Switch from onBefore/onAfterEmitNode to onEmitNode

Author: rbuckton

src/compiler/printer.ts

@@ -151,8 +151,7 @@ const _super = (function (geti, seti) {
             let isEmitNotificationEnabled: (node: Node) => boolean;
             let expressionSubstitution: (node: Expression) => Expression;
             let identifierSubstitution: (node: Identifier) => Identifier;
-            let onBeforeEmitNode: (node: Node) => void;
-            let onAfterEmitNode: (node: Node) => void;
+            let onEmitNode: (node: Node, emit: (node: Node) => void) => void;
             let nodeToGeneratedName: string[];
             let generatedNameSet: Map<string>;
             let tempFlags: TempFlags;
@@ -213,8 +212,7 @@ const _super = (function (geti, seti) {
                 isEmitNotificationEnabled = undefined;
                 expressionSubstitution = undefined;
                 identifierSubstitution = undefined;
-                onBeforeEmitNode = undefined;
-                onAfterEmitNode = undefined;
+                onEmitNode = undefined;
                 tempFlags = TempFlags.Auto;
                 currentSourceFile = undefined;
                 currentText = undefined;
@@ -234,8 +232,7 @@ const _super = (function (geti, seti) {
                 isEmitNotificationEnabled = context.isEmitNotificationEnabled;
                 expressionSubstitution = context.expressionSubstitution;
                 identifierSubstitution = context.identifierSubstitution;
-                onBeforeEmitNode = context.onBeforeEmitNode;
-                onAfterEmitNode = context.onAfterEmitNode;
+                onEmitNode = context.onEmitNode;
                 return printSourceFile;
             }
 
@@ -249,46 +246,62 @@ const _super = (function (geti, seti) {
                 return node;
             }
 
+            /**
+             * Emits a node.
+             */
             function emit(node: Node) {
-                emitWithWorker(node, emitWorker);
+                emitNodeWithNotificationOption(node, emitWithoutNotificationOption);
+            }
+
+            /**
+             * Emits a node without calling onEmitNode.
+             * NOTE: Do not call this method directly.
+             */
+            function emitWithoutNotificationOption(node: Node) {
+                emitNodeWithWorker(node, emitWorker);
             }
 
+            /**
+             * Emits an expression node.
+             */
             function emitExpression(node: Expression) {
-                emitWithWorker(node, emitExpressionWorker);
+                emitNodeWithNotificationOption(node, emitExpressionWithoutNotificationOption);
+            }
+
+            /**
+             * Emits an expression without calling onEmitNode.
+             * NOTE: Do not call this method directly.
+             */
+            function emitExpressionWithoutNotificationOption(node: Expression) {
+                emitNodeWithWorker(node, emitExpressionWorker);
             }
 
-            function emitWithWorker(node: Node, emitWorker: (node: Node) => void) {
+            /**
+             * Emits a node with emit notification if available.
+             */
+            function emitNodeWithNotificationOption(node: Node, emit: (node: Node) => void) {
                 if (node) {
-                    const adviseOnEmit = isEmitNotificationEnabled(node);
-                    if (adviseOnEmit && onBeforeEmitNode) {
-                        onBeforeEmitNode(node);
+                    if (isEmitNotificationEnabled(node)) {
+                        onEmitNode(node, emit);
+                    }
+                    else {
+                        emit(node);
                     }
+                }
+            }
 
+            function emitNodeWithWorker(node: Node, emitWorker: (node: Node) => void) {
+                if (node) {
                     const leadingComments = getLeadingComments(node, getNotEmittedParent);
                     const trailingComments = getTrailingComments(node, getNotEmittedParent);
                     emitLeadingComments(node, leadingComments);
                     emitStart(node);
                     emitWorker(node);
                     emitEnd(node);
                     emitTrailingComments(node, trailingComments);
-
-                    if (adviseOnEmit && onAfterEmitNode) {
-                        onAfterEmitNode(node);
-                    }
                 }
             }
 
-            function getNotEmittedParent(node: Node): Node {
-                if (getNodeEmitFlags(node) & NodeEmitFlags.EmitCommentsOfNotEmittedParent) {
-                    const parent = getOriginalNode(node).parent;
-                    if (getNodeEmitFlags(parent) & NodeEmitFlags.IsNotEmittedNode) {
-                        return parent;
-                    }
-                }
-
-                return undefined;
-            }
-
             function emitWorker(node: Node): void {
                 const kind = node.kind;
                 switch (kind) {
@@ -2361,6 +2374,17 @@ const _super = (function (geti, seti) {
                     && rangeEndIsOnSameLineAsRangeStart(block, block);
             }
 
+            function getNotEmittedParent(node: Node): Node {
+                if (getNodeEmitFlags(node) & NodeEmitFlags.EmitCommentsOfNotEmittedParent) {
+                    const parent = getOriginalNode(node).parent;
+                    if (getNodeEmitFlags(parent) & NodeEmitFlags.IsNotEmittedNode) {
+                        return parent;
+                    }
+                }
+
+                return undefined;
+            }
+
             function isUniqueName(name: string): boolean {
                 return !resolver.hasGlobalName(name) &&
                     !hasProperty(currentFileIdentifiers, name) &&

src/compiler/transformer.ts

@@ -46,8 +46,7 @@ namespace ts {
             expressionSubstitution: node => node,
             enableExpressionSubstitution,
             isExpressionSubstitutionEnabled,
-            onBeforeEmitNode: node => { },
-            onAfterEmitNode: node => { },
+            onEmitNode: (node, emit) => emit(node),
             enableEmitNotification,
             isEmitNotificationEnabled,
         };

src/compiler/types.ts

@@ -2865,16 +2865,10 @@ namespace ts {
         isEmitNotificationEnabled(node: Node): boolean;
 
         /**
-         * Hook used to notify transformers immediately before the pretty printer
-         * emits a node.
+         * Hook used to allow transformers to capture state before or after
+         * the printer emits a node.
          */
-        onBeforeEmitNode?: (node: Node) => void;
-
-        /**
-         * Hook used to notify transformers immediately after the pretty printer
-         * emits a node.
-         */
-        onAfterEmitNode?: (node: Node) => void;
+        onEmitNode?: (node: Node, emit: (node: Node) => void) => void;
     }
 
     /* @internal */