Destructure as patterns, allow destructured 'as'

Author: rattrayalex

src/parser/expression.js

@@ -678,8 +678,7 @@ pp.parseExprAtom = function (refShorthandDefaultPos) {
       return this.parseParenAndDistinguishExpression(null, null, canBeArrow);
 
     case tt.bracketL:
-      if (this.hasPlugin("lightscript") && this.state.inMatchCaseTest && !refShorthandDefaultPos) {
-        // re-enter this fn, but with refShorthandDefaultPos and state tracking
+      if (this.hasPlugin("lightscript") && this.state.inMatchCaseTest) {
         return this.parseMatchCaseTestPattern();
       }
       node = this.startNode();
@@ -692,8 +691,7 @@ pp.parseExprAtom = function (refShorthandDefaultPos) {
       return this.finishNode(node, "ArrayExpression");
 
     case tt.braceL:
-      if (this.hasPlugin("lightscript") && this.state.inMatchCaseTest && !refShorthandDefaultPos) {
-        // re-enter this fn, but with refShorthandDefaultPos and state tracking
+      if (this.hasPlugin("lightscript") && this.state.inMatchCaseTest) {
         return this.parseMatchCaseTestPattern();
       }
       return this.parseObj(false, refShorthandDefaultPos);

src/plugins/lightscript.js

@@ -593,15 +593,16 @@ pp.parseMatch = function (node, isExpression) {
 pp.parseMatchCase = function (isExpression) {
   const node = this.startNode();
 
+  this.state.allowMatchCaseTestPattern = true;
   node.test = this.parseMatchCaseTest();
-
   if (this.isContextual("as")) {
     if (!this.state.allowMatchCaseTestPattern) {
       this.unexpected(null, "Cannot rename after destructuring.");
     }
     this.next();
-    node.binding = this.parseIdentifier();
+    node.binding = this.parseBindingAtom();
   }
+  this.state.allowMatchCaseTestPattern = false;
 
   if (isExpression) {
     // disallow return/continue/break, etc. c/p doExpression
@@ -624,7 +625,6 @@ pp.parseMatchCase = function (isExpression) {
 pp.parseMatchCaseTest = function () {
   // can't be nested so no need to read/restore old value
   this.state.inMatchCaseTest = true;
-  this.state.allowMatchCaseTestPattern = true;
 
   this.expect(tt.bitwiseOR);
   if (this.isLineBreak()) this.unexpected(this.state.lastTokEnd, "Illegal newline.");
@@ -639,7 +639,6 @@ pp.parseMatchCaseTest = function () {
   }
 
   this.state.inMatchCaseTest = false;
-  this.state.allowMatchCaseTestPattern = false;
   return test;
 };
 
@@ -686,9 +685,7 @@ pp.parseMatchCaseTestPattern = function () {
   const oldInMatchCaseTestPattern = this.state.inMatchCaseTestPattern;
   this.state.inMatchCaseTestPattern = true;
 
-  // re-enter parent function, allowing patterns.
-  const refShorthandDefaultPos = { start: 0 };
-  const node = this.parseExprAtom(refShorthandDefaultPos);
+  const node = this.parseBindingAtom();
 
   // once we have finished recursing through a pattern, disallow future patterns
   this.state.inMatchCaseTestPattern = oldInMatchCaseTestPattern;

test/fixtures/lightscript/match/basic-destructuring/actual.js renamed to test/fixtures/lightscript/match/basic-renaming/actual.js

@@ -0,0 +1,3 @@
+match x:
+  | .a as { a, b = 1 }: a + b
+  | .0 and .1 as [ a, b ]: a + b