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fix(parser): performance improvements
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@KFlash
KFlash committed Jul 22, 2019
1 parent 89c4006 commit 5bd745a
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Showing 55 changed files with 7,528 additions and 1,014 deletions.
2 changes: 1 addition & 1 deletion README.md
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Original file line number Diff line number Diff line change
Expand Up @@ -23,7 +23,7 @@
* Emits an ESTree-compatible abstract syntax tree.
* No backtracking
* Reduced memory usage
* Very well tested (~81 000 unit tests with full code coverage)
* Very well tested (~83 000 unit tests with full code coverage)
* Lightweight - ~82 KB minified

## ESNext features
Expand Down
285 changes: 269 additions & 16 deletions src/common.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -3,6 +3,14 @@ import { Errors, report } from './errors';
import { Node } from './estree';
import { nextToken } from './lexer/scan';

export const presetBlockIdentifiers: { [key: string]: string } = {
['Infinity']: 'Infinity',
['NaN']: 'NaN',
['Number']: 'Number',
['String']: 'String',
['undefined']: 'undefined'
};

/**
* The core context, passed around everywhere as a simple immutable bit set.
*/
Expand All @@ -22,7 +30,7 @@ export const enum Context {
Module = 1 << 11, // Current code should be parsed as a module body
InSwitch = 1 << 12,
InGlobal = 1 << 13,
TopLevel = 1 << 14,
InClass = 1 << 14,
AllowRegExp = 1 << 15,
TaggedTemplate = 1 << 16,
InIteration = 1 << 17,
Expand All @@ -35,9 +43,8 @@ export const enum Context {
InMethod = 1 << 25,
AllowNewTarget = 1 << 26,
DisallowIn = 1 << 27,
InClass = 1 << 28,
OptionsIdentifierPattern = 1 << 29,
OptionsSpecDeviation = 1 << 30,
OptionsIdentifierPattern = 1 << 28,
OptionsSpecDeviation = 1 << 29,
}

export const enum PropertyKind {
Expand Down Expand Up @@ -65,6 +72,14 @@ export const enum BindingKind {
Variable = 1 << 2,
Let = 1 << 3,
Const = 1 << 4,
Class = 1 << 5,
FunctionLexical = 1 << 6,
FunctionStatement = 1 << 7,
CatchPattern = 1 << 8,
CatchIdentifier = 1 << 9,
CatchIdentifierOrPattern = CatchIdentifier | CatchPattern,
LexicalOrFunction = Variable | FunctionLexical,
LexicalBinding = Let | Const | FunctionLexical | FunctionStatement | Class
}

export const enum BindingOrigin {
Expand All @@ -75,9 +90,8 @@ export const enum BindingOrigin {
Statement = 1 << 3,
Export = 1 << 4,
Other = 1 << 5,
IfStatement = 1 << 6,
BlockStatement = 1 << 9,
TopLevel = 1 << 10
BlockStatement = 1 << 7,
TopLevel = 1 << 8,
}

export const enum AssignmentKind {
Expand Down Expand Up @@ -107,7 +121,8 @@ export const enum Flags {
HasConstructor = 1 << 5,
Octals = 1 << 6,
SimpleParameterList = 1 << 7,
Yield = 1 << 8
HasStrictReserved = 1 << 8,
StrictEvalArguments = 1 << 9,
}

export const enum HoistedClassFlags {
Expand All @@ -122,9 +137,45 @@ export const enum HoistedFunctionFlags {
Export = 1 << 1
}

export const enum FunctionStatement {
Disallow,
Allow
/**
* Scope types
*/
export const enum ScopeKind {
None = 0,
For = 1 << 0,
Block = 1 << 1,
Catch = 1 << 2,
Switch = 1 << 3,
ArgList = 1 << 4,
Try = 1 << 5,
CatchHead = 1 << 6,
CatchBody = 1 << 7,
Finally = 1 << 8,
FuncBody = 1 << 9,
FuncRoot = 1 << 10,
ArrowParams = 1 << 11,
FakeBlock = 1 << 12,
Global = 1 << 13,
CatchIdentifier = 1 << 14,
ForHeader = 1 << 15,
FunctionParams = 1 << 16
}

/**
* Lexical scope interface
*/
export interface ScopeState {
parent: ScopeState | undefined;
type: ScopeKind;
scopeError?: ScopeError | null;
}

/** Scope error interface */
export interface ScopeError {
type: Errors;
index: number;
line: number;
column: number;
}

/**
Expand All @@ -136,14 +187,15 @@ export interface ParserState {
index: number;
line: number;
column: number;
tokenIndex: number;
startIndex: number;
tokenPos: number;
startPos: number;
startColumn: number;
startLine: number;
colPos: number;
linePos: number;
end: number;
token: Token;
onComment: any;
tokenValue: any;
tokenRaw: string;
tokenRegExp: void | {
Expand Down Expand Up @@ -174,6 +226,15 @@ export function consumeSemicolon(parser: ParserState, context: Context, specDevi
consumeOpt(parser, context, Token.Semicolon);
}

export function isValidStrictMode(parser: ParserState, index: number, tokenPos: number, tokenValue: string): 0 | 1 {
if (index - tokenPos < 13 && tokenValue === 'use strict') {
if ((parser.token & Token.IsAutoSemicolon) === Token.IsAutoSemicolon || parser.flags & Flags.NewLine) {
return 1;
}
}
return 0;
}

/**
* Consumes the current token if the current token kind is
* the specified `kind` and returns `0`. Otherwise returns `1`.
Expand Down Expand Up @@ -376,10 +437,10 @@ export function isValidLabel(parser: ParserState, labels: any, name: string, isI
*/
export function validateAndDeclareLabel(parser: ParserState, labels: any, name: string): void {
let set = labels;
do {
while (set) {
if (set['$' + name]) report(parser, Errors.LabelRedeclaration, name);
set = set['$'];
} while (set);
}

labels['$' + name] = 1;
}
Expand All @@ -394,7 +455,7 @@ export function finishNode<T extends Node>(
): T {
if (context & Context.OptionsRanges) {
node.start = start;
node.end = parser.startIndex;
node.end = parser.startPos;
}

if (context & Context.OptionsLoc) {
Expand Down Expand Up @@ -431,3 +492,195 @@ export function isEqualTagName(elementName: any): any {
// ignore
}
}

export function recordScopeError(parser: ParserState, type: Errors): ScopeError {
const { index, line, column } = parser;
return {
type,
index, line, column
}
}

/**
* Creates a block scope
*/
export function createScope(): ScopeState {
return {
parent: void 0,
type: ScopeKind.Global
};
}

/**
* Inherit scope
*
* @param scope Parser object
* @param type Scope type
*/
export function addChildScope(parent: any, type: ScopeKind): ScopeState {
return {
parent,
type,
scopeError: void 0
};
}

export function addVarName(
parser: ParserState,
context: Context,
scope: ScopeState,
name: any,
type: BindingKind
): void {
if (scope === null) return;

const hashed = '#' + name;
const isLexicalBinding = (type & BindingKind.LexicalBinding) !== 0;
const isWebCompat = context & Context.OptionsWebCompat && (context & Context.Strict) === 0

let currentScope: any = scope;

while (currentScope && (currentScope.type & ScopeKind.FuncRoot) === 0) {

const value: ScopeKind = currentScope[hashed];

if (value & BindingKind.LexicalBinding) {
if (isWebCompat &&
((type & BindingKind.FunctionStatement && value & BindingKind.LexicalOrFunction) ||
(value & BindingKind.FunctionStatement && type & BindingKind.LexicalOrFunction))
) {
} else {
report(parser, Errors.DuplicateBinding, name);
}
}
if (currentScope === scope) {
if (value && (value & BindingKind.EmptyBinding) === 0 && isLexicalBinding) {
report(parser, Errors.DuplicateBinding, name);
} else if (value & BindingKind.ArgumentList && type & BindingKind.ArgumentList) {
currentScope.scopeError = recordScopeError(parser, Errors.Unexpected);
}
}
if (value & (BindingKind.CatchIdentifier | BindingKind.CatchPattern)) {
if (((value & BindingKind.CatchIdentifier) === 0 || (context & Context.OptionsWebCompat) === 0) || context & Context.Strict) {
report(parser, Errors.DuplicateBinding, name);
}
}

currentScope[hashed] = type;

currentScope = currentScope.parent;
}
}

export function addBlockName(
parser: ParserState,
context: Context,
scope: any,
name: string,
type: BindingKind,
origin: BindingOrigin
) {
if (!scope) return;

if (presetBlockIdentifiers[name]) report(parser, Errors.DuplicateIdentifier, name);

const hashed = '#' + name;
const value = scope[hashed];

if (value && (value & BindingKind.EmptyBinding) === 0) {
if (type & BindingKind.ArgumentList) {
scope.scopeError = recordScopeError(parser, Errors.Unexpected);
} else if (
context & Context.OptionsWebCompat &&
value & BindingKind.FunctionLexical &&
origin & BindingOrigin.BlockStatement
) {
} else {
report(parser, Errors.DuplicateBinding, name);
}
}

if (
scope.type & ScopeKind.FuncBody &&
(scope.parent[hashed] && (scope.parent[hashed] & BindingKind.EmptyBinding) === 0)
) {
report(parser, Errors.DuplicateBinding, name);
}

if (scope.type & ScopeKind.ArrowParams && value && (value & BindingKind.EmptyBinding) === 0) {
if (type & BindingKind.ArgumentList) {
scope.scopeError = recordScopeError(parser, Errors.Unexpected);
} else if ((type & (BindingKind.CatchIdentifier | BindingKind.CatchPattern)) === 0) {
report(parser, Errors.DuplicateBinding, name);
}
}

if (type & (BindingKind.CatchIdentifier | BindingKind.CatchPattern)) {
if (value & (BindingKind.CatchIdentifier | BindingKind.CatchPattern)) report(parser, Errors.ShadowedCatchClause, name);
} else if (scope.type & ScopeKind.CatchBody) {
if (scope.parent[hashed] & BindingKind.CatchIdentifierOrPattern) report(parser, Errors.ShadowedCatchClause, name);
}

let currentScope = scope.parent;

while (currentScope && (currentScope.type & ScopeKind.FuncRoot) !== ScopeKind.FuncRoot) {
const value = currentScope[hashed];
if (currentScope.type & ScopeKind.ArrowParams) {
if (value & BindingKind.EmptyBinding && (type & BindingKind.CatchIdentifierOrPattern) === 0 ) {
report(parser, Errors.DuplicateBinding, name);
} else if (type & BindingKind.ArgumentList) {
currentScope.dupeParamErrorToken = recordScopeError(parser, Errors.Unexpected);
}
}
currentScope = currentScope.parent;
}

scope[hashed] = type;
}

/**
* Appends a name to the `ExportedNames` of the `ExportsList`, and checks
* for duplicates
*
* @see [Link](https://tc39.github.io/ecma262/$sec-exports-static-semantics-exportednames)
*
* @param parser Parser object
* @param name Exported name
*/
export function updateExportsList(parser: ParserState, name: string): void {
if (parser.exportedNames !== void 0 && name !== '') {
if (parser.exportedNames['#' + name]) {
report(parser, Errors.DuplicateExportBinding, name);
}
parser.exportedNames['#' + name] = 1;
}
}

/**
* Appends a name to the `ExportedBindings` of the `ExportsList`,
*
* @see [Link](https://tc39.es/ecma262/$sec-exports-static-semantics-exportedbindings)
*
* @param parser Parser object
* @param name Exported binding name
*/
export function addBindingToExports(parser: ParserState, name: string): void {
if (parser.exportedBindings !== void 0 && name !== '') {
parser.exportedBindings['#' + name] = 1;
}
}

export function pushComment(context: Context, array: any[]): any {
return function(type: string, value: string, start: number, end: number) {
const comment: any = {
type,
value
};

if (context & Context.OptionsLoc) {
comment.start = start;
comment.end = end;
}
array.push(comment);
};
}
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1 comment on commit 5bd745a

@KFlash
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@KFlash KFlash commented on 5bd745a Jul 23, 2019

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This is the v. 1.4 source. It's now feature complete, but not ready to be published to NPM yet. I still need to make sure it's stable because of the mayor internal improvements. The parser logic changed a little - hopefully to the better so everyone can understand it. But I suspect I did it worse instead :)

onComment have been added to support comment extraction.

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