Allow paren expressions in if, etc (take two)

src/parser/statement.js

@@ -236,15 +236,14 @@ pp.parseDoStatement = function (node) {
   // b/c it expects a trailing colon or brace, which you don't have here.
 
   if (this.hasPlugin("lightscript")) {
-    // allow parens; if not used, enforce semicolon or newline.
-    if (this.eat(tt.parenL)) {
-      node.test = this.parseExpression();
-      this.expect(tt.parenR);
-      this.eat(tt.semi);
-    } else {
-      node.test = this.parseExpression();
-      this.semicolon();
+    // allow parens; enforce semicolon or newline whether they're used or not.
+    node.test = this.parseExpression();
+    if (node.test.extra && node.test.extra.parenthesized) {
+      delete node.test.extra.parenthesized;
+      delete node.test.extra.parenStart;
+      this.addExtra(node, "hasParens", true);
     }
+    this.semicolon();
   } else {
     node.test = this.parseParenExpression();
     this.eat(tt.semi);
@@ -272,8 +271,9 @@ pp.parseForStatement = function (node) {
   }
 
   if (this.hasPlugin("lightscript")) {
-    // TODO: check that closing paren is/isnt there to match
-    this.eat(tt.parenL);
+    if (this.eat(tt.parenL)) {
+      this.addExtra(node, "hasParens", true);
+    }
   } else {
     this.expect(tt.parenL);
   }
@@ -450,14 +450,16 @@ pp.parseTryStatement = function (node) {
     this.next();
 
     if (this.hasPlugin("lightscript")) {
-      this.eat(tt.parenL);
+      if (this.eat(tt.parenL)) {
+        this.addExtra(clause, "hasParens", true);
+      }
     } else {
       this.expect(tt.parenL);
     }
     clause.param = this.parseBindingAtom();
     this.checkLVal(clause.param, true, Object.create(null), "catch clause");
     if (this.hasPlugin("lightscript")) {
-      this.eat(tt.parenR);
+      this.expectParenFreeBlockStart(clause);
     } else {
       this.expect(tt.parenR);
     }
@@ -617,7 +619,7 @@ pp.parseFor = function (node, init) {
   node.update = this.match(tt.parenR) ? null : this.parseExpression();
 
   if (this.hasPlugin("lightscript")) {
-    this.expectParenFreeBlockStart();
+    this.expectParenFreeBlockStart(node);
   } else {
     this.expect(tt.parenR);
   }
@@ -643,7 +645,7 @@ pp.parseForIn = function (node, init, forAwait) {
   node.right = this.parseExpression();
 
   if (this.hasPlugin("lightscript")) {
-    this.expectParenFreeBlockStart();
+    this.expectParenFreeBlockStart(node);
   } else {
     this.expect(tt.parenR);
   }

src/plugins/lightscript.js

@@ -93,7 +93,7 @@ pp.parseEnhancedForIn = function (node) {
 
   const iterable = this.parseMaybeAssign(true);
 
-  this.expectParenFreeBlockStart();
+  this.expectParenFreeBlockStart(node);
   node.body = this.parseStatement(false);
 
   if ((matchingIterationType === "idx") || (matchingIterationType === "elem")) {
@@ -105,12 +105,13 @@ pp.parseEnhancedForIn = function (node) {
   }
 };
 
-pp.expectParenFreeBlockStart = function () {
+pp.expectParenFreeBlockStart = function (node) {
   // if true: blah
   // if true { blah }
   // if (true) blah
-  // TODO: ensure matching parens, not just allowing one on either side
-  if (!(this.match(tt.colon) || this.match(tt.braceL) || this.eat(tt.parenR))) {
+  if (node && node.extra && node.extra.hasParens) {
+    this.expect(tt.parenR);
+  } else if (!(this.match(tt.colon) || this.match(tt.braceL))) {
     this.unexpected(null, "Paren-free test expressions must be followed by braces or a colon.");
   }
 };
@@ -483,7 +484,29 @@ export default function (instance) {
 
   instance.extend("parseParenExpression", function (inner) {
     return function () {
-      if (this.match(tt.parenL)) return inner.apply(this, arguments);
+      // parens are special here; they might be `if (x) -1` or `if (x < 1) and y: -1`
+      if (this.match(tt.parenL)) {
+        const state = this.state.clone();
+
+        // first, try paren-free style
+        try {
+          const val = this.parseExpression();
+          if (this.match(tt.braceL) || this.match(tt.colon)) {
+            if (val.extra && val.extra.parenthesized) {
+              delete val.extra.parenthesized;
+              delete val.extra.parenStart;
+            }
+            return val;
+          }
+        } catch (_err) {
+          // fall-through, will re-raise if it's an error below
+        }
+
+        // otherwise, try traditional parseParenExpression
+        this.state = state;
+        return inner.apply(this, arguments);
+      }
+
       const val = this.parseExpression();
       this.expectParenFreeBlockStart();
       return val;

test/fixtures/es2015/uncategorised/197/options.lightscript.json

@@ -0,0 +1,4 @@
+{
+  "ecmaVersion": 6,
+  "throws": "Unexpected token, expected ; (1:20)"
+}

test/fixtures/lightscript/paren-free/do-while-then-paren-unfortunate/actual.js

@@ -0,0 +1 @@
+do {} while (a) (b)

test/fixtures/lightscript/paren-free/do-while-then-paren-unfortunate/expected.json

@@ -0,0 +1,124 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 19,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 19
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 19,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 19
+      }
+    },
+    "sourceType": "script",
+    "body": [
+      {
+        "type": "DoWhileStatement",
+        "start": 0,
+        "end": 19,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 19
+          }
+        },
+        "body": {
+          "type": "BlockStatement",
+          "start": 3,
+          "end": 5,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 3
+            },
+            "end": {
+              "line": 1,
+              "column": 5
+            }
+          },
+          "body": [],
+          "directives": [],
+          "extra": {
+            "curly": true
+          }
+        },
+        "test": {
+          "type": "CallExpression",
+          "start": 12,
+          "end": 19,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 12
+            },
+            "end": {
+              "line": 1,
+              "column": 19
+            }
+          },
+          "callee": {
+            "type": "Identifier",
+            "start": 13,
+            "end": 14,
+            "loc": {
+              "start": {
+                "line": 1,
+                "column": 13
+              },
+              "end": {
+                "line": 1,
+                "column": 14
+              },
+              "identifierName": "a"
+            },
+            "name": "a",
+            "extra": {
+              "parenthesized": true,
+              "parenStart": 12
+            }
+          },
+          "arguments": [
+            {
+              "type": "Identifier",
+              "start": 17,
+              "end": 18,
+              "loc": {
+                "start": {
+                  "line": 1,
+                  "column": 17
+                },
+                "end": {
+                  "line": 1,
+                  "column": 18
+                },
+                "identifierName": "b"
+              },
+              "name": "b"
+            }
+          ]
+        }
+      }
+    ],
+    "directives": []
+  }
+}

test/fixtures/lightscript/paren-free/for-mismatched-paren-left/actual.js

@@ -0,0 +1 @@
+for (;; {}

test/fixtures/lightscript/paren-free/for-mismatched-paren-left/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Unexpected token, expected ) (1:10)"
+}

test/fixtures/lightscript/paren-free/for-mismatched-paren-right/actual.js

@@ -0,0 +1 @@
+for ;;) {}

test/fixtures/lightscript/paren-free/for-mismatched-paren-right/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Paren-free test expressions must be followed by braces or a colon. (1:6)"
+}

test/fixtures/lightscript/paren-free/for-of-mismatched-left/actual.js

@@ -0,0 +1 @@
+for (let x of {a: 1} {}

test/fixtures/lightscript/paren-free/for-of-mismatched-left/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Unexpected token, expected ) (1:21)"
+}

test/fixtures/lightscript/paren-free/for-of-mismatched-right/actual.js

@@ -0,0 +1 @@
+for let x of {a: 1}) {}

test/fixtures/lightscript/paren-free/for-of-mismatched-right/options.json

@@ -0,0 +1,3 @@
+{
+  "throws": "Paren-free test expressions must be followed by braces or a colon. (1:19)"
+}

test/fixtures/lightscript/paren-free/paren-block-no-space/actual.js

@@ -0,0 +1 @@
+if (a){}

test/fixtures/lightscript/paren-free/paren-block-no-space/expected.json

@@ -0,0 +1,87 @@
+{
+  "type": "File",
+  "start": 0,
+  "end": 8,
+  "loc": {
+    "start": {
+      "line": 1,
+      "column": 0
+    },
+    "end": {
+      "line": 1,
+      "column": 8
+    }
+  },
+  "program": {
+    "type": "Program",
+    "start": 0,
+    "end": 8,
+    "loc": {
+      "start": {
+        "line": 1,
+        "column": 0
+      },
+      "end": {
+        "line": 1,
+        "column": 8
+      }
+    },
+    "sourceType": "script",
+    "body": [
+      {
+        "type": "IfStatement",
+        "start": 0,
+        "end": 8,
+        "loc": {
+          "start": {
+            "line": 1,
+            "column": 0
+          },
+          "end": {
+            "line": 1,
+            "column": 8
+          }
+        },
+        "test": {
+          "type": "Identifier",
+          "start": 4,
+          "end": 5,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 4
+            },
+            "end": {
+              "line": 1,
+              "column": 5
+            },
+            "identifierName": "a"
+          },
+          "name": "a"
+        },
+        "consequent": {
+          "type": "BlockStatement",
+          "start": 6,
+          "end": 8,
+          "loc": {
+            "start": {
+              "line": 1,
+              "column": 6
+            },
+            "end": {
+              "line": 1,
+              "column": 8
+            }
+          },
+          "body": [],
+          "directives": [],
+          "extra": {
+            "curly": true
+          }
+        },
+        "alternate": null
+      }
+    ],
+    "directives": []
+  }
+}

test/fixtures/lightscript/paren-free/paren-identifier-body-no-space/actual.js

@@ -0,0 +1 @@
+if (1)a;