fix(transform-eventual-send): split out rewriter.js to fix cycle

The old default export (used for SES1's evaluator transforms array) is now in
a separate file:

```js
import makeEventualSendTransformer from '@agoric/transform-eventual-send/src/rewriter';
```

The new smaller `makeTransform` function (used by bundle-source) is a named
export of the package:

```js
import { makeTransform } from '@agoric/transform-eventual-send';
```

This breaks the dependency cycle between bundle-source (which needs
`makeTransform`) and `makeEventualSendTransformer` (which needs a file
created at `yarn build` time by running bundle-source).

packages/default-evaluate-options/src/index.js

@@ -1,6 +1,6 @@
 import { parse } from '@agoric/babel-parser';
 import generate from '@babel/generator';
-import makeEventualSendTransformer from '@agoric/transform-eventual-send';
+import makeEventualSendTransformer from '@agoric/transform-eventual-send/src/rewriter';
 
 export default function makeDefaultEvaluateOptions() {
   const shims = [];

packages/transform-eventual-send/src/index.js

@@ -1,5 +1,3 @@
-import eventualSendBundle from './bundles/eventual-send';
-
 export function makeTransform(parser, generate) {
   function transform(source) {
     // Parse with eventualSend enabled, rewriting to
@@ -17,87 +15,3 @@ export function makeTransform(parser, generate) {
   }
   return transform;
 }
-
-// this transformer is meant for the SES1 evaluation format, with mutable
-// endowments and stuff
-
-function makeEventualSendTransformer(parser, generate) {
-  const transformer = makeTransform(parser, generate);
-  let HandledPromise;
-  let evaluateProgram;
-  let myRequire;
-  let recursive = false;
-  const transform = {
-    closeOverSES(s) {
-      // FIXME: This will go away when we can bundle an @agoric/harden that understands SES.
-      myRequire = name => {
-        if (name === '@agoric/harden') {
-          return s.global.SES.harden;
-        }
-        throw Error(`Unrecognized require ${name}`);
-      };
-      // FIXME: This should be replaced with ss.evaluateProgram support in SES.
-      evaluateProgram = (src, endowments = {}) => s.evaluate(src, endowments);
-    },
-    rewrite(ss) {
-      const source = ss.src;
-      const endowments = ss.endowments || {};
-      if (!recursive && !('HandledPromise' in endowments)) {
-        // Use a getter to postpone initialization.
-        Object.defineProperty(endowments, 'HandledPromise', {
-          get() {
-            if (!HandledPromise) {
-              // Get a HandledPromise endowment for the evaluator.
-              // It will be hardened in the evaluator's context.
-              const nestedEvaluate = src =>
-                (evaluateProgram || ss.evaluateProgram)(src, {
-                  require: myRequire || require,
-                  nestedEvaluate,
-                });
-              const {
-                source: evSendSrc,
-                moduleFormat,
-                sourceMap,
-              } = eventualSendBundle;
-              if (
-                moduleFormat === 'getExport' ||
-                moduleFormat === 'nestedEvaluate'
-              ) {
-                recursive = true;
-                try {
-                  const ns = nestedEvaluate(`(${evSendSrc}\n${sourceMap})`)();
-                  HandledPromise = ns.HandledPromise;
-                } finally {
-                  recursive = false;
-                }
-              } else {
-                throw Error(`Unrecognized moduleFormat ${moduleFormat}`);
-              }
-            }
-            return HandledPromise;
-          },
-        });
-      }
-
-      const maybeSource = transformer(source);
-
-      // Work around Babel appending semicolons.
-      const actualSource =
-        ss.sourceType === 'expression' &&
-        maybeSource.endsWith(';') &&
-        !source.endsWith(';')
-          ? maybeSource.slice(0, -1)
-          : maybeSource;
-
-      return {
-        ...ss,
-        endowments,
-        src: actualSource,
-      };
-    },
-  };
-
-  return [transform];
-}
-
-export default makeEventualSendTransformer;

packages/transform-eventual-send/src/rewriter.js

@@ -0,0 +1,86 @@
+import { makeTransform } from './index';
+import eventualSendBundle from './bundles/eventual-send';
+
+// this transformer is meant for the SES1 evaluation format, with mutable
+// endowments and stuff
+
+function makeEventualSendTransformer(parser, generate) {
+  const transformer = makeTransform(parser, generate);
+  let HandledPromise;
+  let evaluateProgram;
+  let myRequire;
+  let recursive = false;
+  const transform = {
+    closeOverSES(s) {
+      // FIXME: This will go away when we can bundle an @agoric/harden that understands SES.
+      myRequire = name => {
+        if (name === '@agoric/harden') {
+          return s.global.SES.harden;
+        }
+        throw Error(`Unrecognized require ${name}`);
+      };
+      // FIXME: This should be replaced with ss.evaluateProgram support in SES.
+      evaluateProgram = (src, endowments = {}) => s.evaluate(src, endowments);
+    },
+    rewrite(ss) {
+      const source = ss.src;
+      const endowments = ss.endowments || {};
+      if (!recursive && !('HandledPromise' in endowments)) {
+        // Use a getter to postpone initialization.
+        Object.defineProperty(endowments, 'HandledPromise', {
+          get() {
+            if (!HandledPromise) {
+              // Get a HandledPromise endowment for the evaluator.
+              // It will be hardened in the evaluator's context.
+              const nestedEvaluate = src =>
+                (evaluateProgram || ss.evaluateProgram)(src, {
+                  require: myRequire || require,
+                  nestedEvaluate,
+                });
+              const {
+                source: evSendSrc,
+                moduleFormat,
+                sourceMap,
+              } = eventualSendBundle;
+              if (
+                moduleFormat === 'getExport' ||
+                moduleFormat === 'nestedEvaluate'
+              ) {
+                recursive = true;
+                try {
+                  const ns = nestedEvaluate(`(${evSendSrc}\n${sourceMap})`)();
+                  HandledPromise = ns.HandledPromise;
+                } finally {
+                  recursive = false;
+                }
+              } else {
+                throw Error(`Unrecognized moduleFormat ${moduleFormat}`);
+              }
+            }
+            return HandledPromise;
+          },
+        });
+      }
+
+      const maybeSource = transformer(source);
+
+      // Work around Babel appending semicolons.
+      const actualSource =
+        ss.sourceType === 'expression' &&
+        maybeSource.endsWith(';') &&
+        !source.endsWith(';')
+          ? maybeSource.slice(0, -1)
+          : maybeSource;
+
+      return {
+        ...ss,
+        endowments,
+        src: actualSource,
+      };
+    },
+  };
+
+  return [transform];
+}
+
+export default makeEventualSendTransformer;

packages/transform-eventual-send/test/ses-test.js

@@ -10,7 +10,7 @@ import eventualSend from '@agoric/acorn-eventual-send';
 import * as acorn from 'acorn';
 import * as astring from 'astring';
 
-import makeEventualSendTransformer from '../src';
+import makeEventualSendTransformer from '../src/rewriter';
 
 // FIXME: This should be unnecessary when SES has support
 // for passing `evaluateProgram` through to the rewriter state.