Merge pull request #732 from shawnhyam/collect-line-comments

Merge adjacent .line and .docLine comments into a single element.

Author: allevato

Sources/SwiftFormat/PrettyPrint/Comment.swift

@@ -64,7 +64,7 @@ struct Comment {
 
     switch kind {
     case .line, .docLine:
-      self.text = [text.trimmingTrailingWhitespace()]
+      self.text = [text]
       self.text[0].removeFirst(kind.prefixLength)
       self.length = self.text.reduce(0, { $0 + $1.count + kind.prefixLength + 1 })
 
@@ -88,8 +88,9 @@ struct Comment {
   func print(indent: [Indent]) -> String {
     switch self.kind {
     case .line, .docLine:
-      let separator = "\n" + kind.prefix
-      return kind.prefix + self.text.joined(separator: separator)
+      let separator = "\n" + indent.indentation() + kind.prefix
+      let trimmedLines = self.text.map { $0.trimmingTrailingWhitespace() }
+      return kind.prefix + trimmedLines.joined(separator: separator)
     case .block, .docBlock:
       let separator = "\n"
       return kind.prefix + self.text.joined(separator: separator) + "*/"

Sources/SwiftFormat/PrettyPrint/TokenStreamCreator.swift

@@ -3384,14 +3384,37 @@ fileprivate final class TokenStreamCreator: SyntaxVisitor {
   /// This function also handles collapsing neighboring tokens in situations where that is
   /// desired, like merging adjacent comments and newlines.
   private func appendToken(_ token: Token) {
+    func breakAllowsCommentMerge(_ breakKind: BreakKind) -> Bool {
+      return breakKind == .same || breakKind == .continue || breakKind == .contextual
+    }
+
     if let last = tokens.last {
       switch (last, token) {
-      case (.comment(let c1, _), .comment(let c2, _))
-      where c1.kind == .docLine && c2.kind == .docLine:
-        var newComment = c1
-        newComment.addText(c2.text)
-        tokens[tokens.count - 1] = .comment(newComment, wasEndOfLine: false)
-        return
+      case (.break(let breakKind, _, .soft(1, _)), .comment(let c2, _))
+        where breakAllowsCommentMerge(breakKind) && (c2.kind == .docLine || c2.kind == .line):
+        // we are search for the pattern of [line comment] - [soft break 1] - [line comment]
+        // where the comment type is the same; these can be merged into a single comment
+        if let nextToLast = tokens.dropLast().last,
+          case let .comment(c1, false) = nextToLast, 
+          c1.kind == c2.kind
+        {
+          var mergedComment = c1
+          mergedComment.addText(c2.text)
+          tokens.removeLast()  // remove the soft break
+          // replace the original comment with the merged one
+          tokens[tokens.count - 1] = .comment(mergedComment, wasEndOfLine: false)
+
+          // need to fix lastBreakIndex because we just removed the last break
+          lastBreakIndex = tokens.lastIndex(where: {
+            switch $0 {
+            case .break: return true
+            default: return false
+            }
+          })
+          canMergeNewlinesIntoLastBreak = false
+
+          return
+        }
 
       // If we see a pair of spaces where one or both are flexible, combine them into a new token
       // with the maximum of their counts.

Tests/SwiftFormatTests/PrettyPrint/CommentTests.swift

@@ -83,6 +83,8 @@ final class CommentTests: PrettyPrintTestCase {
   func testLineComments() {
     let input =
       """
+      // Line Comment0
+
       // Line Comment1
       // Line Comment2
       let a = 123
@@ -93,6 +95,7 @@ final class CommentTests: PrettyPrintTestCase {
       // Comment 4
 
       let reallyLongVariableName = 123 // This comment should not wrap
+      // and should not combine with this comment
 
       func MyFun() {
         // just a comment
@@ -135,6 +138,8 @@ final class CommentTests: PrettyPrintTestCase {
 
     let expected =
       """
+      // Line Comment0
+
       // Line Comment1
       // Line Comment2
       let a = 123
@@ -145,6 +150,7 @@ final class CommentTests: PrettyPrintTestCase {
       // Comment 4
 
       let reallyLongVariableName = 123  // This comment should not wrap
+      // and should not combine with this comment
 
       func MyFun() {
         // just a comment
@@ -208,6 +214,13 @@ final class CommentTests: PrettyPrintTestCase {
       let c = [123, 456  // small comment
       ]
 
+      // Multiline comment
+      let d = [123,
+        // comment line 1
+        // comment line 2
+        456
+      ]
+
       /* Array comment */
       let a = [456, /* small comment */
         789]
@@ -236,6 +249,14 @@ final class CommentTests: PrettyPrintTestCase {
         123, 456,  // small comment
       ]
 
+      // Multiline comment
+      let d = [
+        123,
+        // comment line 1
+        // comment line 2
+        456,
+      ]
+
       /* Array comment */
       let a = [
         456, /* small comment */
@@ -760,4 +781,55 @@ final class CommentTests: PrettyPrintTestCase {
       ]
     )
   }
+
+  func testLineWithDocLineComment() {
+    // none of these should be merged if/when there is comment formatting
+    let input =
+      """
+      /// Doc line comment
+      // Line comment
+      /// Doc line comment
+      // Line comment
+
+      // Another line comment
+
+      """
+    assertPrettyPrintEqual(input: input, expected: input, linelength: 80)
+  }
+
+  func testNonmergeableComments() {
+    // none of these should be merged if/when there is comment formatting
+    let input =
+      """
+      let x = 1  // end of line comment
+      //
+
+      let y =  // eol comment
+        1  // another
+        + 2  // and another
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: input, linelength: 80)
+  }
+
+  func testMergeableComments() {
+    // these examples should be merged and formatted if/when there is comment formatting
+    let input =
+      """
+      let z =
+        // one comment
+        // and another comment
+        1 + 2
+
+      let w = [1, 2, 3]
+        .foo()
+        // this comment
+        // could be merged with this one
+        .bar()
+
+      """
+
+    assertPrettyPrintEqual(input: input, expected: input, linelength: 80)
+  }
 }