Converted no-increment-decrement to use a walk function

src/noIncrementDecrementRule.ts

@@ -1,10 +1,15 @@
 import * as ts from 'typescript';
 import * as Lint from 'tslint';
+import * as tsutils from 'tsutils';
 
 import { ExtendedMetadata } from './utils/ExtendedMetadata';
 
 const OPTION_ALLOW_FOR_LOOPS = 'allow-for-loops';
 
+interface Options {
+    allowForLoops: boolean;
+}
+
 /**
  * Implementation of the no-increment-decrement rule.
  */
@@ -44,51 +49,53 @@ export class Rule extends Lint.Rules.AbstractRule {
             Rule.isWarningShown = true;
         }
 
-        return this.applyWithWalker(new NoIncrementDecrementWalker(sourceFile, this.getOptions()));
+        return this.applyWithFunction(sourceFile, walk, this.parseOptions(this.getOptions()));
     }
-}
-
-class NoIncrementDecrementWalker extends Lint.RuleWalker {
-    private readonly allowForLoops: boolean;
-
-    constructor(sourceFile: ts.SourceFile, options: Lint.IOptions) {
-        super(sourceFile, options);
 
-        this.allowForLoops = options.ruleArguments.indexOf(OPTION_ALLOW_FOR_LOOPS) > -1;
+    private parseOptions(options: Lint.IOptions): Options {
+        return {
+            allowForLoops: options.ruleArguments.indexOf(OPTION_ALLOW_FOR_LOOPS) > -1
+        };
     }
+}
 
-    protected visitForStatement(node: ts.ForStatement): void {
-        if (this.allowForLoops) {
-            // If for loops are allowed to contain increment and decrement,
-            // check everything except the incrementor
-            super.visitNode(node.statement);
-            if (node.initializer) {
-                super.visitNode(node.initializer);
-            }
-            if (node.condition) {
-                super.visitNode(node.condition);
-            }
-        } else {
-            // Otherwise check the node
-            super.visitForStatement(node);
+function walk(ctx: Lint.WalkContext<Options>) {
+    function validateUnaryExpression(node: ts.PrefixUnaryExpression | ts.PostfixUnaryExpression) {
+        if (node.operator === ts.SyntaxKind.PlusPlusToken) {
+            ctx.addFailureAt(node.getStart(), node.getWidth(), 'Forbidden ++ operator');
+        } else if (node.operator === ts.SyntaxKind.MinusMinusToken) {
+            ctx.addFailureAt(node.getStart(), node.getWidth(), 'Forbidden -- operator');
         }
     }
 
-    protected visitPostfixUnaryExpression(node: ts.PostfixUnaryExpression): void {
-        this.validateUnaryExpression(node);
-        super.visitPostfixUnaryExpression(node);
-    }
+    function cb(node: ts.Node): void {
+        if (tsutils.isForStatement(node)) {
+            if (ctx.options.allowForLoops) {
+                // If for loops are allowed to contain increment and decrement,
+                // check everything except the incrementor
+                cb(node.statement);
+                if (node.initializer) {
+                    cb(node.initializer);
+                }
+                if (node.condition) {
+                    cb(node.condition);
+                }
+            } else {
+                // Otherwise check the node
+                ts.forEachChild(node, cb);
+            }
 
-    protected visitPrefixUnaryExpression(node: ts.PrefixUnaryExpression): void {
-        this.validateUnaryExpression(node);
-        super.visitPrefixUnaryExpression(node);
-    }
+            return;
+        }
 
-    private validateUnaryExpression(node: ts.PrefixUnaryExpression | ts.PostfixUnaryExpression) {
-        if (node.operator === ts.SyntaxKind.PlusPlusToken) {
-            this.addFailureAt(node.getStart(), node.getWidth(), 'Forbidden ++ operator');
-        } else if (node.operator === ts.SyntaxKind.MinusMinusToken) {
-            this.addFailureAt(node.getStart(), node.getWidth(), 'Forbidden -- operator');
+        if (tsutils.isPostfixUnaryExpression(node)) {
+            validateUnaryExpression(node);
+        } else if (tsutils.isPrefixUnaryExpression(node)) {
+            validateUnaryExpression(node);
         }
+
+        return ts.forEachChild(node, cb);
     }
+
+    return ts.forEachChild(ctx.sourceFile, cb);
 }