postcss/lib/input.js

let path = require('path')

let CssSyntaxError = require('./css-syntax-error')
let PreviousMap = require('./previous-map')

let sequence = 0

/**
 * Represents the source CSS.
 *
 * @example
 * const root  = postcss.parse(css, { from: file })
 * const input = root.source.input
 */
class Input {
  /**
   * @param {string} css    Input CSS source.
   * @param {object} [opts] {@link Processor#process} options.
   */
  constructor (css, opts = { }) {
    if (
      css === null ||
      typeof css === 'undefined' ||
      (typeof css === 'object' && !css.toString)
    ) {
      throw new Error(`PostCSS received ${ css } instead of CSS string`)
    }

    /**
     * Input CSS source
     *
     * @type {string}
     *
     * @example
     * const input = postcss.parse('a{}', { from: file }).input
     * input.css //=> "a{}"
     */
    this.css = css.toString()

    if (this.css[0] === '\uFEFF' || this.css[0] === '\uFFFE') {
      this.hasBOM = true
      this.css = this.css.slice(1)
    } else {
      this.hasBOM = false
    }

    if (opts.from) {
      if (/^\w+:\/\//.test(opts.from) || path.isAbsolute(opts.from)) {
        /**
         * The absolute path to the CSS source file defined
         * with the `from` option.
         *
         * @type {string}
         *
         * @example
         * const root = postcss.parse(css, { from: 'a.css' })
         * root.source.input.file //=> '/home/ai/a.css'
         */
        this.file = opts.from
      } else {
        this.file = path.resolve(opts.from)
      }
    }

    let map = new PreviousMap(this.css, opts)
    if (map.text) {
      /**
       * The input source map passed from a compilation step before PostCSS
       * (for example, from Sass compiler).
       *
       * @type {PreviousMap}
       *
       * @example
       * root.source.input.map.consumer().sources //=> ['a.sass']
       */
      this.map = map
      let file = map.consumer().file
      if (!this.file && file) this.file = this.mapResolve(file)
    }

    if (!this.file) {
      sequence += 1
      /**
       * The unique ID of the CSS source. It will be created if `from` option
       * is not provided (because PostCSS does not know the file path).
       *
       * @type {string}
       *
       * @example
       * const root = postcss.parse(css)
       * root.source.input.file //=> undefined
       * root.source.input.id   //=> "<input css 1>"
       */
      this.id = '<input css ' + sequence + '>'
    }
    if (this.map) this.map.file = this.from
  }

  error (message, line, column, opts = { }) {
    let result
    let origin = this.origin(line, column)
    if (origin) {
      result = new CssSyntaxError(
        message, origin.line, origin.column,
        origin.source, origin.file, opts.plugin
      )
    } else {
      result = new CssSyntaxError(
        message, line, column, this.css, this.file, opts.plugin)
    }

    result.input = { line, column, source: this.css }
    if (this.file) result.input.file = this.file

    return result
  }

  /**
   * Reads the input source map and returns a symbol position
   * in the input source (e.g., in a Sass file that was compiled
   * to CSS before being passed to PostCSS).
   *
   * @param {number} line   Line in input CSS.
   * @param {number} column Column in input CSS.
   *
   * @return {filePosition} Position in input source.
   *
   * @example
   * root.source.input.origin(1, 1) //=> { file: 'a.css', line: 3, column: 1 }
   */
  origin (line, column) {
    if (!this.map) return false
    let consumer = this.map.consumer()

    let from = consumer.originalPositionFor({ line, column })
    if (!from.source) return false

    let result = {
      file: this.mapResolve(from.source),
      line: from.line,
      column: from.column
    }

    let source = consumer.sourceContentFor(from.source)
    if (source) result.source = source

    return result
  }

  mapResolve (file) {
    if (/^\w+:\/\//.test(file)) {
      return file
    }
    return path.resolve(this.map.consumer().sourceRoot || '.', file)
  }

  /**
   * The CSS source identifier. Contains {@link Input#file} if the user
   * set the `from` option, or {@link Input#id} if they did not.
   *
   * @type {string}
   *
   * @example
   * const root = postcss.parse(css, { from: 'a.css' })
   * root.source.input.from //=> "/home/ai/a.css"
   *
   * const root = postcss.parse(css)
   * root.source.input.from //=> "<input css 1>"
   */
  get from () {
    return this.file || this.id
  }
}

module.exports = Input

/**
 * @typedef  {object} filePosition
 * @property {string} file   Path to file.
 * @property {number} line   Source line in file.
 * @property {number} column Source column in file.
 */