reducer.js

"use strict";

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = void 0;

var _convert = _interopRequireDefault(require("./convert"));

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

function reduce(node, precision) {
  if (node.type === "MathExpression") return reduceMathExpression(node, precision);
  return node;
}

function isEqual(left, right) {
  return left.type === right.type && left.value === right.value;
}

function isValueType(type) {
  switch (type) {
    case 'LengthValue':
    case 'AngleValue':
    case 'TimeValue':
    case 'FrequencyValue':
    case 'ResolutionValue':
    case 'EmValue':
    case 'ExValue':
    case 'ChValue':
    case 'RemValue':
    case 'VhValue':
    case 'VwValue':
    case 'VminValue':
    case 'VmaxValue':
    case 'PercentageValue':
    case 'Value':
      return true;
  }

  return false;
}

function convertMathExpression(node, precision) {
  var nodes = (0, _convert.default)(node.left, node.right, precision);
  var left = reduce(nodes.left, precision);
  var right = reduce(nodes.right, precision);

  if (left.type === "MathExpression" && right.type === "MathExpression") {
    if (left.operator === '/' && right.operator === '*' || left.operator === '-' && right.operator === '+' || left.operator === '*' && right.operator === '/' || left.operator === '+' && right.operator === '-') {
      if (isEqual(left.right, right.right)) nodes = (0, _convert.default)(left.left, right.left, precision);else if (isEqual(left.right, right.left)) nodes = (0, _convert.default)(left.left, right.right, precision);
      left = reduce(nodes.left, precision);
      right = reduce(nodes.right, precision);
    }
  }

  node.left = left;
  node.right = right;
  return node;
}

function flip(operator) {
  return operator === '+' ? '-' : '+';
}

function flipValue(node) {
  if (isValueType(node.type)) node.value = -node.value;else if (node.type == 'MathExpression') {
    node.left = flipValue(node.left);
    node.right = flipValue(node.right);
  }
  return node;
}

function reduceAddSubExpression(node, precision) {
  var _node = node,
      left = _node.left,
      right = _node.right,
      op = _node.operator;
  if (left.type === 'Function' || right.type === 'Function') return node; // something + 0 => something
  // something - 0 => something

  if (right.value === 0) return left; // 0 + something => something

  if (left.value === 0 && op === "+") return right; // 0 - something => -something

  if (left.value === 0 && op === "-") return flipValue(right); // value + value
  // value - value

  if (left.type === right.type && isValueType(left.type)) {
    node = Object.assign({}, left);
    if (op === "+") node.value = left.value + right.value;else node.value = left.value - right.value;
  } // value <op> (expr)


  if (isValueType(left.type) && (right.operator === '+' || right.operator === '-') && right.type === 'MathExpression') {
    // value + (value + something) => (value + value) + something
    // value + (value - something) => (value + value) - something
    // value - (value + something) => (value - value) - something
    // value - (value - something) => (value - value) + something
    if (left.type === right.left.type) {
      node = Object.assign({}, node);
      node.left = reduce({
        type: 'MathExpression',
        operator: op,
        left: left,
        right: right.left
      }, precision);
      node.right = right.right;
      node.operator = op === '-' ? flip(right.operator) : right.operator;
      return reduce(node, precision);
    } // value + (something + value) => (value + value) + something
    // value + (something - value) => (value - value) + something
    // value - (something + value) => (value - value) - something
    // value - (something - value) => (value + value) - something
    else if (left.type === right.right.type) {
        node = Object.assign({}, node);
        node.left = reduce({
          type: 'MathExpression',
          operator: op === '-' ? flip(right.operator) : right.operator,
          left: left,
          right: right.right
        }, precision);
        node.right = right.left;
        return reduce(node, precision);
      } // value - (something + something) => value - something - something
      else if (op === '-' && right.operator === '+') {
          node = Object.assign({}, node);
          node.right.operator = '-';
          return reduce(node, precision);
        }
  } // (expr) <op> value


  if (left.type === 'MathExpression' && (left.operator === '+' || left.operator === '-') && isValueType(right.type)) {
    // (value + something) + value => (value + value) + something
    // (value - something) + value => (value + value) - something
    // (value + something) - value => (value - value) + something
    // (value - something) - value => (value - value) - something
    if (right.type === left.left.type) {
      node = Object.assign({}, left);
      node.left = reduce({
        type: 'MathExpression',
        operator: op,
        left: left.left,
        right: right
      }, precision);
      return reduce(node, precision);
    } // (something + value) + value => something + (value + value)
    // (something - value1) + value2 => something - (value2 - value1)
    // (something + value) - value => something + (value - value)
    // (something - value) - value => something - (value + value)
    else if (right.type === left.right.type) {
        node = Object.assign({}, left);

        if (left.operator === '-') {
          node.right = reduce({
            type: 'MathExpression',
            operator: flip(op),
            left: left.right,
            right: right
          }, precision);

          if (node.right.value && node.right.value < 0) {
            node.right.value = Math.abs(node.right.value);
            node.operator = '+';
          } else {
            node.operator = left.operator;
          }
        } else {
          node.right = reduce({
            type: 'MathExpression',
            operator: op,
            left: left.right,
            right: right
          }, precision);
        }

        if (node.right.value < 0) {
          node.right.value *= -1;
          node.operator = node.operator === '-' ? '+' : '-';
        }

        return reduce(node, precision);
      }
  }

  if (left.type === 'MathExpression' && right.type === 'MathExpression' && op === '-' && right.operator === '-') {
    node.right.operator = flip(node.right.operator);
  }

  return node;
}

function reduceDivisionExpression(node) {
  if (!isValueType(node.right.type)) return node;
  if (node.right.type !== 'Value') throw new Error(`Cannot divide by "${node.right.unit}", number expected`);
  if (node.right.value === 0) throw new Error('Cannot divide by zero'); // something / value

  if (isValueType(node.left.type)) {
    node.left.value /= node.right.value;
    return node.left;
  }

  return node;
}

function reduceMultiplicationExpression(node) {
  // (expr) * value
  if (node.left.type === 'MathExpression' && node.right.type === 'Value') {
    if (isValueType(node.left.left.type) && isValueType(node.left.right.type)) {
      node.left.left.value *= node.right.value;
      node.left.right.value *= node.right.value;
      return node.left;
    }
  } // something * value
  else if (isValueType(node.left.type) && node.right.type === 'Value') {
      node.left.value *= node.right.value;
      return node.left;
    } // value * (expr)
    else if (node.left.type === 'Value' && node.right.type === 'MathExpression') {
        if (isValueType(node.right.left.type) && isValueType(node.right.right.type)) {
          node.right.left.value *= node.left.value;
          node.right.right.value *= node.left.value;
          return node.right;
        }
      } // value * something
      else if (node.left.type === 'Value' && isValueType(node.right.type)) {
          node.right.value *= node.left.value;
          return node.right;
        }

  return node;
}

function reduceMathExpression(node, precision) {
  node = convertMathExpression(node, precision);

  switch (node.operator) {
    case "+":
    case "-":
      return reduceAddSubExpression(node, precision);

    case "/":
      return reduceDivisionExpression(node, precision);

    case "*":
      return reduceMultiplicationExpression(node);
  }

  return node;
}

var _default = reduce;
exports.default = _default;
module.exports = exports.default;