mathjs/src/function/algebra/simplify/resolve.js

Math.js is an extensive math library for JavaScript and Node.js. It features a flexible expression parser with support for symbolic computation, comes with a large set of built-in functions and constants, and offers an integrated solution to work with dif

'use strict'

function factory (type, config, load, typed, math) {
  const Node = math.expression.node.Node
  const OperatorNode = math.expression.node.OperatorNode
  const FunctionNode = math.expression.node.FunctionNode
  const ParenthesisNode = math.expression.node.ParenthesisNode

  /**
   * resolve(expr, scope) replaces variable nodes with their scoped values
   *
   * Syntax:
   *
   *     simplify.resolve(expr, scope)
   *
   * Examples:
   *
   *     math.simplify.resolve('x + y', {x:1, y:2})           // Node {1 + 2}
   *     math.simplify.resolve(math.parse('x+y'), {x:1, y:2}) // Node {1 + 2}
   *     math.simplify('x+y', {x:2, y:'x+x'}).toString()      // "6"
   *
   * @param {Node} node
   *     The expression tree to be simplified
   * @param {Object} scope with variables to be resolved
   */
  function resolve (node, scope) {
    if (!scope) {
      return node
    }
    if (type.isSymbolNode(node)) {
      const value = scope[node.name]
      if (value instanceof Node) {
        return resolve(value, scope)
      } else if (typeof value === 'number') {
        return math.parse(String(value))
      }
    } else if (type.isOperatorNode(node)) {
      const args = node.args.map(function (arg) {
        return resolve(arg, scope)
      })
      return new OperatorNode(node.op, node.fn, args, node.implicit)
    } else if (type.isParenthesisNode(node)) {
      return new ParenthesisNode(resolve(node.content, scope))
    } else if (type.isFunctionNode(node)) {
      const args = node.args.map(function (arg) {
        return resolve(arg, scope)
      })
      return new FunctionNode(node.name, args)
    }
    return node
  }

  return resolve
}

exports.math = true
exports.name = 'resolve'
exports.path = 'algebra.simplify'
exports.factory = factory