fix(parser): tweaked performance

README.md

@@ -16,8 +16,8 @@ A 100% compliant, self-hosted javascript parser with high focus on both performa
 * Emits an ESTree-compatible abstract syntax tree.
 * No backtracking
 * Reduced memory usage
-* Very well tested (~75 000 unit tests with full code coverage))
-* Lightweight - ~74 KB minified
+* Very well tested (~81 000 unit tests with full code coverage))
+* Lightweight - ~76 KB minified
 
 ## ESNext features
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "meriyah",
-  "version": "0.3.1",
+  "version": "0.4.0",
   "description": "A 100% compliant, self-hosted javascript parser with high focus on both performance and stability",
   "main": "dist/meriyah.umd.js",
   "module": "dist/meriyah.esm.js",
@@ -61,27 +61,27 @@
   },
   "devDependencies": {
     "@types/mocha": "^5.2.7",
-    "@types/node": "^12.0.7",
+    "@types/node": "^12.0.8",
     "coveralls": "^3.0.4",
     "cross-env": "^5.2.0",
-    "husky": "^2.4.0",
+    "husky": "^2.4.1",
     "mocha": "^6.1.4",
     "nyc": "^14.1.1",
     "path": "^0.12.7",
     "prettier": "^1.18.2",
     "rimraf": "^2.6.3",
-    "rollup": "^1.14.4",
+    "rollup": "^1.15.6",
     "rollup-plugin-replace": "^2.2.0",
     "rollup-plugin-terser": "^5.0.0",
-    "rollup-plugin-typescript2": "^0.21.1",
+    "rollup-plugin-typescript2": "^0.21.2",
     "source-map-support": "^0.5.12",
     "test262-parser-tests": "0.0.5",
-    "ts-node": "^8.2.0",
+    "ts-node": "^8.3.0",
     "tsconfig-paths": "^3.8.0",
     "tslint": "^5.17.0",
     "tslint-microsoft-contrib": "^6.2.0",
-    "typescript": "^3.5.1",
-    "unexpected": "^11.6.0",
+    "typescript": "^3.5.2",
+    "unexpected": "^11.6.1",
     "unicode-12.0.0": "^0.8.0"
   },
   "husky": {

src/common.ts

@@ -60,11 +60,10 @@ export const enum PropertyKind {
 
 export const enum BindingType {
   None          = 0,
-  ArgumentList  = 1 << 0,
+  ArgList       = 1 << 0,
   Variable      = 1 << 2,
   Let           = 1 << 3,
-  Const         = 1 << 4,
-  Class         = 1 << 5
+  Const         = 1 << 4
 }
 
 export const enum BindingOrigin {
@@ -78,10 +77,8 @@ export const enum BindingOrigin {
 
 export const enum AssignmentKind {
   None           = 0,
-  IsAssignable   = 1 << 0,
-  CannotAssign   = 1 << 1,
-  Await          = 1 << 2,
-  Yield          = 1 << 3,
+  Assignable   = 1 << 0,
+  NotAssignable   = 1 << 1
 }
 
 export const enum DestructuringKind {
@@ -105,7 +102,7 @@ export const enum Flags {
   HasConstructor      = 1 << 5,
   Octals              = 1 << 6,
   SimpleParameterList = 1 << 7,
-  Yield          = 1 << 8,
+  Yield               = 1 << 8,
 }
 
 export const enum FunctionStatement {
@@ -334,14 +331,14 @@ export function isPropertyWithPrivateFieldKey(expr: any): boolean {
  */
 export function isValidLabel(parser: ParserState, labels: any, name: string, isIterationStatement: 0 | 1): 0 | 1 {
 
-  do {
+  while (labels) {
     if (labels['€' + name]) {
       if (isIterationStatement) report(parser, Errors.InvalidNestedStatement);
       return 1;
     }
     if (isIterationStatement && labels.loop) isIterationStatement = 0;
     labels = labels['€'];
-  } while (labels);
+  }
 
   return 0;
 }
@@ -356,7 +353,6 @@ export function isValidLabel(parser: ParserState, labels: any, name: string, isI
  */
 export function validateAndDeclareLabel(parser: ParserState, labels: any, name: string): void {
   let set = labels;
-
   do {
     if (set['€' + name]) report(parser, Errors.LabelRedeclaration, name);
     set = set['€'];

src/errors.ts

@@ -157,7 +157,12 @@ export const enum Errors {
   ImportNotOneArg,
   InvalidImportNew,
   InvalidSpreadInImport,
-  UncompleteArrow
+  UncompleteArrow,
+  DuplicateBinding,
+  DuplicateExportBinding,
+  UndeclaredExportedBinding,
+  UnexpectedPrivateField,
+  DuplicateLetConstBinding
 }
 
 /*@internal*/
@@ -328,7 +333,12 @@ export const errorMessages: {
   [Errors.ImportNotOneArg]: 'import() requires exactly one argument',
   [Errors.InvalidImportNew]: 'Cannot use new with import(...)',
   [Errors.InvalidSpreadInImport]: '... is not allowed in import()',
-  [Errors.UncompleteArrow]: "Expected '=>'"
+  [Errors.UncompleteArrow]: "Expected '=>'",
+  [Errors.DuplicateBinding]: "Duplicate binding '%0'",
+  [Errors.DuplicateExportBinding]: "Cannot export a duplicate name '%0'",
+  [Errors.DuplicateLetConstBinding]: 'Duplicate %0 for-binding',
+  [Errors.UndeclaredExportedBinding]: "Exported binding '%0' needs to refer to a top-level declared variable",
+  [Errors.UnexpectedPrivateField]: 'Unexpected private field'
 };
 
 export class ParseError extends SyntaxError {