JavaScriptMinifier.php

<?php
/**
 * Copyright 2011 Paul Copperman <paul.copperman@gmail.com>
 * Copyright 2018 Timo Tijhof
 * Copyright 2021 Roan Kattouw <roan.kattouw@gmail.com>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 *
 * @file
 * @license Apache-2.0
 * @license MIT
 * @license GPL-2.0-or-later
 * @license LGPL-2.1-or-later
 */

/**
 * JavaScript Minifier
 *
 * This class is meant to safely minify JavaScript code, while leaving syntactically correct
 * programs intact. Other libraries, such as JSMin require a certain coding style to work
 * correctly. OTOH, libraries like jsminplus, that do parse the code correctly are rather
 * slow, because they construct a complete parse tree before outputting the code minified.
 * So this class is meant to allow arbitrary (but syntactically correct) input, while being
 * fast enough to be used for on-the-fly minifying.
 *
 * This class was written with ECMA-262 Edition 6 in mind ("ECMAScript 6"). Parsing features
 * new to later editions of ECMAScript might not be supported. It's assumed that the input is
 * syntactically correct; if it's not, this class may not detect that, and may produce incorrect
 * output.
 *
 * See <https://262.ecma-international.org/6.0/>.
 */
class JavaScriptMinifier {

	/* Parsing states.
	 * The state machine is necessary to decide whether to parse a slash as division
	 * operator or as regexp literal, and to know where semicolon insertion is possible.
	 * States are generally named after the next expected item. We only distinguish states when the
	 * distinction is relevant for our purpose. The meaning of these states is documented
	 * in $model below.
	 *
	 * Negative numbers are used to indicate that the state is inside a generator function,
	 * which changes the behavior of 'yield'
	 */
	private const STATEMENT                     = 1;
	private const CONDITION                     = 2;
	private const FUNC                          = 3;
	private const GENFUNC                       = 4;
	private const PROPERTY_ASSIGNMENT           = 5;
	private const EXPRESSION                    = 6;
	private const EXPRESSION_NO_NL              = 7;
	private const EXPRESSION_OP                 = 8;
	private const EXPRESSION_DOT                = 9;
	private const EXPRESSION_END                = 10;
	private const EXPRESSION_ARROWFUNC          = 11;
	private const EXPRESSION_TERNARY            = 12;
	private const EXPRESSION_TERNARY_OP         = 13;
	private const EXPRESSION_TERNARY_DOT        = 14;
	private const EXPRESSION_TERNARY_ARROWFUNC  = 15;
	private const PAREN_EXPRESSION              = 16;
	private const PAREN_EXPRESSION_OP           = 17;
	private const PAREN_EXPRESSION_DOT          = 18;
	private const PAREN_EXPRESSION_ARROWFUNC    = 19;
	private const PROPERTY_EXPRESSION           = 20;
	private const PROPERTY_EXPRESSION_OP        = 21;
	private const PROPERTY_EXPRESSION_DOT       = 22;
	private const PROPERTY_EXPRESSION_ARROWFUNC = 23;
	private const CLASS_DEF                     = 24;
	private const IMPORT_EXPORT                 = 25;
	private const TEMPLATE_STRING_HEAD          = 26;
	private const TEMPLATE_STRING_TAIL          = 27;

	/* Token types */
	private const TYPE_UN_OP         = 101; // unary operators
	private const TYPE_INCR_OP       = 102; // ++ and --
	private const TYPE_BIN_OP        = 103; // binary operators (except .)
	private const TYPE_ADD_OP        = 104; // + and - which can be either unary or binary ops
	private const TYPE_DOT           = 105; // .
	private const TYPE_HOOK          = 106; // ?
	private const TYPE_COLON         = 107; // :
	private const TYPE_COMMA         = 108; // ,
	private const TYPE_SEMICOLON     = 109; // ;
	private const TYPE_BRACE_OPEN    = 110; // {
	private const TYPE_BRACE_CLOSE   = 111; // }
	private const TYPE_PAREN_OPEN    = 112; // ( and [
	private const TYPE_PAREN_CLOSE   = 113; // ) and ]
	private const TYPE_ARROW         = 114; // =>
	private const TYPE_RETURN        = 115; // keywords: break, continue, return, throw
	private const TYPE_IF            = 116; // keywords: catch, for, with, switch, while, if
	private const TYPE_DO            = 117; // keywords: case, finally, else, do, try
	private const TYPE_VAR           = 118; // keywords: var, let, const
	private const TYPE_YIELD         = 119; // keywords: yield
	private const TYPE_FUNC          = 120; // keywords: function
	private const TYPE_CLASS         = 121; // keywords: class
	private const TYPE_LITERAL       = 122; // all literals, identifiers, unrecognised tokens, and other keywords
	private const TYPE_SPECIAL       = 123; // For special treatment of tokens that usually mean something else

	private const ACTION_GOTO = 201; // Go to another state
	private const ACTION_PUSH = 202; // Push a state to the stack
	private const ACTION_POP = 203; // Pop the state from the top of the stack, and go to that state

	// Limit to avoid excessive memory usage
	private const STACK_LIMIT = 1000;

	// Length of the longest token in $tokenTypes made of punctuation characters,
	// as defined in $opChars. Update this if you add longer tokens to $tokenTypes.
	//
	// Currently the longest punctuation token is `>>>=`, which is 4 characters.
	private const LONGEST_PUNCTUATION_TOKEN = 4;

	/**
	 * @var int $maxLineLength
	 *
	 * Maximum line length
	 *
	 * This is not a strict maximum, but a guideline. Longer lines will be
	 * produced when literals (e.g. quoted strings) longer than this are
	 * encountered, or when required to guard against semicolon insertion.
	 *
	 * This is a private member (instead of constant) to allow tests to
	 * set it to 1, to verify ASI and line-breaking behaviour.
	 */
	private static $maxLineLength = 1000;

	private static $expandedStates = false;

	/**
	 * @var array $opChars
	 *
	 * Characters which can be combined without whitespace between them.
	 */
	private static $opChars = [
		// ECMAScript 6.0 § 11.7 Punctuators
		// Unlike the spec, these are individual symbols, not sequences.
		'{' => true,
		'}' => true,
		'(' => true,
		')' => true,
		'[' => true,
		']' => true,
		// Dots have a special case after $dotlessNum which require whitespace
		'.' => true,
		';' => true,
		',' => true,
		'<' => true,
		'>' => true,
		'=' => true,
		'!' => true,
		'+' => true,
		'-' => true,
		'*' => true,
		'%' => true,
		'&' => true,
		'|' => true,
		'^' => true,
		'~' => true,
		'?' => true,
		':' => true,
		'/' => true,
		// ECMAScript 6.0 § 11.8.4 String Literals
		'"' => true,
		"'" => true,
		// ECMAScript 6.0 § 11.8.6 Template Literal Lexical Components
		'`' => true,
	];

	/**
	 * @var array $tokenTypes
	 *
	 * Tokens and their types.
	 */
	private static $tokenTypes = [
		// ECMAScript 6.0 § 12.5 Unary Operators
		// UnaryExpression includes PostfixExpression, which includes 'new'.
		'new'        => self::TYPE_UN_OP,
		'delete'     => self::TYPE_UN_OP,
		'void'       => self::TYPE_UN_OP,
		'typeof'     => self::TYPE_UN_OP,
		'~'          => self::TYPE_UN_OP,
		'!'          => self::TYPE_UN_OP,
		// ECMAScript 6.0 § 12.2 Primary Expression, among others
		'...'        => self::TYPE_UN_OP,
		// ECMAScript 6.0 § 12.7 Additive Operators
		'++'         => self::TYPE_INCR_OP,
		'--'         => self::TYPE_INCR_OP,
		'+'          => self::TYPE_ADD_OP,
		'-'          => self::TYPE_ADD_OP,
		// ECMAScript 6.0 § 12.6 Multiplicative Operators
		'*'          => self::TYPE_BIN_OP,
		'/'          => self::TYPE_BIN_OP,
		'%'          => self::TYPE_BIN_OP,
		// ECMAScript 6.0 § 12.8 Bitwise Shift Operators
		'<<'         => self::TYPE_BIN_OP,
		'>>'         => self::TYPE_BIN_OP,
		'>>>'        => self::TYPE_BIN_OP,
		// ECMAScript 6.0 § 12.9 Relational Operators
		'<'          => self::TYPE_BIN_OP,
		'>'          => self::TYPE_BIN_OP,
		'<='         => self::TYPE_BIN_OP,
		'>='         => self::TYPE_BIN_OP,
		'instanceof' => self::TYPE_BIN_OP,
		'in'         => self::TYPE_BIN_OP,
		// ECMAScript 6.0 § 12.10 Equality Operators
		'=='         => self::TYPE_BIN_OP,
		'!='         => self::TYPE_BIN_OP,
		'==='        => self::TYPE_BIN_OP,
		'!=='        => self::TYPE_BIN_OP,
		// ECMAScript 6.0 § 12.11 Binary Bitwise Operators
		'&'          => self::TYPE_BIN_OP,
		'^'          => self::TYPE_BIN_OP,
		'|'          => self::TYPE_BIN_OP,
		// ECMAScript 6.0 § 12.12 Binary Logical Operators
		'&&'         => self::TYPE_BIN_OP,
		'||'         => self::TYPE_BIN_OP,
		// ECMAScript 6.0 § 12.13 Conditional Operator
		// Also known as ternary.
		'?'          => self::TYPE_HOOK,
		':'          => self::TYPE_COLON,
		// ECMAScript 6.0 § 12.14 Assignment Operators
		'='          => self::TYPE_BIN_OP,
		'*='         => self::TYPE_BIN_OP,
		'/='         => self::TYPE_BIN_OP,
		'%='         => self::TYPE_BIN_OP,
		'+='         => self::TYPE_BIN_OP,
		'-='         => self::TYPE_BIN_OP,
		'<<='        => self::TYPE_BIN_OP,
		'>>='        => self::TYPE_BIN_OP,
		'>>>='       => self::TYPE_BIN_OP,
		'&='         => self::TYPE_BIN_OP,
		'^='         => self::TYPE_BIN_OP,
		'|='         => self::TYPE_BIN_OP,
		// ECMAScript 6.0 § 12.15 Comma Operator
		','          => self::TYPE_COMMA,

		// The keywords that disallow LineTerminator before their
		// (sometimes optional) Expression or Identifier.
		//
		//    keyword ;
		//    keyword [no LineTerminator here] Identifier ;
		//    keyword [no LineTerminator here] Expression ;
		//
		// See also ECMAScript 6.0 § 11.9.1 Rules of Automatic Semicolon Insertion
		'continue'   => self::TYPE_RETURN,
		'break'      => self::TYPE_RETURN,
		'return'     => self::TYPE_RETURN,
		'throw'      => self::TYPE_RETURN,
		// yield is only a keyword inside generator functions, otherwise it's an identifier
		// This is handled with the negative states hack: if the state is negative, TYPE_YIELD
		// is treated as TYPE_RETURN, if it's positive it's treated as TYPE_LITERAL
		'yield'      => self::TYPE_YIELD,

		// The keywords require a parenthesised Expression or Identifier
		// before the next Statement.
		//
		//     keyword ( Expression ) Statement
		//     keyword ( Identifier ) Statement
		//
		// See also ECMAScript 6.0:
		// - § 13.6 The if Statement
		// - § 13.7 Iteration Statements (do, while, for)
		// - § 12.10 The with Statement
		// - § 12.11 The switch Statement
		// - § 12.13 The throw Statement
		'if'         => self::TYPE_IF,
		'catch'      => self::TYPE_IF,
		'while'      => self::TYPE_IF,
		'for'        => self::TYPE_IF,
		'switch'     => self::TYPE_IF,
		'with'       => self::TYPE_IF,

		// The keywords followed by a Statement, Expression, or Block.
		//
		//     else Statement
		//     do Statement
		//     case Expression
		//     try Block
		//     finally Block
		//
		// See also ECMAScript 6.0:
		// - § 13.6 The if Statement (else)
		// - § 13.7 Iteration Statements (do, while, for)
		// - § 13.12 The switch Statement (case)
		// - § 13.15 The try Statement
		'else'       => self::TYPE_DO,
		'do'         => self::TYPE_DO,
		'case'       => self::TYPE_DO,
		'try'        => self::TYPE_DO,
		'finally'    => self::TYPE_DO,

		// Keywords followed by a variable declaration
		// This is different from the group above, because a { begins
		// object destructuring, rather than a block
		'var'        => self::TYPE_VAR,
		'let'        => self::TYPE_VAR,
		'const'      => self::TYPE_VAR,

		// ECMAScript 6.0 § 14.1 Function Definitions
		'function'   => self::TYPE_FUNC,
		// ECMAScript 6.0 § 14.2 Arrow Function Definitions
		'=>'         => self::TYPE_ARROW,

		// Class declaration or expression:
		//     class Identifier { ClassBody }
		//     class { ClassBody }
		//     class Identifier extends Expression { ClassBody }
		//     class extends Expression { ClassBody }
		'class'      => self::TYPE_CLASS,

		// ECMAScript 6.0 § 12.3 Left-Hand-Side Expressions (MemberExpression)
		// A dot can also be part of a DecimalLiteral, but in that case we handle the entire
		// DecimalLiteral as one token. A separate '.' token is always part of a MemberExpression.
		'.'          => self::TYPE_DOT,

		// Can be one of:
		// - Block (ECMAScript 6.0 § 13.2 Block)
		// - ObjectLiteral (ECMAScript 6.0 § 12.2 Primary Expression)
		'{'          => self::TYPE_BRACE_OPEN,
		'}'          => self::TYPE_BRACE_CLOSE,

		// Can be one of:
		// - Parenthesised Identifier or Expression after a
		//   TYPE_IF or TYPE_FUNC keyword.
		// - PrimaryExpression (ECMAScript 6.0 § 12.2 Primary Expression)
		// - CallExpression (ECMAScript 6.0 § 12.3 Left-Hand-Side Expressions)
		// - Beginning of an ArrowFunction (ECMAScript 6.0 § 14.2 Arrow Function Definitions)
		'('          => self::TYPE_PAREN_OPEN,
		')'          => self::TYPE_PAREN_CLOSE,

		// Can be one of:
		// - ArrayLiteral (ECMAScript 6.0 § 12.2 Primary Expressions)
		// - ComputedPropertyName (ECMAScript 6.0 § 12.2.6 Object Initializer)
		'['          => self::TYPE_PAREN_OPEN,
		']'          => self::TYPE_PAREN_CLOSE,

		// Can be one of:
		// - End of any statement
		// - EmptyStatement (ECMAScript 6.0 § 13.4 Empty Statement)
		';'          => self::TYPE_SEMICOLON,
	];

	/**
	 * @var array $model
	 *
	 * The main table for the state machine. Defines the desired action for every state/token pair.
	 *
	 * The state pushed onto the stack by ACTION_PUSH will be returned to by ACTION_POP.
	 * A state/token pair may not specify both ACTION_POP and ACTION_GOTO. If that does happen,
	 * ACTION_POP takes precedence.
	 *
	 * This table is augmented by self::ensureExpandedStates().
	 */
	private static $model = [
		// Statement - This is the initial state.
		self::STATEMENT => [
			self::TYPE_UN_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_INCR_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_BRACE_OPEN => [
				// Use of '{' in statement context, creates a Block.
				self::ACTION_PUSH => self::STATEMENT,
			],
			self::TYPE_BRACE_CLOSE => [
				// Ends a Block
				self::ACTION_POP => true,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_RETURN => [
				self::ACTION_GOTO => self::EXPRESSION_NO_NL,
			],
			self::TYPE_IF => [
				self::ACTION_GOTO => self::CONDITION,
			],
			self::TYPE_VAR => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::STATEMENT,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::STATEMENT,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_SPECIAL => [
				'import' => [
					self::ACTION_GOTO => self::IMPORT_EXPORT,
				],
				'export' => [
					self::ACTION_GOTO => self::IMPORT_EXPORT,
				],
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
		],
		// The state after if/catch/while/for/switch/with
		// Waits for an expression in parentheses, then goes to STATEMENT
		self::CONDITION => [
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::STATEMENT,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
		],
		// The state after the function keyword. Waits for {, then goes to STATEMENT.
		// The function body's closing } will pop the stack, so the state to return to
		// after the function should be pushed to the stack first
		self::FUNC => [
			// Needed to prevent * in an expression in the argument list from improperly
			// triggering GENFUNC
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::FUNC,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_BRACE_OPEN => [
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_SPECIAL => [
				'*' => [
					self::ACTION_GOTO => self::GENFUNC,
				],
			],
		],
		// After function*. Waits for { , then goes to a generator function statement.
		self::GENFUNC => [
			self::TYPE_BRACE_OPEN => [
				// Note negative value: generator function states are negative
				self::ACTION_GOTO => -self::STATEMENT
			],
		],
		// Property assignment - This is an object literal declaration.
		// For example: `{ key: value, key2, [computedKey3]: value3, method4() { ... } }`
		self::PROPERTY_ASSIGNMENT => [
			// Note that keywords like if, class, var, delete, instanceof etc. can be used as keys,
			// and should be treated as literals here, as they are in EXPRESSION_DOT. In this state,
			// that is implicitly true because TYPE_LITERAL has no action, so it stays in this state.
			// If we later add a state transition for TYPE_LITERAL, that same transition should
			// also be applied to TYPE_RETURN, TYPE_IF, TYPE_DO, TYPE_VAR, TYPE_FUNC and TYPE_CLASS.
			self::TYPE_COLON => [
				self::ACTION_GOTO => self::PROPERTY_EXPRESSION,
			],
			// For {, which begins a method
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::PROPERTY_ASSIGNMENT,
				// This is not flipped, see "Special cases" below
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_BRACE_CLOSE => [
				self::ACTION_POP => true,
			],
			// For [, which begins a computed key
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::PROPERTY_ASSIGNMENT,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_SPECIAL => [
				'*' => [
					self::ACTION_PUSH => self::PROPERTY_ASSIGNMENT,
					self::ACTION_GOTO => self::GENFUNC,
				],
			],
		],
		// Place in an expression where we expect an operand or a unary operator: the start
		// of an expression or after an operator. Note that unary operators (including INCR_OP
		// and ADD_OP) cause us to stay in this state, while operands take us to EXPRESSION_OP
		self::EXPRESSION => [
			self::TYPE_SEMICOLON => [
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::PROPERTY_ASSIGNMENT,
			],
			self::TYPE_BRACE_CLOSE => [
				self::ACTION_POP => true,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
		],
		// An expression immediately after return/throw/break/continue, where a newline
		// is not allowed. This state is identical to EXPRESSION, except that semicolon
		// insertion can happen here, and we never stay here: in cases where EXPRESSION would
		// do nothing, we go to EXPRESSION.
		self::EXPRESSION_NO_NL => [
			self::TYPE_UN_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_INCR_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			// BIN_OP seems impossible at the start of an expression, but it can happen in
			// yield *foo
			self::TYPE_BIN_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_SEMICOLON => [
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::PROPERTY_ASSIGNMENT,
			],
			self::TYPE_BRACE_CLOSE => [
				self::ACTION_POP => true,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
		],
		// Place in an expression after an operand, where we expect an operator
		self::EXPRESSION_OP => [
			self::TYPE_BIN_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_DOT => [
				self::ACTION_GOTO => self::EXPRESSION_DOT,
			],
			self::TYPE_HOOK => [
				self::ACTION_PUSH => self::EXPRESSION,
				self::ACTION_GOTO => self::EXPRESSION_TERNARY,
			],
			self::TYPE_COLON => [
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_COMMA => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_SEMICOLON => [
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_ARROW => [
				self::ACTION_GOTO => self::EXPRESSION_ARROWFUNC,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_BRACE_CLOSE => [
				self::ACTION_POP => true,
			],
		],
		// State after a dot (.). Like EXPRESSION, except that many keywords behave like literals
		// (e.g. class, if, else, var, function) because they're not valid as identifiers but are
		// valid as property names.
		self::EXPRESSION_DOT => [
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
			// The following are keywords behaving as literals
			self::TYPE_RETURN => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
			self::TYPE_IF => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
			self::TYPE_DO => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
			self::TYPE_VAR => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
			self::TYPE_FUNC => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
			self::TYPE_CLASS => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
			// We don't expect real unary/binary operators here, but some keywords
			// (new, delete, void, typeof, instanceof, in) are classified as such, and they can be
			// used as property names
			self::TYPE_UN_OP => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
			self::TYPE_BIN_OP => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
		],
		// State after the } closing an arrow function body: like STATEMENT except
		// that it has semicolon insertion, COMMA can continue the expression, and after
		// a function we go to STATEMENT instead of EXPRESSION_OP
		self::EXPRESSION_END => [
			self::TYPE_UN_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_INCR_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_COMMA => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_SEMICOLON => [
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::STATEMENT,
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_BRACE_CLOSE => [
				self::ACTION_POP => true,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_RETURN => [
				self::ACTION_GOTO => self::EXPRESSION_NO_NL,
			],
			self::TYPE_IF => [
				self::ACTION_GOTO => self::CONDITION,
			],
			self::TYPE_VAR => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::STATEMENT,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::STATEMENT,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
		],
		// State after =>. Like EXPRESSION, except that { begins an arrow function body
		// rather than an object literal.
		self::EXPRESSION_ARROWFUNC => [
			self::TYPE_UN_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_INCR_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::EXPRESSION,
			],
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_END,
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::EXPRESSION_OP,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::EXPRESSION_OP,
			],
		],
		// Expression after a ? . This differs from EXPRESSION because a : ends the ternary
		// rather than starting STATEMENT (outside a ternary, : comes after a goto label)
		// The actual rule for : ending the ternary is in EXPRESSION_TERNARY_OP.
		self::EXPRESSION_TERNARY => [
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY_OP,
				self::ACTION_GOTO => self::PROPERTY_ASSIGNMENT,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY_OP,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY_OP,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
		],
		// Like EXPRESSION_OP, but for ternaries, see EXPRESSION_TERNARY
		self::EXPRESSION_TERNARY_OP => [
			self::TYPE_BIN_OP => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY,
			],
			self::TYPE_DOT => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_DOT,
			],
			self::TYPE_HOOK => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY,
				self::ACTION_GOTO => self::EXPRESSION_TERNARY,
			],
			self::TYPE_COMMA => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY,
			],
			self::TYPE_ARROW => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_ARROWFUNC,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_COLON => [
				self::ACTION_POP => true,
			],
		],
		// Like EXPRESSION_DOT, but for ternaries, see EXPRESSION_TERNARY
		self::EXPRESSION_TERNARY_DOT => [
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
			// The following are keywords behaving as literals
			self::TYPE_RETURN => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
			self::TYPE_IF => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
			self::TYPE_DO => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
			self::TYPE_VAR => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
			self::TYPE_FUNC => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
			self::TYPE_CLASS => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
			// We don't expect real unary/binary operators here, but some keywords
			// (new, delete, void, typeof, instanceof, in) are classified as such, and they can be
			// used as property names
			self::TYPE_UN_OP => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
			self::TYPE_BIN_OP => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
		],
		// Like EXPRESSION_ARROWFUNC, but for ternaries, see EXPRESSION_TERNARY
		self::EXPRESSION_TERNARY_ARROWFUNC => [
			self::TYPE_UN_OP => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY,
			],
			self::TYPE_INCR_OP => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY,
			],
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY_OP,
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY_OP,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::EXPRESSION_TERNARY_OP,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::EXPRESSION_TERNARY_OP,
			],
		],
		// Expression inside parentheses. Like EXPRESSION, except that ) ends this state
		// This differs from EXPRESSION because semicolon insertion can't happen here
		self::PAREN_EXPRESSION => [
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::PAREN_EXPRESSION_OP,
				self::ACTION_GOTO => self::PROPERTY_ASSIGNMENT,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::PAREN_EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_PAREN_CLOSE => [
				self::ACTION_POP => true,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::PAREN_EXPRESSION_OP,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::PAREN_EXPRESSION_OP,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
		],
		// Like EXPRESSION_OP, but in parentheses, see PAREN_EXPRESSION
		self::PAREN_EXPRESSION_OP => [
			self::TYPE_BIN_OP => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_DOT => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_DOT,
			],
			self::TYPE_HOOK => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_COLON => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_COMMA => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_SEMICOLON => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_ARROW => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_ARROWFUNC,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::PAREN_EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_PAREN_CLOSE => [
				self::ACTION_POP => true,
			],
		],
		// Like EXPRESSION_DOT, but in parentheses, see PAREN_EXPRESSION
		self::PAREN_EXPRESSION_DOT => [
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
			// The following are keywords behaving as literals
			self::TYPE_RETURN => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
			self::TYPE_IF => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
			self::TYPE_DO => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
			self::TYPE_VAR => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
			self::TYPE_FUNC => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
			self::TYPE_CLASS => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
			// We don't expect real unary/binary operators here, but some keywords
			// (new, delete, void, typeof, instanceof, in) are classified as such, and they can be
			// used as property names
			self::TYPE_UN_OP => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
			self::TYPE_BIN_OP => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
		],
		// Like EXPRESSION_ARROWFUNC, but in parentheses, see PAREN_EXPRESSION
		self::PAREN_EXPRESSION_ARROWFUNC => [
			self::TYPE_UN_OP => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_INCR_OP => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::PAREN_EXPRESSION_OP,
				self::ACTION_GOTO => self::STATEMENT,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::PAREN_EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::PAREN_EXPRESSION_OP,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::PAREN_EXPRESSION_OP,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::PAREN_EXPRESSION_OP,
			],
		],
		// Expression as the value of a key in an object literal. Like EXPRESSION, except that
		// a comma (in PROPERTY_EXPRESSION_OP) goes to PROPERTY_ASSIGNMENT instead
		self::PROPERTY_EXPRESSION => [
			self::TYPE_BRACE_OPEN => [
				self::ACTION_PUSH => self::PROPERTY_EXPRESSION_OP,
				self::ACTION_GOTO => self::PROPERTY_ASSIGNMENT,
			],
			self::TYPE_BRACE_CLOSE => [
				self::ACTION_POP => true,
			],
			self::TYPE_PAREN_OPEN => [
				self::ACTION_PUSH => self::PROPERTY_EXPRESSION_OP,
				self::ACTION_GOTO => self::PAREN_EXPRESSION,
			],
			self::TYPE_FUNC => [
				self::ACTION_PUSH => self::PROPERTY_EXPRESSION_OP,
				self::ACTION_GOTO => self::FUNC,
			],
			self::TYPE_CLASS => [
				self::ACTION_PUSH => self::PROPERTY_EXPRESSION_OP,
				self::ACTION_GOTO => self::CLASS_DEF,
			],
			self::TYPE_LITERAL => [
				self::ACTION_GOTO => self::PROPERTY_EXPRESSION_OP,
			],
		],
		// Like EXPRESSION_OP, but in a property expression, see PROPERTY_EXPRESSION
		self::PROPERTY_EXPRESSION_OP => [
			self::TYPE_BIN_OP => [
				self::ACTION_GOTO => self::PROPERTY_EXPRESSION,
			],
			self::TYPE_ADD_OP => [
				self::ACTION_GOTO => self::PROPERTY_EXPRESSION,
			],
			self::TYPE_DOT => [
				self::ACTION_GOTO => self::PROPERTY_EXPRESSION_DOT,
			],
			self::TYPE_HOOK => [
				self::ACTION_PUSH => self::PROPERTY_EXPRESSION,
				self::ACTION_GOTO => self::EXPRESSION_TERNARY,
			],
			self::TYPE_COMMA => [
				self::ACTION_GOTO => self::PROPERTY_ASSIGNMENT,
			],
			self::TYPE_ARROW => [
				self::ACTION_GOTO => self::PROPERTY_EXPRESSION_ARROWFUNC,
			],
			self::TYPE_BRACE_OPEN => [