = node.textContent;
 					node.textContent = agevalue;
 				}
 			}
 		}
 	}
 })(document, RegExp, Math, isNaN, Date, false, true)
 
 function toggleDiffstat() {
     var curdetails = document.getElementById('diffstatdetails').style.display;
     var curexpand = curdetails == 'none' ? 'inline' : 'none';
     document.getElementById('diffstatdetails').style.display = curexpand;
     document.getElementById('diffstatexpand').style.display = curdetails;
 }
 
 function toggleLinewrap() {
     function getLinewrap() {
         var nodes = document.getElementsByClassName('sourcelines');
         // if there are no such nodes, error is thrown here
         return nodes[0].classList.contains('wrap');
     }
 
     function setLinewrap(enable) {
         var nodes = document.getElementsByClassName('sourcelines');
         for (var i = 0; i < nodes.length; i++) {
             if (enable) {
                 nodes[i].classList.add('wrap');
             } else {
                 nodes[i].classList.remove('wrap');
             }
         }
 
         var links = document.getElementsByClassName('linewraplink');
         for (var i = 0; i < links.length; i++) {
             links[i].innerHTML = enable ? 'on' : 'off';
         }
     }
 
     setLinewrap(!getLinewrap());
 }
 
 function format(str, replacements) {
     return str.replace(/%(\w+)%/g, function(match, p1) {
         return String(replacements[p1]);
     });
 }
 
 function makeRequest(url, method, onstart, onsuccess, onerror, oncomplete) {
     xfr = new XMLHttpRequest();
     xfr.onreadystatechange = function() {
         if (xfr.readyState === 4) {
             try {
                 if (xfr.status === 200) {
                     onsuccess(xfr.responseText);
                 } else {
                     throw 'server error';
                 }
             } catch (e) {
                 onerror(e);
             } finally {
                 oncomplete();
             }
         }
     };
 
     xfr.open(method, url);
     xfr.send();
     onstart();
     return xfr;
 }
+
+function docFromHTML(html) {
+    var doc = document.implementation.createHTMLDocument('');
+    doc.documentElement.innerHTML = html;
+    return doc;
+}