add builder-style functionality to the SnippetString, #3210

src/vs/vscode.d.ts

@@ -2039,7 +2039,35 @@ declare module 'vscode' {
 		 */
 		value: string;
 
-		constructor(value: string);
+		constructor(value?: string);
+
+		/**
+		 * Builder-function that appends the given string to
+		 * the [`value`](#SnippetString.value) of this snippet string.
+		 *
+		 * @param string A value to append 'as given'. The string will be escaped.
+		 */
+		appendText(string: string): SnippetString;
+
+		/**
+		 * Builder-function that appends a tabstop (`$1`, `$2` etc) to
+		 * the [`value`](#SnippetString.value) of this snippet string.
+		 *
+		 * @param number The number of this tabstop, defaults to an auto-incremet
+		 * value starting at 1.
+		 */
+		appendTabstop(number?: number): SnippetString;
+
+		/**
+		 * Builder-function that appends a placeholder (`${1:value}`) to
+		 * the [`value`](#SnippetString.value) of this snippet string.
+		 *
+		 * @param value The value of this placeholder - either a string or a function
+		 * with which a nested snippet can be created.
+		 * @param number The number of this tabstop, defaults to an auto-incremet
+		 * value starting at 1.
+		 */
+		appendPlaceholder(value: string | ((snippet: SnippetString) => any), number?: number): SnippetString;
 	}
 
 	/**

src/vs/workbench/api/node/extHostTypes.ts

@@ -524,10 +524,44 @@ export class WorkspaceEdit {
 
 export class SnippetString {
 
+	private _tabstop: number = 1;
+
 	value: string;
 
-	constructor(value: string) {
-		this.value = value;
+	constructor(value?: string) {
+		this.value = value || '';
+	}
+
+	appendText(string: string): SnippetString {
+		this.value += string.replace(/\$/g, '\\$');
+		return this;
+	}
+
+	appendTabstop(number: number = this._tabstop++): SnippetString {
+		this.value += '$';
+		this.value += number;
+		return this;
+	}
+
+	appendPlaceholder(value: string | ((snippet: SnippetString) => any), number: number = this._tabstop++): SnippetString {
+
+		if (typeof value === 'function') {
+			const nested = new SnippetString();
+			nested._tabstop = this._tabstop;
+			value(nested);
+			this._tabstop = nested._tabstop;
+			value = nested.value;
+		} else {
+			value = value.replace(/\$|}/g, '\\$&');
+		}
+
+		this.value += '${';
+		this.value += number;
+		this.value += ':';
+		this.value += value;
+		this.value += '}';
+
+		return this;
 	}
 }
 

src/vs/workbench/test/node/api/extHostTypes.test.ts

@@ -416,4 +416,41 @@ suite('ExtHostTypes', function () {
 		assert.ok(info.location instanceof types.Location);
 		assert.equal(info.location.uri, undefined);
 	});
-});
\ No newline at end of file
+
+	test('SnippetString, builder-methods', function () {
+
+		let string: types.SnippetString;
+
+		string = new types.SnippetString();
+		assert.equal(string.appendText('I need $ and $').value, 'I need \\$ and \\$');
+
+		string = new types.SnippetString();
+		string.appendPlaceholder('fo$o}');
+		assert.equal(string.value, '${1:fo\\$o\\}}');
+
+		string = new types.SnippetString();
+		string.appendText('foo').appendTabstop(0).appendText('bar');
+		assert.equal(string.value, 'foo$0bar');
+
+		string = new types.SnippetString();
+		string.appendText('foo').appendTabstop().appendText('bar');
+		assert.equal(string.value, 'foo$1bar');
+
+		string = new types.SnippetString();
+		string.appendText('foo').appendTabstop(42).appendText('bar');
+		assert.equal(string.value, 'foo$42bar');
+
+		string = new types.SnippetString();
+		string.appendText('foo').appendPlaceholder('farboo').appendText('bar');
+		assert.equal(string.value, 'foo${1:farboo}bar');
+
+		string = new types.SnippetString();
+		string.appendText('foo').appendPlaceholder('far$boo').appendText('bar');
+		assert.equal(string.value, 'foo${1:far\\$boo}bar');
+
+		string = new types.SnippetString();
+		string.appendText('foo').appendPlaceholder(b => b.appendText('abc').appendPlaceholder('nested')).appendText('bar');
+		assert.equal(string.value, 'foo${1:abc${2:nested}}bar');
+
+	});
+});