findAncestor: Add generic overload for use with type predicates

Andy Hanson · Andy Hanson · commit badfcbfb43f5 · 2017-05-16T09:45:01.000-07:00
diff --git a/src/compiler/checker.ts b/src/compiler/checker.ts
@@ -1300,7 +1300,7 @@ namespace ts {
                     return <ImportEqualsDeclaration>node;
                 }
 
-                return findAncestor(node, n => n.kind === SyntaxKind.ImportDeclaration) as ImportDeclaration;
+                return findAncestor(node, isImportDeclaration);
             }
         }
 
@@ -22638,7 +22638,7 @@ namespace ts {
                             const symbolIsUmdExport = symbolFile !== referenceFile;
                             return symbolIsUmdExport ? undefined : symbolFile;
                         }
-                        return findAncestor(node.parent, n => isModuleOrEnumDeclaration(n) && getSymbolOfNode(n) === parentSymbol) as ModuleDeclaration | EnumDeclaration;
+                        return findAncestor(node.parent, (n): n is ModuleDeclaration | EnumDeclaration => isModuleOrEnumDeclaration(n) && getSymbolOfNode(n) === parentSymbol);
                     }
                 }
             }
diff --git a/src/compiler/core.ts b/src/compiler/core.ts
@@ -230,6 +230,8 @@ namespace ts {
      * If no such value is found, it applies the callback until the parent pointer is undefined or the callback returns "quit"
      * At that point findAncestor returns undefined.
      */
+    export function findAncestor<T extends Node>(node: Node, callback: (element: Node) => element is T): T | undefined;
+    export function findAncestor(node: Node, callback: (element: Node) => boolean | "quit"): Node | undefined;
     export function findAncestor(node: Node, callback: (element: Node) => boolean | "quit"): Node {
         while (node) {
             const result = callback(node);
diff --git a/src/compiler/utilities.ts b/src/compiler/utilities.ts
@@ -4010,6 +4010,10 @@ namespace ts {
         return node.kind === SyntaxKind.ImportEqualsDeclaration;
     }
 
+    export function isImportDeclaration(node: Node): node is ImportDeclaration {
+        return node.kind === SyntaxKind.ImportDeclaration;
+    }
+
     export function isImportClause(node: Node): node is ImportClause {
         return node.kind === SyntaxKind.ImportClause;
     }

Original file line number	Diff line number	Diff line change
`@@ -1300,7 +1300,7 @@ namespace ts {`
`1300`	`1300`	`return <ImportEqualsDeclaration>node;`
`1301`	`1301`	`}`
`1302`	`1302`
`1303`		`- return findAncestor(node, n => n.kind === SyntaxKind.ImportDeclaration) as ImportDeclaration;`
	`1303`	`+ return findAncestor(node, isImportDeclaration);`
`1304`	`1304`	`}`
`1305`	`1305`	`}`
`1306`	`1306`
`@@ -22638,7 +22638,7 @@ namespace ts {`
`22638`	`22638`	`const symbolIsUmdExport = symbolFile !== referenceFile;`
`22639`	`22639`	`return symbolIsUmdExport ? undefined : symbolFile;`
`22640`	`22640`	`}`
`22641`		`- return findAncestor(node.parent, n => isModuleOrEnumDeclaration(n) && getSymbolOfNode(n) === parentSymbol) as ModuleDeclaration \| EnumDeclaration;`
	`22641`	`+ return findAncestor(node.parent, (n): n is ModuleDeclaration \| EnumDeclaration => isModuleOrEnumDeclaration(n) && getSymbolOfNode(n) === parentSymbol);`
`22642`	`22642`	`}`
`22643`	`22643`	`}`
`22644`	`22644`	`}`
Original file line number	Diff line number	Diff line change
`@@ -4010,6 +4010,10 @@ namespace ts {`
`4010`	`4010`	`return node.kind === SyntaxKind.ImportEqualsDeclaration;`
`4011`	`4011`	`}`
`4012`	`4012`
	`4013`	`+ export function isImportDeclaration(node: Node): node is ImportDeclaration {`
	`4014`	`+ return node.kind === SyntaxKind.ImportDeclaration;`
	`4015`	`+ }`
	`4016`	`+`
`4013`	`4017`	`export function isImportClause(node: Node): node is ImportClause {`
`4014`	`4018`	`return node.kind === SyntaxKind.ImportClause;`
`4015`	`4019`	`}`