Transform for the smart pipeline operator proposal (#9179)

packages/babel-plugin-proposal-pipeline-operator/src/index.js

@@ -1,64 +1,19 @@
 import { declare } from "@babel/helper-plugin-utils";
 import syntaxPipelineOperator from "@babel/plugin-syntax-pipeline-operator";
-import { types as t } from "@babel/core";
+import minimalVisitor from "./minimalVisitor";
+import smartVisitor from "./smartVisitor";
 
-export default declare(api => {
+const visitorsPerProposal = {
+  minimal: minimalVisitor,
+  smart: smartVisitor,
+};
+
+export default declare((api, options) => {
   api.assertVersion(7);
 
   return {
     name: "proposal-pipeline-operator",
     inherits: syntaxPipelineOperator,
-
+    visitor: visitorsPerProposal[options.proposal],
-    visitor: {
-      BinaryExpression(path) {
-        const { scope } = path;
-        const { node } = path;
-        const { operator, left } = node;
-        let { right } = node;
-        if (operator !== "|>") return;
-
-        let optimizeArrow =
-          t.isArrowFunctionExpression(right) &&
-          t.isExpression(right.body) &&
-          !right.async &&
-          !right.generator;
-        let param;
-
-        if (optimizeArrow) {
-          const { params } = right;
-          if (params.length === 1 && t.isIdentifier(params[0])) {
-            param = params[0];
-          } else if (params.length > 0) {
-            optimizeArrow = false;
-          }
-        } else if (t.isIdentifier(right, { name: "eval" })) {
-          right = t.sequenceExpression([t.numericLiteral(0), right]);
-        }
-
-        if (optimizeArrow && !param) {
-          // Arrow function with 0 arguments
-          path.replaceWith(t.sequenceExpression([left, right.body]));
-          return;
-        }
-
-        const placeholder = scope.generateUidIdentifierBasedOnNode(
-          param || left,
-        );
-        scope.push({ id: placeholder });
-        if (param) {
-          path.get("right").scope.rename(param.name, placeholder.name);
-        }
-
-        const call = optimizeArrow
-          ? right.body
-          : t.callExpression(right, [t.cloneNode(placeholder)]);
-        path.replaceWith(
-          t.sequenceExpression([
-            t.assignmentExpression("=", t.cloneNode(placeholder), left),
-            call,
-          ]),
-        );
-      },
-    },
   };
 });

packages/babel-plugin-proposal-pipeline-operator/src/minimalVisitor.js

@@ -0,0 +1,55 @@
+import { types as t } from "@babel/core";
+
+const minimalVisitor = {
+  BinaryExpression: {
+    exit(path) {
+      const { scope } = path;
+      const { node } = path;
+      const { operator, left } = node;
+      let { right } = node;
+      if (operator !== "|>") return;
+
+      let optimizeArrow =
+        t.isArrowFunctionExpression(right) &&
+        t.isExpression(right.body) &&
+        !right.async &&
+        !right.generator;
+      let param;
+
+      if (optimizeArrow) {
+        const { params } = right;
+        if (params.length === 1 && t.isIdentifier(params[0])) {
+          param = params[0];
+        } else if (params.length > 0) {
+          optimizeArrow = false;
+        }
+      } else if (t.isIdentifier(right, { name: "eval" })) {
+        right = t.sequenceExpression([t.numericLiteral(0), right]);
+      }
+
+      if (optimizeArrow && !param) {
+        // Arrow function with 0 arguments
+        path.replaceWith(t.sequenceExpression([left, right.body]));
+        return;
+      }
+
+      const placeholder = scope.generateUidIdentifierBasedOnNode(param || left);
+      scope.push({ id: placeholder });
+      if (param) {
+        path.get("right").scope.rename(param.name, placeholder.name);
+      }
+
+      const call = optimizeArrow
+        ? right.body
+        : t.callExpression(right, [t.cloneNode(placeholder)]);
+      path.replaceWith(
+        t.sequenceExpression([
+          t.assignmentExpression("=", t.cloneNode(placeholder), left),
+          call,
+        ]),
+      );
+    },
+  },
+};
+
+export default minimalVisitor;

packages/babel-plugin-proposal-pipeline-operator/src/smartVisitor.js

@@ -0,0 +1,42 @@
+import { types as t } from "@babel/core";
+import minimalVisitor from "./minimalVisitor";
+
+const updateTopicReferenceVisitor = {
+  PipelinePrimaryTopicReference(path) {
+    path.replaceWith(this.topicId);
+  },
+  AwaitExpression(path) {
+    throw path.buildCodeFrameError(
+      "await is not supported inside pipeline expressions yet",
+    );
+  },
+  YieldExpression(path) {
+    throw path.buildCodeFrameError(
+      "yield is not supported inside pipeline expressions yet",
+    );
+  },
+  PipelineTopicExpression(path) {
+    path.skip();
+  },
+};
+
+const smartVisitor = {
+  ...minimalVisitor,
+  PipelineTopicExpression(path) {
+    const topicId = path.scope.generateUidIdentifier("topic");
+
+    path.traverse(updateTopicReferenceVisitor, { topicId });
+
+    const arrowFunctionExpression = t.arrowFunctionExpression(
+      [topicId],
+      path.node.expression,
+    );
+
+    path.replaceWith(arrowFunctionExpression);
+  },
+  PipelineBareFunction(path) {
+    path.replaceWith(path.node.callee);
+  },
+};
+
+export default smartVisitor;

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/minimal/arrow-functions/output.js

@@ -1,6 +1,6 @@
-var _sum, _ref, _ref2;
+var _ref, _ref2, _sum;
 
-var result = (_sum = (_ref = (_ref2 = [5, 10], _ref2.map(x => x * 2)), _ref.reduce((a, b) => a + b)), _sum + 1);
+var result = (_sum = (_ref2 = (_ref = [5, 10], _ref.map(x => x * 2)), _ref2.reduce((a, b) => a + b)), _sum + 1);
 expect(result).toBe(31);
 
 var inc = x => x + 1;
@@ -8,7 +8,7 @@ var inc = x => x + 1;
 var double = x => x * 2;
 
 var result2 = [4, 9].map(x => {
-  var _ref3, _x;
+  var _x, _ref3;
 
   return _ref3 = (_x = x, inc(_x)), double(_ref3);
 });

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/minimal/async-arrow/output.js

@@ -1,4 +1,4 @@
-var _ref, _;
+var _, _ref;
 
 function then(fn) {
   return async value => {

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/minimal/chaining/output.js

@@ -1,4 +1,4 @@
-var _ref, _;
+var _, _ref;
 
 var inc = x => x + 1;
 

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/minimal/deoptimize-multi-param-arrow/output.js

@@ -1,4 +1,4 @@
-var _ref, _a;
+var _a, _ref;
 
 var a = 1,
     b = 2,

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/minimal/precedence/output.js

@@ -1,4 +1,4 @@
-var _ref, _ref2, _;
+var _ref, _, _ref2;
 
 var inc = x => x + 1;
 

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/await/input.js

@@ -0,0 +1,5 @@
+async function myFunction() {
+  const value = -5.9
+  |> abs
+  |> await Math.floor(#);
+}

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/await/options.json

@@ -0,0 +1,6 @@
+{
+  "throws": "await is not supported inside pipeline expressions yet",
+  "plugins": [
+    ["proposal-pipeline-operator", { "proposal": "smart" }]
+  ]
+}

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/bare-function/exec.js

@@ -0,0 +1,7 @@
+const abs = Math.abs;
+
+const value = -5.9
+|> abs
+|> Math.floor;
+
+expect(value).toBe(5);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/bare-function/input.js

@@ -0,0 +1,5 @@
+const abs = Math.abs;
+
+const value = -5.9
+|> abs
+|> Math.floor;

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/bare-function/output.js

@@ -0,0 +1,4 @@
+var _ref, _ref2;
+
+const abs = Math.abs;
+const value = (_ref2 = (_ref = -5.9, abs(_ref)), Math.floor(_ref2));

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/basic/exec.js

@@ -0,0 +1,6 @@
+var result = 5
+  |> # + 1
+  |> # + #
+  |> Math.pow(((x) => (x * 7))(#), 2)
+
+expect(result).toBe(7056);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/basic/input.js

@@ -0,0 +1,4 @@
+var result = 5
+  |> # + 1
+  |> # + #
+  |> Math.pow(((x) => (x * 7))(#), 2)

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/basic/output.js

@@ -0,0 +1,3 @@
+var _topic2, _topic4, _topic6;
+
+var result = (_topic6 = (_topic4 = (_topic2 = 5, _topic2 + 1), _topic4 + _topic4), Math.pow((x => x * 7)(_topic6), 2));

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/nested/exec.js

@@ -0,0 +1,7 @@
+var result = 5
+  |> Math.pow(#, 2)
+  |> [ 10, 20, 30, 40, 50 ].filter(n => #
+    |> n > #
+    |> !#);
+
+expect(result).toEqual([10, 20]);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/nested/input.js

@@ -0,0 +1,5 @@
+var result = 5
+  |> Math.pow(#, 2)
+  |> [ 10, 20, 30, 40, 50 ].filter(n => #
+    |> n > #
+    |> !#);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/nested/output.js

@@ -0,0 +1,7 @@
+var _topic2, _topic8;
+
+var result = (_topic8 = (_topic2 = 5, Math.pow(_topic2, 2)), [10, 20, 30, 40, 50].filter(n => {
+  var _topic5, _topic7;
+
+  return _topic7 = (_topic5 = _topic8, n > _topic5), !_topic7;
+}));

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/object-literal/exec.js

@@ -0,0 +1,10 @@
+function area(rect) {
+  return rect.width * rect.height;
+}
+
+const result = -5
+  |> Math.abs
+  |> ({ width: #, height: # + 3 })
+  |> area;
+
+expect(result).toBe(40);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/object-literal/input.js

@@ -0,0 +1,8 @@
+function area(rect) {
+  return rect.width * rect.height;
+}
+
+const result = -5
+  |> Math.abs
+  |> ({ width: #, height: # + 3 })
+  |> area;

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/object-literal/output.js

@@ -0,0 +1,10 @@
+var _ref, _topic2, _ref2;
+
+function area(rect) {
+  return rect.width * rect.height;
+}
+
+const result = (_ref2 = (_topic2 = (_ref = -5, Math.abs(_ref)), {
+  width: _topic2,
+  height: _topic2 + 3
+}), area(_ref2));

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/options.json

@@ -0,0 +1,5 @@
+{
+  "plugins": [
+    ["proposal-pipeline-operator", { "proposal": "smart" }]
+  ]
+}

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/topic-as-callee/input.js

@@ -0,0 +1 @@
+v |> #.method |> f;

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/topic-as-callee/output.js

@@ -0,0 +1,3 @@
+var _topic2, _ref;
+
+_ref = (_topic2 = v, _topic2.method), f(_ref);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/topic-inside-arrow-function/exec.js

@@ -0,0 +1,7 @@
+const result = -2.2   // -2.2
+  |> Math.floor       // -3
+  |> (() => Math.pow(#, 5))   // () => -243
+  |> #()              // -243
+  |> Math.sign;       // -1
+
+expect(result).toBe(-1);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/topic-inside-arrow-function/input.js

@@ -0,0 +1,5 @@
+const result = -2.2   // -2.2
+  |> Math.floor       // -3
+  |> (() => Math.pow(#, 5))   // () => -243
+  |> #()              // -243
+  |> Math.sign;       // -1

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/topic-inside-arrow-function/output.js

@@ -0,0 +1,7 @@
+var _ref, _topic2, _topic4, _ref2;
+
+const result = (_ref2 = (_topic4 = (_topic2 = (_ref = -2.2 // -2.2
+, Math.floor(_ref) // -3
+), () => Math.pow(_topic2, 5) // () => -243
+), _topic4() // -243
+), Math.sign(_ref2)); // -1

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/yield/input.js

@@ -0,0 +1,5 @@
+function *myGenerator() {
+  return v
+  |> (yield #)
+  |> g;
+}

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/smart/yield/options.json

@@ -0,0 +1,6 @@
+{
+  "throws": "yield is not supported inside pipeline expressions yet",
+  "plugins": [
+    ["proposal-pipeline-operator", { "proposal": "smart" }]
+  ]
+}

packages/babel-plugin-syntax-pipeline-operator/src/index.js

@@ -1,6 +1,6 @@
 import { declare } from "@babel/helper-plugin-utils";
 
-export const proposals = ["minimal"];
+export const proposals = ["minimal", "smart"];
 
 export default declare((api, { proposal }) => {
   api.assertVersion(7);