Format declared variable pattern. (#1361)

* Format declared variable patterns.

* Capitalize test descriptions.

* Add _indentInValue in AssignPiece and update tests.

* Clean up visitor and also handle long names with no types.

* Make TODO a regular comment.

Author: kallentu

lib/src/back_end/code_writer.dart

@@ -172,6 +172,8 @@ class CodeWriter {
   /// piece to [indent], relative to the indentation of the surrounding piece.
   ///
   /// Replaces any previous indentation set by this piece.
+  ///
+  // TODO(tall): Add another API that adds/subtracts existing indentation.
   void setIndent(int indent) {
     _options.indent = _pieceOptions[_pieceOptions.length - 2].indent + indent;
   }

lib/src/front_end/ast_node_visitor.dart

@@ -452,7 +452,15 @@ class AstNodeVisitor extends ThrowingAstVisitor<Piece> with PieceFactory {
 
   @override
   Piece visitDeclaredVariablePattern(DeclaredVariablePattern node) {
-    throw UnimplementedError();
+    var header = buildPiece((b) {
+      b.modifier(node.keyword);
+      b.visit(node.type);
+    });
+    return VariablePiece(
+      header,
+      [tokenPiece(node.name)],
+      hasType: node.type != null,
+    );
   }
 
   @override
@@ -959,6 +967,7 @@ class AstNodeVisitor extends ThrowingAstVisitor<Piece> with PieceFactory {
           b.add(AssignPiece(
             expressionPiece,
             caseClausePiece,
+            indentInValue: true,
           ));
         } else {
           b.add(expressionPiece);

lib/src/piece/assign.dart

@@ -48,8 +48,20 @@ class AssignPiece extends Piece {
   /// split at the assignment operator.
   final bool _allowInnerSplit;
 
-  AssignPiece(this.target, this.value, {bool allowInnerSplit = false})
-      : _allowInnerSplit = allowInnerSplit;
+  /// Whether there's an extra indent needed in the [value] piece when it
+  /// splits, like:
+  //
+  //    if (obj
+  //        case SomeLongTypeName
+  //            longVariableName) {
+  //      ;
+  //    }
+  final bool _indentInValue;
+
+  AssignPiece(this.target, this.value,
+      {bool allowInnerSplit = false, bool indentInValue = false})
+      : _allowInnerSplit = allowInnerSplit,
+        _indentInValue = indentInValue;
 
   // TODO(tall): The old formatter allows the first operand of a split
   // conditional expression to be on the same line as the `=`, as in:
@@ -102,6 +114,9 @@ class AssignPiece extends Piece {
 
     writer.format(target);
     writer.splitIf(state == _atOperator);
+    if (_indentInValue) {
+      writer.setIndent(Indent.expression * 2);
+    }
     writer.format(value);
   }
 

test/README.md

@@ -69,6 +69,7 @@ declaration/  - Typedef, class, enum, extension, mixin, and member declarations.
                 directories below.
 expression/   - Expressions and collection elements.
 invocation/   - Function and member invocations.
+pattern/      - Patterns.
 selection/    - Test preserving selection information.
 statement/    - Statements.
 top_level/    - Top-level directives.

test/pattern/declared_variable.stmt

@@ -0,0 +1,33 @@
+40 columns                              |
+>>> No split after "var".
+if (obj case var thisIsReallyQuiteAVeryLongVariableName) {;}
+<<<
+if (obj
+    case var thisIsReallyQuiteAVeryLongVariableName) {
+  ;
+}
+>>> No split after "final".
+if (obj case final thisIsReallyQuiteAVeryLongVariableName) {;}
+<<<
+if (obj
+    case final thisIsReallyQuiteAVeryLongVariableName) {
+  ;
+}
+>>> No split between "final" and type.
+if (obj case final ThisIsReallyQuiteAVeryLongTypeName variable) {;}
+<<<
+if (obj
+    case final ThisIsReallyQuiteAVeryLongTypeName
+        variable) {
+  ;
+}
+>>> Split between type and name.
+if (obj case SomeLongTypeName longVariableName) {
+  ;
+}
+<<<
+if (obj
+    case SomeLongTypeName
+        longVariableName) {
+  ;
+}

test/pattern/declared_variable_comment.stmt

@@ -0,0 +1,48 @@
+40 columns                              |
+>>> Line comment before "var".
+if (obj case // c
+var x) {;}
+<<<
+if (obj
+    case // c
+        var x) {
+  ;
+}
+>>> Line comment after "var".
+if (obj case var // c
+x) {;}
+<<<
+if (obj
+    case var // c
+        x) {
+  ;
+}
+>>> Line comment after variable (looks weird, but user should move comment).
+if (obj case var x // c
+) {;}
+<<<
+if (obj
+    case var x // c
+        ) {
+  ;
+}
+>>> Line comment after type.
+if (obj case List<int> // c
+x) {;}
+<<<
+if (obj
+    case List<int> // c
+        x) {
+  ;
+}
+>>> Line comment after type, before long name.
+if (obj
+    case final // c
+    thisIsReallyQuiteAVeryLongVariableName) {
+  ;
+}
+<<<
+if (obj case final // c
+        thisIsReallyQuiteAVeryLongVariableName) {
+  ;
+}

test/statement/if_case_comment.stmt

@@ -13,7 +13,7 @@ true) {;}
 <<<
 if (obj
     case // comment
-    true) {
+        true) {
   ;
 }
 >>> Line comment after case clause.
@@ -22,6 +22,6 @@ if (obj case true // comment
 <<<
 if (obj
     case true // comment
-    ) {
+        ) {
   ;
 }

test/tall_format_test.dart

@@ -14,6 +14,7 @@ void main() async {
   await testDirectory('expression', tall: true);
   await testDirectory('function', tall: true);
   await testDirectory('invocation', tall: true);
+  await testDirectory('pattern', tall: true);
   await testDirectory('selection', tall: true);
   await testDirectory('statement', tall: true);
   await testDirectory('top_level', tall: true);