parse <:Window> tags

src/parse/index.js

@@ -32,6 +32,7 @@ export default function parse ( template, options = {} ) {
 		index: 0,
 		template,
 		stack: [],
+		metaTags: {},
 
 		current () {
 			return this.stack[ this.stack.length - 1 ];

src/parse/state/tag.js

@@ -11,6 +11,10 @@ const invalidUnquotedAttributeCharacters = /[\s"'=<>\/`]/;
 
 const SELF = ':Self';
 
+const metaTags = {
+	':Window': true
+};
+
 const specials = {
 	script: {
 		read: readScript,
@@ -81,6 +85,22 @@ export default function tag ( parser ) {
 
 	const name = readTagName( parser );
 
+	if ( name in metaTags ) {
+		if ( name in parser.metaTags ) {
+			if ( isClosingTag && parser.current().children.length ) {
+				parser.error( `<${name}> cannot have children`, parser.current().children[0].start );
+			}
+
+			parser.error( `A component can only have one <${name}> tag`, start );
+		}
+
+		parser.metaTags[ name ] = true;
+
+		if ( parser.stack.length > 1 ) {
+			parser.error( `<${name}> tags cannot be inside elements or blocks`, start );
+		}
+	}
+
 	parser.allowWhitespace();
 
 	if ( isClosingTag ) {
@@ -194,6 +214,9 @@ function readTagName ( parser ) {
 	}
 
 	const name = parser.readUntil( /(\s|\/|>)/ );
+
+	if ( name in metaTags ) return name;
+
 	if ( !validTagName.test( name ) ) {
 		parser.error( `Expected valid tag name`, start );
 	}

test/parser/samples/error-window-children/error.json

@@ -0,0 +1,8 @@
+{
+	"message": "<:Window> cannot have children",
+	"loc": {
+		"line": 1,
+		"column": 9
+	},
+	"pos": 9
+}

test/parser/samples/error-window-children/input.html

@@ -0,0 +1 @@
+<:Window>contents</:Window>

test/parser/samples/error-window-duplicate/error.json

@@ -0,0 +1,8 @@
+{
+	"message": "A component can only have one <:Window> tag",
+	"loc": {
+		"line": 2,
+		"column": 0
+	},
+	"pos": 11
+}

test/parser/samples/error-window-duplicate/input.html

@@ -0,0 +1,2 @@
+<:Window/>
+<:Window/>

test/parser/samples/error-window-inside-block/error.json

@@ -0,0 +1,8 @@
+{
+	"message": "<:Window> tags cannot be inside elements or blocks",
+	"loc": {
+		"line": 2,
+		"column": 1
+	},
+	"pos": 13
+}

test/parser/samples/error-window-inside-block/input.html

@@ -0,0 +1,3 @@
+{{#if foo}}
+	<:Window/>
+{{/if}}

test/parser/samples/error-window-inside-element/error.json

@@ -0,0 +1,8 @@
+{
+	"message": "<:Window> tags cannot be inside elements or blocks",
+	"loc": {
+		"line": 2,
+		"column": 1
+	},
+	"pos": 7
+}

test/parser/samples/error-window-inside-element/input.html

@@ -0,0 +1,3 @@
+<div>
+	<:Window/>
+</div>>