From d2e046b413927fe8e100b5647ab50609f961e334 Mon Sep 17 00:00:00 2001
From: Ryan Hendrickson <ryan.hendrickson@alum.mit.edu>
Date: Tue, 3 Sep 2019 02:11:47 -0400
Subject: [PATCH] Add support for destructuring in var declarations

Covers var, let, and const.
---
 src/Language/JavaScript/Parser/Grammar7.y        | 8 ++++----
 test/Test/Language/Javascript/Minify.hs          | 1 +
 test/Test/Language/Javascript/RoundTrip.hs       | 2 ++
 test/Test/Language/Javascript/StatementParser.hs | 2 ++
 4 files changed, 9 insertions(+), 4 deletions(-)

diff --git a/src/Language/JavaScript/Parser/Grammar7.y b/src/Language/JavaScript/Parser/Grammar7.y
index d1e750d..8df5f18 100644
--- a/src/Language/JavaScript/Parser/Grammar7.y
+++ b/src/Language/JavaScript/Parser/Grammar7.y
@@ -958,14 +958,14 @@ VariableDeclarationListNoIn : VariableDeclarationNoIn
 -- VariableDeclaration :                                          See 12.2
 --         Identifier Initialiseropt
 VariableDeclaration :: { AST.JSExpression }
-VariableDeclaration : Identifier SimpleAssign AssignmentExpression { AST.JSVarInitExpression $1 (AST.JSVarInit $2 $3) {- 'JSVarInitExpression1' -} }
-                    | Identifier                                   { AST.JSVarInitExpression $1 AST.JSVarInitNone     {- 'JSVarInitExpression2' -} }
+VariableDeclaration : PrimaryExpression SimpleAssign AssignmentExpression { AST.JSVarInitExpression $1 (AST.JSVarInit $2 $3) {- 'JSVarInitExpression1' -} }
+                    | Identifier                                          { AST.JSVarInitExpression $1 AST.JSVarInitNone     {- 'JSVarInitExpression2' -} }
 
 -- VariableDeclarationNoIn :                                      See 12.2
 --         Identifier InitialiserNoInopt
 VariableDeclarationNoIn :: { AST.JSExpression }
-VariableDeclarationNoIn : Identifier SimpleAssign AssignmentExpression { AST.JSVarInitExpression $1 (AST.JSVarInit $2 $3) {- 'JSVarInitExpressionInit2' -} }
-                        | Identifier                                   { AST.JSVarInitExpression $1 AST.JSVarInitNone     {- 'JSVarInitExpression2' -} }
+VariableDeclarationNoIn : PrimaryExpression SimpleAssign AssignmentExpression { AST.JSVarInitExpression $1 (AST.JSVarInit $2 $3) {- 'JSVarInitExpressionInit2' -} }
+                        | Identifier                                          { AST.JSVarInitExpression $1 AST.JSVarInitNone     {- 'JSVarInitExpression2' -} }
 
 -- EmptyStatement :                                                                         See 12.3
 --         ;
diff --git a/test/Test/Language/Javascript/Minify.hs b/test/Test/Language/Javascript/Minify.hs
index 2389681..84d9f00 100644
--- a/test/Test/Language/Javascript/Minify.hs
+++ b/test/Test/Language/Javascript/Minify.hs
@@ -225,6 +225,7 @@ testMinifyStmt = describe "Minify statements:" $ do
         minifyStmt " var d = 1, x = 2 ; " `shouldBe` "var d=1,x=2"
         minifyStmt " let c = 1 ; " `shouldBe` "let c=1"
         minifyStmt " let d = 1, x = 2 ; " `shouldBe` "let d=1,x=2"
+        minifyStmt " const { a : [ b , c ] } = d; " `shouldBe` "const{a:[b,c]}=d"
 
     it "string concatenation" $
         minifyStmt " f (\"ab\"+\"cd\") " `shouldBe` "f('abcd')"
diff --git a/test/Test/Language/Javascript/RoundTrip.hs b/test/Test/Language/Javascript/RoundTrip.hs
index d27fd09..33afed0 100644
--- a/test/Test/Language/Javascript/RoundTrip.hs
+++ b/test/Test/Language/Javascript/RoundTrip.hs
@@ -105,6 +105,8 @@ testRoundTrip = describe "Roundtrip:" $ do
         testRT "switch (x) {default:break;}"
         testRT "switch (x) {default:\ncase 1:break;}"
         testRT "var x=1;let y=2;"
+        testRT "var [x, y]=z;"
+        testRT "let {x: [y]}=z;"
 
     it "module" $ do
         testRTModule "import  def  from 'mod'"
diff --git a/test/Test/Language/Javascript/StatementParser.hs b/test/Test/Language/Javascript/StatementParser.hs
index cd54550..fcf0e67 100644
--- a/test/Test/Language/Javascript/StatementParser.hs
+++ b/test/Test/Language/Javascript/StatementParser.hs
@@ -61,6 +61,8 @@ testStatementParser = describe "Parse statements:" $ do
         testStmt "var x=1;"         `shouldBe` "Right (JSAstStatement (JSVariable (JSVarInitExpression (JSIdentifier 'x') [JSDecimal '1'])))"
         testStmt "const x=1,y=2;"   `shouldBe` "Right (JSAstStatement (JSConstant (JSVarInitExpression (JSIdentifier 'x') [JSDecimal '1'],JSVarInitExpression (JSIdentifier 'y') [JSDecimal '2'])))"
         testStmt "let x=1,y=2;"     `shouldBe` "Right (JSAstStatement (JSLet (JSVarInitExpression (JSIdentifier 'x') [JSDecimal '1'],JSVarInitExpression (JSIdentifier 'y') [JSDecimal '2'])))"
+        testStmt "var [a,b]=x"      `shouldBe` "Right (JSAstStatement (JSVariable (JSVarInitExpression (JSArrayLiteral [JSIdentifier 'a',JSComma,JSIdentifier 'b']) [JSIdentifier 'x'])))"
+        testStmt "const {a:b}=x"    `shouldBe` "Right (JSAstStatement (JSConstant (JSVarInitExpression (JSObjectLiteral [JSPropertyNameandValue (JSIdentifier 'a') [JSIdentifier 'b']]) [JSIdentifier 'x'])))"
 
     it "break" $ do
         testStmt "break;"       `shouldBe` "Right (JSAstStatement (JSBreak,JSSemicolon))"