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[DAS] Inline enclosing else block assist
Fixes #56924 Change-Id: Ib697e7b29671331f4e5b87a2472e3be60f89ffa1 Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/391021 Reviewed-by: Samuel Rawlins <[email protected]> Reviewed-by: Konstantin Shcheglov <[email protected]> Auto-Submit: Felipe Morschel <[email protected]> Commit-Queue: Konstantin Shcheglov <[email protected]>
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‎pkg/analysis_server/lib/src/services/correction/assist.dart‎

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@@ -362,6 +362,16 @@ abstract final class DartAssistKind {
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DartAssistKindPriority.DEFAULT,
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"Invert 'if' statement",
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);
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static const JOIN_ELSE_WITH_IF = AssistKind(
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'dart.assist.inlineElseBlock',
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DartAssistKindPriority.DEFAULT,
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"Join the 'else' block with inner 'if' statement",
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);
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static const JOIN_IF_WITH_ELSE = AssistKind(
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'dart.assist.inlineEnclosingElseBlock',
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DartAssistKindPriority.DEFAULT,
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"Join 'if' statement with outer 'else' block",
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);
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static const JOIN_IF_WITH_INNER = AssistKind(
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'dart.assist.joinWithInnerIf',
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DartAssistKindPriority.DEFAULT,

‎pkg/analysis_server/lib/src/services/correction/assist_internal.dart‎

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@@ -60,6 +60,7 @@ import 'package:analysis_server/src/services/correction/dart/import_add_show.dar
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import 'package:analysis_server/src/services/correction/dart/inline_invocation.dart';
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import 'package:analysis_server/src/services/correction/dart/invert_conditional_expression.dart';
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import 'package:analysis_server/src/services/correction/dart/invert_if_statement.dart';
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import 'package:analysis_server/src/services/correction/dart/join_else_with_if.dart';
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import 'package:analysis_server/src/services/correction/dart/join_if_with_inner.dart';
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import 'package:analysis_server/src/services/correction/dart/join_if_with_outer.dart';
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import 'package:analysis_server/src/services/correction/dart/join_variable_declaration.dart';
@@ -147,6 +148,8 @@ class AssistProcessor {
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InlineInvocation.new,
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InvertConditionalExpression.new,
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InvertIfStatement.new,
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JoinElseWithIf.new,
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JoinIfWithElse.new,
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JoinIfWithInner.new,
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JoinIfWithOuter.new,
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JoinVariableDeclaration.new,

‎pkg/analysis_server/lib/src/services/correction/dart/join_else_with_if.dart‎

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@@ -0,0 +1,304 @@
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// Copyright (c) 2024, the Dart project authors. Please see the AUTHORS file
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// for details. All rights reserved. Use of this source code is governed by a
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// BSD-style license that can be found in the LICENSE file.
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import 'package:analysis_server/src/services/correction/assist.dart';
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import 'package:analysis_server_plugin/edit/dart/correction_producer.dart';
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import 'package:analyzer/dart/ast/ast.dart';
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import 'package:analyzer/dart/ast/token.dart';
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import 'package:analyzer_plugin/utilities/assist/assist.dart';
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import 'package:analyzer_plugin/utilities/change_builder/change_builder_core.dart';
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import 'package:analyzer_plugin/utilities/range_factory.dart';
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/// A correction processor that joins the `else` block of an `if` statement
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/// with the inner `if` statement.
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///
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/// This implementation triggers only on the enclosing `else` keyword of an if
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/// statement that contains an inner `if` statement.
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///
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/// The enclosing else block must have only one statement which is the inner
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/// `if` statement.
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class JoinElseWithIf extends _JoinIfWithElseBlock {
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JoinElseWithIf({required super.context})
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: super(DartAssistKind.JOIN_ELSE_WITH_IF);
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@override
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Future<void> compute(ChangeBuilder builder) async {
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var enclosingIfStatement = node;
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if (enclosingIfStatement is! IfStatement) {
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return;
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}
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// Checks if there is an `else` keyword in the enclosing `if` statement.
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var elseKeyword = enclosingIfStatement.elseKeyword;
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if (elseKeyword == null) {
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return;
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}
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// Check if the cursor is over the `else` keyword of the enclosing `if`.
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if (elseKeyword.offset > selectionOffset ||
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elseKeyword.end < selectionEnd) {
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return;
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}
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var elseStatement = enclosingIfStatement.elseStatement;
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if (elseStatement == null) {
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return;
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}
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// Check if the enclosing else block has only one statement which is the
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// inner `if` statement.
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if (elseStatement case Block(:var statements) when statements.length == 1) {
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if (statements.first case IfStatement innerIfStatement) {
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await _compute(
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builder,
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_getStatements(innerIfStatement),
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enclosingIfStatement,
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);
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}
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}
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}
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}
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/// A correction processor that joins the `else` block of an `if` statement
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/// with the inner `if` statement.
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///
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/// This implementation triggers only on the inner `if` keyword of an if
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/// statement that is inside the `else` block of an enclosing `if` statement.
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///
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/// The enclosing else block must have only one statement which is the inner
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/// `if` statement.
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class JoinIfWithElse extends _JoinIfWithElseBlock {
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JoinIfWithElse({required super.context})
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: super(DartAssistKind.JOIN_IF_WITH_ELSE);
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@override
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Future<void> compute(ChangeBuilder builder) async {
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var innerIfStatement = node;
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if (innerIfStatement is! IfStatement) {
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return;
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}
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// Check if the cursor is over the `if` keyword of the inner `if` statement.
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if (innerIfStatement.ifKeyword case var keyword
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when keyword.offset > selectionOffset || keyword.end < selectionEnd) {
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return;
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}
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var block = innerIfStatement.parent;
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IfStatement enclosingIfStatement;
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// If the parent is a block, the look for the enclosing `if` statement.
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if (block case Block(:var statements, parent: var blockParent)
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// Checks if the enclosing else block has only one statement which is
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// the inner `if` statement.
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when statements.length == 1 &&
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// This is just a precaution since it should alyways be true.
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statements.first == innerIfStatement &&
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// Checks if the parent is an `else` block of an enclosing `if`.
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blockParent is IfStatement &&
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blockParent.elseStatement == block) {
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enclosingIfStatement = blockParent;
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} else {
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return;
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}
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await _compute(
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builder,
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_getStatements(innerIfStatement),
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enclosingIfStatement,
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);
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}
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}
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/// A correction processor that joins the `else` block of an `if` statement
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/// with the inner `if` statement.
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///
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/// This implements [_compute] and [_getStatements] to help the subclasses
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/// with this functionality.
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///
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/// Here is an example:
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///
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/// ```dart
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/// void f() {
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/// if (1 == 1) {
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/// } else {
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/// if (2 == 2) {
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/// print(0);
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/// }
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/// }
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/// }
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/// ```
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///
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/// Becomes:
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///
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/// ```dart
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/// void f() {
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/// if (1 == 1) {
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/// } else if (2 == 2) {
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/// print(0);
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/// }
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/// }
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/// ```
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abstract class _JoinIfWithElseBlock extends ResolvedCorrectionProducer {
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@override
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final AssistKind assistKind;
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_JoinIfWithElseBlock(this.assistKind, {required super.context});
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@override
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CorrectionApplicability get applicability =>
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// TODO(applicability): comment on why.
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CorrectionApplicability.singleLocation;
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String _blockSource(Block block, String? startCommentsSource, String prefix,
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String? endCommentSource) {
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var lineRanges = range.node(block);
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var blockSource = utils.getRangeText(lineRanges);
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blockSource = utils.indentSourceLeftRight(blockSource).trimRight();
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var rightBraceIndex =
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blockSource.lastIndexOf(TokenType.CLOSE_CURLY_BRACKET.lexeme);
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var blockAfterRightBrace = blockSource.substring(rightBraceIndex);
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// If starting comments, insert them after the first new line.
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if (startCommentsSource != null) {
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var firstNewLine = blockSource.indexOf(eol);
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// If the block is missing new lines, add it (else).
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if (firstNewLine != -1) {
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var blockBeforeComment = blockSource.substring(0, firstNewLine);
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var blockAfterComment =
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blockSource.substring(firstNewLine, rightBraceIndex);
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blockSource = '$blockBeforeComment$eol$startCommentsSource'
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'$blockAfterComment';
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} else {
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var leftBraceIndex =
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blockSource.indexOf(TokenType.OPEN_CURLY_BRACKET.lexeme);
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var blockAfterComment =
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blockSource.substring(leftBraceIndex + 1, rightBraceIndex);
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if (!blockAfterComment.startsWith('$prefix${utils.oneIndent}')) {
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blockAfterComment = '$prefix${utils.oneIndent}$blockAfterComment';
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}
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blockSource = '{$eol$startCommentsSource$eol$blockAfterComment';
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}
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} else {
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blockSource = blockSource.substring(0, rightBraceIndex);
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}
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if (endCommentSource != null) {
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blockSource = blockSource.trimRight();
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blockSource += '$eol$endCommentSource$eol$prefix';
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}
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blockSource += blockAfterRightBrace;
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return blockSource;
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}
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/// Receives the [ChangeBuilder] and the enclosing and inner `if` statements.
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/// It then joins the `else` block of the outer `if` statement with the inner
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/// `if` statement.
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Future<void> _compute(ChangeBuilder builder, List<Statement> statements,
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IfStatement outerIfStatement) async {
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var elseKeyword = outerIfStatement.elseKeyword;
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if (elseKeyword == null) {
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return;
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}
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var elseStatement = outerIfStatement.elseStatement;
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if (elseStatement == null) {
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return;
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}
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// Comments after the main `else` keyword and before the block are not
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// handled.
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if (elseStatement.beginToken.precedingComments != null) {
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return;
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}
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var prefix = utils.getNodePrefix(outerIfStatement);
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await builder.addDartFileEdit(file, (builder) {
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var source = '';
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for (var statement in statements) {
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String newBlockSource;
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source += ' else ';
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CommentToken? beforeIfKeywordComments;
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CommentToken? beforeConditionComments;
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if (statement is IfStatement) {
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beforeIfKeywordComments = statement.beginToken.precedingComments;
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beforeConditionComments = statement.ifKeyword.next?.precedingComments;
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var elseCondition = statement.expression;
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var elseConditionSource = utils.getNodeText(elseCondition);
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if (statement.caseClause case var elseCaseClause?) {
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elseConditionSource += ' ${utils.getNodeText(elseCaseClause)}';
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}
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source += 'if ($elseConditionSource) ';
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statement = statement.thenStatement;
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}
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var endingComment = statement.endToken.next?.precedingComments;
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var endCommentSource = _joinCommentsSources([
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if (endingComment case var comment?) comment,
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], prefix);
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var beginCommentsSource = _joinCommentsSources([
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if (beforeIfKeywordComments case var comment?) comment,
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if (beforeConditionComments case var comment?) comment,
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if (statement.beginToken.precedingComments case var comment?) comment,
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], prefix);
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if (statement case Block block) {
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newBlockSource = _blockSource(
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block, beginCommentsSource, prefix, endCommentSource);
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} else {
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var statementSource = utils.getNodeText(statement);
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// Add indentation for the else statement if it is missing.
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if (!statementSource.startsWith(prefix)) {
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statementSource = '$prefix$statementSource';
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}
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source += '{$eol';
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if (beginCommentsSource != null) {
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source += '$beginCommentsSource$eol';
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}
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newBlockSource = '${utils.oneIndent}$statementSource';
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if (endCommentSource != null) {
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newBlockSource += '$eol$endCommentSource';
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}
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newBlockSource += '$eol$prefix}';
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}
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source += newBlockSource;
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}
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builder.addSimpleReplacement(
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range.startOffsetEndOffset(
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elseKeyword.offset - 1,
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elseStatement.end,
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),
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source,
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);
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});
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}
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/// Returns the list of statements in the `else` block of the `if` statement.
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List<Statement> _getStatements(IfStatement innerIfStatement) {
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var elses = <Statement>[innerIfStatement];
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var currentElse = innerIfStatement.elseStatement;
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while (currentElse != null) {
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if (currentElse is IfStatement) {
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elses.add(currentElse);
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currentElse = currentElse.elseStatement;
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} else {
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elses.add(currentElse);
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break;
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}
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}
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return elses;
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}
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String? _joinCommentsSources(List<CommentToken> comments, String prefix) {
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if (comments.isEmpty) {
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return null;
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}
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String source = '';
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for (var comment in comments) {
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var commentsSource = comment.lexeme;
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var nextComment = comment.next;
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var nextCommentStart = eol + prefix + utils.oneIndent;
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while (nextComment is CommentToken) {
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commentsSource += nextCommentStart + nextComment.lexeme;
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nextComment = nextComment.next;
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}
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source = '$source$eol$commentsSource';
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}
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return '$prefix${utils.oneIndent}${source.trim()}';
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}
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}

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