Reduce stack depth due to substitution

Author: rbuckton

src/compiler/emitter.ts

@@ -37,7 +37,7 @@ namespace ts {
 
             // transform hooks
             onEmitNode: transform.emitNodeWithNotification,
-            onSubstituteNode: transform.emitNodeWithSubstitution,
+            substituteNode: transform.substituteNode,
 
             // sourcemap hooks
             onEmitSourceMapOfNode: sourceMap.emitNodeWithSourceMap,
@@ -198,7 +198,7 @@ namespace ts {
             onEmitNode,
             onEmitHelpers,
             onSetSourceFile,
-            onSubstituteNode,
+            substituteNode,
         } = handlers;
 
         const newLine = getNewLineCharacter(printerOptions);
@@ -327,8 +327,8 @@ namespace ts {
             setWriter(/*output*/ undefined);
         }
 
-        function emit(node: Node, hint = EmitHint.Unspecified) {
-            pipelineEmitWithNotification(hint, node);
+        function emit(node: Node) {
+            pipelineEmitWithNotification(EmitHint.Unspecified, node);
         }
 
         function emitIdentifierName(node: Identifier) {
@@ -349,6 +349,7 @@ namespace ts {
         }
 
         function pipelineEmitWithComments(hint: EmitHint, node: Node) {
+            node = trySubstituteNode(hint, node);
             if (emitNodeWithComments && hint !== EmitHint.SourceFile) {
                 emitNodeWithComments(hint, node, pipelineEmitWithSourceMap);
             }
@@ -359,16 +360,7 @@ namespace ts {
 
         function pipelineEmitWithSourceMap(hint: EmitHint, node: Node) {
             if (onEmitSourceMapOfNode && hint !== EmitHint.SourceFile && hint !== EmitHint.IdentifierName) {
-                onEmitSourceMapOfNode(hint, node, pipelineEmitWithSubstitution);
-            }
-            else {
-                pipelineEmitWithSubstitution(hint, node);
-            }
-        }
-
-        function pipelineEmitWithSubstitution(hint: EmitHint, node: Node) {
-            if (onSubstituteNode) {
-                onSubstituteNode(hint, node, pipelineEmitWithHint);
+                onEmitSourceMapOfNode(hint, node, pipelineEmitWithHint);
             }
             else {
                 pipelineEmitWithHint(hint, node);
@@ -634,7 +626,7 @@ namespace ts {
             // If the node is an expression, try to emit it as an expression with
             // substitution.
             if (isExpression(node)) {
-                return pipelineEmitWithSubstitution(EmitHint.Expression, node);
+                return pipelineEmitExpression(trySubstituteNode(EmitHint.Expression, node));
             }
         }
 
@@ -731,6 +723,10 @@ namespace ts {
             }
         }
 
+        function trySubstituteNode(hint: EmitHint, node: Node) {
+            return node && substituteNode && substituteNode(hint, node) || node;
+        }
+
         function emitBodyIndirect(node: Node, elements: NodeArray<Node>, emitCallback: (node: Node) => void): void {
             if (emitBodyWithDetachedComments) {
                 emitBodyWithDetachedComments(node, elements, emitCallback);

src/compiler/transformer.ts

@@ -159,7 +159,7 @@ namespace ts {
 
         return {
             transformed,
-            emitNodeWithSubstitution,
+            substituteNode,
             emitNodeWithNotification,
             dispose
         };
@@ -191,14 +191,9 @@ namespace ts {
          * @param node The node to emit.
          * @param emitCallback The callback used to emit the node or its substitute.
          */
-        function emitNodeWithSubstitution(hint: EmitHint, node: Node, emitCallback: (hint: EmitHint, node: Node) => void) {
-            Debug.assert(state < TransformationState.Disposed, "Cannot invoke TransformationResult callbacks after the result is disposed.");
-            if (node) {
-                if (isSubstitutionEnabled(node)) {
-                    node = onSubstituteNode(hint, node) || node;
-                }
-                emitCallback(hint, node);
-            }
+        function substituteNode(hint: EmitHint, node: Node) {
+            Debug.assert(state < TransformationState.Disposed, "Cannot substitute a node after the result is disposed.");
+            return node && isSubstitutionEnabled(node) && onSubstituteNode(hint, node) || node;
         }
 
         /**

src/compiler/transformers/es2015.ts

@@ -3549,7 +3549,7 @@ namespace ts {
             if (enabledSubstitutions & ES2015SubstitutionFlags.BlockScopedBindings) {
                 const original = getParseTreeNode(node, isIdentifier);
                 if (original && isNameOfDeclarationWithCollidingName(original)) {
-                    return getGeneratedNameForNode(original);
+                    return setTextRange(getGeneratedNameForNode(original), node);
                 }
             }
 
@@ -3602,7 +3602,7 @@ namespace ts {
             if (enabledSubstitutions & ES2015SubstitutionFlags.BlockScopedBindings) {
                 const declaration = resolver.getReferencedDeclarationWithCollidingName(node);
                 if (declaration) {
-                    return getGeneratedNameForNode(declaration.name);
+                    return setTextRange(getGeneratedNameForNode(declaration.name), node);
                 }
             }
 

src/compiler/transformers/ts.ts

@@ -3322,8 +3322,6 @@ namespace ts {
                         : getTextOfNode(node.argumentExpression);
 
                     addSyntheticTrailingComment(substitute, SyntaxKind.MultiLineCommentTrivia, ` ${propertyName} `);
-                    // wrap the substituted node so that it emits its own comments.
-                    return createPartiallyEmittedExpression(substitute);
                 }
 
                 return substitute;

src/compiler/types.ts

@@ -3901,13 +3901,12 @@
         diagnostics?: Diagnostic[];
 
         /**
-         * Emits the substitute for a node, if one is available; otherwise, emits the node.
+         * Gets a substitute for a node, if one is available; otherwise, returns the original node.
          *
          * @param hint A hint as to the intended usage of the node.
          * @param node The node to substitute.
-         * @param emitCallback A callback used to emit the node or its substitute.
          */
-        emitNodeWithSubstitution(hint: EmitHint, node: Node, emitCallback: (hint: EmitHint, node: Node) => void): void;
+        substituteNode(hint: EmitHint, node: Node): Node;
 
         /**
          * Emits a node with possible notification.
@@ -3998,23 +3997,20 @@
         /**
          * A hook used by the Printer to perform just-in-time substitution of a node. This is
          * primarily used by node transformations that need to substitute one node for another,
-         * such as replacing `myExportedVar` with `exports.myExportedVar`. A compatible
-         * implementation **must** invoke `emitCallback` eith the provided `hint` and either
-         * the provided `node`, or its substitute.
+         * such as replacing `myExportedVar` with `exports.myExportedVar`.
          * @param hint A hint indicating the intended purpose of the node.
          * @param node The node to emit.
-         * @param emitCallback A callback that, when invoked, will emit the node.
          * @example
          * ```ts
          * var printer = createPrinter(printerOptions, {
-         *   onSubstituteNode(hint, node, emitCallback) {
+         *   substituteNode(hint, node) {
          *     // perform substitution if necessary...
-         *     emitCallback(hint, node);
+         *     return node;
          *   }
          * });
          * ```
          */
-        onSubstituteNode?(hint: EmitHint, node: Node, emitCallback: (hint: EmitHint, node: Node) => void): void;
+        substituteNode?(hint: EmitHint, node: Node): Node;
         /*@internal*/ onEmitSourceMapOfNode?: (hint: EmitHint, node: Node, emitCallback: (hint: EmitHint, node: Node) => void) => void;
         /*@internal*/ onEmitSourceMapOfToken?: (node: Node, token: SyntaxKind, pos: number, emitCallback: (token: SyntaxKind, pos: number) => number) => number;
         /*@internal*/ onEmitSourceMapOfPosition?: (pos: number) => void;

src/compiler/visitor.ts

@@ -709,7 +709,7 @@ namespace ts {
         return node ? f(initial, node) : initial;
     }
 
-    function reduceNodeArray<T>(nodes: Node[], f: (memo: T, nodes: Node[]) => T, initial: T) {
+    function reduceNodeArray<T>(nodes: NodeArray<Node>, f: (memo: T, nodes: NodeArray<Node>) => T, initial: T) {
         return nodes ? f(initial, nodes) : initial;
     }
 
@@ -721,12 +721,12 @@ namespace ts {
      * @param initial The initial value to supply to the reduction.
      * @param f The callback function
      */
-    export function reduceEachChild<T>(node: Node, initial: T, cbNode: (memo: T, node: Node) => T, cbNodeArray?: (memo: T, nodes: Node[]) => T): T {
+    export function reduceEachChild<T>(node: Node, initial: T, cbNode: (memo: T, node: Node) => T, cbNodeArray?: (memo: T, nodes: NodeArray<Node>) => T): T {
         if (node === undefined) {
             return initial;
         }
 
-        const reduceNodes: (nodes: Node[], f: (memo: T, node: Node | Node[]) => T, initial: T) => T = cbNodeArray ? reduceNodeArray : reduceLeft;
+        const reduceNodes: (nodes: NodeArray<Node>, f: (memo: T, node: Node | NodeArray<Node>) => T, initial: T) => T = cbNodeArray ? reduceNodeArray : reduceLeft;
         const cbNodes = cbNodeArray || cbNode;
         const kind = node.kind;
 

src/harness/unittests/transform.ts

@@ -9,7 +9,7 @@ namespace ts {
                     const transformed = transform(createSourceFile("source.ts", source, ScriptTarget.ES2015), transformers);
                     const printer = createPrinter({ newLine: NewLineKind.CarriageReturnLineFeed }, {
                         onEmitNode: transformed.emitNodeWithNotification,
-                        onSubstituteNode: transformed.emitNodeWithSubstitution
+                        substituteNode: transformed.substituteNode
                     });
                     const result = printer.printBundle(createBundle(transformed.transformed));
                     transformed.dispose();