Indent Options and Clarify Tab Width (#171)

<!--- IMPORTANT: If this PR addresses multiple unrelated issues, it will
be closed until separated. -->

### Description

> This is a near clone of #147, but git got messed up on that branch.
This PR improves that branch anyways.

This enables configuration of the behavior when the tab key is pressed.
Previously all tabs were converted to spaces and inserted `tabWidth`
spaces in place of the tab character. This PR clarifies that the
`tabWidth` parameter should be used for the *visual* width of tabs, and
adds an `indentOption` parameter that specifies how to handle inserting
tab characters.

Adds an `IndentOption` enum with two cases for this behavior:
- `spaces(count: Int)`
- `tab`

If `spaces(count: Int)` is specified, the editor will insert the given
number of spaces when the tab key is pressed, otherwise the tab
character will be kept.

### Related Issues

<!--- REQUIRED: Tag all related issues (e.g. * #123) -->
<!--- If this PR resolves the issue please specify (e.g. * closes #123)
-->
<!--- If this PR addresses multiple issues, these issues must be related
to one other -->

* #80 - Does not close, needs an additional PR for the tab width
setting.

### Checklist

<!--- Add things that are not yet implemented above -->

- [x] I read and understood the [contributing
guide](https://github.com/CodeEditApp/CodeEdit/blob/main/CONTRIBUTING.md)
as well as the [code of
conduct](https://github.com/CodeEditApp/CodeEdit/blob/main/CODE_OF_CONDUCT.md)
- [x] The issues this PR addresses are related to each other
- [x] My changes generate no new warnings
- [x] My code builds and runs on my machine
- [x] My changes are all related to the related issue above
- [x] I documented my code

### Screenshots


https://user-images.githubusercontent.com/35942988/228014785-85a20e2e-0465-4767-9d53-b97b4df2e11e.mov

Sources/CodeEditTextView/CodeEditTextView.swift

@@ -18,7 +18,8 @@ public struct CodeEditTextView: NSViewControllerRepresentable {
     ///   - language: The language for syntax highlighting
     ///   - theme: The theme for syntax highlighting
     ///   - font: The default font
-    ///   - tabWidth: The tab width
+    ///   - tabWidth: The visual tab width in number of spaces
+    ///   - indentOption: The behavior to use when the tab key is pressed. Defaults to 4 spaces.
     ///   - lineHeight: The line height multiplier (e.g. `1.2`)
     ///   - wrapLines: Whether lines wrap to the width of the editor
     ///   - editorOverscroll: The percentage for overscroll, between 0-1 (default: `0.0`)
@@ -33,6 +34,7 @@ public struct CodeEditTextView: NSViewControllerRepresentable {
         theme: Binding<EditorTheme>,
         font: Binding<NSFont>,
         tabWidth: Binding<Int>,
+        indentOption: Binding<IndentOption> = .constant(.spaces(count: 4)),
         lineHeight: Binding<Double>,
         wrapLines: Binding<Bool>,
         editorOverscroll: Binding<Double> = .constant(0.0),
@@ -48,6 +50,7 @@ public struct CodeEditTextView: NSViewControllerRepresentable {
         self.useThemeBackground = useThemeBackground
         self._font = font
         self._tabWidth = tabWidth
+        self._indentOption = indentOption
         self._lineHeight = lineHeight
         self._wrapLines = wrapLines
         self._editorOverscroll = editorOverscroll
@@ -62,6 +65,7 @@ public struct CodeEditTextView: NSViewControllerRepresentable {
     @Binding private var theme: EditorTheme
     @Binding private var font: NSFont
     @Binding private var tabWidth: Int
+    @Binding private var indentOption: IndentOption
     @Binding private var lineHeight: Double
     @Binding private var wrapLines: Bool
     @Binding private var editorOverscroll: Double
@@ -80,6 +84,7 @@ public struct CodeEditTextView: NSViewControllerRepresentable {
             font: font,
             theme: theme,
             tabWidth: tabWidth,
+            indentOption: indentOption,
             wrapLines: wrapLines,
             cursorPosition: $cursorPosition,
             editorOverscroll: editorOverscroll,
@@ -94,20 +99,25 @@ public struct CodeEditTextView: NSViewControllerRepresentable {
 
     public func updateNSViewController(_ controller: NSViewControllerType, context: Context) {
         controller.font = font
-        controller.tabWidth = tabWidth
         controller.wrapLines = wrapLines
         controller.useThemeBackground = useThemeBackground
         controller.lineHeightMultiple = lineHeight
         controller.editorOverscroll = editorOverscroll
         controller.contentInsets = contentInsets
 
-        // Updating the language and theme needlessly can cause highlights to be re-calculated.
+        // Updating the language, theme, tab width and indent option needlessly can cause highlights to be re-calculated
         if controller.language.id != language.id {
             controller.language = language
         }
         if controller.theme != theme {
             controller.theme = theme
         }
+        if controller.indentOption != indentOption {
+            controller.indentOption = indentOption
+        }
+        if controller.tabWidth != tabWidth {
+            controller.tabWidth = tabWidth
+        }
 
         controller.reloadUI()
         return

Sources/CodeEditTextView/Controller/STTextViewController.swift

@@ -37,8 +37,20 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
     /// Whether the code editor should use the theme background color or be transparent
     public var useThemeBackground: Bool
 
-    /// The number of spaces to use for a `tab '\t'` character
-    public var tabWidth: Int
+    /// The visual width of tab characters in the text view measured in number of spaces.
+    public var tabWidth: Int {
+        didSet {
+            paragraphStyle = generateParagraphStyle()
+            reloadUI()
+        }
+    }
+
+    /// The behavior to use when the tab key is pressed.
+    public var indentOption: IndentOption {
+        didSet {
+            setUpTextFormation()
+        }
+    }
 
     /// A multiplier for setting the line height. Defaults to `1.0`
     public var lineHeightMultiple: Double = 1.0
@@ -68,9 +80,6 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
 
     internal var highlighter: Highlighter?
 
-    /// Internal variable for tracking whether or not the textView has the correct standard attributes.
-    private var hasSetStandardAttributes: Bool = false
-
     /// The provided highlight provider.
     private var highlightProvider: HighlightProviding?
 
@@ -82,6 +91,7 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
         font: NSFont,
         theme: EditorTheme,
         tabWidth: Int,
+        indentOption: IndentOption,
         wrapLines: Bool,
         cursorPosition: Binding<(Int, Int)>,
         editorOverscroll: Double,
@@ -95,6 +105,7 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
         self.font = font
         self.theme = theme
         self.tabWidth = tabWidth
+        self.indentOption = indentOption
         self.wrapLines = wrapLines
         self.cursorPosition = cursorPosition
         self.editorOverscroll = editorOverscroll
@@ -142,6 +153,7 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
         scrollView.verticalRulerView = rulerView
         scrollView.rulersVisible = true
 
+        textView.typingAttributes = attributesFor(nil)
         textView.defaultParagraphStyle = self.paragraphStyle
         textView.font = self.font
         textView.textColor = theme.text
@@ -214,11 +226,17 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
     // MARK: UI
 
     /// A default `NSParagraphStyle` with a set `lineHeight`
-    private var paragraphStyle: NSMutableParagraphStyle {
+    private lazy var paragraphStyle: NSMutableParagraphStyle = generateParagraphStyle()
+
+    private func generateParagraphStyle() -> NSMutableParagraphStyle {
         // swiftlint:disable:next force_cast
         let paragraph = NSParagraphStyle.default.mutableCopy() as! NSMutableParagraphStyle
         paragraph.minimumLineHeight = lineHeight
         paragraph.maximumLineHeight = lineHeight
+        // TODO: Fix Tab widths
+        // This adds tab stops throughout the document instead of only changing the width of tab characters
+//        paragraph.tabStops = [NSTextTab(type: .decimalTabStopType, location: 0.0)]
+//        paragraph.defaultTabInterval = CGFloat(tabWidth) * (" " as NSString).size(withAttributes: [.font: font]).width
         return paragraph
     }
 
@@ -238,9 +256,6 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
     internal func reloadUI() {
         // if font or baseline has been modified, set the hasSetStandardAttributesFlag
         // to false to ensure attributes are updated. This allows live UI updates when changing preferences.
-        if textView?.font != font || rulerView.baselineOffset != baselineOffset {
-            hasSetStandardAttributes = false
-        }
 
         textView?.textColor = theme.text
         textView.backgroundColor = useThemeBackground ? theme.background : .clear
@@ -249,6 +264,8 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
         textView?.selectedLineHighlightColor = theme.lineHighlight
         textView?.isEditable = isEditable
         textView.highlightSelectedLine = isEditable
+        textView?.typingAttributes = attributesFor(nil)
+        textView?.defaultParagraphStyle = paragraphStyle
 
         rulerView?.backgroundColor = useThemeBackground ? theme.background : .clear
         rulerView?.separatorColor = theme.invisibles
@@ -267,15 +284,6 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
             scrollView.contentInsets.bottom = bottomContentInsets + (contentInsets?.bottom ?? 0)
         }
 
-        setStandardAttributes()
-    }
-
-    /// Sets the standard attributes (`font`, `baselineOffset`) to the whole text
-    internal func setStandardAttributes() {
-        guard let textView = textView else { return }
-        guard !hasSetStandardAttributes else { return }
-        hasSetStandardAttributes = true
-        textView.addAttributes(attributesFor(nil), range: .init(0..<textView.string.count))
         highlighter?.invalidate()
     }
 
@@ -286,7 +294,8 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
         return [
             .font: font,
             .foregroundColor: theme.colorFor(capture),
-            .baselineOffset: baselineOffset
+            .baselineOffset: baselineOffset,
+            .paragraphStyle: paragraphStyle
         ]
     }
 
@@ -331,11 +340,14 @@ public class STTextViewController: NSViewController, STTextViewDelegate, ThemeAt
         }
     }
 
-    // MARK: Key Presses
+    // MARK: Selectors
 
-    /// Handles `keyDown` events in the `textView`
     override public func keyDown(with event: NSEvent) {
-        // TODO: - This should be uncessecary
+        // This should be uneccessary but if removed STTextView receives some `keydown`s twice.
+    }
+
+    public override func insertTab(_ sender: Any?) {
+        textView.insertText("\t", replacementRange: textView.selectedRange)
     }
 
     deinit {

Sources/CodeEditTextView/Enums/IndentOption.swift

@@ -0,0 +1,32 @@
+//
+//  IndentOption.swift
+//
+//
+//  Created by Khan Winter on 3/26/23.
+//
+
+/// Represents what to insert on a tab key press.
+public enum IndentOption: Equatable {
+    case spaces(count: Int)
+    case tab
+
+    var stringValue: String {
+        switch self {
+        case .spaces(let count):
+            return String(repeating: " ", count: count)
+        case .tab:
+            return "\t"
+        }
+    }
+
+    public static func == (lhs: IndentOption, rhs: IndentOption) -> Bool {
+        switch (lhs, rhs) {
+        case (.tab, .tab):
+            return true
+        case (.spaces(let lhsCount), .spaces(let rhsCount)):
+            return lhsCount == rhsCount
+        default:
+            return false
+        }
+    }
+}

Sources/CodeEditTextView/Extensions/STTextView+/STTextView+TextInterface.swift

@@ -42,5 +42,7 @@ extension STTextView: TextInterface {
         textContentStorage.performEditingTransaction {
             textContentStorage.applyMutation(mutation)
         }
+
+        didChangeText()
     }
 }

Sources/CodeEditTextView/Filters/DeleteWhitespaceFilter.swift

@@ -11,10 +11,10 @@ import TextStory
 
 /// Filter for quickly deleting indent whitespace
 struct DeleteWhitespaceFilter: Filter {
-    let indentationUnit: String
+    let indentOption: IndentOption
 
     func processMutation(_ mutation: TextMutation, in interface: TextInterface) -> FilterAction {
-        guard mutation.string == "" && mutation.range.length == 1 else {
+        guard mutation.string == "" && mutation.range.length == 1 && indentOption != .tab else {
             return .none
         }
 
@@ -26,13 +26,14 @@ struct DeleteWhitespaceFilter: Filter {
             return .none
         }
 
+        let indentLength = indentOption.stringValue.count
         let length = mutation.range.max - preceedingNonWhitespace
-        let numberOfExtraSpaces = length % indentationUnit.count
+        let numberOfExtraSpaces = length % indentLength
 
-        if numberOfExtraSpaces == 0 && length >= indentationUnit.count {
+        if numberOfExtraSpaces == 0 && length >= indentLength {
             interface.applyMutation(
-                TextMutation(delete: NSRange(location: mutation.range.max - indentationUnit.count,
-                                             length: indentationUnit.count),
+                TextMutation(delete: NSRange(location: mutation.range.max - indentLength,
+                                             length: indentLength),
                              limit: mutation.limit)
             )
             return .discard

Sources/CodeEditTextView/Filters/STTextViewController+TextFormation.swift

@@ -18,7 +18,7 @@ extension STTextViewController {
     internal func setUpTextFormation() {
         textFilters = []
 
-        let indentationUnit = String(repeating: " ", count: tabWidth)
+        let indentationUnit = indentOption.stringValue
 
         let pairsToHandle: [(String, String)] = [
             ("{", "}"),
@@ -38,9 +38,9 @@ extension STTextViewController {
 
         setUpOpenPairFilters(pairs: pairsToHandle, whitespaceProvider: whitespaceProvider)
         setUpNewlineTabFilters(whitespaceProvider: whitespaceProvider,
-                               indentationUnit: indentationUnit)
+                               indentOption: indentOption)
         setUpDeletePairFilters(pairs: pairsToHandle)
-        setUpDeleteWhitespaceFilter(indentationUnit: indentationUnit)
+        setUpDeleteWhitespaceFilter(indentOption: indentOption)
     }
 
     /// Returns a `TextualIndenter` based on available language configuration.
@@ -70,9 +70,9 @@ extension STTextViewController {
     /// - Parameters:
     ///   - whitespaceProvider: The whitespace providers to use.
     ///   - indentationUnit: The unit of indentation to use.
-    private func setUpNewlineTabFilters(whitespaceProvider: WhitespaceProviders, indentationUnit: String) {
+    private func setUpNewlineTabFilters(whitespaceProvider: WhitespaceProviders, indentOption: IndentOption) {
         let newlineFilter: Filter = NewlineProcessingFilter(whitespaceProviders: whitespaceProvider)
-        let tabReplacementFilter: Filter = TabReplacementFilter(indentationUnit: indentationUnit)
+        let tabReplacementFilter: Filter = TabReplacementFilter(indentOption: indentOption)
 
         textFilters.append(contentsOf: [newlineFilter, tabReplacementFilter])
     }
@@ -86,8 +86,8 @@ extension STTextViewController {
     }
 
     /// Configures up the delete whitespace filter.
-    private func setUpDeleteWhitespaceFilter(indentationUnit: String) {
-        let filter = DeleteWhitespaceFilter(indentationUnit: indentationUnit)
+    private func setUpDeleteWhitespaceFilter(indentOption: IndentOption) {
+        let filter = DeleteWhitespaceFilter(indentOption: indentOption)
         textFilters.append(filter)
     }
 

Sources/CodeEditTextView/Filters/TabReplacementFilter.swift

@@ -12,11 +12,11 @@ import TextStory
 /// Filter for replacing tab characters with the user-defined indentation unit.
 /// - Note: The undentation unit can be another tab character, this is merely a point at which this can be configured.
 struct TabReplacementFilter: Filter {
-    let indentationUnit: String
+    let indentOption: IndentOption
 
     func processMutation(_ mutation: TextMutation, in interface: TextInterface) -> FilterAction {
-        if mutation.string == "\t" {
-            interface.applyMutation(TextMutation(insert: indentationUnit,
+        if mutation.string == "\t" && indentOption != .tab && mutation.delta > 0 {
+            interface.applyMutation(TextMutation(insert: indentOption.stringValue,
                                                  at: mutation.range.location,
                                                  limit: mutation.limit))
             return .discard