Add support for destructuring in var declarations

Covers var, let, and const.

Author: rhendric

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
 --         ;

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')"

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'"

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))"