Remember parentheses in syntax trees.

Adding this wasn't particularly hard. Just need to ensure we don't
throw the tokens from the parser away.

To test, evaluate `5 * (2 / 3)` versus `5 * 2 / 3`.

src/Data/Syntax.hs

@@ -146,6 +146,17 @@ instance Show1 Empty where liftShowsPrec _ _ _ _ = showString "Empty"
 instance Evaluatable Empty where
   eval _ = unit
 
+-- | A parenthesized expression or statement. All the languages we target support this concept.
+
+newtype Paren a = Paren a
+  deriving (Diffable, Eq, Foldable, Functor, GAlign, Generic1, Mergeable, Ord, Show, Traversable, FreeVariables1)
+
+instance Eq1 Paren where liftEq = genericLiftEq
+instance Ord1 Paren where liftCompare = genericLiftCompare
+instance Show1 Paren where liftShowsPrec = genericLiftShowsPrec
+
+instance Evaluatable Paren where
+  eval (Paren a) = subtermValue a
 
 -- | Syntax representing a parsing or assignment error.
 data Error a = Error { errorCallStack :: ErrorStack, errorExpected :: [String], errorActual :: Maybe String, errorChildren :: [a] }

src/Language/Go/Assignment.hs

@@ -89,6 +89,7 @@ type Syntax =
    , Syntax.Error
    , Syntax.Empty
    , Syntax.Identifier
+   , Syntax.Paren
    , Syntax.Program
    , Type.Annotation
    , Type.Array
@@ -428,7 +429,7 @@ parameterDeclaration :: Assignment
 parameterDeclaration = makeTerm <$> symbol ParameterDeclaration <*> children (manyTerm expression)
 
 parenthesizedExpression :: Assignment
-parenthesizedExpression = symbol ParenthesizedExpression *> children expressions
+parenthesizedExpression = makeTerm <$> symbol ParenthesizedExpression <*> (Syntax.Paren <$> children expressions)
 
 selectorExpression :: Assignment
 selectorExpression = makeTerm <$> symbol SelectorExpression <*> children (Expression.MemberAccess <$> expression <*> expression)

src/Language/PHP/Assignment.hs

@@ -103,6 +103,7 @@ type Syntax = '[
   , Syntax.NamespaceUseDeclaration
   , Syntax.NamespaceUseGroupClause
   , Syntax.NewVariable
+  , Syntax.Paren
   , Syntax.PrintIntrinsic
   , Syntax.Program
   , Syntax.PropertyDeclaration
@@ -287,7 +288,7 @@ primaryExpression = choice [
   ]
 
 parenthesizedExpression :: Assignment
-parenthesizedExpression = symbol ParenthesizedExpression *> children (term expression)
+parenthesizedExpression = makeTerm <$> symbol ParenthesizedExpression <*> (Syntax.Paren <$> children (term expression))
 
 classConstantAccessExpression :: Assignment
 classConstantAccessExpression = makeTerm <$> symbol ClassConstantAccessExpression <*> children (Expression.MemberAccess <$> term scopeResolutionQualifier <*> term name)

src/Language/Python/Assignment.hs

@@ -79,6 +79,7 @@ type Syntax =
    , Syntax.Empty
    , Syntax.Error
    , Syntax.Identifier
+   , Syntax.Paren
    , Syntax.Program
    , Type.Annotation
    , []
@@ -190,7 +191,7 @@ keywordArgument :: Assignment
 keywordArgument = makeTerm <$> symbol KeywordArgument <*> children (Statement.Assignment [] <$> term expression <*> term expression)
 
 parenthesizedExpression :: Assignment
-parenthesizedExpression = symbol ParenthesizedExpression *> children expressions
+parenthesizedExpression = makeTerm <$> symbol ParenthesizedExpression <*> (Syntax.Paren <$> children expressions)
 
 parameter :: Assignment
 parameter =  makeTerm <$> symbol DefaultParameter <*> children (Statement.Assignment [] <$> term expression <*> term expression)

src/Language/TypeScript/Assignment.hs

@@ -86,6 +86,7 @@ type Syntax = '[
   , Syntax.Empty
   , Syntax.Error
   , Syntax.Identifier
+  , Syntax.Paren
   , Syntax.Program
   , Syntax.Context
   , Type.Readonly
@@ -783,7 +784,7 @@ variableDeclarator = makeVarDecl <$> symbol VariableDeclarator <*> children ((,,
   where makeVarDecl loc (subject, annotations, value) = makeTerm loc (Statement.Assignment [annotations] subject value)
 
 parenthesizedExpression :: Assignment
-parenthesizedExpression = symbol ParenthesizedExpression *> children (term expressions)
+parenthesizedExpression = makeTerm <$> symbol ParenthesizedExpression <*> (Syntax.Paren <$> children (term expressions))
 
 switchStatement :: Assignment
 switchStatement = makeTerm <$> symbol SwitchStatement <*> children (Statement.Match <$> term parenthesizedExpression <*> term switchBody)