[Formatter] Colorize buffer outline and line numbers cyan

Help frame the formatter buffer for color terminals by making
the buffer outline and line numbers cyan.

Author: DougGregor

Sources/SwiftDiagnostics/DiagnosticsFormatter.swift

@@ -92,8 +92,8 @@ public struct DiagnosticsFormatter {
 
     // If there was a filename, add it first.
     if let fileName = fileName {
-      annotatedSource.append(indentString)
-      annotatedSource.append("=== \(fileName) ===\n")
+      let header = colorizeBufferOutline("===")
+      annotatedSource.append("\(indentString)\(header) \(fileName) \(header)\n")
     }
 
     /// Keep track if a line missing char should be printed
@@ -115,11 +115,11 @@ public struct DiagnosticsFormatter {
       // line numbers should be right aligned
       let lineNumberString = String(lineNumber)
       let leadingSpaces = String(repeating: " ", count: maxNumberOfDigits - lineNumberString.count)
-      let linePrefix = "\(leadingSpaces)\(lineNumberString) │ "
+      let linePrefix = "\(leadingSpaces)\(colorizeBufferOutline("\(lineNumberString) │")) "
 
       // If necessary, print a line that indicates that there was lines skipped in the source code
       if hasLineBeenSkipped && !annotatedSource.isEmpty {
-        let lineMissingInfoLine = indentString + String(repeating: " ", count: maxNumberOfDigits) + " ┆"
+        let lineMissingInfoLine = indentString + String(repeating: " ", count: maxNumberOfDigits) + " \(colorizeBufferOutline("┆"))"
         annotatedSource.append("\(lineMissingInfoLine)\n")
       }
       hasLineBeenSkipped = false
@@ -144,7 +144,7 @@ public struct DiagnosticsFormatter {
 
       for (column, diags) in diagsPerColumn {
         // compute the string that is shown before each message
-        var preMessage = indentString + String(repeating: " ", count: maxNumberOfDigits) + " ∣"
+        var preMessage = indentString + String(repeating: " ", count: maxNumberOfDigits) + " " + colorizeBufferOutline("∣")
         for c in 0..<column {
           if columnsWithDiagnostics.contains(c) {
             preMessage.append("│")
@@ -201,6 +201,24 @@ public struct DiagnosticsFormatter {
       return message.message
     }
   }
+
+  /// Apply the given color and trait to the specified text, when we are
+  /// supposed to color the output.
+  private func colorizeIfRequested(
+    _ text: String,
+    annotation: ANSIAnnotation
+  ) -> String {
+    guard colorize, !text.isEmpty else {
+      return text
+    }
+
+    return annotation.applied(to: text)
+  }
+
+  /// Colorize for the buffer outline and line numbers.
+  func colorizeBufferOutline(_ text: String) -> String {
+    colorizeIfRequested(text, annotation: .bufferOutline)
+  }
 }
 
 struct ANSIAnnotation {
@@ -248,4 +266,9 @@ struct ANSIAnnotation {
   static var normal: ANSIAnnotation {
     self.init(color: .normal, trait: .normal)
   }
+
+  /// Annotation used for the outline and line numbers of a buffer.
+  static var bufferOutline: ANSIAnnotation {
+    ANSIAnnotation(color: .cyan, trait: .normal)
+  }
 }

Sources/SwiftDiagnostics/GroupedDiagnostics.swift

@@ -145,6 +145,8 @@ extension GroupedDiagnostics {
       tree: sourceFile.tree
     )
 
+    let colorizeBufferOutline = formatter.colorizeBufferOutline
+
     let childPadding = String(slc.sourceLines.count + 1).count + 1;
 
     let childSources: [(AbsolutePosition, String)] = sourceFiles[sourceFileID.id].children.map { childBufferID in
@@ -170,16 +172,16 @@ extension GroupedDiagnostics {
 
       // Should we make this depend on the width of the snippet itself?
       let targetLineLength = 72
-      let extraLengthNeeded = targetLineLength - padding.count - sourceFile.displayName.count - 5
+      let extraLengthNeeded = targetLineLength - padding.count - sourceFile.displayName.count - 6
       let boxSuffix: String
       if extraLengthNeeded > 0 {
-        boxSuffix = String(repeating: "─", count: extraLengthNeeded)
+        boxSuffix = colorizeBufferOutline(String(repeating: "─", count: extraLengthNeeded))
       } else {
         boxSuffix = ""
       }
 
-      prefixString = padding + "╭-── " + sourceFile.displayName + boxSuffix + "\n"
-      suffixString = padding + "╰-──" + String(repeating: "─", count: sourceFile.displayName.count + 1) + boxSuffix + "\n"
+      prefixString = colorizeBufferOutline(padding + "╭-── ") + sourceFile.displayName + " " + boxSuffix + "\n"
+      suffixString = colorizeBufferOutline(padding + "╰-──" + String(repeating: "─", count: sourceFile.displayName.count + 2)) + boxSuffix + "\n"
     }
 
     // Render the buffer.
@@ -188,7 +190,7 @@ extension GroupedDiagnostics {
         fileName: isRoot ? sourceFile.displayName : nil,
         tree: sourceFile.tree,
         diags: sourceFile.diagnostics,
-        indentString: indentString,
+        indentString: colorizeBufferOutline(indentString),
         suffixText: childSources,
         sourceLocationConverter: slc
       ) + suffixString

Tests/SwiftDiagnosticsTest/DiagnosticsFormatterTests.swift

@@ -100,8 +100,8 @@ final class DiagnosticsFormatterTests: XCTestCase {
       """
 
     let expectedOutput = """
-      1 │ var foo = bar +
-        ∣                ╰─ \u{001B}[1;31merror: expected expression after operator\u{001B}[0;0m
+      \u{001B}[0;36m1 │\u{001B}[0;0m var foo = bar +
+        \u{001B}[0;36m∣\u{001B}[0;0m                ╰─ \u{001B}[1;31merror: expected expression after operator\u{001B}[0;0m
 
       """
     AssertStringsEqualWithDiff(annotate(source: source, colorize: true), expectedOutput)
@@ -112,10 +112,10 @@ final class DiagnosticsFormatterTests: XCTestCase {
       foo.[].[].[]
       """
     let expectedOutput = """
-      1 │ foo.[].[].[]
-        ∣     │  │  ╰─ \u{001B}[1;31merror: expected name in member access\u{001B}[0;0m
-        ∣     │  ╰─ \u{001B}[1;31merror: expected name in member access\u{001B}[0;0m
-        ∣     ╰─ \u{001B}[1;31merror: expected name in member access\u{001B}[0;0m
+      \u{001B}[0;36m1 │\u{001B}[0;0m foo.[].[].[]
+        \u{001B}[0;36m∣\u{001B}[0;0m     │  │  ╰─ \u{001B}[1;31merror: expected name in member access\u{001B}[0;0m
+        \u{001B}[0;36m∣\u{001B}[0;0m     │  ╰─ \u{001B}[1;31merror: expected name in member access\u{001B}[0;0m
+        \u{001B}[0;36m∣\u{001B}[0;0m     ╰─ \u{001B}[1;31merror: expected name in member access\u{001B}[0;0m
 
       """
     AssertStringsEqualWithDiff(annotate(source: source, colorize: true), expectedOutput)

Tests/SwiftDiagnosticsTest/GroupDiagnosticsFormatterTests.swift

@@ -115,7 +115,7 @@ final class GroupedDiagnosticsFormatterTests: XCTestCase {
       1 │ let pi = 3.14159
       2 │ #myAssert(pi == 3)
         ∣ ╰─ in expansion of macro 'myAssert' here
-        ╭-── #myAssert────────────────────────────────────────────────────────
+        ╭-── #myAssert ───────────────────────────────────────────────────────
         │1 │ let __a = pi
         │2 │ let __b = 3
         │3 │ if !(__a == __b) {
@@ -184,12 +184,12 @@ final class GroupedDiagnosticsFormatterTests: XCTestCase {
       1 │ let pi = 3.14159
       2 │ #myAssert(pi == 3)
         ∣ ╰─ in expansion of macro 'myAssert' here
-        ╭-── #myAssert────────────────────────────────────────────────────────
+        ╭-── #myAssert ───────────────────────────────────────────────────────
         │1 │ let __a = pi
         │2 │ let __b = 3
         │3 │ if #invertedEqualityCheck(__a, __b) {
         │  ∣    ╰─ in expansion of macro 'invertedEqualityCheck' here
-        │  ╭-── #invertedEqualityCheck────────────────────────────────────────
+        │  ╭-── #invertedEqualityCheck ───────────────────────────────────────
         │  │1 │ !(__a == __b)
         │  │  ∣       ╰─ no matching operator '==' for types 'Double' and 'Int'
         │  ╰-─────────────────────────────────────────────────────────────────