[WIP] Implement SA1138: Indent elements correctly

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/Helpers/IndentationHelper.cs

@@ -3,6 +3,7 @@
 
 namespace StyleCop.Analyzers.Helpers
 {
+    using System.Text;
     using Microsoft.CodeAnalysis;
     using Microsoft.CodeAnalysis.CSharp;
     using Settings.ObjectModel;
@@ -65,7 +66,7 @@ public static int GetIndentationSteps(IndentationSettings indentationSettings, S
         /// <param name="indentationSettings">The indentation settings to use.</param>
         /// <param name="indentationSteps">The number of indentation steps.</param>
         /// <returns>A string containing the amount of whitespace needed for the given indentation steps.</returns>
-        public static string GenerateIndentationString(IndentationSettings indentationSettings, int indentationSteps)
+        public static string GenerateIndentationStringForSteps(IndentationSettings indentationSettings, int indentationSteps)
         {
             string result;
             var indentationCount = indentationSteps * indentationSettings.IndentationSize;
@@ -83,6 +84,42 @@ public static string GenerateIndentationString(IndentationSettings indentationSe
             return result;
         }
 
+        /// <summary>
+        /// Generate a new indentation string for the given indentation width.
+        /// </summary>
+        /// <param name="indentationSettings">The indentation settings to use.</param>
+        /// <param name="indentationWidth">The width of the indentation string.</param>
+        /// <returns>A string containing the whitespace needed to indent code to the specified width.</returns>
+        public static string GenerateIndentationString(IndentationSettings indentationSettings, int indentationWidth) =>
+            GenerateIndentationString(indentationSettings, indentationWidth, 0);
+
+        /// <summary>
+        /// Generate a new indentation string for the given indentation width.
+        /// </summary>
+        /// <param name="indentationSettings">The indentation settings to use.</param>
+        /// <param name="indentationWidth">The width of the indentation string.</param>
+        /// <param name="startColumn">The starting column for the indentation.</param>
+        /// <returns>A string containing the whitespace needed to indent code to the specified width.</returns>
+        public static string GenerateIndentationString(IndentationSettings indentationSettings, int indentationWidth, int startColumn)
+        {
+            if (!indentationSettings.UseTabs)
+            {
+                return new string(' ', indentationWidth);
+            }
+
+            // Adjust the indentation width so a narrower first tab doesn't affect the outcome
+            indentationWidth += startColumn % indentationSettings.TabSize;
+
+            int tabCount = indentationWidth / indentationSettings.TabSize;
+            int spaceCount = indentationWidth - (tabCount * indentationSettings.TabSize);
+
+            StringBuilder builder = StringBuilderPool.Allocate();
+            builder.EnsureCapacity(tabCount + spaceCount);
+            builder.Append('\t', tabCount);
+            builder.Append(' ', spaceCount);
+            return StringBuilderPool.ReturnAndFree(builder);
+        }
+
         /// <summary>
         /// Generates a whitespace trivia with the requested indentation.
         /// </summary>
@@ -91,7 +128,7 @@ public static string GenerateIndentationString(IndentationSettings indentationSe
         /// <returns>A <see cref="SyntaxTrivia"/> containing the indentation whitespace.</returns>
         public static SyntaxTrivia GenerateWhitespaceTrivia(IndentationSettings indentationSettings, int indentationSteps)
         {
-            return SyntaxFactory.Whitespace(GenerateIndentationString(indentationSettings, indentationSteps));
+            return SyntaxFactory.Whitespace(GenerateIndentationStringForSteps(indentationSettings, indentationSteps));
         }
 
         private static int GetIndentationSteps(IndentationSettings indentationSettings, SyntaxTree syntaxTree, SyntaxTriviaList leadingTrivia)

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/LayoutRules/SA1501CodeFixProvider.cs

@@ -135,7 +135,7 @@ private static SyntaxNode ReformatStatementAndParent(Document document, Indentat
             if (nextTokenLine == statementCloseLine)
             {
                 var parentIndentationLevel = IndentationHelper.GetIndentationSteps(indentationSettings, GetStatementParent(statement.Parent));
-                var indentationString = IndentationHelper.GenerateIndentationString(indentationSettings, parentIndentationLevel);
+                var indentationString = IndentationHelper.GenerateIndentationStringForSteps(indentationSettings, parentIndentationLevel);
                 newParentNextToken = newParentNextToken.WithLeadingTrivia(SyntaxFactory.Whitespace(indentationString));
             }
 
@@ -179,8 +179,8 @@ private static BlockSyntax ReformatBlock(Document document, IndentationSettings
                 break;
             }
 
-            var indentationString = IndentationHelper.GenerateIndentationString(indentationSettings, parentIndentationLevel);
-            var statementIndentationString = IndentationHelper.GenerateIndentationString(indentationSettings, parentIndentationLevel + 1);
+            var indentationString = IndentationHelper.GenerateIndentationStringForSteps(indentationSettings, parentIndentationLevel);
+            var statementIndentationString = IndentationHelper.GenerateIndentationStringForSteps(indentationSettings, parentIndentationLevel + 1);
 
             var newOpenBraceLeadingTrivia = block.OpenBraceToken.LeadingTrivia
                 .WithoutTrailingWhitespace()
@@ -258,7 +258,7 @@ private static StatementSyntax ReformatStatement(Document document, IndentationS
                 break;
             }
 
-            var statementIndentationString = IndentationHelper.GenerateIndentationString(indentationSettings, parentIndentationLevel + 1);
+            var statementIndentationString = IndentationHelper.GenerateIndentationStringForSteps(indentationSettings, parentIndentationLevel + 1);
 
             var newFirstTokenLeadingTrivia = statement.GetFirstToken().LeadingTrivia
                 .WithoutTrailingWhitespace()

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/LayoutRules/SA1502CodeFixProvider.cs

@@ -132,8 +132,8 @@ private SyntaxNode ReformatElement(SyntaxNode syntaxRoot, SyntaxNode element, Sy
             }
 
             var parentIndentationLevel = IndentationHelper.GetIndentationSteps(indentationSettings, element);
-            var indentationString = IndentationHelper.GenerateIndentationString(indentationSettings, parentIndentationLevel);
-            var contentIndentationString = IndentationHelper.GenerateIndentationString(indentationSettings, parentIndentationLevel + 1);
+            var indentationString = IndentationHelper.GenerateIndentationStringForSteps(indentationSettings, parentIndentationLevel);
+            var contentIndentationString = IndentationHelper.GenerateIndentationStringForSteps(indentationSettings, parentIndentationLevel + 1);
 
             // reformat opening brace
             tokenSubstitutions.Add(openBraceToken, this.FormatBraceToken(openBraceToken, indentationString));

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/OrderingRules/ElementOrderCodeFixProvider.cs

@@ -141,7 +141,7 @@ private static SyntaxNode MoveMember(SyntaxNode syntaxRoot, MemberDeclarationSyn
             if (!memberToMove.HasLeadingTrivia)
             {
                 var targetIndentationLevel = IndentationHelper.GetIndentationSteps(indentationSettings, targetMember);
-                var indentationString = IndentationHelper.GenerateIndentationString(indentationSettings, targetIndentationLevel);
+                var indentationString = IndentationHelper.GenerateIndentationStringForSteps(indentationSettings, targetIndentationLevel);
                 memberToMove = memberToMove.WithLeadingTrivia(SyntaxFactory.Whitespace(indentationString));
             }
 

StyleCop.Analyzers/StyleCop.Analyzers.CodeFixes/OrderingRules/UsingCodeFixProvider.cs

@@ -123,7 +123,7 @@ private static async Task<Document> GetTransformedDocumentAsync(Document documen
             {
                 var rootNamespace = compilationUnit.Members.OfType<NamespaceDeclarationSyntax>().First();
                 var indentationLevel = IndentationHelper.GetIndentationSteps(settings.Indentation, rootNamespace);
-                usingsIndentation = IndentationHelper.GenerateIndentationString(settings.Indentation, indentationLevel + 1);
+                usingsIndentation = IndentationHelper.GenerateIndentationStringForSteps(settings.Indentation, indentationLevel + 1);
             }
             else
             {
@@ -203,7 +203,7 @@ private static void BuildReplaceMapForNamespaces(UsingsHelper usingsHelper, Dict
                         indentationSteps++;
                     }
 
-                    var indentation = IndentationHelper.GenerateIndentationString(indentationSettings, indentationSteps);
+                    var indentation = IndentationHelper.GenerateIndentationStringForSteps(indentationSettings, indentationSteps);
 
                     var modifiedUsings = usingsHelper.GenerateGroupedUsings(usingList, indentation, false, qualifyNames);
 
@@ -231,7 +231,7 @@ private static void BuildReplaceMapForConditionalDirectives(UsingsHelper usingsH
                         indentationSteps++;
                     }
 
-                    var indentation = IndentationHelper.GenerateIndentationString(indentationSettings, indentationSteps);
+                    var indentation = IndentationHelper.GenerateIndentationStringForSteps(indentationSettings, indentationSteps);
 
                     var modifiedUsings = usingsHelper.GenerateGroupedUsings(childSpan, indentation, false, qualifyNames: false);