mathjs/src/expression/node/RangeNode.js

import { isNode, isSymbolNode } from '../../utils/is'
import { factory } from '../../utils/factory'
import { getPrecedence } from '../operators'

const name = 'RangeNode'
const dependencies = [
  'Node'
]

export const createRangeNode = /* #__PURE__ */ factory(name, dependencies, ({ Node }) => {
  /**
   * @constructor RangeNode
   * @extends {Node}
   * create a range
   * @param {Node} start  included lower-bound
   * @param {Node} end    included upper-bound
   * @param {Node} [step] optional step
   */
  function RangeNode (start, end, step) {
    if (!(this instanceof RangeNode)) {
      throw new SyntaxError('Constructor must be called with the new operator')
    }

    // validate inputs
    if (!isNode(start)) throw new TypeError('Node expected')
    if (!isNode(end)) throw new TypeError('Node expected')
    if (step && !isNode(step)) throw new TypeError('Node expected')
    if (arguments.length > 3) throw new Error('Too many arguments')

    this.start = start // included lower-bound
    this.end = end // included upper-bound
    this.step = step || null // optional step
  }

  RangeNode.prototype = new Node()

  RangeNode.prototype.type = 'RangeNode'

  RangeNode.prototype.isRangeNode = true

  /**
   * Check whether the RangeNode needs the `end` symbol to be defined.
   * This end is the size of the Matrix in current dimension.
   * @return {boolean}
   */
  RangeNode.prototype.needsEnd = function () {
    // find all `end` symbols in this RangeNode
    const endSymbols = this.filter(function (node) {
      return isSymbolNode(node) && (node.name === 'end')
    })

    return endSymbols.length > 0
  }

  /**
   * Compile a node into a JavaScript function.
   * This basically pre-calculates as much as possible and only leaves open
   * calculations which depend on a dynamic scope with variables.
   * @param {Object} math     Math.js namespace with functions and constants.
   * @param {Object} argNames An object with argument names as key and `true`
   *                          as value. Used in the SymbolNode to optimize
   *                          for arguments from user assigned functions
   *                          (see FunctionAssignmentNode) or special symbols
   *                          like `end` (see IndexNode).
   * @return {function} Returns a function which can be called like:
   *                        evalNode(scope: Object, args: Object, context: *)
   */
  RangeNode.prototype._compile = function (math, argNames) {
    const range = math.range
    const evalStart = this.start._compile(math, argNames)
    const evalEnd = this.end._compile(math, argNames)

    if (this.step) {
      const evalStep = this.step._compile(math, argNames)

      return function evalRangeNode (scope, args, context) {
        return range(
          evalStart(scope, args, context),
          evalEnd(scope, args, context),
          evalStep(scope, args, context)
        )
      }
    } else {
      return function evalRangeNode (scope, args, context) {
        return range(
          evalStart(scope, args, context),
          evalEnd(scope, args, context)
        )
      }
    }
  }

  /**
   * Execute a callback for each of the child nodes of this node
   * @param {function(child: Node, path: string, parent: Node)} callback
   */
  RangeNode.prototype.forEach = function (callback) {
    callback(this.start, 'start', this)
    callback(this.end, 'end', this)
    if (this.step) {
      callback(this.step, 'step', this)
    }
  }

  /**
   * Create a new RangeNode having it's childs be the results of calling
   * the provided callback function for each of the childs of the original node.
   * @param {function(child: Node, path: string, parent: Node): Node} callback
   * @returns {RangeNode} Returns a transformed copy of the node
   */
  RangeNode.prototype.map = function (callback) {
    return new RangeNode(
      this._ifNode(callback(this.start, 'start', this)),
      this._ifNode(callback(this.end, 'end', this)),
      this.step && this._ifNode(callback(this.step, 'step', this))
    )
  }

  /**
   * Create a clone of this node, a shallow copy
   * @return {RangeNode}
   */
  RangeNode.prototype.clone = function () {
    return new RangeNode(this.start, this.end, this.step && this.step)
  }

  /**
   * Calculate the necessary parentheses
   * @param {Node} node
   * @param {string} parenthesis
   * @return {Object} parentheses
   * @private
   */
  function calculateNecessaryParentheses (node, parenthesis) {
    const precedence = getPrecedence(node, parenthesis)
    const parens = {}

    const startPrecedence = getPrecedence(node.start, parenthesis)
    parens.start = ((startPrecedence !== null) && (startPrecedence <= precedence)) ||
      (parenthesis === 'all')

    if (node.step) {
      const stepPrecedence = getPrecedence(node.step, parenthesis)
      parens.step = ((stepPrecedence !== null) && (stepPrecedence <= precedence)) ||
        (parenthesis === 'all')
    }

    const endPrecedence = getPrecedence(node.end, parenthesis)
    parens.end = ((endPrecedence !== null) && (endPrecedence <= precedence)) ||
      (parenthesis === 'all')

    return parens
  }

  /**
   * Get string representation
   * @param {Object} options
   * @return {string} str
   */
  RangeNode.prototype._toString = function (options) {
    const parenthesis = (options && options.parenthesis) ? options.parenthesis : 'keep'
    const parens = calculateNecessaryParentheses(this, parenthesis)

    // format string as start:step:stop
    let str

    let start = this.start.toString(options)
    if (parens.start) {
      start = '(' + start + ')'
    }
    str = start

    if (this.step) {
      let step = this.step.toString(options)
      if (parens.step) {
        step = '(' + step + ')'
      }
      str += ':' + step
    }

    let end = this.end.toString(options)
    if (parens.end) {
      end = '(' + end + ')'
    }
    str += ':' + end

    return str
  }

  /**
   * Get a JSON representation of the node
   * @returns {Object}
   */
  RangeNode.prototype.toJSON = function () {
    return {
      mathjs: 'RangeNode',
      start: this.start,
      end: this.end,
      step: this.step
    }
  }

  /**
   * Instantiate an RangeNode from its JSON representation
   * @param {Object} json  An object structured like
   *                       `{"mathjs": "RangeNode", "start": ..., "end": ..., "step": ...}`,
   *                       where mathjs is optional
   * @returns {RangeNode}
   */
  RangeNode.fromJSON = function (json) {
    return new RangeNode(json.start, json.end, json.step)
  }

  /**
   * Get HTML representation
   * @param {Object} options
   * @return {string} str
   */
  RangeNode.prototype.toHTML = function (options) {
    const parenthesis = (options && options.parenthesis) ? options.parenthesis : 'keep'
    const parens = calculateNecessaryParentheses(this, parenthesis)

    // format string as start:step:stop
    let str

    let start = this.start.toHTML(options)
    if (parens.start) {
      start = '<span class="math-parenthesis math-round-parenthesis">(</span>' + start + '<span class="math-parenthesis math-round-parenthesis">)</span>'
    }
    str = start

    if (this.step) {
      let step = this.step.toHTML(options)
      if (parens.step) {
        step = '<span class="math-parenthesis math-round-parenthesis">(</span>' + step + '<span class="math-parenthesis math-round-parenthesis">)</span>'
      }
      str += '<span class="math-operator math-range-operator">:</span>' + step
    }

    let end = this.end.toHTML(options)
    if (parens.end) {
      end = '<span class="math-parenthesis math-round-parenthesis">(</span>' + end + '<span class="math-parenthesis math-round-parenthesis">)</span>'
    }
    str += '<span class="math-operator math-range-operator">:</span>' + end

    return str
  }

  /**
   * Get LaTeX representation
   * @params {Object} options
   * @return {string} str
   */
  RangeNode.prototype._toTex = function (options) {
    const parenthesis = (options && options.parenthesis) ? options.parenthesis : 'keep'
    const parens = calculateNecessaryParentheses(this, parenthesis)

    let str = this.start.toTex(options)
    if (parens.start) {
      str = `\\left(${str}\\right)`
    }

    if (this.step) {
      let step = this.step.toTex(options)
      if (parens.step) {
        step = `\\left(${step}\\right)`
      }
      str += ':' + step
    }

    let end = this.end.toTex(options)
    if (parens.end) {
      end = `\\left(${end}\\right)`
    }
    str += ':' + end

    return str
  }

  return RangeNode
}, { isClass: true, isNode: true })