stylus/lib/nodes/unit.js

Robust, expressive, and feature-rich CSS superset

/*!
 * Stylus - Unit
 * Copyright (c) Automattic <developer.wordpress.com>
 * MIT Licensed
 */

/**
 * Module dependencies.
 */

var Node = require('./node')
  , nodes = require('./');

/**
 * Unit conversion table.
 */

var FACTOR_TABLE = {
  'mm': { val: 1, label: 'mm' },
  'cm': { val: 10, label: 'mm' },
  'in': { val: 25.4, label: 'mm' },
  'pt': { val: 25.4 / 72, label: 'mm' },
  'ms': { val: 1, label: 'ms' },
  's': { val: 1000, label: 'ms' },
  'Hz': { val: 1, label: 'Hz' },
  'kHz': { val: 1000, label: 'Hz' }
};

module.exports = class Unit extends Node {
  /**
   * Initialize a new `Unit` with the given `val` and unit `type`
   * such as "px", "pt", "in", etc.
   *
   * @param {String} val
   * @param {String} type
   * @api public
   */

  constructor(val, type) {
    super();
    this.val = val;
    this.type = type;
  }

  /**
   * Return Boolean based on the unit value.
   *
   * @return {Boolean}
   * @api public
   */

  toBoolean() {
    return new nodes.Boolean(this.type
      ? true
      : this.val);
  };

  /**
   * Return unit string.
   *
   * @return {String}
   * @api public
   */

  toString() {
    return this.val + (this.type || '');
  };

  /**
   * Return a clone of this node.
   *
   * @return {Node}
   * @api public
   */

  clone() {
    var clone = new Unit(this.val, this.type);
    clone.lineno = this.lineno;
    clone.column = this.column;
    clone.filename = this.filename;
    return clone;
  };

  /**
   * Return a JSON representation of this node.
   *
   * @return {Object}
   * @api public
   */

  toJSON() {
    return {
      __type: 'Unit',
      val: this.val,
      type: this.type,
      lineno: this.lineno,
      column: this.column,
      filename: this.filename
    };
  };

  /**
   * Operate on `right` with the given `op`.
   *
   * @param {String} op
   * @param {Node} right
   * @return {Node}
   * @api public
   */

  operate(op, right) {
    var type = this.type || right.first.type;

    // swap color
    if ('rgba' == right.nodeName || 'hsla' == right.nodeName) {
      return right.operate(op, this);
    }

    // operate
    if (this.shouldCoerce(op)) {
      right = right.first;
      // percentages
      if ('%' != this.type && ('-' == op || '+' == op) && '%' == right.type) {
        right = new Unit(this.val * (right.val / 100), '%');
      } else {
        right = this.coerce(right);
      }

      switch (op) {
        case '-':
          return new Unit(this.val - right.val, type);
        case '+':
          // keyframes interpolation
          type = type || (right.type == '%' && right.type);
          return new Unit(this.val + right.val, type);
        case '/':
          return new Unit(this.val / right.val, type);
        case '*':
          return new Unit(this.val * right.val, type);
        case '%':
          return new Unit(this.val % right.val, type);
        case '**':
          return new Unit(Math.pow(this.val, right.val), type);
        case '..':
        case '...':
          var start = this.val
            , end = right.val
            , expr = new nodes.Expression
            , inclusive = '..' == op;
          if (start < end) {
            do {
              expr.push(new nodes.Unit(start));
            } while (inclusive ? ++start <= end : ++start < end);
          } else {
            do {
              expr.push(new nodes.Unit(start));
            } while (inclusive ? --start >= end : --start > end);
          }
          return expr;
      }
    }

    return super.operate(op, right);
  };

  /**
   * Coerce `other` unit to the same type as `this` unit.
   *
   * Supports:
   *
   *    mm -> cm | in
   *    cm -> mm | in
   *    in -> mm | cm
   *
   *    ms -> s
   *    s  -> ms
   *
   *    Hz  -> kHz
   *    kHz -> Hz
   *
   * @param {Unit} other
   * @return {Unit}
   * @api public
   */

  coerce(other) {
    if ('unit' == other.nodeName) {
      var a = this
        , b = other
        , factorA = FACTOR_TABLE[a.type]
        , factorB = FACTOR_TABLE[b.type];

      if (factorA && factorB && (factorA.label == factorB.label)) {
        var bVal = b.val * (factorB.val / factorA.val);
        return new nodes.Unit(bVal, a.type);
      } else {
        return new nodes.Unit(b.val, a.type);
      }
    } else if ('string' == other.nodeName) {
      // keyframes interpolation
      if ('%' == other.val) return new nodes.Unit(0, '%');
      var val = parseFloat(other.val);
      if (isNaN(val)) super.coerce(other);
      return new nodes.Unit(val);
    } else {
      return super.coerce(other);
    }
  };
};