add supports of completion label list

src/services/completions.ts

@@ -39,6 +39,11 @@ namespace ts.Completions {
             return getStringLiteralCompletionEntries(sourceFile, position, typeChecker, compilerOptions, host, log);
         }
 
+        const contextToken = findPrecedingToken(position, sourceFile);
+        if (isInBreakOrContinue(contextToken)) {
+            return getLabelCompletionAtPosition(contextToken);
+        }
+
         const completionData = getCompletionData(typeChecker, log, sourceFile, position, allSourceFiles, options, compilerOptions.target);
         if (!completionData) {
             return undefined;
@@ -223,6 +228,18 @@ namespace ts.Completions {
         return uniques;
     }
 
+    function isInBreakOrContinue(contextToken: Node): boolean {
+        return contextToken && isBreakOrContinueStatement(contextToken.parent) &&
+            (contextToken.kind === SyntaxKind.BreakKeyword || contextToken.kind === SyntaxKind.ContinueKeyword || contextToken.kind === SyntaxKind.Identifier);
+    }
+
+    function getLabelCompletionAtPosition(contextToken: Node): CompletionInfo | undefined {
+        const entries = getLabelStatementCompletions(contextToken.parent);
+        if (entries.length) {
+            return { isGlobalCompletion: false, isMemberCompletion: false, isNewIdentifierLocation: false, entries };
+        }
+    }
+
     function getStringLiteralCompletionEntries(sourceFile: SourceFile, position: number, typeChecker: TypeChecker, compilerOptions: CompilerOptions, host: LanguageServiceHost, log: Log): CompletionInfo | undefined {
         const node = findPrecedingToken(position, sourceFile);
         if (!node || node.kind !== SyntaxKind.StringLiteral) {
@@ -358,6 +375,32 @@ namespace ts.Completions {
         return undefined;
     }
 
+    function getLabelStatementCompletions(node: Node): CompletionEntry[] {
+        const entries: CompletionEntry[] = [];
+        const uniques = createMap<true>();
+        let current = node;
+
+        while (current) {
+            if (isFunctionLike(current)) {
+                break;
+            }
+            if (isLabeledStatement(current)) {
+                const name = current.label.text;
+                if (!uniques.has(name)) {
+                    uniques.set(name, true);
+                    entries.push({
+                        name,
+                        kindModifiers: ScriptElementKindModifier.none,
+                        kind: ScriptElementKind.label,
+                        sortText: "0"
+                    });
+                }
+            }
+            current = current.parent;
+        }
+        return entries;
+    }
+
     function addStringLiteralCompletionsFromType(type: Type, result: Push<CompletionEntry>, typeChecker: TypeChecker, uniques = createMap<true>()): void {
         if (type && type.flags & TypeFlags.TypeParameter) {
             type = typeChecker.getBaseConstraintOfType(type);

tests/cases/fourslash/completionListWithLabel.ts

@@ -0,0 +1,44 @@
+/// <reference path="fourslash.ts"/>
+
+//// label: while (true) {
+////    break /*1*/
+////    continue /*2*/
+////    testlabel: while (true) {
+////        break /*3*/
+////        continue /*4*/
+////        break tes/*5*/
+////        continue tes/*6*/
+////    }
+////    break /*7*/
+////    break; /*8*/
+////}
+
+goTo.marker("1");
+verify.completionListContains("label");
+
+goTo.marker("2");
+verify.completionListContains("label");
+verify.not.completionListContains("testlabel");
+
+goTo.marker("3");
+verify.completionListContains("label");
+verify.completionListContains("testlabel");
+
+goTo.marker("4");
+verify.completionListContains("label");
+verify.completionListContains("testlabel");
+
+goTo.marker("5");
+verify.completionListContains("testlabel");
+verify.completionListContains("label");
+
+goTo.marker("6");
+verify.completionListContains("testlabel");
+verify.completionListContains("label");
+
+goTo.marker("7");
+verify.completionListContains("label");
+verify.not.completionListContains("testlabel");
+
+goTo.marker("8");
+verify.not.completionListContains("label");