123 lines
2.5 KiB
Go
123 lines
2.5 KiB
Go
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// Package token defines constants representing the lexical tokens of JavaScript (ECMA5).
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package token
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import (
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"strconv"
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)
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// Token is the set of lexical tokens in JavaScript (ECMA5).
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type Token int
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// String returns the string corresponding to the token.
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// For operators, delimiters, and keywords the string is the actual
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// token string (e.g., for the token PLUS, the String() is
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// "+"). For all other tokens the string corresponds to the token
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// name (e.g. for the token IDENTIFIER, the string is "IDENTIFIER").
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func (tkn Token) String() string {
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if tkn == 0 {
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return "UNKNOWN"
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}
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if tkn < Token(len(token2string)) {
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return token2string[tkn]
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}
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return "token(" + strconv.Itoa(int(tkn)) + ")"
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}
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//lint:ignore U1000 This is not used for anything
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func (tkn Token) precedence(in bool) int {
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switch tkn {
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case LOGICAL_OR:
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return 1
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case LOGICAL_AND:
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return 2
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case OR, OR_ASSIGN:
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return 3
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case EXCLUSIVE_OR:
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return 4
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case AND, AND_ASSIGN:
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return 5
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case EQUAL,
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NOT_EQUAL,
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STRICT_EQUAL,
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STRICT_NOT_EQUAL:
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return 6
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case LESS, GREATER, LESS_OR_EQUAL, GREATER_OR_EQUAL, INSTANCEOF:
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return 7
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case IN:
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if in {
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return 7
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}
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return 0
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case SHIFT_LEFT, SHIFT_RIGHT, UNSIGNED_SHIFT_RIGHT:
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fallthrough
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case SHIFT_LEFT_ASSIGN, SHIFT_RIGHT_ASSIGN, UNSIGNED_SHIFT_RIGHT_ASSIGN:
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return 8
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case PLUS, MINUS, ADD_ASSIGN, SUBTRACT_ASSIGN:
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return 9
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case MULTIPLY, SLASH, REMAINDER, MULTIPLY_ASSIGN, QUOTIENT_ASSIGN, REMAINDER_ASSIGN:
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return 11
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}
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return 0
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}
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type _keyword struct {
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token Token
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futureKeyword bool
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strict bool
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}
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// IsKeyword returns the keyword token if literal is a keyword, a KEYWORD token
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// if the literal is a future keyword (const, let, class, super, ...), or 0 if the literal is not a keyword.
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//
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// If the literal is a keyword, IsKeyword returns a second value indicating if the literal
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// is considered a future keyword in strict-mode only.
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//
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// 7.6.1.2 Future Reserved Words:
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//
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// const
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// class
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// enum
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// export
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// extends
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// import
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// super
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//
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// 7.6.1.2 Future Reserved Words (strict):
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//
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// implements
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// interface
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// let
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// package
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// private
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// protected
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// public
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// static
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func IsKeyword(literal string) (Token, bool) {
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if keyword, exists := keywordTable[literal]; exists {
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if keyword.futureKeyword {
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return KEYWORD, keyword.strict
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}
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return keyword.token, false
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}
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return 0, false
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}
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func IsId(tkn Token) bool {
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return tkn >= IDENTIFIER
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}
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func IsUnreservedWord(tkn Token) bool {
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return tkn > ESCAPED_RESERVED_WORD
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}
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