Frontend/Typing assists: handle enter inside single line brackets

ReSharper.FSharp/test/data/features/service/typingAssist/Enter - Parens - Begin 01.fs.gold

@@ -1,4 +1,4 @@
-// ${CHAR:Enter} 
+// ${CHAR:Enter} 
 module Module
 
 let _ =

ReSharper.FSharp/test/data/features/service/typingAssist/Enter - Parens - Begin 02.fs.gold

@@ -1,4 +1,4 @@
-// ${CHAR:Enter} 
+// ${CHAR:Enter} 
 module Module
 
 let _ =

ReSharper.FSharp/test/data/features/service/typingAssist/Enter - Parens - Type 01.fs.gold

@@ -1,4 +1,4 @@
-// ${CHAR:Enter} 
+// ${CHAR:Enter} 
 module Module
 
 type T() =

ReSharper.FSharp/test/data/features/service/typingAssist/Enter - Parens - Type 02.fs.gold

@@ -1,4 +1,4 @@
-// ${CHAR:Enter} 
+// ${CHAR:Enter} 
 module Module
 
 type T() =

ReSharper.FSharp/test/data/features/service/typingAssist/Enter - Parens - Type 03.fs.gold

@@ -1,4 +1,4 @@
-// ${CHAR:Enter} 
+// ${CHAR:Enter} 
 module Module
 
 type T() =

ReSharper.FSharp/test/data/features/service/typingAssist/Enter - Parens - Type 04.fs.gold

@@ -1,4 +1,4 @@
-// ${CHAR:Enter} 
+// ${CHAR:Enter} 
 module Module
 
 type T() =

rider-fsharp/src/main/java/com/jetbrains/rider/plugins/fsharp/editorActions/FSharpEnterHandlerDelegate.kt

@@ -92,6 +92,13 @@ class FSharpEnterHandlerDelegate : EnterHandlerDelegateAdapter() {
     FSharpTokenType.END
   )
 
+  private val bracketsAllowingDeindent: TokenSet = TokenSet.create(
+    FSharpTokenType.LBRACE,
+    FSharpTokenType.LBRACK,
+    FSharpTokenType.LBRACK_BAR,
+    FSharpTokenType.LPAREN
+  )
+
   private val emptyBracketsToAddSpace = setOf(
     Pair(FSharpTokenType.LBRACE, FSharpTokenType.RBRACE),
     Pair(FSharpTokenType.LBRACK, FSharpTokenType.RBRACK),
@@ -108,7 +115,13 @@ class FSharpEnterHandlerDelegate : EnterHandlerDelegateAdapter() {
     FSharpTokenType.LBRACK_BAR,
     FSharpTokenType.LBRACK_LESS,
     FSharpTokenType.LQUOTE_TYPED,
-    FSharpTokenType.LQUOTE_UNTYPED
+    FSharpTokenType.LQUOTE_UNTYPED,
+
+    FSharpTokenType.CLASS,
+    FSharpTokenType.INTERFACE,
+    FSharpTokenType.STRUCT,
+
+    FSharpTokenType.BEGIN
   )
 
   private val rightBracketsToAddSpace = emptyBracketsToAddSpace.map { it.second }.toSet()
@@ -621,6 +634,8 @@ class FSharpEnterHandlerDelegate : EnterHandlerDelegateAdapter() {
     val document = editor.document
     val line = document.getLineNumber(tokenStart)
 
+    if (handleEnterInsideSingleLineBrackets(editor, iterator, line)) return true
+
     if (leftBracketsToAddIndent.contains(tokenType) &&
       !isSingleLineBrackets(editor, tokenStart) &&
       !isLastTokenOnLine(editor, tokenStart) &&
@@ -705,6 +720,71 @@ class FSharpEnterHandlerDelegate : EnterHandlerDelegateAdapter() {
     return true
   }
 
+  fun handleEnterInsideSingleLineBrackets(editor: Editor, iterator: HighlighterIterator, line: Int): Boolean {
+    val document = editor.document
+    val iterator = editor.highlighter.createIterator(iterator.start)
+
+    val tokenType = iterator.tokenType
+    val leftBracketStartOffset = iterator.start
+    val leftBracketEndOffset = iterator.end
+    val leftBracketLine = document.getLineNumber(leftBracketStartOffset)
+
+    if (!findRightBracket(iterator)) return false
+    if (document.getLineNumber(iterator.start) != leftBracketLine) return false
+
+    val rightBracketStartOffset = iterator.start
+
+    iterator.retreat()
+    while (iterator.tokenTypeSafe == FSharpTokenType.WHITESPACE)
+        iterator.retreat()
+
+    val lastElementEndOffset = iterator.end
+
+    val deindentIter = editor.highlighter.createIterator(leftBracketStartOffset - 1)
+    while (!deindentIter.atEnd() && isIgnored(iterator.tokenType))
+        deindentIter.retreat()
+
+    val shouldDeindent =
+        bracketsAllowingDeindent.contains(tokenType) && deindentIter.tokenType != FSharpTokenType.NEW_LINE
+
+    val baseIndentLength =
+        if (!shouldDeindent)
+            getOffsetInLine(document, line, leftBracketStartOffset)
+        else {
+            val line = getContinuedIndentLine(editor, leftBracketStartOffset, true)
+            getLineWhitespaceIndent(editor, line)
+        }
+
+    val indent = getIndentSettings(editor).indentSize
+    val baseIndentString = "\n" + " ".repeat(baseIndentLength)
+    val indentString = baseIndentString + " ".repeat(indent)
+
+    if (lastElementEndOffset == leftBracketEndOffset) {
+      val newText = if (tokenType == FSharpTokenType.LPAREN) {
+        indentString
+      } else {
+        indentString + baseIndentString
+      }
+      document.replaceString(lastElementEndOffset, rightBracketStartOffset, newText)
+    } else {
+      val firstElementIter = editor.highlighter.createIterator(leftBracketEndOffset)
+
+      while (!firstElementIter.atEnd() && isIgnored(firstElementIter.tokenTypeSafe))
+          firstElementIter.advance()
+
+      val firstElementStartOffset = firstElementIter.start
+
+      if (tokenType != FSharpTokenType.LPAREN) {
+        document.replaceString(lastElementEndOffset, rightBracketStartOffset, baseIndentString)
+      }
+      document.replaceString(leftBracketEndOffset, firstElementStartOffset, indentString)
+    }
+
+    editor.caretModel.moveToOffset(leftBracketEndOffset + indentString.length)
+    editor.scrollingModel.scrollToCaret(ScrollType.MAKE_VISIBLE)
+    return true
+  }
+
   private fun handleEnter(
     editor: Editor,
     caretOffset: Int,

rider-fsharp/src/main/java/com/jetbrains/rider/plugins/fsharp/editorActions/FSharpTypingAssistUtils.kt

@@ -42,6 +42,12 @@ class FSharpBracketMatcher : BracketMatcher(
     Pair(FSharpTokenType.LBRACE_BAR, FSharpTokenType.BAR_RBRACE),
     Pair(FSharpTokenType.LBRACK_LESS, FSharpTokenType.GREATER_RBRACK),
     Pair(FSharpTokenType.LQUOTE_TYPED, FSharpTokenType.RQUOTE_TYPED),
-    Pair(FSharpTokenType.LQUOTE_UNTYPED, FSharpTokenType.RQUOTE_UNTYPED)
+    Pair(FSharpTokenType.LQUOTE_UNTYPED, FSharpTokenType.RQUOTE_UNTYPED),
+
+    Pair(FSharpTokenType.CLASS, FSharpTokenType.END),
+    Pair(FSharpTokenType.INTERFACE, FSharpTokenType.END),
+    Pair(FSharpTokenType.STRUCT, FSharpTokenType.END),
+
+    Pair(FSharpTokenType.BEGIN, FSharpTokenType.END)
   )
 )

rider-fsharp/src/test/kotlin/com/jetbrains/rider/plugins/fsharp/test/cases/typingAssist/FSharpPatchEngineTypingAssists.kt

@@ -185,12 +185,19 @@ class FSharpEnterTypingAssistSyncTest : FSharpBackendSyncTypingAssistTestBase(Id
     "Enter 28 - No indent after else and new line",
     "Enter 29 - No indent before source",
     "Enter 30 - No indent before source 2",
+    "Enter 31 - Inside empty ctor",
     "Enter 32 - Nested binding",
     "Enter 33 - After then on line with multiple parens in row",
     "Enter 34 - After line with multiple parens in row",
     "Enter 35 - Nested binding and indent",
     "Enter 36 - Indent after =, trim before source",
+    "Enter 38 - Empty list",
+    "Enter 39 - Empty list with spaces",
+    "Enter 40 - Empty list continuing line",
+    "Enter 41 - Empty array continuing line",
     "Enter 42 - Before first list element and new line",
+    "Enter 43 - Before first list element",
+    "Enter 44 - Before first list element and spaces",
     "Enter 45 - Before first list element in multiline list",
     "Enter 46 - Before first list element in multiline list",
     "Enter 47 - Before first list element in multiline list",
@@ -261,7 +268,13 @@ class FSharpEnterTypingAssistSyncTest : FSharpBackendSyncTypingAssistTestBase(Id
     "Enter - String 12",
     "Enter - String 13",
     "Enter - String 14",
-    "Enter - String 15"
+    "Enter - String 15",
+    "Enter - Parens - Begin 01",
+    "Enter - Parens - Begin 02",
+    "Enter - Parens - Type 01",
+    "Enter - Parens - Type 02",
+    "Enter - Parens - Type 03",
+    "Enter - Parens - Type 04"
   )
 
   @DataProvider(name = SUPPORTED_BACKEND_CASES)