add some packages

node_modules/babel-helper-flip-expressions/lib/index.js

@@ -0,0 +1,109 @@
+"use strict";
+
+const flipSeen = Symbol("flipSeen");
+
+module.exports = function (t) {
+  return {
+    hasSeen(node) {
+      return !!node[flipSeen];
+    },
+
+    // Takes an expressions and determines if it has
+    // more nodes that could benifit from flipping than not.
+    shouldFlip(topNode, savings = 0) {
+      visit(topNode);
+      return savings > 0;
+
+      function visit(node) {
+        if (t.isUnaryExpression(node, {
+          operator: "!"
+        })) {
+          savings++;
+          return;
+        }
+
+        if (t.isLogicalExpression(node)) {
+          visit(node.left);
+          visit(node.right);
+          return;
+        }
+
+        if (!(t.isBinaryExpression(node) && t.EQUALITY_BINARY_OPERATORS.indexOf(node.operator) > -1)) {
+          // Binary expressions wouldn't hurut because we know how to flip them
+          savings--;
+        }
+      }
+    },
+
+    flip(node, resultNotUsed) {
+      let lastNodeDesc;
+      const ret = visit(node);
+      ret[flipSeen] = true;
+
+      if (resultNotUsed && lastNodeDesc) {
+        const _lastNodeDesc = lastNodeDesc,
+              parent = _lastNodeDesc.parent,
+              key = _lastNodeDesc.key;
+
+        if (parent && key && t.isUnaryExpression(parent[key], {
+          operator: "!"
+        })) {
+          parent[key] = parent[key].argument;
+        }
+      }
+
+      return ret;
+
+      function visit(node, parent, key) {
+        lastNodeDesc = {
+          parent,
+          key
+        };
+
+        if (t.isUnaryExpression(node, {
+          operator: "!"
+        })) {
+          return node.argument;
+        }
+
+        if (t.isLogicalExpression(node)) {
+          node.operator = node.operator === "&&" ? "||" : "&&";
+          node.left = visit(node.left, node, "left");
+          node.right = visit(node.right, node, "right");
+          return node;
+        }
+
+        if (t.isBinaryExpression(node)) {
+          let operator;
+
+          switch (node.operator) {
+            case "!==":
+              operator = "===";
+              break;
+
+            case "===":
+              operator = "!==";
+              break;
+
+            case "!=":
+              operator = "==";
+              break;
+
+            case "==":
+              operator = "!=";
+              break;
+          }
+
+          if (operator) {
+            node.operator = operator;
+            return node;
+          } // Falls through to unary expression
+
+        }
+
+        return t.unaryExpression("!", node, true);
+      }
+    }
+
+  };
+};