clean up babel-plugin-transform-regenerator

packages/babel-plugin-transform-regenerator/src/hoist.js

@@ -0,0 +1,148 @@
+/**
+ * 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.
+ */
+
+import * as t from "babel-types";
+let 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);
+
+  let vars = {};
+
+  function varDeclToExpr(vdec, includeIdentifiers) {
+    t.assertVariableDeclaration(vdec);
+    // TODO assert.equal(vdec.kind, "var");
+    let exprs = [];
+
+    vdec.declarations.forEach(function(dec) {
+      vars[dec.id.name] = dec.id;
+
+      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(path) {
+        let 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.
+          path.replaceWith(t.expressionStatement(expr));
+        }
+
+        // Since the original node has been either removed or replaced,
+        // avoid traversing it any further.
+        path.skip();
+      }
+    },
+
+    ForStatement: function(path) {
+      let init = path.node.init;
+      if (t.isVariableDeclaration(init)) {
+        path.get("init").replaceWith(varDeclToExpr(init, false));
+      }
+    },
+
+    ForXStatement: function(path) {
+      let left = path.get("left");
+      if (left.isVariableDeclaration()) {
+        left.replaceWith(varDeclToExpr(left.node, true));
+      }
+    },
+
+    FunctionDeclaration: function(path) {
+      let node = path.node;
+      vars[node.id.name] = node.id;
+
+      let 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.
+        path.replaceWith(assignment);
+      }
+
+      // Don't hoist variables out of inner functions.
+      path.skip();
+    },
+
+    FunctionExpression: function(path) {
+      // Don't descend into nested function expressions.
+      path.skip();
+    }
+  });
+
+  let paramNames = {};
+  funPath.get("params").forEach(function(paramPath) {
+    let param = paramPath.node;
+    if (t.isIdentifier(param)) {
+      paramNames[param.name] = param;
+    } else {
+      // Variables declared by destructuring parameter patterns will be
+      // harmlessly re-declared.
+    }
+  });
+
+  let declarations = [];
+
+  Object.keys(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);
+};

packages/babel-plugin-transform-regenerator/src/index.js

@@ -0,0 +1,13 @@
+/**
+ * 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.
+ */
+
+export default function () {
+  return require("./visit");
+}

packages/babel-plugin-transform-regenerator/src/leap.js

@@ -0,0 +1,174 @@
+/**
+ * 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.
+ */
+
+import assert from "assert";
+import * as t from "babel-types";
+import { inherits } from "util";
+
+function Entry() {
+  assert.ok(this instanceof Entry);
+}
+
+function FunctionEntry(returnLoc) {
+  Entry.call(this);
+  t.assertLiteral(returnLoc);
+  this.returnLoc = returnLoc;
+}
+
+inherits(FunctionEntry, Entry);
+exports.FunctionEntry = FunctionEntry;
+
+function LoopEntry(breakLoc, continueLoc, label) {
+  Entry.call(this);
+
+  t.assertLiteral(breakLoc);
+  t.assertLiteral(continueLoc);
+
+  if (label) {
+    t.assertIdentifier(label);
+  } else {
+    label = null;
+  }
+
+  this.breakLoc = breakLoc;
+  this.continueLoc = continueLoc;
+  this.label = label;
+}
+
+inherits(LoopEntry, Entry);
+exports.LoopEntry = LoopEntry;
+
+function SwitchEntry(breakLoc) {
+  Entry.call(this);
+  t.assertLiteral(breakLoc);
+  this.breakLoc = breakLoc;
+}
+
+inherits(SwitchEntry, Entry);
+exports.SwitchEntry = SwitchEntry;
+
+function TryEntry(firstLoc, catchEntry, finallyEntry) {
+  Entry.call(this);
+
+  t.assertLiteral(firstLoc);
+
+  if (catchEntry) {
+    assert.ok(catchEntry instanceof CatchEntry);
+  } else {
+    catchEntry = null;
+  }
+
+  if (finallyEntry) {
+    assert.ok(finallyEntry instanceof FinallyEntry);
+  } else {
+    finallyEntry = null;
+  }
+
+  // Have to have one or the other (or both).
+  assert.ok(catchEntry || finallyEntry);
+
+  this.firstLoc = firstLoc;
+  this.catchEntry = catchEntry;
+  this.finallyEntry = finallyEntry;
+}
+
+inherits(TryEntry, Entry);
+exports.TryEntry = TryEntry;
+
+function CatchEntry(firstLoc, paramId) {
+  Entry.call(this);
+
+  t.assertLiteral(firstLoc);
+  t.assertIdentifier(paramId);
+
+  this.firstLoc = firstLoc;
+  this.paramId = paramId;
+}
+
+inherits(CatchEntry, Entry);
+exports.CatchEntry = CatchEntry;
+
+function FinallyEntry(firstLoc, afterLoc) {
+  Entry.call(this);
+  t.assertLiteral(firstLoc);
+  t.assertLiteral(afterLoc);
+  this.firstLoc = firstLoc;
+  this.afterLoc = afterLoc;
+}
+
+inherits(FinallyEntry, Entry);
+exports.FinallyEntry = FinallyEntry;
+
+function LabeledEntry(breakLoc, label) {
+  Entry.call(this);
+
+  t.assertLiteral(breakLoc);
+  t.assertIdentifier(label);
+
+  this.breakLoc = breakLoc;
+  this.label = label;
+}
+
+inherits(LabeledEntry, Entry);
+exports.LabeledEntry = LabeledEntry;
+
+function LeapManager(emitter) {
+  assert.ok(this instanceof LeapManager);
+
+  let Emitter = require("./emit").Emitter;
+  assert.ok(emitter instanceof Emitter);
+
+  this.emitter = emitter;
+  this.entryStack = [new FunctionEntry(emitter.finalLoc)];
+}
+
+let LMp = LeapManager.prototype;
+exports.LeapManager = LeapManager;
+
+LMp.withEntry = function(entry, callback) {
+  assert.ok(entry instanceof Entry);
+  this.entryStack.push(entry);
+  try {
+    callback.call(this.emitter);
+  } finally {
+    let popped = this.entryStack.pop();
+    assert.strictEqual(popped, entry);
+  }
+};
+
+LMp._findLeapLocation = function(property, label) {
+  for (let i = this.entryStack.length - 1; i >= 0; --i) {
+    let entry = this.entryStack[i];
+    let loc = entry[property];
+    if (loc) {
+      if (label) {
+        if (entry.label &&
+            entry.label.name === label.name) {
+          return loc;
+        }
+      } else if (entry instanceof LabeledEntry) {
+        // Ignore LabeledEntry entries unless we are actually breaking to
+        // a label.
+      } else {
+        return loc;
+      }
+    }
+  }
+
+  return null;
+};
+
+LMp.getBreakLoc = function(label) {
+  return this._findLeapLocation("breakLoc", label);
+};
+
+LMp.getContinueLoc = function(label) {
+  return this._findLeapLocation("continueLoc", label);
+};

packages/babel-plugin-transform-regenerator/src/meta.js

@@ -0,0 +1,103 @@
+/**
+ * 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.
+ */
+
+import assert from "assert";
+let m = require("private").makeAccessor();
+import * as t from "babel-types";
+let hasOwn = Object.prototype.hasOwnProperty;
+
+function makePredicate(propertyName, knownTypes) {
+  function onlyChildren(node) {
+    t.assertNode(node);
+
+    // Assume no side effects until we find out otherwise.
+    let result = false;
+
+    function check(child) {
+      if (result) {
+        // Do nothing.
+      } else if (Array.isArray(child)) {
+        child.some(check);
+      } else if (t.isNode(child)) {
+        assert.strictEqual(result, false);
+        result = predicate(child);
+      }
+      return result;
+    }
+
+    let keys = t.VISITOR_KEYS[node.type];
+    if (keys) {
+      for (let i = 0; i < keys.length; i++) {
+        let key = keys[i];
+        let child = node[key];
+        check(child);
+      }
+    }
+
+    return result;
+  }
+
+  function predicate(node) {
+    t.assertNode(node);
+
+    let meta = m(node);
+    if (hasOwn.call(meta, propertyName))
+      return meta[propertyName];
+
+    // Certain types are "opaque," which means they have no side
+    // effects or leaps and we don't care about their subexpressions.
+    if (hasOwn.call(opaqueTypes, node.type))
+      return meta[propertyName] = false;
+
+    if (hasOwn.call(knownTypes, node.type))
+      return meta[propertyName] = true;
+
+    return meta[propertyName] = onlyChildren(node);
+  }
+
+  predicate.onlyChildren = onlyChildren;
+
+  return predicate;
+}
+
+let opaqueTypes = {
+  FunctionExpression: true
+};
+
+// These types potentially have side effects regardless of what side
+// effects their subexpressions have.
+let sideEffectTypes = {
+  CallExpression: true, // Anything could happen!
+  ForInStatement: true, // Modifies the key variable.
+  UnaryExpression: true, // Think delete.
+  BinaryExpression: true, // Might invoke .toString() or .valueOf().
+  AssignmentExpression: true, // Side-effecting by definition.
+  UpdateExpression: true, // Updates are essentially assignments.
+  NewExpression: true // Similar to CallExpression.
+};
+
+// These types are the direct cause of all leaps in control flow.
+let leapTypes = {
+  YieldExpression: true,
+  BreakStatement: true,
+  ContinueStatement: true,
+  ReturnStatement: true,
+  ThrowStatement: true
+};
+
+// All leap types are also side effect types.
+for (let type in leapTypes) {
+  if (hasOwn.call(leapTypes, type)) {
+    sideEffectTypes[type] = leapTypes[type];
+  }
+}
+
+exports.hasSideEffects = makePredicate("hasSideEffects", sideEffectTypes);
+exports.containsLeap = makePredicate("containsLeap", leapTypes);

packages/babel-plugin-transform-regenerator/src/util.js

@@ -0,0 +1,23 @@
+/**
+ * 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.
+ */
+
+import * as t from "babel-types";
+
+export function runtimeProperty(name) {
+  return t.memberExpression(
+    t.identifier("regeneratorRuntime"),
+    t.identifier(name),
+    false
+  );
+}
+
+export function isReference(path) {
+  return path.isReferenced() || path.parentPath.isAssignmentExpression({ left: path.node });
+}

packages/babel-plugin-transform-regenerator/src/visit.js

@@ -0,0 +1,252 @@
+/**
+ * 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.
+ */
+
+import assert from "assert";
+import * as t from "babel-types";
+import { hoist } from "./hoist";
+import { Emitter } from "./emit";
+import * as util from "./util";
+
+let getMarkInfo = require("private").makeAccessor();
+
+exports.visitor = {
+  Function: {
+    exit: function(path, state) {
+      let node = path.node;
+
+      if (node.generator) {
+        if (node.async) {
+          // Async generator
+          if (state.opts.asyncGenerators === false) return;
+        } else {
+          // Plain generator
+          if (state.opts.generators === false) return;
+        }
+      } else if (node.async) {
+        // Async function
+        if (state.opts.async === false) return;
+      } else {
+        // Not a generator or async function.
+        return;
+      }
+
+      if (node.expression) {
+        // Transform expression lambdas into normal functions.
+        node.expression = false;
+        node.body = t.blockStatement([
+          t.returnStatement(node.body)
+        ]);
+      }
+
+      if (node.async) {
+        path.get("body").traverse(awaitVisitor);
+      }
+
+      let bodyBlockPath = path.get("body");
+      let outerBody = [];
+      let innerBody = [];
+
+      bodyBlockPath.get("body").forEach(function(childPath) {
+        let node = childPath.node;
+        if (node && node._blockHoist != null) {
+          outerBody.push(node);
+        } else {
+          innerBody.push(node);
+        }
+      });
+
+      if (outerBody.length > 0) {
+        // Only replace the inner body if we actually hoisted any statements
+        // to the outer body.
+        bodyBlockPath.node.body = innerBody;
+      }
+
+      let outerFnExpr = getOuterFnExpr(path);
+      // Note that getOuterFnExpr has the side-effect of ensuring that the
+      // function has a name (so node.id will always be an Identifier), even
+      // if a temporary name has to be synthesized.
+      t.assertIdentifier(node.id);
+      let innerFnId = t.identifier(node.id.name + "$");
+      let contextId = path.scope.generateUidIdentifier("context");
+      let argsId = path.scope.generateUidIdentifier("args");
+
+      // Turn all declarations into vars, and replace the original
+      // declarations with equivalent assignment expressions.
+      let vars = hoist(path);
+
+      let didRenameArguments = renameArguments(path, argsId);
+      if (didRenameArguments) {
+        vars = vars || t.variableDeclaration("var", []);
+        vars.declarations.push(t.variableDeclarator(
+          argsId, t.identifier("arguments")
+        ));
+      }
+
+      let emitter = new Emitter(contextId);
+      emitter.explode(path.get("body"));
+
+      if (vars && vars.declarations.length > 0) {
+        outerBody.push(vars);
+      }
+
+      let wrapArgs = [
+        emitter.getContextFunction(innerFnId),
+        // Async functions that are not generators don't care about the
+        // outer function because they don't need it to be marked and don't
+        // inherit from its .prototype.
+        node.generator ? outerFnExpr : t.nullLiteral(),
+        t.thisExpression()
+      ];
+
+      let tryLocsList = emitter.getTryLocsList();
+      if (tryLocsList) {
+        wrapArgs.push(tryLocsList);
+      }
+
+      let wrapCall = t.callExpression(
+        util.runtimeProperty(node.async ? "async" : "wrap"),
+        wrapArgs
+      );
+
+      outerBody.push(t.returnStatement(wrapCall));
+      node.body = t.blockStatement(outerBody);
+
+      let wasGeneratorFunction = node.generator;
+      if (wasGeneratorFunction) {
+        node.generator = false;
+      }
+
+      if (node.async) {
+        node.async = false;
+      }
+
+      if (wasGeneratorFunction &&
+          t.isExpression(node)) {
+        path.replaceWith(t.callExpression(util.runtimeProperty("mark"), [node]));
+      }
+    }
+  }
+};
+
+// Given a NodePath for a Function, return an Expression node that can be
+// used to refer reliably to the function object from inside the function.
+// This expression is essentially a replacement for arguments.callee, with
+// the key advantage that it works in strict mode.
+function getOuterFnExpr(funPath) {
+  let node = funPath.node;
+  t.assertFunction(node);
+
+  if (node.generator && // Non-generator functions don't need to be marked.
+      t.isFunctionDeclaration(node)) {
+    let pp = funPath.findParent(function (path) {
+      return path.isProgram() || path.isBlockStatement();
+    });
+
+    if (!pp) {
+      return node.id;
+    }
+
+    let markDecl = getRuntimeMarkDecl(pp);
+    let markedArray = markDecl.declarations[0].id;
+    let funDeclIdArray = markDecl.declarations[0].init.callee.object;
+    t.assertArrayExpression(funDeclIdArray);
+
+    let index = funDeclIdArray.elements.length;
+    funDeclIdArray.elements.push(node.id);
+
+    return t.memberExpression(
+      markedArray,
+      t.numericLiteral(index),
+      true
+    );
+  }
+
+  return node.id || (
+    node.id = funPath.scope.parent.generateUidIdentifier("callee")
+  );
+}
+
+function getRuntimeMarkDecl(blockPath) {
+  let block = blockPath.node;
+  assert.ok(Array.isArray(block.body));
+
+  let info = getMarkInfo(block);
+  if (info.decl) {
+    return info.decl;
+  }
+
+  info.decl = t.variableDeclaration("var", [
+    t.variableDeclarator(
+      blockPath.scope.generateUidIdentifier("marked"),
+      t.callExpression(
+        t.memberExpression(
+          t.arrayExpression([]),
+          t.identifier("map"),
+          false
+        ),
+        [util.runtimeProperty("mark")]
+      )
+    )
+  ]);
+
+  blockPath.unshiftContainer("body", info.decl);
+
+  return info.decl;
+}
+
+function renameArguments(funcPath, argsId) {
+  let state = {
+    didRenameArguments: false,
+    argsId: argsId
+  };
+
+  funcPath.traverse(argumentsVisitor, state);
+
+  // If the traversal replaced any arguments references, then we need to
+  // alias the outer function's arguments binding (be it the implicit
+  // arguments object or some other parameter or variable) to the variable
+  // named by argsId.
+  return state.didRenameArguments;
+}
+
+let argumentsVisitor = {
+  "FunctionExpression|FunctionDeclaration": function(path) {
+    path.skip();
+  },
+
+  Identifier: function(path, state) {
+    if (path.node.name === "arguments" && util.isReference(path)) {
+      path.replaceWith(state.argsId);
+      state.didRenameArguments = true;
+    }
+  }
+};
+
+let awaitVisitor = {
+  Function: function(path) {
+    path.skip(); // Don't descend into nested function scopes.
+  },
+
+  AwaitExpression: function(path) {
+    // Convert await and await* expressions to yield expressions.
+    let argument = path.node.argument;
+
+    // Transforming `await x` to `yield regeneratorRuntime.awrap(x)`
+    // causes the argument to be wrapped in such a way that the runtime
+    // can distinguish between awaited and merely yielded values.
+    path.replaceWith(t.yieldExpression(
+      t.callExpression(
+        util.runtimeProperty("awrap"),
+        [argument]
+      ),
+      false
+    ));
+  }
+};