(PowerShellGH-793) Add support for Folding Range client settings

This commit uses the the client configuration settings to modify the behaviour
of the server. In particular the Enable and ShowLastLine setting.

* The enable setting will change the provider to return null when disabled
* The ShowLastLine setting emulates the behaviour in PowerShell/vscode-powershell#1557
  * Modifies conversion method for the internal region class to FoldingRange
    object to show/hide the last line based on the extension settings
  * Modifies the tests for the default value and adds tests for the show and hide
    scenarios

Author: glennsarti

src/PowerShellEditorServices.Protocol/Server/LanguageServer.cs

@@ -1300,9 +1300,12 @@ protected Task HandleEvaluateRequest(
         private FoldingRange[] Fold(
             string documentUri)
         {
+            // TODO Should be using dynamic registrations
+            if (!this.currentSettings.CodeFolding.Enable) { return null; }
             var result = new List<FoldingRange>();
             foreach (FoldingReference fold in TokenOperations.FoldableRegions(
-                editorSession.Workspace.GetFile(documentUri).ScriptTokens))
+                editorSession.Workspace.GetFile(documentUri).ScriptTokens,
+                this.currentSettings.CodeFolding.ShowLastLine))
             {
                 result.Add(new FoldingRange {
                     EndCharacter   = value.EndCharacter,

src/PowerShellEditorServices.Protocol/Server/LanguageServerSettings.cs

@@ -20,10 +20,13 @@ public class LanguageServerSettings
 
         public CodeFormattingSettings CodeFormatting { get; set; }
 
+        public CodeFoldingSettings CodeFolding { get; set; }
+
         public LanguageServerSettings()
         {
             this.ScriptAnalysis = new ScriptAnalysisSettings();
             this.CodeFormatting = new CodeFormattingSettings();
+            this.CodeFolding = new CodeFoldingSettings();
         }
 
         public void Update(
@@ -39,6 +42,7 @@ public void Update(
                     workspaceRootPath,
                     logger);
                 this.CodeFormatting = new CodeFormattingSettings(settings.CodeFormatting);
+                this.CodeFolding.Update(settings.CodeFolding, logger);
             }
         }
     }
@@ -261,6 +265,41 @@ private Hashtable GetCustomPSSASettingsHashtable(int tabSize, bool insertSpaces)
         }
     }
 
+    /// <summary>
+    /// Code folding settings
+    /// </summary>
+    public class CodeFoldingSettings
+    {
+        /// <summary>
+        /// Whether the folding is enabled. Default is true as per VSCode
+        /// </summary>
+        public bool Enable { get; set; } = true;
+
+        /// <summary>
+        /// Whether to show or hide the last line of a folding region. Default is true as per VSCode
+        /// </summary>
+        public bool ShowLastLine { get; set; } = true;
+
+        /// <summary>
+        /// Update these settings from another settings object
+        /// </summary>
+        public void Update(
+            CodeFoldingSettings settings,
+            ILogger logger)
+        {
+            if (settings != null) {
+                if (this.Enable != settings.Enable) {
+                    this.Enable = settings.Enable;
+                    logger.Write(LogLevel.Verbose, string.Format("Using Code Folding Enabled - {0}", this.Enable));
+                }
+                if (this.ShowLastLine != settings.ShowLastLine) {
+                    this.ShowLastLine = settings.ShowLastLine;
+                    logger.Write(LogLevel.Verbose, string.Format("Using Code Folding ShowLastLine - {0}", this.ShowLastLine));
+                }
+            }
+        }
+    }
+
     public class LanguageServerSettingsWrapper
         {
             // NOTE: This property is capitalized as 'Powershell' because the

src/PowerShellEditorServices/Language/TokenOperations.cs

@@ -22,7 +22,10 @@ internal static class TokenOperations
         /// <summary>
         /// Extracts all of the unique foldable regions in a script given the list tokens
         /// </summary>
-        internal static FoldingReference[] FoldableRegions(Token[] tokens) {
+        internal static FoldingReference[] FoldableRegions(
+            Token[] tokens,
+            bool ShowLastLine)
+        {
             List<FoldingReference> foldableRegions = new List<FoldingReference>();
 
             // Find matching braces { -> }
@@ -93,6 +96,12 @@ internal static FoldingReference[] FoldableRegions(Token[] tokens) {
                 return (item.StartLine == foldableRegions[index - 1].StartLine);
             });
 
+            // Some editors have different folding UI, sometimes the lastline should be displayed
+            // If we do want to show the last line, just change the region to be one line less
+            if (ShowLastLine) {
+                foldableRegions.ForEach( item => { item.EndLine--; });
+            }
+
             return foldableRegions.ToArray();
         }
 

test/PowerShellEditorServices.Test/Language/TokenOperationsTests.cs

@@ -13,13 +13,13 @@ public class TokenOperationsTests
         /// <summary>
         /// Helper method to create a stub script file and then call FoldableRegions
         /// </summary>
-        private FoldingReference[] GetRegions(string text) {
+        private FoldingReference[] GetRegions(string text, bool showLastLine = true) {
             ScriptFile scriptFile = new ScriptFile(
                 "testfile",
                 "clienttestfile",
                 text,
                 Version.Parse("5.0"));
-            return Microsoft.PowerShell.EditorServices.TokenOperations.FoldableRegions(scriptFile.ScriptTokens);
+            return Microsoft.PowerShell.EditorServices.TokenOperations.FoldableRegions(scriptFile.ScriptTokens, showLastLine);
         }
 
         /// <summary>
@@ -113,21 +113,21 @@ double quoted herestrings should also fold
 $something = $true
 #endregion Comment Block 3";
         private FoldingReference[] expectedAllInOneScriptFolds = {
-            CreateFoldingReference(0,   0,  4, 10, "region"),
-            CreateFoldingReference(1,   0,  3,  2, "comment"),
-            CreateFoldingReference(10,  0, 15,  2, "comment"),
-            CreateFoldingReference(16, 30, 60,  1, null),
-            CreateFoldingReference(17,  0, 22,  2, "comment"),
-            CreateFoldingReference(23,  7, 26,  2, null),
-            CreateFoldingReference(28,  5, 31,  2, null),
-            CreateFoldingReference(35,  2, 37,  0, "comment"),
-            CreateFoldingReference(39,  2, 49, 14, "region"),
-            CreateFoldingReference(41,  4, 45, 14, "region"),
-            CreateFoldingReference(51,  7, 53,  3, null),
-            CreateFoldingReference(56,  7, 59,  3, null),
-            CreateFoldingReference(64,  0, 66,  0, "comment"),
-            CreateFoldingReference(67,  0, 72, 26, "region"),
-            CreateFoldingReference(68,  0, 70,  0, "comment")
+            CreateFoldingReference(0,   0,  3, 10, "region"),
+            CreateFoldingReference(1,   0,  2,  2, "comment"),
+            CreateFoldingReference(10,  0, 14,  2, "comment"),
+            CreateFoldingReference(16, 30, 59,  1, null),
+            CreateFoldingReference(17,  0, 21,  2, "comment"),
+            CreateFoldingReference(23,  7, 25,  2, null),
+            CreateFoldingReference(28,  5, 30,  2, null),
+            CreateFoldingReference(35,  2, 36,  0, "comment"),
+            CreateFoldingReference(39,  2, 48, 14, "region"),
+            CreateFoldingReference(41,  4, 44, 14, "region"),
+            CreateFoldingReference(51,  7, 52,  3, null),
+            CreateFoldingReference(56,  7, 58,  3, null),
+            CreateFoldingReference(64,  0, 65,  0, "comment"),
+            CreateFoldingReference(67,  0, 71, 26, "region"),
+            CreateFoldingReference(68,  0, 69,  0, "comment")
         };
 
         /// <summary>
@@ -168,6 +168,19 @@ public void LaguageServiceFindsFoldablRegionsWithCRLF() {
             AssertFoldingReferenceArrays(expectedAllInOneScriptFolds, result);
         }
 
+        [Fact]
+        public void LaguageServiceFindsFoldablRegionsWithoutLastLine() {
+            FoldingReference[] result = GetRegions(allInOneScript, false);
+            // Incrememnt the end line of the expected regions by one as we will
+            // be hiding the last line
+            FoldingReference[] expectedFolds = expectedAllInOneScriptFolds.Clone() as FoldingReference[];
+            for (int index = 0; index < expectedFolds.Length; index++)
+            {
+                expectedFolds[index].EndLine++;
+            }
+            AssertFoldingReferenceArrays(expectedFolds, result);
+        }
+
         [Fact]
         public void LaguageServiceFindsFoldablRegionsWithMismatchedRegions() {
             string testString =
@@ -180,7 +193,7 @@ public void LaguageServiceFindsFoldablRegionsWithMismatchedRegions() {
 #region should not fold - mismatched
 ";
             FoldingReference[] expectedFolds = {
-                CreateFoldingReference(2, 0, 4, 10, "region")
+                CreateFoldingReference(2, 0, 3, 10, "region")
             };
 
             FoldingReference[] result = GetRegions(testString);
@@ -197,8 +210,8 @@ public void LaguageServiceFindsFoldablRegionsWithDuplicateRegions() {
 })
 ";
             FoldingReference[] expectedFolds = {
-                CreateFoldingReference(1, 64, 2, 27, null),
-                CreateFoldingReference(2, 35, 4,  2, null)
+                CreateFoldingReference(1, 64, 1, 27, null),
+                CreateFoldingReference(2, 35, 3,  2, null)
             };
 
             FoldingReference[] result = GetRegions(testString);