From 99d626d23f0bac9b7318b08c2e92e11ed9ddaff2 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Mon, 13 Oct 2014 03:26:49 +1100
Subject: [PATCH] add file class to simplify transforming

---
 lib/6to5/file.js                              | 102 ++++++++++++++++++
 lib/6to5/transform.js                         |  91 +++-------------
 lib/6to5/transformers/array-comprehension.js  |  10 +-
 lib/6to5/transformers/classes.js              |  32 +++---
 .../transformers/computed-property-names.js   |   4 +-
 lib/6to5/transformers/destructuring.js        |  22 ++--
 lib/6to5/transformers/for-of.js               |   6 +-
 .../property-method-assignment.js             |   4 +-
 8 files changed, 156 insertions(+), 115 deletions(-)
 create mode 100644 lib/6to5/file.js

diff --git a/lib/6to5/file.js b/lib/6to5/file.js
new file mode 100644
index 0000000000..253f5a6d6c
--- /dev/null
+++ b/lib/6to5/file.js
@@ -0,0 +1,102 @@
+module.exports = File;
+
+var transform = require("./transform");
+var traverse  = require("./traverse");
+var util      = require("./util");
+var _         = require("lodash");
+
+function File(opts) {
+  this.uids = {};
+  this.opts = File.normaliseOptions(opts);
+  this.ast  = {};
+}
+
+File.normaliseOptions = function (opts) {
+  opts = opts || {};
+
+  _.defaults(opts, {
+    blacklist: [],
+    whitelist: [],
+    sourceMap: false,
+    filename:  "unknown",
+    format:    {}
+  });
+
+  _.defaults(opts, {
+    sourceFileName: opts.filename,
+    sourceMapName:  opts.filename
+  });
+
+  transform._ensureTransformerNames("blacklist", opts.blacklist);
+  transform._ensureTransformerNames("whitelist", opts.whitelist);
+
+  return opts;
+};
+
+File.prototype.transform = function (ast) {
+  this.ast = ast;
+
+  var self = this;
+  var opts = this.opts;
+
+  _.each(transform.transformers, function (transformer, name) {
+    self.runTransformer(name, transformer);
+  });
+
+  var result = util.generate(ast, opts);
+
+  if (opts.sourceMap === "inline") {
+    result.code += "\n" + util.sourceMapToComment(result.map);
+  }
+
+  result.map = result.map || null;
+  result.ast = ast;
+
+  return result;
+};
+
+File.prototype.generateUid = function (name) {
+  var uids = this.uids;
+  var i = uids[name] || 1;
+
+  var id = name;
+  if (i > 1) id += i;
+  uids[name] = i + 1;
+  return "_" + id;
+};
+
+File.prototype.canRunTransformer = function (name) {
+  var opts = this.opts;
+
+  var blacklist = opts.blacklist;
+  if (blacklist.length && _.contains(blacklist, name)) return false;
+
+  var whitelist = opts.whitelist;
+  if (whitelist.length && !_.contains(whitelist, name)) return false;
+
+  return true;
+};
+
+File.prototype.runTransformer = function (name, transformer) {
+  if (!this.canRunTransformer(name)) return;
+
+  var self = this;
+
+  var build = function (exit) {
+    return function (node, parent) {
+      var fns = transformer[node.type] || transformer.all;
+      if (!fns) return;
+
+      var fn = fns.enter || fns;
+      if (exit) fn = fns.exit;
+      if (!fn || !_.isFunction(fn)) return;
+
+      return fn(node, parent, self);
+    };
+  };
+
+  traverse(this.ast, {
+    enter: build(),
+    exit:  build(true)
+  });
+};
diff --git a/lib/6to5/transform.js b/lib/6to5/transform.js
index 6bf572cc6d..1233403165 100644
--- a/lib/6to5/transform.js
+++ b/lib/6to5/transform.js
@@ -1,86 +1,21 @@
+module.exports = transform;
+
 var sourceMap = require("source-map");
-var traverse  = require("./traverse");
 var recast    = require("recast");
+var File      = require("./file");
 var util      = require("./util");
 var _         = require("lodash");
 
-var ensureTransformerNames = function (type, keys) {
-  _.each(keys, function (key) {
-    if (!transform.transformers[key]) {
-      throw new ReferenceError("unknown transformer " + key + " specified in " + type);
-    }
-  });
-};
-
-var transform = module.exports = function (code, opts) {
+function transform(code, opts) {
   opts = opts || {};
   code = (code || "") + "";
 
-  _.defaults(opts, {
-    blacklist: [],
-    whitelist: [],
-    sourceMap: false,
-    filename:  "unknown",
-    format:    {}
-  });
-
-  _.defaults(opts, {
-    sourceFileName: opts.filename,
-    sourceMapName:  opts.filename
-  });
-
-  ensureTransformerNames("blacklist", opts.blacklist);
-  ensureTransformerNames("whitelist", opts.whitelist);
+  var file = new File(opts);
 
   return util.parse(opts, code, function (tree) {
-    return transform._run(code, tree, opts);
+    return file.transform(tree);
   });
-};
-
-transform._run = function (code, tree, opts) {
-  var generateUid = util.buildUidGenerator();
-
-  _.each(transform.transformers, function (transformer, name) {
-    var blacklist = opts.blacklist;
-    if (blacklist.length && _.contains(blacklist, name)) return;
-
-    var whitelist = opts.whitelist;
-    if (whitelist.length && !_.contains(whitelist, name)) return;
-
-    transform._runTransformer(transformer, tree, opts, generateUid);
-  });
-
-  var result = util.generate(tree, opts);
-
-  if (opts.sourceMap === "inline") {
-    result.code += "\n" + util.sourceMapToComment(result.map);
-  }
-
-  result.map = result.map || null;
-  result.ast = tree;
-
-  return result;
-};
-
-transform._runTransformer = function (transformer, tree, opts, generateUid) {
-  var build = function (exit) {
-    return function (node, parent) {
-      var fns = transformer[node.type] || transformer.all;
-      if (!fns) return;
-
-      var fn = fns.enter || fns;
-      if (exit) fn = fns.exit;
-      if (!fn || !_.isFunction(fn)) return;
-
-      return fn(node, parent, opts, generateUid);
-    };
-  };
-
-  traverse(tree, {
-    enter: build(),
-    exit:  build(true)
-  });
-};
+}
 
 transform.test = function (task, assert) {
   var actual = task.actual;
@@ -111,12 +46,20 @@ transform.test = function (task, assert) {
 
     _.each(task.sourceMappings, function (mapping, i) {
       var pos = consumer.originalPositionFor(mapping.generated);
-      var msg = "source mapping " + ++i + " - generated: " + mapping.generated.line + ":" + mapping.generated.column;
+      var msg = "source mapping " + i + " - generated: " + mapping.generated.line + ":" + mapping.generated.column;
       assert.equal(pos.line + ":" + pos.column, mapping.original.line + ":" + mapping.original.column, msg);
     });
   }
 };
 
+transform._ensureTransformerNames = function (type, keys) {
+  _.each(keys, function (key) {
+    if (!transform.transformers[key]) {
+      throw new ReferenceError("unknown transformer " + key + " specified in " + type);
+    }
+  });
+};
+
 transform.transformers = {
   modules:                  require("./transformers/modules"),
   computedPropertyNames:    require("./transformers/computed-property-names"),
@@ -130,7 +73,7 @@ transform.transformers = {
   propertyMethodAssignment: require("./transformers/property-method-assignment"),
   defaultParameters:        require("./transformers/default-parameters"),
   generators:               require("./transformers/generators"),
-  blockBinding:             require("./transformers/block-binding"),
+  letScoping:               require("./transformers/let-scoping"),
   restParameters:           require("./transformers/rest-parameters"),
   destructuring:            require("./transformers/destructuring"),
   forOf:                    require("./transformers/for-of"),
diff --git a/lib/6to5/transformers/array-comprehension.js b/lib/6to5/transformers/array-comprehension.js
index f7ba4ba315..e7eb3de107 100644
--- a/lib/6to5/transformers/array-comprehension.js
+++ b/lib/6to5/transformers/array-comprehension.js
@@ -1,6 +1,8 @@
 var util = require("../util");
 var _    = require("lodash");
 
+// TODO: support `arguments` and `this` inside
+
 var single = function (node) {
   var block = node.blocks[0];
 
@@ -15,8 +17,8 @@ var single = function (node) {
   });
 };
 
-var multiple = function (node, generateUid) {
-  var uid = generateUid("arr");
+var multiple = function (node, file) {
+  var uid = file.generateUid("arr");
 
   var container = util.template("array-comprehension-container", {
     KEY: uid
@@ -64,7 +66,7 @@ var multiple = function (node, generateUid) {
   return container;
 };
 
-exports.ComprehensionExpression = function (node, parent, opts, generateUid) {
+exports.ComprehensionExpression = function (node, parent, file) {
   _.each(node.blocks, function (block) {
     if (!block.of) {
       throw util.errorWithNode(block, "for-in array comprehension is not supported");
@@ -74,6 +76,6 @@ exports.ComprehensionExpression = function (node, parent, opts, generateUid) {
   if (node.blocks.length === 1) {
     return single(node);
   } else {
-    return multiple(node, generateUid);
+    return multiple(node, file);
   }
 };
diff --git a/lib/6to5/transformers/classes.js b/lib/6to5/transformers/classes.js
index d358409a29..6f11d8c1f0 100644
--- a/lib/6to5/transformers/classes.js
+++ b/lib/6to5/transformers/classes.js
@@ -3,14 +3,14 @@ var util     = require("../util");
 var b        = require("ast-types").builders;
 var _        = require("lodash");
 
-exports.ClassDeclaration = function (node, parent, opts, generateUid) {
+exports.ClassDeclaration = function (node, parent, file) {
   return b.variableDeclaration("var", [
-    b.variableDeclarator(node.id, buildClass(node, generateUid))
+    b.variableDeclarator(node.id, buildClass(node, file))
   ]);
 };
 
-exports.ClassExpression = function (node, parent, opts, generateUid) {
-  return buildClass(node, generateUid);
+exports.ClassExpression = function (node, parent, file) {
+  return buildClass(node, file);
 };
 
 var getMemberExpressionObject = function (node) {
@@ -20,15 +20,9 @@ var getMemberExpressionObject = function (node) {
   return node;
 };
 
-var buildClass = function (node, generateUid) {
+var buildClass = function (node, file) {
   var superName = node.superClass;
-  var className = node.id;
-
-  var noName = false;
-  if (!className) {
-    className = b.identifier(generateUid("class"));
-    noName = true;
-  }
+  var className = node.id || b.identifier(file.generateUid("class"));
 
   var superClassArgument = node.superClass;
   var superClassCallee   = node.superClass;
@@ -38,7 +32,7 @@ var buildClass = function (node, generateUid) {
       superClassArgument = superClassCallee = getMemberExpressionObject(superName);
     } else if (superName.type !== "Identifier") {
       superClassArgument = superName;
-      superClassCallee = superName = b.identifier(generateUid("ref"));
+      superClassCallee = superName = b.identifier(file.generateUid("ref"));
     }
   }
 
@@ -49,8 +43,8 @@ var buildClass = function (node, generateUid) {
   var block     = container.callee.body;
   var body      = block.body;
 
-  if (noName) {
-    body[0].declarations[0].init.id = null;
+  if (node.id) {
+    body[0].declarations[0].init.id = className;
   }
 
   var returnStatement = body.pop();
@@ -135,10 +129,10 @@ var buildClassBody = function (body, className, superName, node) {
 };
 
 var superIdentifier = function (superName, methodNode, methodName, node, parent) {
-  if (parent.property === node) return;
-
-  // super(); -> ClassName.prototype.MethodName.call(this);
-  if (parent.type === "CallExpression" && parent.callee === node) {
+  if (parent.property === node) {
+    return;
+  } else if (parent.type === "CallExpression" && parent.callee === node) {
+    // super(); -> ClassName.prototype.MethodName.call(this);
     parent.arguments.unshift(b.thisExpression());
 
     if (methodName === "constructor") {
diff --git a/lib/6to5/transformers/computed-property-names.js b/lib/6to5/transformers/computed-property-names.js
index 174c83f2c4..967bbbd5a5 100644
--- a/lib/6to5/transformers/computed-property-names.js
+++ b/lib/6to5/transformers/computed-property-names.js
@@ -3,7 +3,7 @@ var util     = require("../util");
 var b        = require("ast-types").builders;
 var _        = require("lodash");
 
-exports.ObjectExpression = function (node, parent, opts, generateUid) {
+exports.ObjectExpression = function (node, parent, file) {
   var hasComputed = false;
   var hasThis     = false;
 
@@ -25,7 +25,7 @@ exports.ObjectExpression = function (node, parent, opts, generateUid) {
   var templateName = "function-return-obj";
   if (hasThis) templateName += "-this";
 
-  var objId = b.identifier(generateUid("ref"));
+  var objId = b.identifier(file.generateUid("ref"));
 
   var container = util.template(templateName, {
     KEY: objId,
diff --git a/lib/6to5/transformers/destructuring.js b/lib/6to5/transformers/destructuring.js
index eb703d76ea..0dd0f2db4a 100644
--- a/lib/6to5/transformers/destructuring.js
+++ b/lib/6to5/transformers/destructuring.js
@@ -47,9 +47,9 @@ var pushArrayPattern = function (kind, nodes, pattern, parentId) {
   });
 };
 
-var pushPattern = function (kind, nodes, pattern, parentId, generateUid) {
+var pushPattern = function (kind, nodes, pattern, parentId, file) {
   if (parentId.type !== "MemberExpression" && parentId.type !== "Identifier") {
-    var key = generateUid("ref");
+    var key = file.generateUid("ref");
 
     nodes.push(util.template("variable-assign", {
       KEY: key,
@@ -63,14 +63,14 @@ var pushPattern = function (kind, nodes, pattern, parentId, generateUid) {
 };
 
 exports.ForInStatement =
-exports.ForOfStatement = function (node, parent, opts, generateUid) {
+exports.ForOfStatement = function (node, parent, file) {
   var declar = node.left;
   if (declar.type !== "VariableDeclaration") return;
 
   var pattern = declar.declarations[0].id;
   if (!util.isPattern(pattern)) return;
 
-  var key = b.identifier(generateUid("ref"));
+  var key = b.identifier(file.generateUid("ref"));
   node.left = b.variableDeclaration(declar.kind, [
     b.variableDeclarator(key, null)
   ]);
@@ -87,7 +87,7 @@ exports.ForOfStatement = function (node, parent, opts, generateUid) {
 
 exports.ArrowFunctionExpression =
 exports.FunctionDeclaration =
-exports.FunctionExpression = function (node, parent, opts, generateUid) {
+exports.FunctionExpression = function (node, parent, file) {
   var block = node.body;
   var nodes = [];
 
@@ -97,8 +97,8 @@ exports.FunctionExpression = function (node, parent, opts, generateUid) {
     if (!util.isPattern(pattern)) return pattern;
 
     hasDestructuring = true;
-    var parentId = b.identifier(generateUid("ref"));
-    pushPattern("var", nodes, pattern, parentId, generateUid);
+    var parentId = b.identifier(file.generateUid("ref"));
+    pushPattern("var", nodes, pattern, parentId, file);
     return parentId;
   });
 
@@ -107,7 +107,7 @@ exports.FunctionExpression = function (node, parent, opts, generateUid) {
   block.body = nodes.concat(block.body || []);
 };
 
-exports.ExpressionStatement = function (node, parent, opts, generateUid) {
+exports.ExpressionStatement = function (node, parent, file) {
   var expr = node.expression;
   if (expr.type !== "AssignmentExpression") return;
 
@@ -115,7 +115,7 @@ exports.ExpressionStatement = function (node, parent, opts, generateUid) {
 
   var nodes = [];
 
-  var ref = b.identifier(generateUid("ref"));
+  var ref = b.identifier(file.generateUid("ref"));
   nodes.push(b.variableDeclaration("var", [
     b.variableDeclarator(ref, expr.right)
   ]));
@@ -125,7 +125,7 @@ exports.ExpressionStatement = function (node, parent, opts, generateUid) {
   return nodes;
 };
 
-exports.VariableDeclaration = function (node, parent, opts, generateUid) {
+exports.VariableDeclaration = function (node, parent, file) {
   if (parent.type === "ForInStatement") return;
 
   var nodes = [];
@@ -143,7 +143,7 @@ exports.VariableDeclaration = function (node, parent, opts, generateUid) {
     var patternId = declar.init;
     var pattern   = declar.id;
     if (util.isPattern(pattern) && patternId) {
-      pushPattern(node.kind, nodes, pattern, patternId, generateUid);
+      pushPattern(node.kind, nodes, pattern, patternId, file);
     } else {
       nodes.push(buildVariableAssign(node.kind, declar.id, declar.init));
     }
diff --git a/lib/6to5/transformers/for-of.js b/lib/6to5/transformers/for-of.js
index 0e24998be9..77912996a6 100644
--- a/lib/6to5/transformers/for-of.js
+++ b/lib/6to5/transformers/for-of.js
@@ -1,11 +1,11 @@
 var util = require("../util");
 var b    = require("ast-types").builders;
 
-exports.ForOfStatement = function (node, parent, opts, generateUid) {
+exports.ForOfStatement = function (node, parent, file) {
   var left = node.left;
   var declar;
 
-  var stepKey = b.identifier(generateUid("step"));
+  var stepKey = b.identifier(file.generateUid("step"));
   var stepValueId = b.memberExpression(stepKey, b.identifier("value"), false);
 
   if (left.type === "Identifier") {
@@ -19,7 +19,7 @@ exports.ForOfStatement = function (node, parent, opts, generateUid) {
   }
 
   var node2 = util.template("for-of", {
-    ITERATOR_KEY: generateUid("iterator"),
+    ITERATOR_KEY: file.generateUid("iterator"),
     STEP_KEY:     stepKey,
     OBJECT:       node.right
   });
diff --git a/lib/6to5/transformers/property-method-assignment.js b/lib/6to5/transformers/property-method-assignment.js
index a37e2f9f54..ab8543d2b5 100644
--- a/lib/6to5/transformers/property-method-assignment.js
+++ b/lib/6to5/transformers/property-method-assignment.js
@@ -6,7 +6,7 @@ exports.Property = function (node) {
   if (node.method) node.method = false;
 };
 
-exports.ObjectExpression = function (node, parent, opts, generateUid) {
+exports.ObjectExpression = function (node, parent, file) {
   var mutatorMap = {};
 
   node.properties = node.properties.filter(function (prop) {
@@ -20,7 +20,7 @@ exports.ObjectExpression = function (node, parent, opts, generateUid) {
 
   if (_.isEmpty(mutatorMap)) return;
 
-  var objId = b.identifier(generateUid("ref"))
+  var objId = b.identifier(file.generateUid("ref"));
 
   return util.template("object-define-properties-closure", {
     KEY: objId,