WIP - add extractor, generate snippet_data

node_modules/babel-preset-fbjs/plugins/dev-expression.js

@@ -0,0 +1,129 @@
+/**
+ * Copyright (c) 2013-present, Facebook, Inc.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+'use strict';
+
+module.exports = function(babel) {
+  var t = babel.types;
+
+  var SEEN_SYMBOL = Symbol();
+
+  var DEV_EXPRESSION = t.binaryExpression(
+    '!==',
+    t.memberExpression(
+      t.memberExpression(
+        t.identifier('process'),
+        t.identifier('env'),
+        false
+      ),
+      t.identifier('NODE_ENV'),
+      false
+    ),
+    t.stringLiteral('production')
+  );
+
+  return {
+    visitor: {
+      Identifier: {
+        enter: function(path) {
+          // Do nothing when testing
+          if (process.env.NODE_ENV === 'test') {
+            return;
+          }
+          // replace __DEV__ with process.env.NODE_ENV !== 'production'
+          if (path.isIdentifier({name: '__DEV__'})) {
+            path.replaceWith(DEV_EXPRESSION);
+          }
+        },
+      },
+      CallExpression: {
+        exit: function(path) {
+          var node = path.node;
+          // Do nothing when testing
+          if (process.env.NODE_ENV === 'test') {
+            return;
+          }
+          // Ignore if it's already been processed
+          if (node[SEEN_SYMBOL]) {
+            return;
+          }
+          if (path.get('callee').isIdentifier({name: 'invariant'})) {
+            // Turns this code:
+            //
+            // invariant(condition, argument, argument);
+            //
+            // into this:
+            //
+            // if (!condition) {
+            //   if ("production" !== process.env.NODE_ENV) {
+            //     invariant(false, argument, argument);
+            //   } else {
+            //     invariant(false);
+            //   }
+            // }
+            //
+            // Specifically this does 2 things:
+            // 1. Checks the condition first, preventing an extra function call.
+            // 2. Adds an environment check so that verbose error messages aren't
+            //    shipped to production.
+            // The generated code is longer than the original code but will dead
+            // code removal in a minifier will strip that out.
+            var condition = node.arguments[0];
+            var devInvariant = t.callExpression(
+              node.callee,
+              [t.booleanLiteral(false)].concat(node.arguments.slice(1))
+            );
+            devInvariant[SEEN_SYMBOL] = true;
+            var prodInvariant = t.callExpression(
+              node.callee,
+              [t.booleanLiteral(false)]
+            );
+            prodInvariant[SEEN_SYMBOL] = true;
+            path.replaceWith(t.ifStatement(
+              t.unaryExpression('!', condition),
+              t.blockStatement([
+                t.ifStatement(
+                  DEV_EXPRESSION,
+                  t.blockStatement([
+                    t.expressionStatement(devInvariant),
+                  ]),
+                  t.blockStatement([
+                    t.expressionStatement(prodInvariant),
+                  ])
+                ),
+              ])
+            ));
+          } else if (path.get('callee').isIdentifier({name: 'warning'})) {
+            // Turns this code:
+            //
+            // warning(condition, argument, argument);
+            //
+            // into this:
+            //
+            // if ("production" !== process.env.NODE_ENV) {
+            //   warning(condition, argument, argument);
+            // }
+            //
+            // The goal is to strip out warning calls entirely in production. We
+            // don't need the same optimizations for conditions that we use for
+            // invariant because we don't care about an extra call in __DEV__
+
+            node[SEEN_SYMBOL] = true;
+            path.replaceWith(t.ifStatement(
+              DEV_EXPRESSION,
+              t.blockStatement([
+                t.expressionStatement(
+                  node
+                ),
+              ])
+            ));
+          }
+        },
+      },
+    },
+  };
+};