From a1adca6b658aaf8de513ba8312693e29428c3e18 Mon Sep 17 00:00:00 2001
From: Sebastian McKenzie <sebmck@gmail.com>
Date: Sun, 19 Oct 2014 12:11:12 +1100
Subject: [PATCH] add support for custom module formatters - #82

---
 bin/6to5/index.js                             |  25 +++--
 lib/6to5/file.js                              |  13 ++-
 lib/6to5/modules/amd.js                       |   0
 lib/6to5/modules/common.js                    |  96 +++++++++++++++++
 lib/6to5/modules/umd.js                       |   0
 lib/6to5/transform.js                         |   4 +
 lib/6to5/transformer.js                       |  24 +++--
 lib/6to5/transformers/modules.js              | 100 ++----------------
 .../exports-default/actual.js                 |   0
 .../exports-default/expected.js               |   0
 .../exports-from/actual.js                    |   0
 .../exports-from/expected.js                  |   0
 .../exports-named/actual.js                   |   0
 .../exports-named/expected.js                 |   0
 .../exports-variable/actual.js                |   0
 .../exports-variable/expected.js              |   0
 .../hoist-function-exports/actual.js          |   0
 .../hoist-function-exports/expected.js        |   0
 .../imports-default/actual.js                 |   0
 .../imports-default/expected.js               |   0
 .../imports-glob/actual.js                    |   0
 .../imports-glob/expected.js                  |   0
 .../imports-mixing/actual.js                  |   0
 .../imports-mixing/expected.js                |   0
 .../imports-named/actual.js                   |   0
 .../imports-named/expected.js                 |   0
 .../imports/actual.js                         |   0
 .../imports/expected.js                       |   0
 .../syntax/modules-common/options.json        |   3 +
 .../overview/actual.js                        |   0
 .../overview/expected.js                      |   0
 31 files changed, 156 insertions(+), 109 deletions(-)
 create mode 100644 lib/6to5/modules/amd.js
 create mode 100644 lib/6to5/modules/common.js
 create mode 100644 lib/6to5/modules/umd.js
 rename test/fixtures/syntax/{modules => modules-common}/exports-default/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/exports-default/expected.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/exports-from/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/exports-from/expected.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/exports-named/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/exports-named/expected.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/exports-variable/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/exports-variable/expected.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/hoist-function-exports/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/hoist-function-exports/expected.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports-default/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports-default/expected.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports-glob/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports-glob/expected.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports-mixing/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports-mixing/expected.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports-named/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports-named/expected.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/imports/expected.js (100%)
 create mode 100644 test/fixtures/syntax/modules-common/options.json
 rename test/fixtures/syntax/{modules => modules-common}/overview/actual.js (100%)
 rename test/fixtures/syntax/{modules => modules-common}/overview/expected.js (100%)

diff --git a/bin/6to5/index.js b/bin/6to5/index.js
index 0c3c4c3854..5500ff96fd 100755
--- a/bin/6to5/index.js
+++ b/bin/6to5/index.js
@@ -16,19 +16,27 @@ commander.option("-s, --source-maps", "Save source map alongside the compiled co
 commander.option("-f, --filename [filename]", "Filename to use when reading from stdin - this will be used in source-maps, errors etc [stdin]", "stdin");
 commander.option("-w, --watch", "Recompile files on changes");
 
+commander.option("-m, --modules [modules]", "Module formatter type to use [common]", "common");
 commander.option("-w, --whitelist [whitelist]", "Whitelist of transformers to ONLY use", util2.list);
 commander.option("-b, --blacklist [blacklist]", "Blacklist of transformers to NOT use", util2.list);
 commander.option("-o, --out-file [out]", "Compile all input files into a single file");
 commander.option("-d, --out-dir [out]", "Compile an input directory of modules into an output directory");
 
 commander.on("--help", function(){
-  console.log("  Transformers:");
-  console.log();
-  _.each(_.keys(transform.transformers).sort(), function (key) {
-    if (key[0] === "_") return;
-    console.log("  - " + key);
-  });
-  console.log();
+  var outKeys = function (title, obj) {
+    console.log("  " + title + ":");
+    console.log();
+
+    _.each(_.keys(obj).sort(), function (key) {
+      if (key[0] === "_") return;
+      console.log("    - " + key);
+    });
+
+    console.log();
+  };
+
+  outKeys("Transformers", transform.transformers);
+  outKeys("Module formatters", transform.moduleFormatters);
 });
 
 var pkg = require("../../package.json");
@@ -83,7 +91,8 @@ exports.opts = {
   sourceMapName: commander.outFile,
   blacklist:     commander.blacklist,
   whitelist:     commander.whitelist,
-  sourceMap:     commander.sourceMaps || commander.sourceMapsInline
+  sourceMap:     commander.sourceMaps || commander.sourceMapsInline,
+  modules:       commander.modules
 };
 
 var fn;
diff --git a/lib/6to5/file.js b/lib/6to5/file.js
index b530a20833..0611abd28a 100644
--- a/lib/6to5/file.js
+++ b/lib/6to5/file.js
@@ -9,9 +9,11 @@ var b         = require("recast").types.builders;
 var _         = require("lodash");
 
 function File(opts) {
+  this.opts            = File.normaliseOptions(opts);
+  this.moduleFormatter = this.getModuleFormatter(opts.modules);
+
   this.declarations = {};
   this.uids         = {};
-  this.opts         = File.normaliseOptions(opts);
   this.ast          = {};
 }
 
@@ -22,7 +24,8 @@ File.normaliseOptions = function (opts) {
     blacklist: [],
     whitelist: [],
     sourceMap: false,
-    filename:  "unknown"
+    filename:  "unknown",
+    modules:   "common"
   });
 
   _.defaults(opts, {
@@ -36,6 +39,12 @@ File.normaliseOptions = function (opts) {
   return opts;
 };
 
+File.prototype.getModuleFormatter = function (type) {
+  var ModuleLoader = transform.moduleFormatters[type];
+  if (!ModuleLoader) throw new ReferenceError("unknown module formatter type " + type);
+  return new ModuleLoader(this);
+};
+
 File.prototype.parseShebang = function (code) {
   var shebangMatch = code.match(SHEBANG_REGEX);
   if (shebangMatch) {
diff --git a/lib/6to5/modules/amd.js b/lib/6to5/modules/amd.js
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/lib/6to5/modules/common.js b/lib/6to5/modules/common.js
new file mode 100644
index 0000000000..a860eaf0cd
--- /dev/null
+++ b/lib/6to5/modules/common.js
@@ -0,0 +1,96 @@
+module.exports = CommonJSModuleFormatter;
+
+var util = require("../util");
+var b    = require("recast").types.builders;
+
+var getSpecifierName = function (specifier) {
+  return specifier.name || specifier.id;
+};
+
+function CommonJSModuleFormatter(file) {
+  this.file = file;
+}
+
+CommonJSModuleFormatter.prototype.import = function (node, nodes) {
+  // import "foo";
+  nodes.push(util.template("require", {
+    MODULE_NAME: node.source.raw
+  }, true));
+};
+
+CommonJSModuleFormatter.prototype.importSpecifier = function (specifier, node, nodes) {
+  var variableName = getSpecifierName(specifier);
+  var key = specifier.id.name;
+
+  // import foo from "foo";
+  if (specifier.type === "ImportDefaultSpecifier") {
+    key = b.identifier("default");
+  }
+
+  var templateName = "require-assign";
+
+  // import * as bar from "foo";
+  if (specifier.type !== "ImportNamespaceSpecifier") templateName += "-key";
+
+  nodes.push(util.template(templateName, {
+    VARIABLE_NAME: variableName.name,
+    MODULE_NAME:   node.source.raw,
+    KEY:           key
+  }));
+};
+
+CommonJSModuleFormatter.prototype.export = function (node, nodes) {
+  var declar = node.declaration;
+
+  if (node.default) {
+    util.ensureExpressionType(declar);
+
+    nodes.push(util.template("exports-default", {
+      VALUE: declar
+    }, true));
+  } else {
+    var id = declar.id;
+    if (declar.type === "VariableDeclaration") {
+      id = declar.declarations[0].id;
+    }
+
+    var assign = util.template("exports-assign", {
+      VALUE: id,
+      KEY:   id
+    }, true);
+
+    nodes.push(declar);
+
+    if (declar.type === "FunctionDeclaration") {
+      assign._blockHoist = true;
+    }
+
+    nodes.push(assign);
+  }
+};
+
+CommonJSModuleFormatter.prototype.exportSpecifier = function (specifier, node, nodes) {
+  var variableName = getSpecifierName(specifier);
+
+  if (node.source) {
+    if (specifier.type === "ExportBatchSpecifier") {
+      // export * from "foo";
+      nodes.push(util.template("exports-wildcard", {
+        MODULE_NAME: node.source.raw
+      }, true));
+    } else {
+      // export { foo } from "test";
+      nodes.push(util.template("exports-require-assign-key", {
+        VARIABLE_NAME: variableName.name,
+        MODULE_NAME:   node.source.raw,
+        KEY:           specifier.id
+      }, true));
+    }
+  } else {
+    // export { foo };
+    nodes.push(util.template("exports-assign", {
+      VALUE: specifier.id,
+      KEY:   variableName
+    }, true));
+  }
+};
diff --git a/lib/6to5/modules/umd.js b/lib/6to5/modules/umd.js
new file mode 100644
index 0000000000..e69de29bb2
diff --git a/lib/6to5/transform.js b/lib/6to5/transform.js
index 65da474122..a85dd1f37d 100644
--- a/lib/6to5/transform.js
+++ b/lib/6to5/transform.js
@@ -106,6 +106,10 @@ transform.transformers = {
   useStrict:                require("./transformers/use-strict")
 };
 
+transform.moduleFormatters = {
+  common: require("./modules/common")
+};
+
 _.each(transform.transformers, function (transformer, key) {
   transform.transformers[key] = new Transformer(key, transformer);
 });
diff --git a/lib/6to5/transformer.js b/lib/6to5/transformer.js
index ddd248c951..801c84b545 100644
--- a/lib/6to5/transformer.js
+++ b/lib/6to5/transformer.js
@@ -11,13 +11,13 @@ function Transformer(key, transformer) {
 Transformer.normalise = function (transformer) {
   if (_.isFunction(transformer)) {
     transformer = { ast: transformer };
-  } else {
-    _.each(transformer, function (fns, type) {
-      if (type === "ast") return;
-      if (_.isFunction(fns)) fns = { enter: fns };
-      transformer[type] = fns;
-    });
   }
+
+  _.each(transformer, function (fns, type) {
+    if (_.isFunction(fns)) fns = { enter: fns };
+    transformer[type] = fns;
+  });
+
   return transformer;
 };
 
@@ -27,8 +27,8 @@ Transformer.prototype.transform = function (file) {
   var transformer = this.transformer;
   var ast         = file.ast;
 
-  if (transformer.ast) {
-    transformer.ast(ast, file);
+  if (transformer.ast && transformer.ast.enter) {
+    transformer.ast.enter(ast, file);
   }
 
   var build = function (exit) {
@@ -57,6 +57,14 @@ Transformer.prototype.transform = function (file) {
     enter: build(),
     exit:  build(true)
   });
+
+  if (transformer.ast && transformer.ast.exit) {
+    transformer.ast.exit(ast, file);
+  }
+
+  if (file.moduleFormatter.transform) {
+    file.moduleFormatter.transform(ast);
+  }
 };
 
 Transformer.prototype.canRun = function (file) {
diff --git a/lib/6to5/transformers/modules.js b/lib/6to5/transformers/modules.js
index e0af365ad7..c93aab04bc 100644
--- a/lib/6to5/transformers/modules.js
+++ b/lib/6to5/transformers/modules.js
@@ -1,110 +1,28 @@
-var util = require("../util");
-var b    = require("recast").types.builders;
-var _    = require("lodash");
+var _ = require("lodash");
 
-exports.ImportDeclaration = function (node) {
+exports.ImportDeclaration = function (node, parent, file) {
   var nodes = [];
 
   if (node.specifiers.length) {
     _.each(node.specifiers, function (specifier) {
-      var variableName = getSpecifierName(specifier);
-      var key          = specifier.id.name;
-
-      // import foo from "foo";
-      if (specifier.type === "ImportDefaultSpecifier") {
-        key = b.identifier("default");
-      }
-
-      var templateName = "require-assign";
-
-      // import * as bar from "foo";
-      if (specifier.type !== "ImportNamespaceSpecifier") templateName += "-key";
-
-      nodes.push(util.template(templateName, {
-        VARIABLE_NAME: variableName.name,
-        MODULE_NAME:   node.source.raw,
-        KEY:           key
-      }));
+      file.moduleFormatter.importSpecifier(specifier, node, nodes);
     });
   } else {
-    // import "foo";
-    nodes.push(util.template("require", {
-      MODULE_NAME: node.source.raw
-    }, true));
+    file.moduleFormatter.import(node, nodes);
   }
 
   return nodes;
 };
 
-var pushExportSpecifiers = function (node, nodes) {
-  _.each(node.specifiers, function (specifier) {
-    var variableName = getSpecifierName(specifier);
-
-    if (node.source) {
-      if (specifier.type === "ExportBatchSpecifier") {
-        // export * from "foo";
-        nodes.push(util.template("exports-wildcard", {
-          MODULE_NAME: node.source.raw
-        }, true));
-      } else {
-        // export { foo } from "test";
-        nodes.push(util.template("exports-require-assign-key", {
-          VARIABLE_NAME: variableName.name,
-          MODULE_NAME:   node.source.raw,
-          KEY:           specifier.id
-        }, true));
-      }
-    } else {
-      // export { foo };
-      nodes.push(util.template("exports-assign", {
-        VALUE: specifier.id,
-        KEY:   variableName
-      }, true));
-    }
-  });
-};
-
-var getSpecifierName = function (specifier) {
-  return specifier.name || specifier.id;
-};
-
-var pushExportDeclaration = function (node, parent, nodes) {
-  var declar = node.declaration;
-
-  if (node.default) {
-    util.ensureExpressionType(declar);
-
-    nodes.push(util.template("exports-default", {
-      VALUE: declar
-    }, true));
-  } else {
-    var id = declar.id;
-    if (declar.type === "VariableDeclaration") {
-      id = declar.declarations[0].id;
-    }
-
-    var assign = util.template("exports-assign", {
-      VALUE: id,
-      KEY:   id
-    }, true);
-
-    nodes.push(declar);
-
-    if (declar.type === "FunctionDeclaration") {
-      assign._blockHoist = true;
-    }
-
-    nodes.push(assign);
-  }
-};
-
-exports.ExportDeclaration = function (node, parent) {
+exports.ExportDeclaration = function (node, parent, file) {
   var nodes = [];
 
   if (node.declaration) {
-    pushExportDeclaration(node, parent, nodes);
+    file.moduleFormatter.export(node, nodes);
   } else {
-    pushExportSpecifiers(node, nodes);
+    _.each(node.specifiers, function (specifier) {
+      file.moduleFormatter.exportSpecifier(specifier, node, nodes);
+    });
   }
 
   return nodes;
diff --git a/test/fixtures/syntax/modules/exports-default/actual.js b/test/fixtures/syntax/modules-common/exports-default/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/exports-default/actual.js
rename to test/fixtures/syntax/modules-common/exports-default/actual.js
diff --git a/test/fixtures/syntax/modules/exports-default/expected.js b/test/fixtures/syntax/modules-common/exports-default/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/exports-default/expected.js
rename to test/fixtures/syntax/modules-common/exports-default/expected.js
diff --git a/test/fixtures/syntax/modules/exports-from/actual.js b/test/fixtures/syntax/modules-common/exports-from/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/exports-from/actual.js
rename to test/fixtures/syntax/modules-common/exports-from/actual.js
diff --git a/test/fixtures/syntax/modules/exports-from/expected.js b/test/fixtures/syntax/modules-common/exports-from/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/exports-from/expected.js
rename to test/fixtures/syntax/modules-common/exports-from/expected.js
diff --git a/test/fixtures/syntax/modules/exports-named/actual.js b/test/fixtures/syntax/modules-common/exports-named/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/exports-named/actual.js
rename to test/fixtures/syntax/modules-common/exports-named/actual.js
diff --git a/test/fixtures/syntax/modules/exports-named/expected.js b/test/fixtures/syntax/modules-common/exports-named/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/exports-named/expected.js
rename to test/fixtures/syntax/modules-common/exports-named/expected.js
diff --git a/test/fixtures/syntax/modules/exports-variable/actual.js b/test/fixtures/syntax/modules-common/exports-variable/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/exports-variable/actual.js
rename to test/fixtures/syntax/modules-common/exports-variable/actual.js
diff --git a/test/fixtures/syntax/modules/exports-variable/expected.js b/test/fixtures/syntax/modules-common/exports-variable/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/exports-variable/expected.js
rename to test/fixtures/syntax/modules-common/exports-variable/expected.js
diff --git a/test/fixtures/syntax/modules/hoist-function-exports/actual.js b/test/fixtures/syntax/modules-common/hoist-function-exports/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/hoist-function-exports/actual.js
rename to test/fixtures/syntax/modules-common/hoist-function-exports/actual.js
diff --git a/test/fixtures/syntax/modules/hoist-function-exports/expected.js b/test/fixtures/syntax/modules-common/hoist-function-exports/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/hoist-function-exports/expected.js
rename to test/fixtures/syntax/modules-common/hoist-function-exports/expected.js
diff --git a/test/fixtures/syntax/modules/imports-default/actual.js b/test/fixtures/syntax/modules-common/imports-default/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports-default/actual.js
rename to test/fixtures/syntax/modules-common/imports-default/actual.js
diff --git a/test/fixtures/syntax/modules/imports-default/expected.js b/test/fixtures/syntax/modules-common/imports-default/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports-default/expected.js
rename to test/fixtures/syntax/modules-common/imports-default/expected.js
diff --git a/test/fixtures/syntax/modules/imports-glob/actual.js b/test/fixtures/syntax/modules-common/imports-glob/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports-glob/actual.js
rename to test/fixtures/syntax/modules-common/imports-glob/actual.js
diff --git a/test/fixtures/syntax/modules/imports-glob/expected.js b/test/fixtures/syntax/modules-common/imports-glob/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports-glob/expected.js
rename to test/fixtures/syntax/modules-common/imports-glob/expected.js
diff --git a/test/fixtures/syntax/modules/imports-mixing/actual.js b/test/fixtures/syntax/modules-common/imports-mixing/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports-mixing/actual.js
rename to test/fixtures/syntax/modules-common/imports-mixing/actual.js
diff --git a/test/fixtures/syntax/modules/imports-mixing/expected.js b/test/fixtures/syntax/modules-common/imports-mixing/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports-mixing/expected.js
rename to test/fixtures/syntax/modules-common/imports-mixing/expected.js
diff --git a/test/fixtures/syntax/modules/imports-named/actual.js b/test/fixtures/syntax/modules-common/imports-named/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports-named/actual.js
rename to test/fixtures/syntax/modules-common/imports-named/actual.js
diff --git a/test/fixtures/syntax/modules/imports-named/expected.js b/test/fixtures/syntax/modules-common/imports-named/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports-named/expected.js
rename to test/fixtures/syntax/modules-common/imports-named/expected.js
diff --git a/test/fixtures/syntax/modules/imports/actual.js b/test/fixtures/syntax/modules-common/imports/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports/actual.js
rename to test/fixtures/syntax/modules-common/imports/actual.js
diff --git a/test/fixtures/syntax/modules/imports/expected.js b/test/fixtures/syntax/modules-common/imports/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/imports/expected.js
rename to test/fixtures/syntax/modules-common/imports/expected.js
diff --git a/test/fixtures/syntax/modules-common/options.json b/test/fixtures/syntax/modules-common/options.json
new file mode 100644
index 0000000000..878edbcd5d
--- /dev/null
+++ b/test/fixtures/syntax/modules-common/options.json
@@ -0,0 +1,3 @@
+{
+  "modules": "common"
+}
diff --git a/test/fixtures/syntax/modules/overview/actual.js b/test/fixtures/syntax/modules-common/overview/actual.js
similarity index 100%
rename from test/fixtures/syntax/modules/overview/actual.js
rename to test/fixtures/syntax/modules-common/overview/actual.js
diff --git a/test/fixtures/syntax/modules/overview/expected.js b/test/fixtures/syntax/modules-common/overview/expected.js
similarity index 100%
rename from test/fixtures/syntax/modules/overview/expected.js
rename to test/fixtures/syntax/modules-common/overview/expected.js