perf: replace multi-comparison type chains with static readonly Sets

src/metricsAnalyzer/languages/csharpAnalyzer.ts

@@ -86,6 +86,30 @@ export class CSharpMetricsAnalyzer {
     "enum_declaration",
   ]);
 
+  /** Node types that represent function/method declarations — used for O(1) type checks during traversal. */
+  private static readonly FUNCTION_DECLARATION_TYPES: ReadonlySet<string> = new Set([
+    "method_declaration",
+    "constructor_declaration",
+    "destructor_declaration",
+    "operator_declaration",
+    "conversion_operator_declaration",
+    "accessor_declaration",
+    "local_function_statement",
+  ]);
+
+  /** Node types that increase the nesting level for cognitive complexity analysis. */
+  private static readonly NESTING_TYPES: ReadonlySet<string> = new Set([
+    "if_statement",
+    "while_statement",
+    "for_statement",
+    "foreach_statement",
+    "switch_statement",
+    "try_statement",
+    "catch_clause",
+    "lambda_expression",
+    "anonymous_method_expression",
+  ]);
+
   /** Current nesting level during analysis */
   private nesting = 0;
   /** Current complexity score during analysis */
@@ -168,15 +192,7 @@ export class CSharpMetricsAnalyzer {
    * @returns True if the node represents a function declaration
    */
   private isFunctionDeclaration(node: Parser.SyntaxNode): boolean {
-    return (
-      node.type === "method_declaration" ||
-      node.type === "constructor_declaration" ||
-      node.type === "destructor_declaration" ||
-      node.type === "operator_declaration" ||
-      node.type === "conversion_operator_declaration" ||
-      node.type === "accessor_declaration" ||
-      node.type === "local_function_statement"
-    );
+    return CSharpMetricsAnalyzer.FUNCTION_DECLARATION_TYPES.has(node.type);
   }
 
   /**
@@ -829,17 +845,7 @@ export class CSharpMetricsAnalyzer {
    * @returns True if the node increases nesting level
    */
   private increasesNesting(node: Parser.SyntaxNode): boolean {
-    return (
-      node.type === "if_statement" ||
-      node.type === "while_statement" ||
-      node.type === "for_statement" ||
-      node.type === "foreach_statement" ||
-      node.type === "switch_statement" ||
-      node.type === "try_statement" ||
-      node.type === "catch_clause" ||
-      node.type === "lambda_expression" ||
-      node.type === "anonymous_method_expression"
-    );
+    return CSharpMetricsAnalyzer.NESTING_TYPES.has(node.type);
   }
 
   /**

src/metricsAnalyzer/languages/goAnalyzer.ts

@@ -77,6 +77,16 @@ interface GoFunctionMetrics {
  * ```
  */
 export class GoMetricsAnalyzer {
+  /** Node types that increase the nesting level for cognitive complexity analysis. */
+  private static readonly NESTING_TYPES: ReadonlySet<string> = new Set([
+    "if_statement",
+    "for_statement",
+    "expression_switch_statement",
+    "type_switch_statement",
+    "select_statement",
+    "func_literal",
+  ]);
+
   /** Current nesting level during analysis */
   private nesting = 0;
   /** Current complexity score during analysis */
@@ -496,14 +506,7 @@ export class GoMetricsAnalyzer {
    * @returns True if the node increases nesting level
    */
   private increasesNesting(node: Parser.SyntaxNode): boolean {
-    return (
-      node.type === "if_statement" ||
-      node.type === "for_statement" ||
-      node.type === "expression_switch_statement" ||
-      node.type === "type_switch_statement" ||
-      node.type === "select_statement" ||
-      node.type === "func_literal"
-    );
+    return GoMetricsAnalyzer.NESTING_TYPES.has(node.type);
   }
 
   /**

src/metricsAnalyzer/languages/javaAnalyzer.ts

@@ -78,6 +78,24 @@ interface JavaFunctionMetrics {
 export class JavaMetricsAnalyzer {
   private static readonly ELSE_BRANCH_INDEX = 2;
 
+  /** Node types that represent method or constructor declarations. */
+  private static readonly METHOD_DECLARATION_TYPES: ReadonlySet<string> = new Set([
+    "method_declaration",
+    "constructor_declaration",
+  ]);
+
+  /** Node types that increase the nesting level for cognitive complexity analysis. */
+  private static readonly NESTING_TYPES: ReadonlySet<string> = new Set([
+    "if_statement",
+    "while_statement",
+    "for_statement",
+    "enhanced_for_statement",
+    "do_statement",
+    "catch_clause",
+    "switch_expression",
+    "lambda_expression",
+  ]);
+
   /** Current nesting level during analysis */
   private nesting = 0;
   /** Current complexity score during analysis */
@@ -124,10 +142,7 @@ export class JavaMetricsAnalyzer {
    * Determines if a syntax node represents a method or constructor declaration.
    */
   private isMethodDeclaration(node: Parser.SyntaxNode): boolean {
-    return (
-      node.type === "method_declaration" ||
-      node.type === "constructor_declaration"
-    );
+    return JavaMetricsAnalyzer.METHOD_DECLARATION_TYPES.has(node.type);
   }
 
   /**
@@ -409,16 +424,7 @@ export class JavaMetricsAnalyzer {
    * @returns True if the node increases nesting level
    */
   private increasesNesting(node: Parser.SyntaxNode): boolean {
-    return (
-      node.type === "if_statement" ||
-      node.type === "while_statement" ||
-      node.type === "for_statement" ||
-      node.type === "enhanced_for_statement" ||
-      node.type === "do_statement" ||
-      node.type === "catch_clause" ||
-      node.type === "switch_expression" ||
-      node.type === "lambda_expression"
-    );
+    return JavaMetricsAnalyzer.NESTING_TYPES.has(node.type);
   }
 
   /**

src/metricsAnalyzer/languages/jsLikeAnalyzer.ts

@@ -64,6 +64,35 @@ export interface JsLikeFunctionMetrics {
  * a pre-initialised `Parser` instance to the constructor.
  */
 export class JsLikeMetricsAnalyzer {
+  /** Node types that represent top-level function-like nodes eligible for independent analysis. */
+  private static readonly FUNCTION_NODE_TYPES: ReadonlySet<string> = new Set([
+    "function_declaration",
+    "function_expression",
+    "generator_function_declaration",
+    "generator_function",
+    "method_definition",
+    "arrow_function",
+  ]);
+
+  /** Node types that represent nested function expressions subject to a nesting-level increment. */
+  private static readonly NESTED_FUNCTION_TYPES: ReadonlySet<string> = new Set([
+    "function_expression",
+    "generator_function",
+    "arrow_function",
+    "method_definition",
+  ]);
+
+  /** Node types that increase the nesting level for cognitive complexity analysis. */
+  private static readonly NESTING_TYPES: ReadonlySet<string> = new Set([
+    "if_statement",
+    "for_statement",
+    "for_in_statement",
+    "while_statement",
+    "do_statement",
+    "switch_statement",
+    "catch_clause",
+  ]);
+
   /** Current nesting level during analysis */
   private nesting = 0;
   /** Current complexity score during analysis */
@@ -112,13 +141,7 @@ export class JsLikeMetricsAnalyzer {
     node: Parser.SyntaxNode,
     functions: JsLikeFunctionMetrics[]
   ): void {
-    const isFunctionNode =
-      node.type === "function_declaration" ||
-      node.type === "function_expression" ||
-      node.type === "generator_function_declaration" ||
-      node.type === "generator_function" ||
-      node.type === "method_definition" ||
-      node.type === "arrow_function";
+    const isFunctionNode = JsLikeMetricsAnalyzer.FUNCTION_NODE_TYPES.has(node.type);
 
     if (isFunctionNode) {
       // Save current state before analyzing this function
@@ -328,12 +351,7 @@ export class JsLikeMetricsAnalyzer {
    * Checks if a node is a nested function definition.
    */
   private isNestedFunction(node: Parser.SyntaxNode): boolean {
-    return (
-      node.type === "function_expression" ||
-      node.type === "generator_function" ||
-      node.type === "arrow_function" ||
-      node.type === "method_definition"
-    );
+    return JsLikeMetricsAnalyzer.NESTED_FUNCTION_TYPES.has(node.type);
   }
 
   /**
@@ -462,14 +480,6 @@ export class JsLikeMetricsAnalyzer {
    * @returns True if the node increases nesting level
    */
   private increasesNesting(node: Parser.SyntaxNode): boolean {
-    return (
-      node.type === "if_statement" ||
-      node.type === "for_statement" ||
-      node.type === "for_in_statement" ||
-      node.type === "while_statement" ||
-      node.type === "do_statement" ||
-      node.type === "switch_statement" ||
-      node.type === "catch_clause"
-    );
+    return JsLikeMetricsAnalyzer.NESTING_TYPES.has(node.type);
   }
 }

src/metricsAnalyzer/languages/pythonAnalyzer.ts

@@ -71,6 +71,19 @@ interface PythonFunctionMetrics {
  * including the exact location and reason for each complexity increment.
  */
 export class PythonMetricsAnalyzer {
+  /** Node types that increase the nesting level for cognitive complexity analysis. */
+  private static readonly NESTING_TYPES: ReadonlySet<string> = new Set([
+    "if_statement",
+    "for_statement",
+    "while_statement",
+    "except_clause",
+    "match_statement",
+    "list_comprehension",
+    "set_comprehension",
+    "dictionary_comprehension",
+    "generator_expression",
+  ]);
+
   /** Current nesting level during analysis */
   private nesting = 0;
   /** Current complexity score during analysis */
@@ -353,20 +366,7 @@ export class PythonMetricsAnalyzer {
    * @returns True if traversing into this node's children should use an increased nesting level
    */
   private increasesNesting(node: Parser.SyntaxNode): boolean {
-    switch (node.type) {
-      case "if_statement":
-      case "for_statement":
-      case "while_statement":
-      case "except_clause":
-      case "match_statement":
-      case "list_comprehension":
-      case "set_comprehension":
-      case "dictionary_comprehension":
-      case "generator_expression":
-        return true;
-      default:
-        return false;
-    }
+    return PythonMetricsAnalyzer.NESTING_TYPES.has(node.type);
   }
 
   /**

src/metricsAnalyzer/languages/rustAnalyzer.ts

@@ -77,6 +77,16 @@ interface RustFunctionMetrics {
  * ```
  */
 export class RustMetricsAnalyzer {
+  /** Node types that increase the nesting level for cognitive complexity analysis. */
+  private static readonly NESTING_TYPES: ReadonlySet<string> = new Set([
+    "if_expression",
+    "for_expression",
+    "while_expression",
+    "loop_expression",
+    "match_expression",
+    "closure_expression",
+  ]);
+
   /** Current nesting level during analysis */
   private nesting = 0;
   /** Current complexity score during analysis */
@@ -429,14 +439,7 @@ export class RustMetricsAnalyzer {
    * @returns True if the node increases nesting level
    */
   private increasesNesting(node: Parser.SyntaxNode): boolean {
-    return (
-      node.type === "if_expression" ||
-      node.type === "for_expression" ||
-      node.type === "while_expression" ||
-      node.type === "loop_expression" ||
-      node.type === "match_expression" ||
-      node.type === "closure_expression"
-    );
+    return RustMetricsAnalyzer.NESTING_TYPES.has(node.type);
   }
 
   /**