From cd04fa22c6186a6a26616b77ef04535ee220bfac Mon Sep 17 00:00:00 2001
From: Jeremy Ruston <jeremy@osmosoft.com>
Date: Thu, 18 Oct 2012 18:27:27 +0100
Subject: [PATCH] Introduce extensible viewer modules for the view macro

---
 core/modules/macros/view/view.js              | 83 +++----------------
 core/modules/macros/view/viewers/date.js      | 26 ++++++
 core/modules/macros/view/viewers/link.js      | 32 +++++++
 core/modules/macros/view/viewers/text.js      | 30 +++++++
 .../modules/macros/view/viewers/transclude.js | 31 +++++++
 core/modules/macros/view/viewers/wikified.js  | 42 ++++++++++
 core/modules/startup.js                       |  1 +
 core/modules/wiki.js                          | 12 +++
 8 files changed, 186 insertions(+), 71 deletions(-)
 create mode 100644 core/modules/macros/view/viewers/date.js
 create mode 100644 core/modules/macros/view/viewers/link.js
 create mode 100644 core/modules/macros/view/viewers/text.js
 create mode 100644 core/modules/macros/view/viewers/transclude.js
 create mode 100644 core/modules/macros/view/viewers/wikified.js

diff --git a/core/modules/macros/view/view.js b/core/modules/macros/view/view.js
index 31b4e9282..b4e7362a9 100644
--- a/core/modules/macros/view/view.js
+++ b/core/modules/macros/view/view.js
@@ -25,14 +25,11 @@ exports.info = {
 exports.executeMacro = function() {
 	var tiddler = this.wiki.getTiddler(this.tiddlerTitle),
 		field = this.hasParameter("field") ? this.params.field : "title",
-		value,
-		children,
-		t,
-		childrenClone = [],
-		parents = this.parents;
+		value;
+	// Get the value to display
 	if(tiddler) {
 		value = tiddler.fields[field];
-	} else {
+	} else { // Use a special value if the tiddler is missing
 		switch(field) {
 			case "text":
 				value = "";
@@ -49,72 +46,16 @@ exports.executeMacro = function() {
 				break;
 		}
 	}
-	switch(this.params.format) {
-		case "link":
-			if(value === undefined) {
-				return $tw.Tree.Text("");
-			} else {
-				var link = $tw.Tree.Macro("link",{
-											srcParams: {to: value},
-											content: [$tw.Tree.Text(value)],
-											isBlock: this.isBlock,
-											wiki: this.wiki
-										});
-				link.execute(parents,this.tiddlerTitle);
-				return link;
-			}
-			break;
-		case "transclude":
-			if(tiddler && this.params.field && (this.params.field in tiddler.fields)) {
-				children = this.wiki.parseTiddler(tiddler.fields[this.params.field]).tree;
-				for(t=0; t<children.length; t++) {
-					childrenClone.push(children[t].clone());
-				}
-				for(t=0; t<childrenClone.length; t++) {
-					childrenClone[t].execute(parents,this.tiddlerTitle);
-				}
-				return $tw.Tree.Element(this.isBlock ? "div" : "span",{},childrenClone);
-			}
-			break;
-		case "wikified":
-			if(tiddler && this.params.field === "text") {
-				if(parents.indexOf(tiddler.fields.title) !== -1) {
-					children = [$tw.Tree.errorNode("Tiddler recursion error in <<view>> macro")];
-				} else {
-					children = this.wiki.parseTiddler(tiddler.fields.title).tree;
-				}
-				parents = parents.slice(0);
-				parents.push(tiddler.fields.title);
-			} else {
-				children = this.wiki.parseText("text/x-tiddlywiki",value).tree;
-			}
-			for(t=0; t<children.length; t++) {
-				childrenClone.push(children[t].clone());
-			}
-			for(t=0; t<childrenClone.length; t++) {
-				childrenClone[t].execute(parents,this.tiddlerTitle);
-			}
-			return $tw.Tree.Element(this.isBlock ? "div" : "span",{},childrenClone);
-		case "date":
-			var template = this.params.template || "DD MMM YYYY";
-			if(value === undefined) {
-				return $tw.Tree.Text("");
-			} else {
-				return $tw.Tree.Text($tw.utils.formatDateString(value,template));
-			}
-			break;
-		default: // "text"
-			// Get the stringified version of the field value
-			if(field !== "text" && tiddler) {
-				value = tiddler.getFieldString(field);
-			}
-			if(value === undefined || value === null) {
-				return $tw.Tree.Text("");
-			} else {
-				return $tw.Tree.Text(value);
-			}
+	// Figure out which viewer to use
+	// TODO: Tiddler field modules should be able to specify a field type from which the viewer is derived
+	if(tiddler && this.params.format) {
+		var viewer = this.wiki.macros.view.viewers[this.params.format];
 	}
-	return $tw.Tree.Text("");
+	if(!viewer) {
+		viewer = this.wiki.macros.view.viewers["text"];
+	}
+	// Call the viewer to generate the content
+	return viewer(tiddler,field,value,this);
 };
 
 })();
diff --git a/core/modules/macros/view/viewers/date.js b/core/modules/macros/view/viewers/date.js
new file mode 100644
index 000000000..18d69bce5
--- /dev/null
+++ b/core/modules/macros/view/viewers/date.js
@@ -0,0 +1,26 @@
+/*\
+title: $:/core/modules/macros/view/viewers/date.js
+type: application/javascript
+module-type: viewer
+
+A viewer for viewing tiddler fields as a date
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+function renderValue(tiddler,field,value,viewMacro) {
+	var template = viewMacro.params.template || "DD MMM YYYY";
+	if(value === undefined) {
+		return $tw.Tree.Text("");
+	} else {
+		return $tw.Tree.Text($tw.utils.formatDateString(value,template));
+	}
+}
+
+exports["date"] = renderValue;
+
+})();
diff --git a/core/modules/macros/view/viewers/link.js b/core/modules/macros/view/viewers/link.js
new file mode 100644
index 000000000..9e9e41b8f
--- /dev/null
+++ b/core/modules/macros/view/viewers/link.js
@@ -0,0 +1,32 @@
+/*\
+title: $:/core/modules/macros/view/viewers/link.js
+type: application/javascript
+module-type: viewer
+
+A viewer for viewing tiddler fields as a link
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+function renderValue(tiddler,field,value,viewMacro) {
+	if(value === undefined) {
+		return $tw.Tree.Text("");
+	} else {
+		var link = $tw.Tree.Macro("link",{
+									srcParams: {to: value},
+									content: [$tw.Tree.Text(value)],
+									isBlock: viewMacro.isBlock,
+									wiki: viewMacro.wiki
+								});
+		link.execute(viewMacro.parents,viewMacro.tiddlerTitle);
+		return link;
+	}
+}
+
+exports["link"] = renderValue;
+
+})();
diff --git a/core/modules/macros/view/viewers/text.js b/core/modules/macros/view/viewers/text.js
new file mode 100644
index 000000000..1aae9ff18
--- /dev/null
+++ b/core/modules/macros/view/viewers/text.js
@@ -0,0 +1,30 @@
+/*\
+title: $:/core/modules/macros/view/viewers/text.js
+type: application/javascript
+module-type: viewer
+
+A viewer for viewing tiddler fields as plain text
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+function renderValue(tiddler,field,value,viewMacro) {
+	// Get the value as a string
+	if(field !== "text" && tiddler) {
+		value = tiddler.getFieldString(field);
+	}
+	// Return the text
+	if(value === undefined || value === null) {
+		return $tw.Tree.Text("");
+	} else {
+		return $tw.Tree.Text(value);
+	}
+}
+
+exports["text"] = renderValue;
+
+})();
diff --git a/core/modules/macros/view/viewers/transclude.js b/core/modules/macros/view/viewers/transclude.js
new file mode 100644
index 000000000..d64d7c460
--- /dev/null
+++ b/core/modules/macros/view/viewers/transclude.js
@@ -0,0 +1,31 @@
+/*\
+title: $:/core/modules/macros/view/viewers/transclude.js
+type: application/javascript
+module-type: viewer
+
+A viewer that transcludes the tiddler whose title is specified in the viewed field
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+function renderValue(tiddler,field,value,viewMacro) {
+	if(tiddler && viewMacro.params.field && (viewMacro.params.field in tiddler.fields)) {
+		var children = viewMacro.wiki.parseTiddler(tiddler.fields[viewMacro.params.field]).tree,
+			childrenClone = [];
+		for(t=0; t<children.length; t++) {
+			childrenClone.push(children[t].clone());
+		}
+		for(t=0; t<childrenClone.length; t++) {
+			childrenClone[t].execute(parents,viewMacro.tiddlerTitle);
+		}
+		return $tw.Tree.Element(viewMacro.isBlock ? "div" : "span",{},childrenClone);
+	}
+}
+
+exports["transclude"] = renderValue;
+
+})();
diff --git a/core/modules/macros/view/viewers/wikified.js b/core/modules/macros/view/viewers/wikified.js
new file mode 100644
index 000000000..ebe69337d
--- /dev/null
+++ b/core/modules/macros/view/viewers/wikified.js
@@ -0,0 +1,42 @@
+/*\
+title: $:/core/modules/macros/view/viewers/wikified.js
+type: application/javascript
+module-type: viewer
+
+A viewer for viewing tiddler fields as wikified text
+
+\*/
+(function(){
+
+/*jslint node: true, browser: true */
+/*global $tw: false */
+"use strict";
+
+function renderValue(tiddler,field,value,viewMacro) {
+	// Check for recursion
+	var parents = viewMacro.parents,
+		children,t,childrenClone = [];
+	if(tiddler && viewMacro.params.field === "text") {
+		if(parents.indexOf(tiddler.fields.title) !== -1) {
+			children = [$tw.Tree.errorNode("Tiddler recursion error in <<view>> macro")];
+		} else {
+			children = viewMacro.wiki.parseTiddler(tiddler.fields.title).tree;
+		}
+		parents = parents.slice(0);
+		parents.push(tiddler.fields.title);
+	} else {
+		children = viewMacro.wiki.parseText("text/x-tiddlywiki",value).tree;
+	}
+	// Clone and execute the parsed wikitext
+	for(t=0; t<children.length; t++) {
+		childrenClone.push(children[t].clone());
+	}
+	for(t=0; t<childrenClone.length; t++) {
+		childrenClone[t].execute(parents,viewMacro.tiddlerTitle);
+	}
+	return $tw.Tree.Element(viewMacro.isBlock ? "div" : "span",{},childrenClone);
+}
+
+exports["wikified"] = renderValue;
+
+})();
diff --git a/core/modules/startup.js b/core/modules/startup.js
index 10784649f..33fe7f713 100644
--- a/core/modules/startup.js
+++ b/core/modules/startup.js
@@ -33,6 +33,7 @@ exports.startup = function() {
 	// Set up the wiki store
 	$tw.wiki.initMacros();
 	$tw.wiki.initEditors();
+	$tw.wiki.initViewers();
 	$tw.wiki.initStoryViews();
 	$tw.wiki.initParsers();
 	// Set up the command modules
diff --git a/core/modules/wiki.js b/core/modules/wiki.js
index 280b7a756..07709929f 100644
--- a/core/modules/wiki.js
+++ b/core/modules/wiki.js
@@ -523,6 +523,18 @@ exports.initEditors = function(moduleType) {
 	}
 };
 
+/*
+Install viewer modules for the edit macro
+*/
+exports.initViewers = function(moduleType) {
+	moduleType = moduleType || "viewer";
+	var viewMacro = this.macros.view;
+	if(viewMacro) {
+		viewMacro.viewers = {};
+		$tw.modules.applyMethods(moduleType,viewMacro.viewers);
+	}
+};
+
 /*
 Install view modules for the story macro
 */