import { types as tt } from "../tokenizer/types";
import Parser from "./index";
import { lineBreak } from "../util/whitespace";

const pp = Parser.prototype;

// ## Parser utilities

// TODO

pp.addExtra = function (node, key, val) {
  if (!node) return;

  let extra = node.extra = node.extra || {};
  extra[key] = val;
};

// TODO

pp.isRelational = function (op) {
  return this.match(tt.relational) && this.state.value === op;
};

// TODO

pp.expectRelational = function (op) {
  if (this.isRelational(op)) {
    this.next();
  } else {
    this.unexpected();
  }
};

// Tests whether parsed token is a contextual keyword.

pp.isContextual = function (name) {
  return this.match(tt.name) && this.state.value === name;
};

// Consumes contextual keyword if possible.

pp.eatContextual = function (name) {
  return this.state.value === name && this.eat(tt.name);
};

// Asserts that following token is given contextual keyword.

pp.expectContextual = function (name, message) {
  if (!this.eatContextual(name)) this.unexpected(null, message);
};

// Test whether a semicolon can be inserted at the current position.

pp.canInsertSemicolon = function () {
  return this.match(tt.eof) ||
    this.match(tt.braceR) ||
    lineBreak.test(this.input.slice(this.state.lastTokEnd, this.state.start));
};

// TODO

pp.isLineTerminator = function () {
  return this.eat(tt.semi) || this.canInsertSemicolon();
};

// 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.isLineTerminator()) this.unexpected();
};

// Expect a token of a given type. If found, consume it, otherwise,
// raise an unexpected token error.

pp.expect = function (type) {
  return this.eat(type) || this.unexpected();
};

// Raise an unexpected token error.

pp.unexpected = function (pos, message = "Unexpected token") {
  this.raise(pos != null ? pos : this.state.start, message);
};