Function parseRule2

src/expression/parse.js:1139–1182

* Infamous "rule 2" as described in https://github.com/josdejong/mathjs/issues/792#issuecomment-361065370 * And as amended in https://github.com/josdejong/mathjs/issues/2370#issuecomment-1054052164 * Explicit division gets higher precedence than implicit multiplication * when the division m

(state)

   * @private
   */
  function parseRule2 (state) {
    let node = parseUnaryPercentage(state)
    let last = node
    const tokenStates = []

    while (true) {
      // Match the "number /" part of the pattern "number / number symbol"
      if (state.token === '/' && rule2Node(last)) {
        // Look ahead to see if the next token is a number
        tokenStates.push(Object.assign({}, state))
        getTokenSkipNewline(state)

        // Match the "number / number" part of the pattern
        if (state.tokenType === TOKENTYPE.NUMBER) {
          // Look ahead again
          tokenStates.push(Object.assign({}, state))
          getTokenSkipNewline(state)

          // Match the "symbol" part of the pattern, or a left parenthesis
          if (state.tokenType === TOKENTYPE.SYMBOL || state.token === '(' || state.token === 'in') {
            // We've matched the pattern "number / number symbol".
            // Rewind once and build the "number / number" node; the symbol will be consumed later
            Object.assign(state, tokenStates.pop())
            tokenStates.pop()
            last = parseUnaryPercentage(state)
            node = new OperatorNode('/', 'divide', [node, last])
          } else {
            // Not a match, so rewind
            tokenStates.pop()
            Object.assign(state, tokenStates.pop())
            break
          }
        } else {
          // Not a match, so rewind
          Object.assign(state, tokenStates.pop())
          break
        }
      } else {
        break
      }
    }

    return node
  }

  /**
   * Unary percentage operator (treated as `value / 100`)