options.js

import {has, isArray} from "./util"
import {SourceLocation} from "./locutil"

// A second optional argument can be given to further configure
// the parser process. These options are recognized:

export const defaultOptions = {
  // `ecmaVersion` indicates the ECMAScript version to parse. Must
  // be either 3, 5, 6 (2015), 7 (2016), or 8 (2017). This influences support
  // for strict mode, the set of reserved words, and support for
  // new syntax features. The default is 7.
  ecmaVersion: 7,
  // `sourceType` indicates the mode the code should be parsed in.
  // Can be either `"script"` or `"module"`. This influences global
  // strict mode and parsing of `import` and `export` declarations.
  sourceType: "script",
  // `onInsertedSemicolon` can be a callback that will be called
  // when a semicolon is automatically inserted. It will be passed
  // th position of the comma as an offset, and if `locations` is
  // enabled, it is given the location as a `{line, column}` object
  // as second argument.
  onInsertedSemicolon: null,
  // `onTrailingComma` is similar to `onInsertedSemicolon`, but for
  // trailing commas.
  onTrailingComma: null,
  // By default, reserved words are only enforced if ecmaVersion >= 5.
  // Set `allowReserved` to a boolean value to explicitly turn this on
  // an off. When this option has the value "never", reserved words
  // and keywords can also not be used as property names.
  allowReserved: null,
  // When enabled, a return at the top level is not considered an
  // error.
  allowReturnOutsideFunction: false,
  // When enabled, import/export statements are not constrained to
  // appearing at the top of the program.
  allowImportExportEverywhere: false,
  // When enabled, await identifiers are allowed to appear at the top-level scope,
  // but they are still not allowed in non-async functions.
  allowAwaitOutsideFunction: false,
  // When enabled, hashbang directive in the beginning of file
  // is allowed and treated as a line comment.
  allowHashBang: false,
  // When `locations` is on, `loc` properties holding objects with
  // `start` and `end` properties in `{line, column}` form (with
  // line being 1-based and column 0-based) will be attached to the
  // nodes.
  locations: false,
  // A function can be passed as `onToken` option, which will
  // cause Acorn to call that function with object in the same
  // format as tokens returned from `tokenizer().getToken()`. Note
  // that you are not allowed to call the parser from the
  // callback—that will corrupt its internal state.
  onToken: null,
  // A function can be passed as `onComment` option, which will
  // cause Acorn to call that function with `(block, text, start,
  // end)` parameters whenever a comment is skipped. `block` is a
  // boolean indicating whether this is a block (`/* */`) comment,
  // `text` is the content of the comment, and `start` and `end` are
  // character offsets that denote the start and end of the comment.
  // When the `locations` option is on, two more parameters are
  // passed, the full `{line, column}` locations of the start and
  // end of the comments. Note that you are not allowed to call the
  // parser from the callback—that will corrupt its internal state.
  onComment: null,
  // Nodes have their start and end characters offsets recorded in
  // `start` and `end` properties (directly on the node, rather than
  // the `loc` object, which holds line/column data. To also add a
  // [semi-standardized][range] `range` property holding a `[start,
  // end]` array with the same numbers, set the `ranges` option to
  // `true`.
  //
  // [range]: https://bugzilla.mozilla.org/show_bug.cgi?id=745678
  ranges: false,
  // It is possible to parse multiple files into a single AST by
  // passing the tree produced by parsing the first file as
  // `program` option in subsequent parses. This will add the
  // toplevel forms of the parsed file to the `Program` (top) node
  // of an existing parse tree.
  program: null,
  // When `locations` is on, you can pass this to record the source
  // file in every node's `loc` object.
  sourceFile: null,
  // This value, if given, is stored in every node, whether
  // `locations` is on or off.
  directSourceFile: null,
  // When enabled, parenthesized expressions are represented by
  // (non-standard) ParenthesizedExpression nodes
  preserveParens: false,
  plugins: {}
}

// Interpret and default an options object

export function getOptions(opts) {
  let options = {}

  for (let opt in defaultOptions)
    options[opt] = opts && has(opts, opt) ? opts[opt] : defaultOptions[opt]

  if (options.ecmaVersion >= 2015)
    options.ecmaVersion -= 2009

  if (options.allowReserved == null)
    options.allowReserved = options.ecmaVersion < 5

  if (isArray(options.onToken)) {
    let tokens = options.onToken
    options.onToken = (token) => tokens.push(token)
  }
  if (isArray(options.onComment))
    options.onComment = pushComment(options, options.onComment)

  return options
}

function pushComment(options, array) {
  return function(block, text, start, end, startLoc, endLoc) {
    let comment = {
      type: block ? "Block" : "Line",
      value: text,
      start: start,
      end: end
    }
    if (options.locations)
      comment.loc = new SourceLocation(this, startLoc, endLoc)
    if (options.ranges)
      comment.range = [start, end]
    array.push(comment)
  }
}