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import {types as tt} from "./tokentype"
import {Parser} from "./state"
import {lineBreak} from "./whitespace"
const pp = Parser.prototype
// ## Parser utilities
// Test whether a statement node is the string literal `"use strict"`.
pp.isUseStrict = function(stmt) {
return this.options.ecmaVersion >= 5 && stmt.type === "ExpressionStatement" &&
stmt.expression.type === "Literal" &&
stmt.expression.raw.slice(1, -1) === "use strict"
}
// Predicate that tests whether the next token is of the given
// type, and if yes, consumes it as a side effect.
pp.eat = function(type) {
if (this.type === type) {
this.next()
return true
} else {
return false
}
}
// Tests whether parsed token is a contextual keyword.
pp.isContextual = function(name) {
return this.type === tt.name && this.value === name
}
// Consumes contextual keyword if possible.
pp.eatContextual = function(name) {
return this.value === name && this.eat(tt.name)
}
// Asserts that following token is given contextual keyword.
pp.expectContextual = function(name) {
if (!this.eatContextual(name)) this.unexpected()
}
// Test whether a semicolon can be inserted at the current position.
pp.canInsertSemicolon = function() {
return this.type === tt.eof ||
this.type === tt.braceR ||
lineBreak.test(this.input.slice(this.lastTokEnd, this.start))
}
pp.insertSemicolon = function() {
if (this.canInsertSemicolon()) {
if (this.options.onInsertedSemicolon)
this.options.onInsertedSemicolon(this.lastTokEnd, this.lastTokEndLoc)
return true
}
}
// Consume a semicolon, or, failing that, see if we are allowed to
// pretend that there is a semicolon at this position.
pp.semicolon = function() {
if (!this.eat(tt.semi) && !this.insertSemicolon()) this.unexpected()
}
pp.afterTrailingComma = function(tokType) {
if (this.type == tokType) {
if (this.options.onTrailingComma)
this.options.onTrailingComma(this.lastTokStart, this.lastTokStartLoc)
this.next()
return true
}
}
// Expect a token of a given type. If found, consume it, otherwise,
// raise an unexpected token error.
pp.expect = function(type) {
this.eat(type) || this.unexpected()
}
// Raise an unexpected token error.
pp.unexpected = function(pos) {
this.raise(pos != null ? pos : this.start, "Unexpected token")
}
export class DestructuringErrors {
constructor() {
this.shorthandAssign = 0
this.trailingComma = 0
}
}
pp.checkPatternErrors = function(refDestructuringErrors, andThrow) {
let trailing = refDestructuringErrors && refDestructuringErrors.trailingComma
if (!andThrow) return !!trailing
if (trailing) this.raise(trailing, "Comma is not permitted after the rest element")
}
pp.checkExpressionErrors = function(refDestructuringErrors, andThrow) {
let pos = refDestructuringErrors && refDestructuringErrors.shorthandAssign
if (!andThrow) return !!pos
if (pos) this.raise(pos, "Shorthand property assignments are valid only in destructuring patterns")
}
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