postcss/lib/postcss.js

let Declaration = require('./declaration')
let Processor = require('./processor')
let stringify = require('./stringify')
let Comment = require('./comment')
let AtRule = require('./at-rule')
let vendor = require('./vendor')
let parse = require('./parse')
let list = require('./list')
let Rule = require('./rule')
let Root = require('./root')

/**
 * Create a new {@link Processor} instance that will apply `plugins`
 * as CSS processors.
 *
 * @param {Array.<Plugin|pluginFunction>|Processor} plugins PostCSS plugins.
 *        See {@link Processor#use} for plugin format.
 *
 * @return {Processor} Processor to process multiple CSS.
 *
 * @example
 * let postcss = require('postcss')
 *
 * postcss(plugins).process(css, { from, to }).then(result => {
 *   console.log(result.css)
 * })
 *
 * @namespace postcss
 */
function postcss (...plugins) {
  if (plugins.length === 1 && Array.isArray(plugins[0])) {
    plugins = plugins[0]
  }
  return new Processor(plugins)
}

/**
 * Creates a PostCSS plugin with a standard API.
 *
 * The newly-wrapped function will provide both the name and PostCSS
 * version of the plugin.
 *
 * ```js
 * const processor = postcss([replace])
 * processor.plugins[0].postcssPlugin  //=> 'postcss-replace'
 * processor.plugins[0].postcssVersion //=> '6.0.0'
 * ```
 *
 * The plugin function receives 2 arguments: {@link Root}
 * and {@link Result} instance. The function should mutate the provided
 * `Root` node. Alternatively, you can create a new `Root` node
 * and override the `result.root` property.
 *
 * ```js
 * const cleaner = postcss.plugin('postcss-cleaner', () => {
 *   return (root, result) => {
 *     result.root = postcss.root()
 *   }
 * })
 * ```
 *
 * As a convenience, plugins also expose a `process` method so that you can use
 * them as standalone tools.
 *
 * ```js
 * cleaner.process(css, processOpts, pluginOpts)
 * // This is equivalent to:
 * postcss([ cleaner(pluginOpts) ]).process(css, processOpts)
 * ```
 *
 * Asynchronous plugins should return a `Promise` instance.
 *
 * ```js
 * postcss.plugin('postcss-import', () => {
 *   return (root, result) => {
 *     return new Promise( (resolve, reject) => {
 *       fs.readFile('base.css', (base) => {
 *         root.prepend(base)
 *         resolve()
 *       })
 *     })
 *   }
 * })
 * ```
 *
 * Add warnings using the {@link Node#warn} method.
 * Send data to other plugins using the {@link Result#messages} array.
 *
 * ```js
 * postcss.plugin('postcss-caniuse-test', () => {
 *   return (root, result) => {
 *     root.walkDecls(decl => {
 *       if (!caniuse.support(decl.prop)) {
 *         decl.warn(result, 'Some browsers do not support ' + decl.prop)
 *       }
 *     })
 *   }
 * })
 * ```
 *
 * @param {string} name          PostCSS plugin name. Same as in `name`
 *                               property in `package.json`. It will be saved
 *                               in `plugin.postcssPlugin` property.
 * @param {function} initializer Will receive plugin options
 *                               and should return {@link pluginFunction}
 *
 * @return {Plugin} PostCSS plugin.
 */
postcss.plugin = function plugin (name, initializer) {
  function creator (...args) {
    let transformer = initializer(...args)
    transformer.postcssPlugin = name
    transformer.postcssVersion = (new Processor()).version
    return transformer
  }

  let cache
  Object.defineProperty(creator, 'postcss', {
    get () {
      if (!cache) cache = creator()
      return cache
    }
  })

  creator.process = function (css, processOpts, pluginOpts) {
    return postcss([creator(pluginOpts)]).process(css, processOpts)
  }

  return creator
}

/**
 * Default function to convert a node tree into a CSS string.
 *
 * @param {Node} node       Start node for stringifing. Usually {@link Root}.
 * @param {builder} builder Function to concatenate CSS from node’s parts
 *                          or generate string and source map.
 *
 * @return {void}
 *
 * @function
 */
postcss.stringify = stringify

/**
 * Parses source css and returns a new {@link Root} node,
 * which contains the source CSS nodes.
 *
 * @param {string|toString} css   String with input CSS or any object
 *                                with toString() method, like a Buffer
 * @param {processOptions} [opts] Options with only `from` and `map` keys.
 *
 * @return {Root} PostCSS AST.
 *
 * @example
 * // Simple CSS concatenation with source map support
 * const root1 = postcss.parse(css1, { from: file1 })
 * const root2 = postcss.parse(css2, { from: file2 })
 * root1.append(root2).toResult().css
 *
 * @function
 */
postcss.parse = parse

/**
 * Contains the {@link vendor} module.
 *
 * @type {vendor}
 *
 * @example
 * postcss.vendor.unprefixed('-moz-tab') //=> ['tab']
 */
postcss.vendor = vendor

/**
 * Contains the {@link list} module.
 *
 * @member {list}
 *
 * @example
 * postcss.list.space('5px calc(10% + 5px)') //=> ['5px', 'calc(10% + 5px)']
 */
postcss.list = list

/**
 * Creates a new {@link Comment} node.
 *
 * @param {object} [defaults] Properties for the new node.
 *
 * @return {Comment} New comment node
 *
 * @example
 * postcss.comment({ text: 'test' })
 */
postcss.comment = defaults => new Comment(defaults)

/**
 * Creates a new {@link AtRule} node.
 *
 * @param {object} [defaults] Properties for the new node.
 *
 * @return {AtRule} new at-rule node
 *
 * @example
 * postcss.atRule({ name: 'charset' }).toString() //=> "@charset"
 */
postcss.atRule = defaults => new AtRule(defaults)

/**
 * Creates a new {@link Declaration} node.
 *
 * @param {object} [defaults] Properties for the new node.
 *
 * @return {Declaration} new declaration node
 *
 * @example
 * postcss.decl({ prop: 'color', value: 'red' }).toString() //=> "color: red"
 */
postcss.decl = defaults => new Declaration(defaults)

/**
 * Creates a new {@link Rule} node.
 *
 * @param {object} [defaults] Properties for the new node.
 *
 * @return {Rule} new rule node
 *
 * @example
 * postcss.rule({ selector: 'a' }).toString() //=> "a {\n}"
 */
postcss.rule = defaults => new Rule(defaults)

/**
 * Creates a new {@link Root} node.
 *
 * @param {object} [defaults] Properties for the new node.
 *
 * @return {Root} new root node.
 *
 * @example
 * postcss.root({ after: '\n' }).toString() //=> "\n"
 */
postcss.root = defaults => new Root(defaults)

module.exports = postcss