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

import { isFunctionNode, isNode, isOperatorNode, isParenthesisNode, isSymbolNode } from '../../../utils/is'
import { factory } from '../../../utils/factory'

const name = 'resolve'
const dependencies = [
  'parse',
  'FunctionNode',
  'OperatorNode',
  'ParenthesisNode'
]

export const createResolve = /* #__PURE__ */ factory(name, dependencies, ({
  parse,
  FunctionNode,
  OperatorNode,
  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 (isSymbolNode(node)) {
      const value = scope[node.name]
      if (isNode(value)) {
        return resolve(value, scope)
      } else if (typeof value === 'number') {
        return parse(String(value))
      }
    } else if (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 (isParenthesisNode(node)) {
      return new ParenthesisNode(resolve(node.content, scope))
    } else if (isFunctionNode(node)) {
      const args = node.args.map(function (arg) {
        return resolve(arg, scope)
      })
      return new FunctionNode(node.name, args)
    }
    return node
  }

  return resolve
})