flow like the river

VISUALIZACION/node_modules/regenerator-transform/lib/hoist.js

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+"use strict";
+
+var _keys = require("babel-runtime/core-js/object/keys");
+
+var _keys2 = _interopRequireDefault(_keys);
+
+var _babelTypes = require("babel-types");
+
+var t = _interopRequireWildcard(_babelTypes);
+
+var _util = require("./util");
+
+var util = _interopRequireWildcard(_util);
+
+function _interopRequireWildcard(obj) { if (obj && obj.__esModule) { return obj; } else { var newObj = {}; if (obj != null) { for (var key in obj) { if (Object.prototype.hasOwnProperty.call(obj, key)) newObj[key] = obj[key]; } } newObj.default = obj; return newObj; } }
+
+function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }
+
+/**
+ * Copyright (c) 2014, Facebook, Inc.
+ * All rights reserved.
+ *
+ * This source code is licensed under the BSD-style license found in the
+ * https://raw.github.com/facebook/regenerator/master/LICENSE file. An
+ * additional grant of patent rights can be found in the PATENTS file in
+ * the same directory.
+ */
+
+var hasOwn = Object.prototype.hasOwnProperty;
+
+// The hoist function takes a FunctionExpression or FunctionDeclaration
+// and replaces any Declaration nodes in its body with assignments, then
+// returns a VariableDeclaration containing just the names of the removed
+// declarations.
+exports.hoist = function (funPath) {
+  t.assertFunction(funPath.node);
+
+  var vars = {};
+
+  function varDeclToExpr(vdec, includeIdentifiers) {
+    t.assertVariableDeclaration(vdec);
+    // TODO assert.equal(vdec.kind, "var");
+    var exprs = [];
+
+    vdec.declarations.forEach(function (dec) {
+      // Note: We duplicate 'dec.id' here to ensure that the variable declaration IDs don't
+      // have the same 'loc' value, since that can make sourcemaps and retainLines behave poorly.
+      vars[dec.id.name] = t.identifier(dec.id.name);
+
+      if (dec.init) {
+        exprs.push(t.assignmentExpression("=", dec.id, dec.init));
+      } else if (includeIdentifiers) {
+        exprs.push(dec.id);
+      }
+    });
+
+    if (exprs.length === 0) return null;
+
+    if (exprs.length === 1) return exprs[0];
+
+    return t.sequenceExpression(exprs);
+  }
+
+  funPath.get("body").traverse({
+    VariableDeclaration: {
+      exit: function exit(path) {
+        var expr = varDeclToExpr(path.node, false);
+        if (expr === null) {
+          path.remove();
+        } else {
+          // We don't need to traverse this expression any further because
+          // there can't be any new declarations inside an expression.
+          util.replaceWithOrRemove(path, t.expressionStatement(expr));
+        }
+
+        // Since the original node has been either removed or replaced,
+        // avoid traversing it any further.
+        path.skip();
+      }
+    },
+
+    ForStatement: function ForStatement(path) {
+      var init = path.node.init;
+      if (t.isVariableDeclaration(init)) {
+        util.replaceWithOrRemove(path.get("init"), varDeclToExpr(init, false));
+      }
+    },
+
+    ForXStatement: function ForXStatement(path) {
+      var left = path.get("left");
+      if (left.isVariableDeclaration()) {
+        util.replaceWithOrRemove(left, varDeclToExpr(left.node, true));
+      }
+    },
+
+    FunctionDeclaration: function FunctionDeclaration(path) {
+      var node = path.node;
+      vars[node.id.name] = node.id;
+
+      var assignment = t.expressionStatement(t.assignmentExpression("=", node.id, t.functionExpression(node.id, node.params, node.body, node.generator, node.expression)));
+
+      if (path.parentPath.isBlockStatement()) {
+        // Insert the assignment form before the first statement in the
+        // enclosing block.
+        path.parentPath.unshiftContainer("body", assignment);
+
+        // Remove the function declaration now that we've inserted the
+        // equivalent assignment form at the beginning of the block.
+        path.remove();
+      } else {
+        // If the parent node is not a block statement, then we can just
+        // replace the declaration with the equivalent assignment form
+        // without worrying about hoisting it.
+        util.replaceWithOrRemove(path, assignment);
+      }
+
+      // Don't hoist variables out of inner functions.
+      path.skip();
+    },
+
+    FunctionExpression: function FunctionExpression(path) {
+      // Don't descend into nested function expressions.
+      path.skip();
+    }
+  });
+
+  var paramNames = {};
+  funPath.get("params").forEach(function (paramPath) {
+    var param = paramPath.node;
+    if (t.isIdentifier(param)) {
+      paramNames[param.name] = param;
+    } else {
+      // Variables declared by destructuring parameter patterns will be
+      // harmlessly re-declared.
+    }
+  });
+
+  var declarations = [];
+
+  (0, _keys2.default)(vars).forEach(function (name) {
+    if (!hasOwn.call(paramNames, name)) {
+      declarations.push(t.variableDeclarator(vars[name], null));
+    }
+  });
+
+  if (declarations.length === 0) {
+    return null; // Be sure to handle this case!
+  }
+
+  return t.variableDeclaration("var", declarations);
+};