Consolidate jsdoc node getters

They are now used both in getJSDocCommentsAndTagsWorker and in
geParameterSymbolFromJSDoc.

Author: sandersn

src/compiler/utilities.ts

@@ -1538,6 +1538,34 @@ namespace ts {
         return getJSDocCommentsAndTags(node);
     }
 
+    export function getSourceOfAssignment(node: Node): Node {
+        return isExpressionStatement(node) &&
+            node.expression && isBinaryExpression(node.expression) &&
+            node.expression.operatorToken.kind === SyntaxKind.EqualsToken &&
+            node.expression.right;
+    }
+
+    export function getSingleInitializerOfVariableStatement(node: Node, child?: Node): Node {
+        return isVariableStatement(node) &&
+            node.declarationList.declarations.length > 0 &&
+            (!child || node.declarationList.declarations[0].initializer === child) &&
+            node.declarationList.declarations[0].initializer;
+    }
+
+    export function getSingleVariableOfVariableStatement(node: Node, child?: Node): Node {
+        return isVariableStatement(node) &&
+            node.declarationList.declarations.length > 0 &&
+            (!child || node.declarationList.declarations[0] === child) &&
+            node.declarationList.declarations[0];
+    }
+
+    export function getNestedModuleDeclaration(node: Node): Node {
+        return node.kind === SyntaxKind.ModuleDeclaration &&
+            (node as ModuleDeclaration).body &&
+            (node as ModuleDeclaration).body.kind === SyntaxKind.ModuleDeclaration &&
+            (node as ModuleDeclaration).body;
+    }
+
     export function getJSDocCommentsAndTags(node: Node): (JSDoc | JSDocTag)[] {
         let result: (JSDoc | JSDocTag)[] | undefined;
         getJSDocCommentsAndTagsWorker(node);
@@ -1551,35 +1579,15 @@ namespace ts {
             //   * @returns {number}
             //   */
             // var x = function(name) { return name.length; }
-            const isInitializerOfVariableDeclarationInStatement =
-                isVariableLike(parent) &&
-                parent.initializer === node &&
-                parent.parent.parent.kind === SyntaxKind.VariableStatement;
-            const isVariableOfVariableDeclarationStatement = isVariableLike(node) &&
-                parent.parent.kind === SyntaxKind.VariableStatement;
-            const variableStatementNode =
-                isInitializerOfVariableDeclarationInStatement ? parent.parent.parent :
-                    isVariableOfVariableDeclarationStatement ? parent.parent :
-                        undefined;
-            if (variableStatementNode) {
-                getJSDocCommentsAndTagsWorker(variableStatementNode);
+            if (parent && (parent.kind === SyntaxKind.PropertyAssignment || getNestedModuleDeclaration(parent))) {
+                getJSDocCommentsAndTagsWorker(parent);
             }
-
-            // Also recognize when the node is the RHS of an assignment expression
-            const isSourceOfAssignmentExpressionStatement =
-                parent && parent.parent &&
-                parent.kind === SyntaxKind.BinaryExpression &&
-                (parent as BinaryExpression).operatorToken.kind === SyntaxKind.EqualsToken &&
-                parent.parent.kind === SyntaxKind.ExpressionStatement;
-            if (isSourceOfAssignmentExpressionStatement) {
+            if (parent && parent.parent &&
+                (getSingleVariableOfVariableStatement(parent.parent, node) || getSourceOfAssignment(parent.parent))) {
                 getJSDocCommentsAndTagsWorker(parent.parent);
             }
-
-            const isModuleDeclaration = node.kind === SyntaxKind.ModuleDeclaration &&
-                parent && parent.kind === SyntaxKind.ModuleDeclaration;
-            const isPropertyAssignmentExpression = parent && parent.kind === SyntaxKind.PropertyAssignment;
-            if (isModuleDeclaration || isPropertyAssignmentExpression) {
-                getJSDocCommentsAndTagsWorker(parent);
+            if (parent && parent.parent && parent.parent.parent && getSingleInitializerOfVariableStatement(parent.parent.parent, node)) {
+                getJSDocCommentsAndTagsWorker(parent.parent.parent);
             }
 
             // Pull parameter comments from declaring function as well
@@ -1606,24 +1614,16 @@ namespace ts {
             return undefined;
         }
         const name = node.name.escapedText;
-        const decl = getJSDocHost(node);
-        let func: FunctionLike;
-        if (isExpressionStatement(decl) && isBinaryExpression(decl.expression) && isFunctionLike(decl.expression.right)) {
-            func = decl.expression.right;
-        }
-        else if (isVariableStatement(decl) && decl.declarationList.declarations.length === 1 && isVariableDeclaration(decl.declarationList.declarations[0])
-                 && isFunctionLike(decl.declarationList.declarations[0].initializer)) {
-            func = decl.declarationList.declarations[0].initializer as FunctionLike;
-        }
-        else if (isFunctionLike(decl)) {
-            func = decl;
-        }
-        else {
-            return undefined;
+        const host = getJSDocHost(node);
+        const decl = getSourceOfAssignment(host) ||
+            getSingleInitializerOfVariableStatement(host) ||
+            getSingleVariableOfVariableStatement(host) ||
+            getNestedModuleDeclaration(host) ||
+            host;
+        if (decl && isFunctionLike(decl)) {
+            const parameter = find(decl.parameters, p => p.name.kind === SyntaxKind.Identifier && p.name.escapedText === name);
+            return parameter && parameter.symbol;
         }
-        const parameter = find(func.parameters, p =>
-            p.name.kind === SyntaxKind.Identifier && p.name.escapedText === name);
-        return parameter && parameter.symbol;
     }
 
     export function getJSDocHost(node: JSDocTag): HasJSDoc {