Bring pipelineOperator flag in line with minimal

The minimal proposal requires parentheses around arrow functions
and bans await from the pipeline.

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

@@ -1,7 +1,7 @@
 var result = [5,10]
-  |> _ => _.map(x => x * 2)
+  |> (_ => _.map(x => x * 2))
-  |> _ => _.reduce( (a,b) => a + b )
+  |> (_ => _.reduce( (a,b) => a + b ))
-  |> sum => sum + 1
+  |> (sum => sum + 1)
 
 expect(result).toBe(31);
 

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

@@ -1,7 +1,7 @@
 var result = [5,10]
-  |> _ => _.map(x => x * 2)
+  |> (_ => _.map(x => x * 2))
-  |> _ => _.reduce( (a,b) => a + b )
+  |> (_ => _.reduce( (a,b) => a + b ))
-  |> sum => sum + 1
+  |> (sum => sum + 1)
 
 expect(result).toBe(31);
 

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

@@ -1,6 +1,6 @@
-var _ref, _ref2, _sum;
+var _sum, _ref, _ref2;
 
-var result = (_ref = [5, 10], (_ref2 = _ref.map(x => x * 2), (_sum = _ref2.reduce((a, b) => a + b), _sum + 1)));
+var result = (_sum = (_ref = (_ref2 = [5, 10], _ref2.map(x => x * 2)), _ref.reduce((a, b) => a + b)), _sum + 1);
 expect(result).toBe(31);
 
 var inc = x => x + 1;

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

@@ -2,7 +2,7 @@ var a = 1,
     b = 2,
     c = 3;
 var result = a
-  |> (a, b) => b
+  |> ((a, b) => b)
-  |> (a, b) => c;
+  |> ((a, b) => c);
 
 expect(result).toBe(c);

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

@@ -2,7 +2,7 @@ var a = 1,
     b = 2,
     c = 3;
 var result = a
-  |> (a, b) => b
+  |> ((a, b) => b)
-  |> (a, b) => c;
+  |> ((a, b) => c);
 
 expect(result).toBe(c);

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

@@ -1,11 +1,7 @@
-var _a;
+var _ref, _a;
 
 var a = 1,
     b = 2,
     c = 3;
-var result = (_a = a, ((a, b) => {
+var result = (_ref = (_a = a, ((a, b) => b)(_a)), ((a, b) => c)(_ref));
-  var _b;
-
-  return _b = b, ((a, b) => c)(_b);
-})(_a));
 expect(result).toBe(c);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/destructure-arrow-param/exec.js

@@ -1,7 +1,7 @@
 // Array destructing
-const result = [0] |> ([x]) => x;
+const result = [0] |> (([x]) => x);
 expect(result).toBe(0);
 
 // Object destructuring
-const result2 = { y: 1, z: 2 } |> ({ y, z }) => y + z;
+const result2 = { y: 1, z: 2 } |> (({ y, z }) => y + z);
 expect(result2).toBe(3);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/destructure-arrow-param/input.js

@@ -1,7 +1,7 @@
 // Array destructing
-const result = [0] |> ([x]) => x;
+const result = [0] |> (([x]) => x);
 expect(result).toBe(0);
 
 // Object destructuring
-const result2 = { y: 1, z: 2 } |> ({ y, z }) => y + z;
+const result2 = { y: 1, z: 2 } |> (({ y, z }) => y + z);
 expect(result).toBe(3);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/multiple-argument-use/exec.js

@@ -1,5 +1,5 @@
 var array = [10,20,30];
 
-var last = array |> a => a[a.length-1];
+var last = array |> (a => a[a.length-1]);
 
 expect(last).toBe(30);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/multiple-argument-use/input.js

@@ -1,5 +1,5 @@
 var array = [10,20,30];
 
-var last = array |> a => a[a.length-1];
+var last = array |> (a => a[a.length-1]);
 
 expect(last).toBe(30);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/optimize-0-param-arrow/exec.js

@@ -2,7 +2,7 @@ var a = 1,
     b = 2,
     c = 3;
 var result = a
-  |> () => b
+  |> (() => b)
-  |> () => c;
+  |> (() => c);
 
 expect(result).toBe(c);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/optimize-0-param-arrow/input.js

@@ -2,7 +2,7 @@ var a = 1,
     b = 2,
     c = 3;
 var result = a
-  |> () => b
+  |> (() => b)
-  |> () => c;
+  |> (() => c);
 
 expect(result).toBe(c);

packages/babel-plugin-proposal-pipeline-operator/test/fixtures/pipeline-operator/optimize-0-param-arrow/output.js

@@ -1,5 +1,5 @@
 var a = 1,
     b = 2,
     c = 3;
-var result = (a, (b, c));
+var result = ((a, b), c);
 expect(result).toBe(c);

packages/babylon/src/parser/expression.js

@@ -310,8 +310,25 @@ export default class ExpressionParser extends LValParser {
         const startLoc = this.state.startLoc;
 
         if (op === tt.pipeline) {
-          // Support syntax such as 10 |> x => x + 1
+          const lookahead = this.lookahead();
-          this.state.potentialArrowAt = startPos;
+
+          if (lookahead.type === tt.arrow) {
+            throw this.raise(
+              this.state.start,
+              `Unexpected arrow "=>" after pipeline body; arrow function in pipeline body must be parenthesized`, // eslint-disable-line
+            );
+          }
+
+          if (
+            this.match(tt.name) &&
+            this.state.value === "await" &&
+            this.state.inAsync
+          ) {
+            throw this.raise(
+              this.state.start,
+              `Unexpected "await" after pipeline body; await must have parentheses in minimal proposal`,
+            );
+          }
         }
 
         node.right = this.parseExprOp(

packages/babylon/test/fixtures/experimental/pipeline-operator/arrow-requires-parens/input.js

@@ -0,0 +1 @@
+10 |> x => x + 1;

packages/babylon/test/fixtures/experimental/pipeline-operator/arrow-requires-parens/options.json

@@ -0,0 +1,4 @@
+{
+  "plugins": ["pipelineOperator"],
+  "throws": "Unexpected arrow \"=>\" after pipeline body; arrow function in pipeline body must be parenthesized (1:6)"
+}

packages/babylon/test/fixtures/experimental/pipeline-operator/await-requires-parens/input.js

@@ -0,0 +1,3 @@
+async function foo() {
+  return a |> (await f) |> g;
+}

packages/babylon/test/fixtures/experimental/pipeline-operator/await-requires-parens/options.json

@@ -0,0 +1,3 @@
+{
+  "plugins": ["pipelineOperator"]
+}

packages/babylon/test/fixtures/experimental/pipeline-operator/await-requires-parens/output.json

@@ -0,0 +1,204 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 54,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 3,
+      "column": 1
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 54,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 3,
+        "column": 1
+      }
+    },
+    "sourceType": "script",
+    "body": [
+      {
+        "type": "FunctionDeclaration",
+        "start": 0,
+        "end": 54,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 3,
+            "column": 1
+          }
+        },
+        "id": {
+          "type": "Identifier",
+          "start": 15,
+          "end": 18,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 15
+            },
+            "end": {
+              "line": 1,
+              "column": 18
+            },
+            "identifierName": "foo"
+          },
+          "name": "foo"
+        },
+        "generator": false,
+        "async": true,
+        "params": [],
+        "body": {
+          "type": "BlockStatement",
+          "start": 21,
+          "end": 54,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 21
+            },
+            "end": {
+              "line": 3,
+              "column": 1
+            }
+          },
+          "body": [
+            {
+              "type": "ReturnStatement",
+              "start": 25,
+              "end": 52,
+              "loc": {
+                "start": {
+                  "line": 2,
+                  "column": 2
+                },
+                "end": {
+                  "line": 2,
+                  "column": 29
+                }
+              },
+              "argument": {
+                "type": "BinaryExpression",
+                "start": 32,
+                "end": 51,
+                "loc": {
+                  "start": {
+                    "line": 2,
+                    "column": 9
+                  },
+                  "end": {
+                    "line": 2,
+                    "column": 28
+                  }
+                },
+                "left": {
+                  "type": "BinaryExpression",
+                  "start": 32,
+                  "end": 46,
+                  "loc": {
+                    "start": {
+                      "line": 2,
+                      "column": 9
+                    },
+                    "end": {
+                      "line": 2,
+                      "column": 23
+                    }
+                  },
+                  "left": {
+                    "type": "Identifier",
+                    "start": 32,
+                    "end": 33,
+                    "loc": {
+                      "start": {
+                        "line": 2,
+                        "column": 9
+                      },
+                      "end": {
+                        "line": 2,
+                        "column": 10
+                      },
+                      "identifierName": "a"
+                    },
+                    "name": "a"
+                  },
+                  "operator": "|>",
+                  "right": {
+                    "type": "AwaitExpression",
+                    "start": 38,
+                    "end": 45,
+                    "loc": {
+                      "start": {
+                        "line": 2,
+                        "column": 15
+                      },
+                      "end": {
+                        "line": 2,
+                        "column": 22
+                      }
+                    },
+                    "argument": {
+                      "type": "Identifier",
+                      "start": 44,
+                      "end": 45,
+                      "loc": {
+                        "start": {
+                          "line": 2,
+                          "column": 21
+                        },
+                        "end": {
+                          "line": 2,
+                          "column": 22
+                        },
+                        "identifierName": "f"
+                      },
+                      "name": "f"
+                    },
+                    "extra": {
+                      "parenthesized": true,
+                      "parenStart": 37
+                    }
+                  }
+                },
+                "operator": "|>",
+                "right": {
+                  "type": "Identifier",
+                  "start": 50,
+                  "end": 51,
+                  "loc": {
+                    "start": {
+                      "line": 2,
+                      "column": 27
+                    },
+                    "end": {
+                      "line": 2,
+                      "column": 28
+                    },
+                    "identifierName": "g"
+                  },
+                  "name": "g"
+                }
+              }
+            }
+          ],
+          "directives": []
+        }
+      }
+    ],
+    "directives": []
+  }
+}

packages/babylon/test/fixtures/experimental/pipeline-operator/ban-await-f/input.js

@@ -0,0 +1,3 @@
+async function foo() {
+  return a |> await f |> g;
+}

packages/babylon/test/fixtures/experimental/pipeline-operator/ban-await-f/options.json

@@ -0,0 +1,4 @@
+{
+  "plugins": ["pipelineOperator"],
+  "throws": "Unexpected \"await\" after pipeline body; await must have parentheses in minimal proposal (2:14)"
+}

packages/babylon/test/fixtures/experimental/pipeline-operator/ban-await/input.js

@@ -0,0 +1,3 @@
+async function foo() {
+  return a |> await |> f;
+}

packages/babylon/test/fixtures/experimental/pipeline-operator/ban-await/options.json

@@ -0,0 +1,4 @@
+{
+  "plugins": ["pipelineOperator"],
+  "throws": "Unexpected \"await\" after pipeline body; await must have parentheses in minimal proposal (2:14)"
+}

packages/babylon/test/fixtures/experimental/pipeline-operator/with-arrow/input.js

@@ -1 +1 @@
-10 |> x => x + 1;
+10 |> (x => x + 1);

packages/babylon/test/fixtures/experimental/pipeline-operator/with-arrow/output.json

@@ -1,7 +1,7 @@
 {
   "type": "File",
   "start": 0,
-  "end": 17,
+  "end": 19,
   "loc": {
     "start": {
       "line": 1,
@@ -9,13 +9,13 @@
     },
     "end": {
       "line": 1,
-      "column": 17
+      "column": 19
     }
   },
   "program": {
     "type": "Program",
     "start": 0,
-    "end": 17,
+    "end": 19,
     "loc": {
       "start": {
         "line": 1,
@@ -23,7 +23,7 @@
       },
       "end": {
         "line": 1,
-        "column": 17
+        "column": 19
       }
     },
     "sourceType": "script",
@@ -31,7 +31,7 @@
       {
         "type": "ExpressionStatement",
         "start": 0,
-        "end": 17,
+        "end": 19,
         "loc": {
           "start": {
             "line": 1,
@@ -39,13 +39,13 @@
           },
           "end": {
             "line": 1,
-            "column": 17
+            "column": 19
           }
         },
         "expression": {
           "type": "BinaryExpression",
           "start": 0,
-          "end": 16,
+          "end": 18,
           "loc": {
             "start": {
               "line": 1,
@@ -53,7 +53,7 @@
             },
             "end": {
               "line": 1,
-              "column": 16
+              "column": 18
             }
           },
           "left": {
@@ -79,16 +79,16 @@
           "operator": "|>",
           "right": {
             "type": "ArrowFunctionExpression",
-            "start": 6,
+            "start": 7,
-            "end": 16,
+            "end": 17,
             "loc": {
               "start": {
                 "line": 1,
-                "column": 6
+                "column": 7
               },
               "end": {
                 "line": 1,
-                "column": 16
+                "column": 17
               }
             },
             "id": null,
@@ -97,16 +97,16 @@
             "params": [
               {
                 "type": "Identifier",
-                "start": 6,
+                "start": 7,
-                "end": 7,
+                "end": 8,
                 "loc": {
                   "start": {
                     "line": 1,
-                    "column": 6
+                    "column": 7
                   },
                   "end": {
                     "line": 1,
-                    "column": 7
+                    "column": 8
                   },
                   "identifierName": "x"
                 },
@@ -115,30 +115,30 @@
             ],
             "body": {
               "type": "BinaryExpression",
-              "start": 11,
+              "start": 12,
-              "end": 16,
+              "end": 17,
               "loc": {
                 "start": {
                   "line": 1,
-                  "column": 11
+                  "column": 12
                 },
                 "end": {
                   "line": 1,
-                  "column": 16
+                  "column": 17
                 }
               },
               "left": {
                 "type": "Identifier",
-                "start": 11,
+                "start": 12,
-                "end": 12,
+                "end": 13,
                 "loc": {
                   "start": {
                     "line": 1,
-                    "column": 11
+                    "column": 12
                   },
                   "end": {
                     "line": 1,
-                    "column": 12
+                    "column": 13
                   },
                   "identifierName": "x"
                 },
@@ -147,16 +147,16 @@
               "operator": "+",
               "right": {
                 "type": "NumericLiteral",
-                "start": 15,
+                "start": 16,
-                "end": 16,
+                "end": 17,
                 "loc": {
                   "start": {
                     "line": 1,
-                    "column": 15
+                    "column": 16
                   },
                   "end": {
                     "line": 1,
-                    "column": 16
+                    "column": 17
                   }
                 },
                 "extra": {
@@ -165,6 +165,10 @@
                 },
                 "value": 1
               }
+            },
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 6
             }
           }
         }