Fix for left-associativity and subscripts of pipeCalls

Author: wcjohnson

src/parser/expression.js

@@ -379,6 +379,12 @@ pp.parseExprSubscripts = function (refShorthandDefaultPos) {
 };
 
 pp.parseSubscripts = function (base, startPos, startLoc, noCalls) {
+
+  // pipeCall plugin hack: pass noPipes via state to avoid changing args
+  // to core parser function.
+  const noPipes = this.state.noPipeSubscripts;
+  this.state.noPipeSubscripts = false;
+
   for (;;) {
     if (this.hasPlugin("bangCall") && this.shouldUnwindBangSubscript()) {
       return base;
@@ -470,6 +476,7 @@ pp.parseSubscripts = function (base, startPos, startLoc, noCalls) {
       if (next) base = next; else return node;
     } else if (
       !noCalls &&
+      !noPipes &&
       this.hasPlugin("pipeCall") &&
       this.match(tt.pipeCall)
     ) {

src/plugins/pipeCall.js

@@ -13,13 +13,13 @@ export default function(parser) {
 
     node.left = left;
 
-    // Left-associative parsing of pipeCalls
+    // To get left-associative parsing for pipe calls, we can't let the RHS
+    // of a pipe call subscript into another pipe call.
+    // Thus we use a state flag to prevent deep parsing of pipe calls
+    // Hackish but avoids changing the core args of parseSubscripts
     const right = this.parseExprAtom();
-    if (this.match(tt.pipeCall)) {
-      node.right = right;
-    } else {
-      node.right = this.parseSubscripts(right, this.state.start, this.state.startLoc, true);
-    }
+    this.state.noPipeSubscripts = true;
+    node.right = this.parseSubscripts(right, this.state.start, this.state.startLoc);
 
     return this.finishNode(node, "PipeCallExpression");
   };

test/fixtures/pipe-call/basic/rhs-expr/expected.json

@@ -43,7 +43,7 @@
           }
         },
         "expression": {
-          "type": "CallExpression",
+          "type": "PipeCallExpression",
           "start": 0,
           "end": 9,
           "loc": {
@@ -56,38 +56,38 @@
               "column": 9
             }
           },
-          "callee": {
-            "type": "PipeCallExpression",
+          "left": {
+            "type": "Identifier",
             "start": 0,
-            "end": 6,
+            "end": 1,
             "loc": {
               "start": {
                 "line": 1,
                 "column": 0
               },
               "end": {
                 "line": 1,
-                "column": 6
-              }
+                "column": 1
+              },
+              "identifierName": "a"
             },
-            "left": {
-              "type": "Identifier",
-              "start": 0,
-              "end": 1,
-              "loc": {
-                "start": {
-                  "line": 1,
-                  "column": 0
-                },
-                "end": {
-                  "line": 1,
-                  "column": 1
-                },
-                "identifierName": "a"
+            "name": "a"
+          },
+          "right": {
+            "type": "CallExpression",
+            "start": 6,
+            "end": 9,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 6
               },
-              "name": "a"
+              "end": {
+                "line": 1,
+                "column": 9
+              }
             },
-            "right": {
+            "callee": {
               "type": "Identifier",
               "start": 5,
               "end": 6,
@@ -103,27 +103,27 @@
                 "identifierName": "b"
               },
               "name": "b"
-            }
-          },
-          "arguments": [
-            {
-              "type": "Identifier",
-              "start": 7,
-              "end": 8,
-              "loc": {
-                "start": {
-                  "line": 1,
-                  "column": 7
-                },
-                "end": {
-                  "line": 1,
-                  "column": 8
+            },
+            "arguments": [
+              {
+                "type": "Identifier",
+                "start": 7,
+                "end": 8,
+                "loc": {
+                  "start": {
+                    "line": 1,
+                    "column": 7
+                  },
+                  "end": {
+                    "line": 1,
+                    "column": 8
+                  },
+                  "identifierName": "c"
                 },
-                "identifierName": "c"
-              },
-              "name": "c"
-            }
-          ]
+                "name": "c"
+              }
+            ]
+          }
         }
       }
     ],