flow like the river

BACK_BACK/node_modules/postcss-calc/dist/lib/reducer.js

@@ -0,0 +1,320 @@
+"use strict";
+
+Object.defineProperty(exports, "__esModule", {
+  value: true
+});
+exports.default = void 0;
+
+var _convertUnit = _interopRequireDefault(require("./convertUnit"));
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+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 'Number':
+      return true;
+  }
+
+  return false;
+}
+
+function flip(operator) {
+  return operator === '+' ? '-' : '+';
+}
+
+function isAddSubOperator(operator) {
+  return operator === '+' || operator === '-';
+}
+
+function collectAddSubItems(preOperator, node, collected, precision) {
+  if (!isAddSubOperator(preOperator)) {
+    throw new Error(`invalid operator ${preOperator}`);
+  }
+
+  var type = node.type;
+
+  if (isValueType(type)) {
+    var itemIndex = collected.findIndex(function (x) {
+      return x.node.type === type;
+    });
+
+    if (itemIndex >= 0) {
+      if (node.value === 0) {
+        return;
+      }
+
+      var _covertNodesUnits = covertNodesUnits(collected[itemIndex].node, node, precision),
+          reducedNode = _covertNodesUnits.left,
+          current = _covertNodesUnits.right;
+
+      if (collected[itemIndex].preOperator === '-') {
+        collected[itemIndex].preOperator = '+';
+        reducedNode.value *= -1;
+      }
+
+      if (preOperator === "+") {
+        reducedNode.value += current.value;
+      } else {
+        reducedNode.value -= current.value;
+      } // make sure reducedNode.value >= 0
+
+
+      if (reducedNode.value >= 0) {
+        collected[itemIndex] = {
+          node: reducedNode,
+          preOperator: '+'
+        };
+      } else {
+        reducedNode.value *= -1;
+        collected[itemIndex] = {
+          node: reducedNode,
+          preOperator: '-'
+        };
+      }
+    } else {
+      // make sure node.value >= 0
+      if (node.value >= 0) {
+        collected.push({
+          node,
+          preOperator
+        });
+      } else {
+        node.value *= -1;
+        collected.push({
+          node,
+          preOperator: flip(preOperator)
+        });
+      }
+    }
+  } else if (type === "MathExpression") {
+    if (isAddSubOperator(node.operator)) {
+      collectAddSubItems(preOperator, node.left, collected, precision);
+      var collectRightOperator = preOperator === '-' ? flip(node.operator) : node.operator;
+      collectAddSubItems(collectRightOperator, node.right, collected, precision);
+    } else {
+      // * or /
+      var _reducedNode = reduce(node, precision); // prevent infinite recursive call
+
+
+      if (_reducedNode.type !== "MathExpression" || isAddSubOperator(_reducedNode.operator)) {
+        collectAddSubItems(preOperator, _reducedNode, collected, precision);
+      } else {
+        collected.push({
+          node: _reducedNode,
+          preOperator
+        });
+      }
+    }
+  } else {
+    collected.push({
+      node,
+      preOperator
+    });
+  }
+}
+
+function reduceAddSubExpression(node, precision) {
+  var collected = [];
+  collectAddSubItems('+', node, collected, precision);
+  var withoutZeroItem = collected.filter(function (item) {
+    return !(isValueType(item.node.type) && item.node.value === 0);
+  });
+  var firstNonZeroItem = withoutZeroItem[0]; // could be undefined
+  // prevent producing "calc(-var(--a))" or "calc()"
+  // which is invalid css
+
+  if (!firstNonZeroItem || firstNonZeroItem.preOperator === '-' && !isValueType(firstNonZeroItem.node.type)) {
+    var firstZeroItem = collected.find(function (item) {
+      return isValueType(item.node.type) && item.node.value === 0;
+    });
+    withoutZeroItem.unshift(firstZeroItem);
+  } // make sure the preOperator of the first item is +
+
+
+  if (withoutZeroItem[0].preOperator === '-' && isValueType(withoutZeroItem[0].node.type)) {
+    withoutZeroItem[0].node.value *= -1;
+    withoutZeroItem[0].preOperator = '+';
+  }
+
+  var root = withoutZeroItem[0].node;
+
+  for (var i = 1; i < withoutZeroItem.length; i++) {
+    root = {
+      type: 'MathExpression',
+      operator: withoutZeroItem[i].preOperator,
+      left: root,
+      right: withoutZeroItem[i].node
+    };
+  }
+
+  return root;
+}
+
+function reduceDivisionExpression(node) {
+  if (!isValueType(node.right.type)) {
+    return node;
+  }
+
+  if (node.right.type !== 'Number') {
+    throw new Error(`Cannot divide by "${node.right.unit}", number expected`);
+  }
+
+  return applyNumberDivision(node.left, node.right.value);
+} // apply (expr) / number
+
+
+function applyNumberDivision(node, divisor) {
+  if (divisor === 0) {
+    throw new Error('Cannot divide by zero');
+  }
+
+  if (isValueType(node.type)) {
+    node.value /= divisor;
+    return node;
+  }
+
+  if (node.type === "MathExpression" && isAddSubOperator(node.operator)) {
+    // turn (a + b) / num into a/num + b/num
+    // is good for further reduction
+    // checkout the test case
+    // "should reduce division before reducing additions"
+    return {
+      type: "MathExpression",
+      operator: node.operator,
+      left: applyNumberDivision(node.left, divisor),
+      right: applyNumberDivision(node.right, divisor)
+    };
+  } // it is impossible to reduce it into a single value
+  // .e.g the node contains css variable
+  // so we just preserve the division and let browser do it
+
+
+  return {
+    type: "MathExpression",
+    operator: '/',
+    left: node,
+    right: {
+      type: "Number",
+      value: divisor
+    }
+  };
+}
+
+function reduceMultiplicationExpression(node) {
+  // (expr) * number
+  if (node.right.type === 'Number') {
+    return applyNumberMultiplication(node.left, node.right.value);
+  } // number * (expr)
+
+
+  if (node.left.type === 'Number') {
+    return applyNumberMultiplication(node.right, node.left.value);
+  }
+
+  return node;
+} // apply (expr) / number
+
+
+function applyNumberMultiplication(node, multiplier) {
+  if (isValueType(node.type)) {
+    node.value *= multiplier;
+    return node;
+  }
+
+  if (node.type === "MathExpression" && isAddSubOperator(node.operator)) {
+    // turn (a + b) * num into a*num + b*num
+    // is good for further reduction
+    // checkout the test case
+    // "should reduce multiplication before reducing additions"
+    return {
+      type: "MathExpression",
+      operator: node.operator,
+      left: applyNumberMultiplication(node.left, multiplier),
+      right: applyNumberMultiplication(node.right, multiplier)
+    };
+  } // it is impossible to reduce it into a single value
+  // .e.g the node contains css variable
+  // so we just preserve the division and let browser do it
+
+
+  return {
+    type: "MathExpression",
+    operator: '*',
+    left: node,
+    right: {
+      type: "Number",
+      value: multiplier
+    }
+  };
+}
+
+function covertNodesUnits(left, right, precision) {
+  switch (left.type) {
+    case 'LengthValue':
+    case 'AngleValue':
+    case 'TimeValue':
+    case 'FrequencyValue':
+    case 'ResolutionValue':
+      if (right.type === left.type && right.unit && left.unit) {
+        var converted = (0, _convertUnit.default)(right.value, right.unit, left.unit, precision);
+        right = {
+          type: left.type,
+          value: converted,
+          unit: left.unit
+        };
+      }
+
+      return {
+        left,
+        right
+      };
+
+    default:
+      return {
+        left,
+        right
+      };
+  }
+}
+
+function reduce(node, precision) {
+  if (node.type === "MathExpression") {
+    if (isAddSubOperator(node.operator)) {
+      // reduceAddSubExpression will call reduce recursively
+      return reduceAddSubExpression(node, precision);
+    }
+
+    node.left = reduce(node.left, precision);
+    node.right = reduce(node.right, precision);
+
+    switch (node.operator) {
+      case "/":
+        return reduceDivisionExpression(node, precision);
+
+      case "*":
+        return reduceMultiplicationExpression(node, precision);
+    }
+
+    return node;
+  }
+
+  return node;
+}
+
+var _default = reduce;
+exports.default = _default;
+module.exports = exports.default;