Fix vim-surround not working with multiple cursors

Fixes multiple cursors with vim-surround commands `cs, ds, S` (but not `ys`).

CHANGES.md

@@ -55,6 +55,7 @@ usual beta standards.
 * [VIM-696](https://youtrack.jetbrains.com/issue/VIM-696/vim-selection-issue-after-undo) Fix selection after undo
 * [VIM-744](https://youtrack.jetbrains.com/issue/VIM-744/Use-undoredo-with-count-modifier) Add count to undo/redo
 * [VIM-1862](https://youtrack.jetbrains.com/issue/VIM-1862/Ex-commands-executed-in-keymaps-and-macros-are-added-to-the-command-history) Fix command history
+* [VIM-2227](https://youtrack.jetbrains.com/issue/VIM-2227) Wrong behavior when deleting / changing surround with invalid character
 
 ### Merged PRs:
 * [468](https://github.com/JetBrains/ideavim/pull/468) by [Thomas Schouten](https://github.com/PHPirates): Implement UserDataHolder for EditorDataContext
@@ -63,6 +64,7 @@ usual beta standards.
 * [493](https://github.com/JetBrains/ideavim/pull/493) by [Matt Ellis](https://github.com/citizenmatt): Improvements to Commentary extension
 * [494](https://github.com/JetBrains/ideavim/pull/494) by [Matt Ellis](https://github.com/citizenmatt): Cleanup pre-212 CaretVisualAttributes compatibility code
 * [504](https://github.com/JetBrains/ideavim/pull/504) by [Matt Ellis](https://github.com/citizenmatt): Minor bug fixes
+* [519](https://github.com/JetBrains/ideavim/pull/519) by [chylex](https://github.com/chylex): Fix(VIM-2227): Wrong behavior when deleting / changing surround with invalid character
 
 ## 1.10.0, 2022-02-17
 

qodana.yaml

@@ -1,6 +1,8 @@
 version: 1.0
 profile:
   name: Qodana
+include:
+  - name: CheckDependencyLicenses
 exclude:
   - name: MoveVariableDeclarationIntoWhen
   - name: PluginXmlValidity
@@ -9,12 +11,15 @@ exclude:
   - name: UnusedReturnValue
   - name: All
     paths:
-      - build.gradle
+      - build.gradle.kts
       - gradle/wrapper/gradle-wrapper.properties
-      - resources/icons/youtrack.svg
+      - src/main/resources/icons/youtrack.svg
-      - src/com/maddyhome/idea/vim/ex/vimscript/VimScriptCommandHandler.java
+      - src/main/java/com/maddyhome/idea/vim/helper/SearchHelper.java
-      - src/com/maddyhome/idea/vim/helper/SearchHelper.java
+      - src/main/java/com/maddyhome/idea/vim/regexp/RegExp.kt
-      - src/com/maddyhome/idea/vim/regexp/RegExp.java
+      - src/test/java/org/jetbrains/plugins/ideavim/propertybased/samples/JavaText.kt
-      - test/org/jetbrains/plugins/ideavim/propertybased/samples/JavaText.kt
+      - src/test/java/org/jetbrains/plugins/ideavim/propertybased/samples/LoremText.kt
-      - test/org/jetbrains/plugins/ideavim/propertybased/samples/LoremText.kt
+      - src/test/java/org/jetbrains/plugins/ideavim/propertybased/samples/SimpleText.kt
-      - test/org/jetbrains/plugins/ideavim/propertybased/samples/SimpleText.kt
+      - src/main/java/com/maddyhome/idea/vim/vimscript/parser/generated/VimscriptListener.java
+      - src/main/java/com/maddyhome/idea/vim/vimscript/parser/generated/VimscriptLexer.java
+      - src/main/java/com/maddyhome/idea/vim/vimscript/parser/generated/VimscriptParser.java
+      - src/main/java/com/maddyhome/idea/vim/vimscript/parser/generated/VimscriptVisitor.java

src/main/antlr/Vimscript.g4

@@ -146,7 +146,7 @@ rShift: GREATER+;
 
 letCommands:
     (WS | COLON)* range? (WS | COLON)* LET WS+ expr WS*
-        assignmentOperator =  (ASSIGN | PLUS_ASSIGN | MINUS_ASSIGN | STAR_ASSIGN | DIV_ASSIGN | MOD_ASSIGN | DOT_ASSIGN)
+        assignmentOperator
         WS* expr WS* ((inline_comment NEW_LINE) | (NEW_LINE | BAR)+)
     #Let1Command|
 
@@ -154,6 +154,21 @@ letCommands:
     #Let2Command
 ;
 
+assignmentOperator:
+    ASSIGN | plusAssign | minusAssign | startAssign | divAssign | modAssign | dotAssign;
+plusAssign:
+    PLUS ASSIGN;
+minusAssign:
+    MINUS ASSIGN;
+startAssign:
+    STAR ASSIGN;
+divAssign:
+    DIV ASSIGN;
+modAssign:
+    MOD ASSIGN;
+dotAssign:
+    DOT ASSIGN;
+
 shortRange:
     ((QUESTION (~QUESTION)* QUESTION?) | (DIV (~DIV)* DIV?));
 range:
@@ -778,12 +793,12 @@ IS_NOT_CS:              'isnot#';
 
 // Assignment operators
 ASSIGN:                 '=';
-PLUS_ASSIGN:            '+=';
+//PLUS_ASSIGN:            '+=';
-MINUS_ASSIGN:           '-=';
+//MINUS_ASSIGN:           '-=';
-STAR_ASSIGN:            '*=';
+//STAR_ASSIGN:            '*=';
-DIV_ASSIGN:             '/=';
+//DIV_ASSIGN:             '/=';
-MOD_ASSIGN:             '%=';
+//MOD_ASSIGN:             '%=';
-DOT_ASSIGN:             '.=';
+//DOT_ASSIGN:             '.=';
 
 // Escaped chars
 ESCAPED_QUESTION:       '\\?';

src/main/java/com/maddyhome/idea/vim/extension/surround/VimSurroundExtension.kt

@@ -22,6 +22,7 @@ import com.intellij.openapi.application.runWriteAction
 import com.intellij.openapi.editor.Editor
 import com.maddyhome.idea.vim.VimPlugin
 import com.maddyhome.idea.vim.api.ExecutionContext
+import com.maddyhome.idea.vim.api.VimChangeGroup
 import com.maddyhome.idea.vim.api.VimEditor
 import com.maddyhome.idea.vim.api.injector
 import com.maddyhome.idea.vim.command.CommandState
@@ -40,6 +41,7 @@ import com.maddyhome.idea.vim.extension.VimExtensionFacade.setRegister
 import com.maddyhome.idea.vim.extension.VimExtensionHandler
 import com.maddyhome.idea.vim.helper.EditorHelper
 import com.maddyhome.idea.vim.helper.mode
+import com.maddyhome.idea.vim.helper.runWithEveryCaretAndRestore
 import com.maddyhome.idea.vim.key.OperatorFunction
 import com.maddyhome.idea.vim.newapi.IjVimCaret
 import com.maddyhome.idea.vim.newapi.IjVimEditor
@@ -84,22 +86,20 @@ class VimSurroundExtension : VimExtension {
     override val isRepeatable = true
 
     override fun execute(editor: VimEditor, context: ExecutionContext) {
-      setOperatorFunction(Operator())
+      setOperatorFunction(Operator(supportsMultipleCursors = false)) // TODO
       executeNormalWithoutMapping(injector.parser.parseKeys("g@"), editor.ij)
     }
   }
 
   private class VSurroundHandler : VimExtensionHandler {
     override fun execute(editor: VimEditor, context: ExecutionContext) {
-      val selectionStart = editor.ij.caretModel.primaryCaret.selectionStart
       // NB: Operator ignores SelectionType anyway
-      if (!Operator().apply(editor.ij, context.ij, SelectionType.CHARACTER_WISE)) {
+      if (!Operator(supportsMultipleCursors = true).apply(editor.ij, context.ij, SelectionType.CHARACTER_WISE)) {
         return
       }
       runWriteAction {
         // Leave visual mode
         executeNormalWithoutMapping(injector.parser.parseKeys("<Esc>"), editor.ij)
-        editor.ij.caretModel.moveToOffset(selectionStart)
       }
     }
   }
@@ -120,11 +120,19 @@ class VimSurroundExtension : VimExtension {
 
     companion object {
       fun change(editor: Editor, charFrom: Char, newSurround: Pair<String, String>?) {
+        editor.runWithEveryCaretAndRestore { changeAtCaret(editor, charFrom, newSurround) }
+      }
+      
+      fun changeAtCaret(editor: Editor, charFrom: Char, newSurround: Pair<String, String>?) {
         // We take over the " register, so preserve it
         val oldValue: List<KeyStroke>? = getRegister(REGISTER)
+        // Empty the " register
+        setRegister(REGISTER, null)
         // Extract the inner value
         perform("di" + pick(charFrom), editor)
         val innerValue: MutableList<KeyStroke> = getRegister(REGISTER)?.toMutableList() ?: mutableListOf()
+        // If the surrounding characters were not found, the register will be empty
+        if (innerValue.isNotEmpty()) {
           // Delete the surrounding
           perform("da" + pick(charFrom), editor)
           // Insert the surrounding characters and paste
@@ -133,11 +141,12 @@ class VimSurroundExtension : VimExtension {
             innerValue.addAll(injector.parser.parseKeys(newSurround.second))
           }
           pasteSurround(innerValue, editor)
-        // Restore the old value
-        setRegister(REGISTER, oldValue)
           // Jump back to start
           executeNormalWithoutMapping(injector.parser.parseKeys("`["), editor)
         }
+        // Restore the old value
+        setRegister(REGISTER, oldValue)
+      }
 
       private fun perform(sequence: String, editor: Editor) {
         ClipboardOptionHelper.IdeaputDisabler()
@@ -179,26 +188,44 @@ class VimSurroundExtension : VimExtension {
     }
   }
 
-  private class Operator : OperatorFunction {
+  private class Operator(private val supportsMultipleCursors: Boolean) : OperatorFunction {
     override fun apply(editor: Editor, context: DataContext, selectionType: SelectionType): Boolean {
       val c = getChar(editor)
       if (c.code == 0) return true
 
       val pair = getOrInputPair(c, editor) ?: return false
-      // XXX: Will it work with line-wise or block-wise selections?
+
-      val range = getSurroundRange(editor) ?: return false
       runWriteAction {
         val change = VimPlugin.getChange()
-        val leftSurround = pair.first
+        if (supportsMultipleCursors) {
-        val primaryCaret = editor.caretModel.primaryCaret
+          editor.runWithEveryCaretAndRestore {
-        change.insertText(IjVimEditor(editor), IjVimCaret(primaryCaret), range.startOffset, leftSurround)
+            applyOnce(editor, change, pair)
-        change.insertText(IjVimEditor(editor), IjVimCaret(primaryCaret), range.endOffset + leftSurround.length, pair.second)
+          }
+        }
+        else {
+          applyOnce(editor, change, pair)
           // Jump back to start
           executeNormalWithoutMapping(injector.parser.parseKeys("`["), editor)
         }
+      }
       return true
     }
     
+    private fun applyOnce(editor: Editor, change: VimChangeGroup, pair: Pair<String, String>) {
+      // XXX: Will it work with line-wise or block-wise selections?
+      val range = getSurroundRange(editor)
+      if (range != null) {
+        val primaryCaret = editor.caretModel.primaryCaret
+        change.insertText(IjVimEditor(editor), IjVimCaret(primaryCaret), range.startOffset, pair.first)
+        change.insertText(
+          IjVimEditor(editor),
+          IjVimCaret(primaryCaret),
+          range.endOffset + pair.first.length,
+          pair.second
+        )
+      }
+    }
+
     private fun getSurroundRange(editor: Editor): TextRange? = when (editor.mode) {
       CommandState.Mode.COMMAND -> VimPlugin.getMark().getChangeMarks(editor.vim)
       CommandState.Mode.VISUAL -> editor.caretModel.primaryCaret.run { TextRange(selectionStart, selectionEnd) }

src/main/java/com/maddyhome/idea/vim/group/ChangeGroup.java

@@ -39,7 +39,6 @@ import com.intellij.psi.codeStyle.CodeStyleManager;
 import com.intellij.psi.util.PsiUtilBase;
 import com.intellij.util.containers.ContainerUtil;
 import com.maddyhome.idea.vim.EventFacade;
-import com.maddyhome.idea.vim.RegisterActions;
 import com.maddyhome.idea.vim.VimPlugin;
 import com.maddyhome.idea.vim.api.*;
 import com.maddyhome.idea.vim.command.*;
@@ -123,10 +122,10 @@ public class ChangeGroup extends VimChangeGroupBase {
    * @param col    The column to indent to
    */
   private void insertNewLineBelow(@NotNull VimEditor editor, @NotNull VimCaret caret, int col) {
-    if (((IjVimEditor) editor).getEditor().isOneLineMode()) return;
+    if (editor.isOneLineMode()) return;
 
-    injector.getMotion().moveCaret(editor, caret, VimPlugin.getMotion().moveCaretToLineEnd(editor, caret));
+    caret.moveToOffset(injector.getMotion().moveCaretToLineEnd(editor, caret));
-    UserDataManager.setVimChangeActionSwitchMode(((IjVimEditor) editor).getEditor(), CommandState.Mode.INSERT);
+    editor.setVimChangeActionSwitchMode(CommandState.Mode.INSERT);
     insertText(editor, caret, "\n" + IndentConfig.create(((IjVimEditor) editor).getEditor()).createIndentBySize(col));
   }
 
@@ -165,41 +164,6 @@ public class ChangeGroup extends VimChangeGroupBase {
   }
 
 
-  @Override
-  public @Nullable Pair<@NotNull TextRange, @NotNull SelectionType> getDeleteRangeAndType(@NotNull VimEditor editor,
-                                                                        @NotNull VimCaret caret,
-                                                                        @NotNull ExecutionContext context,
-                                                                        final @NotNull Argument argument,
-                                                                        boolean isChange,
-                                                                        @NotNull OperatorArguments operatorArguments) {
-    final TextRange range =
-      injector.getMotion().getMotionRange(editor, caret, context, argument, operatorArguments);
-    if (range == null) return null;
-
-    // Delete motion commands that are not linewise become linewise if all the following are true:
-    // 1) The range is across multiple lines
-    // 2) There is only whitespace before the start of the range
-    // 3) There is only whitespace after the end of the range
-    SelectionType type;
-    if (argument.getMotion().isLinewiseMotion()) {
-      type = SelectionType.LINE_WISE;
-    }
-    else {
-      type = SelectionType.CHARACTER_WISE;
-    }
-    final Command motion = argument.getMotion();
-    if (!isChange && !motion.isLinewiseMotion()) {
-      VimLogicalPosition start = editor.offsetToLogicalPosition(range.getStartOffset());
-      VimLogicalPosition end = editor.offsetToLogicalPosition(range.getEndOffset());
-      if (start.getLine() != end.getLine()) {
-        if (!SearchHelper.anyNonWhitespace(((IjVimEditor) editor).getEditor(), range.getStartOffset(), -1) &&
-            !SearchHelper.anyNonWhitespace(((IjVimEditor) editor).getEditor(), range.getEndOffset(), 1)) {
-          type = SelectionType.LINE_WISE;
-        }
-      }
-    }
-    return new Pair<>(range, type);
-  }
 
   @Override
   public @Nullable Pair<@NotNull TextRange, @NotNull SelectionType> getDeleteRangeAndType2(@NotNull VimEditor editor,
@@ -236,60 +200,6 @@ public class ChangeGroup extends VimChangeGroupBase {
     return new Pair<>(range, type);
   }
 
-  /**
-   * Delete the range of text.
-   *
-   * @param editor   The editor to delete the text from
-   * @param caret    The caret to be moved after deletion
-   * @param range    The range to delete
-   * @param type     The type of deletion
-   * @param isChange Is from a change action
-   * @return true if able to delete the text, false if not
-   */
-  @Override
-  public boolean deleteRange(@NotNull VimEditor editor,
-                             @NotNull VimCaret caret,
-                             @NotNull TextRange range,
-                             @Nullable SelectionType type,
-                             boolean isChange) {
-
-    // Update the last column before we delete, or we might be retrieving the data for a line that no longer exists
-    UserDataManager.setVimLastColumn(((IjVimCaret) caret).getCaret(), InlayHelperKt.getInlayAwareVisualColumn(((IjVimCaret) caret).getCaret()));
-
-    boolean removeLastNewLine = removeLastNewLine(editor, range, type);
-    final boolean res = deleteText(editor, range, type);
-    if (removeLastNewLine) {
-      int textLength = ((IjVimEditor) editor).getEditor().getDocument().getTextLength();
-      ((IjVimEditor) editor).getEditor().getDocument().deleteString(textLength - 1, textLength);
-    }
-
-    if (res) {
-      int pos = EditorHelper.normalizeOffset(((IjVimEditor) editor).getEditor(), range.getStartOffset(), isChange);
-      if (type == SelectionType.LINE_WISE) {
-        pos = VimPlugin.getMotion()
-          .moveCaretToLineWithStartOfLineOption(editor, editor.offsetToLogicalPosition(pos).getLine(),
-                                                caret);
-      }
-      injector.getMotion().moveCaret(editor, caret, pos);
-    }
-    return res;
-  }
-
-  private boolean removeLastNewLine(@NotNull VimEditor editor, @NotNull TextRange range, @Nullable SelectionType type) {
-    int endOffset = range.getEndOffset();
-    int fileSize = EditorHelperRt.getFileSize(((IjVimEditor) editor).getEditor());
-    if (endOffset > fileSize) {
-      if (injector.getOptionService().isSet(OptionScope.GLOBAL.INSTANCE, OptionConstants.ideastrictmodeName, OptionConstants.ideastrictmodeName)) {
-        throw new IllegalStateException("Incorrect offset. File size: " + fileSize + ", offset: " + endOffset);
-      }
-      endOffset = fileSize;
-    }
-    return type == SelectionType.LINE_WISE &&
-           range.getStartOffset() != 0 &&
-           ((IjVimEditor) editor).getEditor().getDocument().getCharsSequence().charAt(endOffset - 1) != '\n' &&
-           endOffset == fileSize;
-  }
-
   @Override
   public void insertLineAround(@NotNull VimEditor editor, @NotNull ExecutionContext context, int shift) {
     com.maddyhome.idea.vim.newapi.ChangeGroupKt.insertLineAround(editor, context, shift);
@@ -303,48 +213,6 @@ public class ChangeGroup extends VimChangeGroupBase {
     return com.maddyhome.idea.vim.newapi.ChangeGroupKt.deleteRange(editor, caret, range, type);
   }
 
-  /**
-   * Delete count characters and then enter insert mode
-   *
-   * @param editor The editor to change
-   * @param caret  The caret to be moved
-   * @param count  The number of characters to change
-   * @return true if able to delete count characters, false if not
-   */
-  @Override
-  public boolean changeCharacters(@NotNull VimEditor editor, @NotNull VimCaret caret, int count) {
-    int len = EditorHelper.getLineLength(((IjVimEditor) editor).getEditor());
-    int col = ((IjVimCaret) caret).getCaret().getLogicalPosition().column;
-    if (col + count >= len) {
-      return changeEndOfLine(editor, caret, 1);
-    }
-
-    boolean res = deleteCharacter(editor, caret, count, true);
-    if (res) {
-      UserDataManager.setVimChangeActionSwitchMode(((IjVimEditor) editor).getEditor(), CommandState.Mode.INSERT);
-    }
-
-    return res;
-  }
-
-  /**
-   * Delete from the cursor to the end of count - 1 lines down and enter insert mode
-   *
-   * @param editor The editor to change
-   * @param caret  The caret to perform action on
-   * @param count  The number of lines to change
-   * @return true if able to delete count lines, false if not
-   */
-  @Override
-  public boolean changeEndOfLine(@NotNull VimEditor editor, @NotNull VimCaret caret, int count) {
-    boolean res = deleteEndOfLine(editor, caret, count);
-    if (res) {
-      injector.getMotion().moveCaret(editor, caret, VimPlugin.getMotion().moveCaretToLineEnd(editor, caret));
-      UserDataManager.setVimChangeActionSwitchMode(((IjVimEditor) editor).getEditor(), CommandState.Mode.INSERT);
-    }
-
-    return res;
-  }
 
   /**
    * Delete the text covered by the motion command argument and enter insert mode
@@ -368,9 +236,9 @@ public class ChangeGroup extends VimChangeGroupBase {
     String id = motion.getAction().getId();
     boolean kludge = false;
     boolean bigWord = id.equals(VIM_MOTION_BIG_WORD_RIGHT);
-    final CharSequence chars = ((IjVimEditor) editor).getEditor().getDocument().getCharsSequence();
+    final CharSequence chars = editor.text();
-    final int offset = ((IjVimCaret) caret).getCaret().getOffset();
+    final int offset = caret.getOffset().getPoint();
-    int fileSize = EditorHelperRt.getFileSize(((IjVimEditor) editor).getEditor());
+    int fileSize = ((int)editor.fileSize());
     if (fileSize > 0 && offset < fileSize) {
       final CharacterHelper.CharacterType charType = CharacterHelper.charType(chars.charAt(offset), bigWord);
       if (charType != CharacterHelper.CharacterType.WHITESPACE) {
@@ -379,24 +247,24 @@ public class ChangeGroup extends VimChangeGroupBase {
         if (wordMotions.contains(id) && lastWordChar && motion.getCount() == 1) {
           final boolean res = deleteCharacter(editor, caret, 1, true);
           if (res) {
-            UserDataManager.setVimChangeActionSwitchMode(((IjVimEditor) editor).getEditor(), CommandState.Mode.INSERT);
+            editor.setVimChangeActionSwitchMode(CommandState.Mode.INSERT);
           }
           return res;
         }
         switch (id) {
           case VIM_MOTION_WORD_RIGHT:
             kludge = true;
-            motion.setAction(RegisterActions.findActionOrDie(VIM_MOTION_WORD_END_RIGHT));
+            motion.setAction(injector.getActionExecutor().findVimActionOrDie(VIM_MOTION_WORD_END_RIGHT));
 
             break;
           case VIM_MOTION_BIG_WORD_RIGHT:
             kludge = true;
-            motion.setAction(RegisterActions.findActionOrDie(VIM_MOTION_BIG_WORD_END_RIGHT));
+            motion.setAction(injector.getActionExecutor().findVimActionOrDie(VIM_MOTION_BIG_WORD_END_RIGHT));
 
             break;
           case VIM_MOTION_CAMEL_RIGHT:
             kludge = true;
-            motion.setAction(RegisterActions.findActionOrDie(VIM_MOTION_CAMEL_END_RIGHT));
+            motion.setAction(injector.getActionExecutor().findVimActionOrDie(VIM_MOTION_CAMEL_END_RIGHT));
 
             break;
         }
@@ -405,8 +273,8 @@ public class ChangeGroup extends VimChangeGroupBase {
 
     if (kludge) {
       int cnt = operatorArguments.getCount1() * motion.getCount();
-      int pos1 = SearchHelper.findNextWordEnd(chars, offset, fileSize, cnt, bigWord, false);
+      int pos1 = injector.getSearchHelper().findNextWordEnd(chars, offset, fileSize, cnt, bigWord, false);
-      int pos2 = SearchHelper.findNextWordEnd(chars, pos1, fileSize, -cnt, bigWord, false);
+      int pos2 = injector.getSearchHelper().findNextWordEnd(chars, pos1, fileSize, -cnt, bigWord, false);
       if (logger.isDebugEnabled()) {
         logger.debug("pos=" + offset);
         logger.debug("pos1=" + pos1);
@@ -427,11 +295,11 @@ public class ChangeGroup extends VimChangeGroupBase {
       }
     }
 
-    if (VimPlugin.getOptionService().isSet(OptionScope.GLOBAL.INSTANCE, OptionConstants.experimentalapiName, OptionConstants.experimentalapiName)) {
+    if (injector.getOptionService().isSet(OptionScope.GLOBAL.INSTANCE, OptionConstants.experimentalapiName, OptionConstants.experimentalapiName)) {
       Pair<TextRange, SelectionType> deleteRangeAndType =
         getDeleteRangeAndType2(editor, caret, context, argument, true, operatorArguments.withCount0(count0));
       if (deleteRangeAndType == null) return false;
-      ChangeGroupKt.changeRange(((IjVimEditor) editor).getEditor(), ((IjVimCaret) caret).getCaret(), deleteRangeAndType.getFirst(), deleteRangeAndType.getSecond(), ((IjExecutionContext) context).getContext());
+      //ChangeGroupKt.changeRange(((IjVimEditor) editor).getEditor(), ((IjVimCaret) caret).getCaret(), deleteRangeAndType.getFirst(), deleteRangeAndType.getSecond(), ((IjExecutionContext) context).getContext());
       return true;
     }
     else {
@@ -442,23 +310,6 @@ public class ChangeGroup extends VimChangeGroupBase {
     }
   }
 
-  /**
-   * Counts number of lines in the visual block.
-   * <p>
-   * The result includes empty and short lines which does not have explicit start position (caret).
-   *
-   * @param editor The editor the block was selected in
-   * @param range  The range corresponding to the selected block
-   * @return total number of lines
-   */
-  public static int getLinesCountInVisualBlock(@NotNull VimEditor editor, @NotNull TextRange range) {
-    final int[] startOffsets = range.getStartOffsets();
-    if (startOffsets.length == 0) return 0;
-    final VimLogicalPosition firstStart = editor.offsetToLogicalPosition(startOffsets[0]);
-    final VimLogicalPosition lastStart = editor.offsetToLogicalPosition(startOffsets[range.size() - 1]);
-    return lastStart.getLine() - firstStart.getLine() + 1;
-  }
-
   /**
    * Toggles the case of count characters
    *
@@ -484,7 +335,7 @@ public class ChangeGroup extends VimChangeGroupBase {
                              @NotNull TextRange range,
                              boolean append,
                              @NotNull OperatorArguments operatorArguments) {
-    final int lines = getLinesCountInVisualBlock(editor, range);
+    final int lines = VimChangeGroupBase.Companion.getLinesCountInVisualBlock(editor, range);
     final VimLogicalPosition startPosition = editor.offsetToLogicalPosition(range.getStartOffset());
 
     boolean visualBlockMode = operatorArguments.getMode() == CommandState.Mode.VISUAL &&
@@ -589,24 +440,24 @@ public class ChangeGroup extends VimChangeGroupBase {
     int col = 0;
     int lines = 0;
     if (type == SelectionType.BLOCK_WISE) {
-      lines = getLinesCountInVisualBlock(editor, range);
+      lines = VimChangeGroupBase.Companion.getLinesCountInVisualBlock(editor, range);
       col = editor.offsetToLogicalPosition(range.getStartOffset()).getColumn();
-      if (UserDataManager.getVimLastColumn(((IjVimCaret) caret).getCaret()) == VimMotionGroupBase.LAST_COLUMN) {
+      if (caret.getVimLastColumn() == VimMotionGroupBase.LAST_COLUMN) {
         col = VimMotionGroupBase.LAST_COLUMN;
       }
     }
-    boolean after = range.getEndOffset() >= EditorHelperRt.getFileSize(((IjVimEditor) editor).getEditor());
+    boolean after = range.getEndOffset() >= editor.fileSize();
 
-    final VimLogicalPosition lp = editor.offsetToLogicalPosition(VimPlugin.getMotion().moveCaretToLineStartSkipLeading(editor, caret));
+    final VimLogicalPosition lp = editor.offsetToLogicalPosition(injector.getMotion().moveCaretToLineStartSkipLeading(editor, caret));
 
     boolean res = deleteRange(editor, caret, range, type, true);
     if (res) {
       if (type == SelectionType.LINE_WISE) {
         // Please don't use `getDocument().getText().isEmpty()` because it converts CharSequence into String
-        if (((IjVimEditor) editor).getEditor().getDocument().getTextLength() == 0) {
+        if (editor.fileSize() == 0) {
           insertBeforeCursor(editor, context);
         }
-        else if (after && !EditorHelperRt.endsWithNewLine(((IjVimEditor) editor).getEditor())) {
+        else if (after && !EngineEditorHelperKt.endsWithNewLine(editor)) {
           insertNewLineBelow(editor, caret, lp.getColumn());
         }
         else {

src/main/java/com/maddyhome/idea/vim/group/SearchGroup.java

@@ -890,6 +890,10 @@ public class SearchGroup extends VimSearchGroupBase implements PersistentStateCo
   @Override
   public void setLastSearchPattern(@Nullable String lastSearchPattern) {
     this.lastSearch = lastSearchPattern;
+    if (showSearchHighlight) {
+      resetIncsearchHighlights();
+      updateSearchHighlights();
+    }
   }
 
   @Override

src/main/java/com/maddyhome/idea/vim/helper/EditorHelper.kt

@@ -22,6 +22,7 @@ package com.maddyhome.idea.vim.helper
 
 import com.intellij.codeWithMe.ClientId
 import com.intellij.openapi.editor.Caret
+import com.intellij.openapi.editor.CaretState
 import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.editor.ex.util.EditorUtil
 import com.intellij.openapi.fileEditor.ex.FileEditorManagerEx
@@ -106,3 +107,41 @@ val Caret.vimLine: Int
  */
 val Editor.vimLine: Int
   get() = this.caretModel.currentCaret.vimLine
+
+inline fun Editor.runWithEveryCaretAndRestore(action: () -> Unit) {
+  val caretModel = this.caretModel
+  val carets = if (this.inBlockSubMode) null else caretModel.allCarets
+  if (carets == null || carets.size == 1) {
+    action()
+  }
+  else {
+    var initialDocumentSize = this.document.textLength
+    var documentSizeDifference = 0
+
+    val caretOffsets = carets.map { it.selectionStart to it.selectionEnd }
+    val restoredCarets = mutableListOf<CaretState>()
+
+    caretModel.removeSecondaryCarets()
+    
+    for ((selectionStart, selectionEnd) in caretOffsets) {
+      if (selectionStart == selectionEnd) {
+        caretModel.primaryCaret.moveToOffset(selectionStart + documentSizeDifference)
+      }
+      else {
+        caretModel.primaryCaret.setSelection(
+          selectionStart + documentSizeDifference,
+          selectionEnd + documentSizeDifference
+        )
+      }
+      
+      action()
+      restoredCarets.add(caretModel.caretsAndSelections.single())
+
+      val documentLength = this.document.textLength
+      documentSizeDifference += documentLength - initialDocumentSize
+      initialDocumentSize = documentLength
+    }
+
+    caretModel.caretsAndSelections = restoredCarets
+  } 
+}

src/main/java/com/maddyhome/idea/vim/helper/IjActionExecutor.kt

@@ -21,18 +21,24 @@ package com.maddyhome.idea.vim.helper
 import com.intellij.openapi.actionSystem.ActionGroup
 import com.intellij.openapi.actionSystem.ActionManager
 import com.intellij.openapi.actionSystem.ActionPlaces
+import com.intellij.openapi.actionSystem.AnAction
 import com.intellij.openapi.actionSystem.AnActionEvent
+import com.intellij.openapi.actionSystem.AnActionResult
 import com.intellij.openapi.actionSystem.DataContext
 import com.intellij.openapi.actionSystem.IdeActions
+import com.intellij.openapi.actionSystem.PlatformCoreDataKeys
 import com.intellij.openapi.actionSystem.PlatformDataKeys
 import com.intellij.openapi.actionSystem.Presentation
+import com.intellij.openapi.actionSystem.ex.ActionManagerEx
 import com.intellij.openapi.actionSystem.ex.ActionUtil
 import com.intellij.openapi.command.CommandProcessor
 import com.intellij.openapi.command.UndoConfirmationPolicy
 import com.intellij.openapi.components.Service
 import com.intellij.openapi.editor.actionSystem.DocCommandGroupId
+import com.intellij.openapi.project.IndexNotReadyException
 import com.intellij.openapi.ui.popup.JBPopupFactory
 import com.intellij.openapi.util.NlsContexts
+import com.intellij.util.SlowOperations
 import com.maddyhome.idea.vim.RegisterActions
 import com.maddyhome.idea.vim.api.ExecutionContext
 import com.maddyhome.idea.vim.api.NativeAction
@@ -95,11 +101,48 @@ class IjActionExecutor : VimActionExecutor {
       popup.showInFocusCenter()
       return true
     } else {
-      ActionUtil.performActionDumbAwareWithCallbacks(ijAction, event)
+      performDumbAwareWithCallbacks(ijAction, event) { ijAction.actionPerformed(event) }
       return true
     }
   }
 
+  // This is taken directly from ActionUtil.performActionDumbAwareWithCallbacks
+  // But with one check removed. With this check some actions (like `:w` doesn't work)
+  // https://youtrack.jetbrains.com/issue/VIM-2691/File-is-not-saved-on-w
+  private fun performDumbAwareWithCallbacks(
+    action: AnAction,
+    event: AnActionEvent,
+    performRunnable: Runnable,
+  ) {
+    val project = event.project
+    var indexError: IndexNotReadyException? = null
+    val manager = ActionManagerEx.getInstanceEx()
+    manager.fireBeforeActionPerformed(action, event)
+    val component = event.getData(PlatformCoreDataKeys.CONTEXT_COMPONENT)
+    var result: AnActionResult? = null
+    try {
+      SlowOperations.allowSlowOperations(SlowOperations.ACTION_PERFORM).use { ignore ->
+        performRunnable.run()
+        result = AnActionResult.PERFORMED
+      }
+    } catch (ex: IndexNotReadyException) {
+      indexError = ex
+      result = AnActionResult.failed(ex)
+    } catch (ex: RuntimeException) {
+      result = AnActionResult.failed(ex)
+      throw ex
+    } catch (ex: Error) {
+      result = AnActionResult.failed(ex)
+      throw ex
+    } finally {
+      if (result == null) result = AnActionResult.failed(Throwable())
+      manager.fireAfterActionPerformed(action, event, result!!)
+    }
+    if (indexError != null) {
+      ActionUtil.showDumbModeWarning(project, event)
+    }
+  }
+
   private fun canBePerformed(event: AnActionEvent, action: ActionGroup, context: DataContext): Boolean {
     val presentation = event.presentation
     return try {
@@ -155,6 +198,10 @@ class IjActionExecutor : VimActionExecutor {
     return RegisterActions.findAction(id)
   }
 
+  override fun findVimActionOrDie(id: String): EditorActionHandlerBase {
+    return RegisterActions.findActionOrDie(id)
+  }
+
   override fun getAction(actionId: String): NativeAction? {
     return ActionManager.getInstance().getAction(actionId)?.let { IjNativeAction(it) }
   }

src/main/java/com/maddyhome/idea/vim/helper/IjEditorHelper.kt

@@ -143,4 +143,8 @@ class IjEditorHelper : EngineEditorHelper {
   override fun getLeadingWhitespace(editor: VimEditor, line: Int): String {
     return EditorHelper.getLeadingWhitespace(editor.ij, line)
   }
+
+  override fun anyNonWhitespace(editor: VimEditor, offset: Int, dir: Int): Boolean {
+    return SearchHelper.anyNonWhitespace(editor.ij, offset, dir)
+  }
 }

src/main/java/com/maddyhome/idea/vim/helper/UndoRedoHelper.kt

@@ -99,5 +99,6 @@ class UndoRedoHelper : UndoRedoBase() {
     while (check() && !changeListener.hasChanged) {
       action.run()
     }
+    vimDocument.removeChangeListener(changeListener)
   }
 }

src/main/java/com/maddyhome/idea/vim/listener/IdeaSpecifics.kt

@@ -32,6 +32,7 @@ import com.intellij.openapi.actionSystem.AnActionEvent
 import com.intellij.openapi.actionSystem.CommonDataKeys
 import com.intellij.openapi.actionSystem.DataContext
 import com.intellij.openapi.actionSystem.ex.AnActionListener
+import com.intellij.openapi.actionSystem.impl.ProxyShortcutSet
 import com.intellij.openapi.editor.Editor
 import com.intellij.openapi.project.DumbAwareToggleAction
 import com.maddyhome.idea.vim.KeyHandler
@@ -70,7 +71,7 @@ object IdeaSpecifics {
       //region Track action id
       if (VimPlugin.getOptionService().isSet(OptionScope.GLOBAL, OptionConstants.trackactionidsName)) {
         if (action !is NotificationService.ActionIdNotifier.CopyActionId && action !is NotificationService.ActionIdNotifier.StopTracking) {
-          val id: String? = ActionManager.getInstance().getId(action)
+          val id: String? = ActionManager.getInstance().getId(action) ?: (action.shortcutSet as? ProxyShortcutSet)?.actionId
           VimPlugin.getNotifications(dataContext.getData(CommonDataKeys.PROJECT)).notifyActionId(id)
         }
       }

src/main/java/com/maddyhome/idea/vim/newapi/ChangeGroup.kt

@@ -28,6 +28,7 @@ import com.maddyhome.idea.vim.VimPlugin
 import com.maddyhome.idea.vim.api.ExecutionContext
 import com.maddyhome.idea.vim.api.LineDeleteShift
 import com.maddyhome.idea.vim.api.VimCaret
+import com.maddyhome.idea.vim.api.VimChangeGroupBase
 import com.maddyhome.idea.vim.api.VimEditor
 import com.maddyhome.idea.vim.api.VimMotionGroupBase
 import com.maddyhome.idea.vim.api.injector
@@ -40,7 +41,6 @@ import com.maddyhome.idea.vim.common.TextRange
 import com.maddyhome.idea.vim.common.VimRange
 import com.maddyhome.idea.vim.common.including
 import com.maddyhome.idea.vim.common.offset
-import com.maddyhome.idea.vim.group.ChangeGroup
 import com.maddyhome.idea.vim.group.MotionGroup
 import com.maddyhome.idea.vim.helper.EditorHelper
 import com.maddyhome.idea.vim.helper.inlayAwareVisualColumn
@@ -62,7 +62,7 @@ fun changeRange(
   var col = 0
   var lines = 0
   if (type === SelectionType.BLOCK_WISE) {
-    lines = ChangeGroup.getLinesCountInVisualBlock(IjVimEditor(editor), range)
+    lines = VimChangeGroupBase.getLinesCountInVisualBlock(IjVimEditor(editor), range)
     col = editor.offsetToLogicalPosition(range.startOffset).column
     if (caret.vimLastColumn == VimMotionGroupBase.LAST_COLUMN) {
       col = VimMotionGroupBase.LAST_COLUMN

src/main/java/com/maddyhome/idea/vim/newapi/IjVimSearchHelper.kt

@@ -110,6 +110,17 @@ class IjVimSearchHelper : VimSearchHelper {
     )
   }
 
+  override fun findNextWordEnd(
+    chars: CharSequence,
+    pos: Int,
+    size: Int,
+    count: Int,
+    bigWord: Boolean,
+    spaceWords: Boolean,
+  ): Int {
+    return SearchHelper.findNextWordEnd(chars, pos, size, count, bigWord, spaceWords)
+  }
+
   override fun findNextWord(editor: VimEditor, searchFrom: Int, count: Int, bigWord: Boolean): Int {
     return SearchHelper.findNextWord(
       (editor as IjVimEditor).editor,

src/main/java/com/maddyhome/idea/vim/vimscript/model/functions/handlers/JoinFunctionHandler.kt

@@ -0,0 +1,49 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2022 The IdeaVim authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.maddyhome.idea.vim.vimscript.model.functions.handlers
+
+import com.maddyhome.idea.vim.api.ExecutionContext
+import com.maddyhome.idea.vim.api.VimEditor
+import com.maddyhome.idea.vim.ex.ExException
+import com.maddyhome.idea.vim.vimscript.model.VimLContext
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimDataType
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimList
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimString
+import com.maddyhome.idea.vim.vimscript.model.expressions.Expression
+import com.maddyhome.idea.vim.vimscript.model.functions.FunctionHandler
+
+class JoinFunctionHandler : FunctionHandler() {
+  override val name: String = "join"
+  override val minimumNumberOfArguments: Int = 1
+  override val maximumNumberOfArguments: Int = 2
+
+  override fun doFunction(
+    argumentValues: List<Expression>,
+    editor: VimEditor,
+    context: ExecutionContext,
+    vimContext: VimLContext,
+  ): VimDataType {
+    val firstArgument = argumentValues[0].evaluate(editor, context, vimContext)
+    if (firstArgument !is VimList) {
+      throw ExException("E714: List required")
+    }
+    val secondArgument = argumentValues.getOrNull(1)?.evaluate(editor, context, vimContext) ?: VimString(" ")
+    return VimString(firstArgument.values.joinToString(secondArgument.asString()) { it.toString() })
+  }
+}

src/main/java/com/maddyhome/idea/vim/vimscript/model/functions/handlers/TolowerFunctionHandler.kt

@@ -0,0 +1,44 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2022 The IdeaVim authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.maddyhome.idea.vim.vimscript.model.functions.handlers
+
+import com.maddyhome.idea.vim.api.ExecutionContext
+import com.maddyhome.idea.vim.api.VimEditor
+import com.maddyhome.idea.vim.vimscript.model.VimLContext
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimDataType
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimString
+import com.maddyhome.idea.vim.vimscript.model.expressions.Expression
+import com.maddyhome.idea.vim.vimscript.model.functions.FunctionHandler
+import java.util.*
+
+class TolowerFunctionHandler : FunctionHandler() {
+  override val name: String = "tolower"
+  override val minimumNumberOfArguments: Int = 1
+  override val maximumNumberOfArguments: Int = 1
+
+  override fun doFunction(
+    argumentValues: List<Expression>,
+    editor: VimEditor,
+    context: ExecutionContext,
+    vimContext: VimLContext,
+  ): VimDataType {
+    val argumentString = argumentValues[0].evaluate(editor, context, vimContext).asString()
+    return VimString(argumentString.lowercase(Locale.getDefault()))
+  }
+}

src/main/java/com/maddyhome/idea/vim/vimscript/model/functions/handlers/ToupperFunctionHandler.kt

@@ -0,0 +1,44 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2022 The IdeaVim authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.maddyhome.idea.vim.vimscript.model.functions.handlers
+
+import com.maddyhome.idea.vim.api.ExecutionContext
+import com.maddyhome.idea.vim.api.VimEditor
+import com.maddyhome.idea.vim.vimscript.model.VimLContext
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimDataType
+import com.maddyhome.idea.vim.vimscript.model.datatypes.VimString
+import com.maddyhome.idea.vim.vimscript.model.expressions.Expression
+import com.maddyhome.idea.vim.vimscript.model.functions.FunctionHandler
+import java.util.*
+
+class ToupperFunctionHandler : FunctionHandler() {
+  override val name: String = "toupper"
+  override val minimumNumberOfArguments: Int = 1
+  override val maximumNumberOfArguments: Int = 1
+
+  override fun doFunction(
+    argumentValues: List<Expression>,
+    editor: VimEditor,
+    context: ExecutionContext,
+    vimContext: VimLContext,
+  ): VimDataType {
+    val argumentString = argumentValues[0].evaluate(editor, context, vimContext).asString()
+    return VimString(argumentString.uppercase(Locale.getDefault()))
+  }
+}

src/main/java/com/maddyhome/idea/vim/vimscript/parser/visitors/CommandVisitor.kt

@@ -180,7 +180,7 @@ object CommandVisitor : VimscriptBaseVisitor<Command>() {
   override fun visitLet1Command(ctx: VimscriptParser.Let1CommandContext): Command {
     val ranges: Ranges = parseRanges(ctx.range())
     val variable: Expression = expressionVisitor.visit(ctx.expr(0))
-    val operator = getByValue(ctx.assignmentOperator.text)
+    val operator = getByValue(ctx.assignmentOperator().text)
     val expression: Expression = expressionVisitor.visit(ctx.expr(1))
     return LetCommand(ranges, variable, operator, expression, true)
   }

src/main/resources/META-INF/includes/VimLibraryFunctions.xml

@@ -11,5 +11,8 @@
     <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.FuncrefFunctionHandler" name="funcref"/>
     <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.HasFunctionHandler" name="has"/>
     <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.SubmatchFunctionHandler" name="submatch"/>
+    <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.TolowerFunctionHandler" name="tolower"/>
+    <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.ToupperFunctionHandler" name="toupper"/>
+    <vimLibraryFunction implementation="com.maddyhome.idea.vim.vimscript.model.functions.handlers.JoinFunctionHandler" name="join"/>
   </extensions>
 </idea-plugin>

src/test/java/org/jetbrains/plugins/ideavim/action/change/UndoActionTest.kt

@@ -88,7 +88,7 @@ class UndoActionTest : VimTestCase() {
     val after = """
                 A Discovery
 
-                I1 found${c} it in a legendary land
+                I1 found$c it in a legendary land
                 all rocks and lavender and tufted grass,
                 where it was settled on some sodden sand
                 hard by the torrent of a mountain pass.

src/test/java/org/jetbrains/plugins/ideavim/ex/implementation/LongerFunctionTest.kt

@@ -0,0 +1,117 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2022 The IdeaVim authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.jetbrains.plugins.ideavim.ex.implementation
+
+import com.maddyhome.idea.vim.api.injector
+import org.jetbrains.plugins.ideavim.VimTestCase
+import org.junit.Ignore
+
+class LongerFunctionTest : VimTestCase() {
+  val script = """
+      function! IsUppercase(char)
+        return a:char >=# 'A' && a:char <=# 'Z'
+      endfunction
+
+      function! IsCaps(word)
+        return a:word ==# toupper(a:word)
+      endfunction
+
+      function! Capitalize(word)
+        return toupper(a:word[0]) .. a:word[1:]
+      endfunction
+
+      function! Split(text, delimeter)
+        let parts = []
+        let part = ''
+        for char in a:text
+          if char ==? a:delimeter
+            let parts += [part]
+            let part = ''
+          else
+            let part .= char
+          endif
+        endfor
+        let parts += [part]
+        return parts
+      endfunction
+
+      function! ToCamelCase()
+        let capitalize = 0
+        
+        normal gv"wy
+        let wordUnderCaret = @w
+        let parts = Split(wordUnderCaret, '_')
+        let result = tolower(parts[0])
+        let counter = 1
+        while counter < len(parts)
+          let result .= Capitalize(tolower(parts[counter])) 
+          let counter += 1
+        endwhile
+        execute 'normal gvc' .. result 
+      endfunction
+
+      function! ToSnakeCase()
+        normal gv"wy
+        let wordUnderCaret = @w
+        
+        let parts = []
+        let subword = ''
+        let atWordStart = 1
+        for char in wordUnderCaret
+          if IsUppercase(char) && !atWordStart
+            let parts += [toupper(subword)]
+            let subword = char
+          else
+            let subword .= char
+          endif
+
+          let atWordStart = char ==? ' '
+        endfor
+        let parts += [toupper(subword)]
+        execute 'normal gvc' .. join(parts, '_')
+      endfunction
+      
+      vnoremap u :<C-u>call ToCamelCase()<CR>
+      vnoremap U :<C-u>call ToSnakeCase()<CR>
+    """.trimIndent()
+
+  // todo normal required
+//  fun `test 1`() {
+//    configureByText("""
+//      const val ${c}VERY_IMPORTANT_VALUE = 42
+//    """.trimIndent())
+//    injector.vimscriptExecutor.execute(script)
+//    typeText(injector.parser.parseKeys("veu"))
+//    assertState("""
+//      const val veryImportantValue${c} = 42
+//    """.trimIndent())
+//  }
+
+  // todo normal required
+//  fun `test 2`() {
+//    configureByText("""
+//      val ${c}myCamelCaseValue = "Hi, I'm a simple value"
+//    """.trimIndent())
+//    injector.vimscriptExecutor.execute(script)
+//    typeText(injector.parser.parseKeys("veU"))
+//    assertState("""
+//      val MY_CAMEL_CASE_VALUE${c} = "Hi, I'm a simple value"
+//    """.trimIndent())
+//  }
+}

src/test/java/org/jetbrains/plugins/ideavim/ex/implementation/functions/BasicStringFunctions.kt

@@ -0,0 +1,55 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2022 The IdeaVim authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.jetbrains.plugins.ideavim.ex.implementation.functions
+
+import org.jetbrains.plugins.ideavim.VimTestCase
+
+class BasicStringFunctions : VimTestCase() {
+
+  fun `test toupper`() {
+    configureByText("\n")
+    typeText(commandToKeys("echo toupper('Vim is awesome')"))
+    assertExOutput("VIM IS AWESOME\n")
+  }
+
+  fun `test tolower`() {
+    configureByText("\n")
+    typeText(commandToKeys("echo toupper('Vim is awesome')"))
+    assertExOutput("vim is awesome\n")
+  }
+
+  fun `test join`() {
+    configureByText("\n")
+    typeText(commandToKeys("echo join(['Vim', 'is', 'awesome'], '_')"))
+    assertExOutput("Vim_is_awesome\n")
+  }
+
+  fun `test join without second argument`() {
+    configureByText("\n")
+    typeText(commandToKeys("echo join(['Vim', 'is', 'awesome'])"))
+    assertExOutput("Vim is awesome\n")
+  }
+
+  fun `test join with wrong first argument type`() {
+    configureByText("\n")
+    typeText(commandToKeys("echo join('Vim is awesome')"))
+    assertPluginError(true)
+    assertPluginErrorMessageContains("E714: List required")
+  }
+}

src/test/java/org/jetbrains/plugins/ideavim/ex/parser/commands/LetCommandTest.kt

@@ -0,0 +1,55 @@
+/*
+ * IdeaVim - Vim emulator for IDEs based on the IntelliJ platform
+ * Copyright (C) 2003-2022 The IdeaVim authors
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program. If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package org.jetbrains.plugins.ideavim.ex.parser.commands
+
+import com.maddyhome.idea.vim.api.injector
+import com.maddyhome.idea.vim.vimscript.model.commands.LetCommand
+import com.maddyhome.idea.vim.vimscript.model.expressions.Register
+import com.maddyhome.idea.vim.vimscript.model.expressions.SimpleExpression
+import com.maddyhome.idea.vim.vimscript.model.expressions.operators.AssignmentOperator
+import junit.framework.TestCase.assertTrue
+import org.junit.Test
+import kotlin.test.assertEquals
+
+class LetCommandTest {
+
+  @Test
+  fun `let with register is parsed correctly`() {
+    val script = injector.vimscriptParser.parse("let @+=5")
+    assertEquals(1, script.units.size)
+    val command = script.units.first()
+    assertTrue(command is LetCommand)
+    command as LetCommand
+    assertEquals(Register('+'), command.variable)
+    assertEquals(AssignmentOperator.ASSIGNMENT, command.operator)
+    assertEquals(SimpleExpression(5), command.expression)
+  }
+
+  @Test
+  fun `let with register is parsed correctly 2`() {
+    val script = injector.vimscriptParser.parse("let @--=42")
+    assertEquals(1, script.units.size)
+    val command = script.units.first()
+    assertTrue(command is LetCommand)
+    command as LetCommand
+    assertEquals(Register('-'), command.variable)
+    assertEquals(AssignmentOperator.SUBTRACTION, command.operator)
+    assertEquals(SimpleExpression(42), command.expression)
+  }
+}

src/test/java/org/jetbrains/plugins/ideavim/extension/surround/VimSurroundExtensionTest.kt

@@ -313,6 +313,17 @@ class VimSurroundExtensionTest : VimTestCase() {
     doTest(listOf("dsb"), before, after, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
   }
 
+  // VIM-2227
+  @TestWithoutNeovim(SkipNeovimReason.PLUGIN)
+  fun testDeleteInvalidSurroundingCharacter() {
+    val text = "if (${c}condition) {"
+    
+    doTest("yibds]", text, text, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
+    doTest("yibds[", text, text, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
+    doTest("yibds}", text, text, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
+    doTest("yibds{", text, text, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
+  }
+
   @TestWithoutNeovim(SkipNeovimReason.PLUGIN)
   fun testRepeatDeleteSurroundParens() {
     val before = "if ((${c}condition)) {\n}\n"
@@ -371,6 +382,17 @@ class VimSurroundExtensionTest : VimTestCase() {
     doTest(listOf("csbrE."), before, after, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
   }
 
+  // VIM-2227
+  @TestWithoutNeovim(SkipNeovimReason.PLUGIN)
+  fun testChangeInvalidSurroundingCharacter() {
+    val text = "if (${c}condition) {"
+
+    doTest("yibcs]}", text, text, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
+    doTest("yibcs[}", text, text, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
+    doTest("yibcs}]", text, text, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
+    doTest("yibcs{]", text, text, CommandState.Mode.COMMAND, CommandState.SubMode.NONE)
+  }
+
   @VimBehaviorDiffers(
     """
       <h1>Title</h1>

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/action/change/insert/InsertRegisterAction.kt

@@ -23,11 +23,12 @@ import com.maddyhome.idea.vim.api.injector
 import com.maddyhome.idea.vim.command.Argument
 import com.maddyhome.idea.vim.command.Command
 import com.maddyhome.idea.vim.command.OperatorArguments
+import com.maddyhome.idea.vim.command.SelectionType
 import com.maddyhome.idea.vim.ex.ExException
 import com.maddyhome.idea.vim.handler.VimActionHandler
+import com.maddyhome.idea.vim.put.PutData
 import com.maddyhome.idea.vim.register.Register
 import com.maddyhome.idea.vim.vimscript.model.Script
-import javax.swing.KeyStroke
 
 class InsertRegisterAction : VimActionHandler.SingleExecution() {
   override val type: Command.Type = Command.Type.INSERT
@@ -84,10 +85,10 @@ class InsertRegisterAction : VimActionHandler.SingleExecution() {
 private fun insertRegister(editor: VimEditor, context: ExecutionContext, key: Char): Boolean {
   val register: Register? = injector.registerGroup.getRegister(key)
   if (register != null) {
-    val keys: List<KeyStroke> = register.keys
+    val text = register.rawText ?: injector.parser.toPrintableString(register.keys)
-    for (k in keys) {
+    val textData = PutData.TextData(text, SelectionType.CHARACTER_WISE, emptyList())
-      injector.changeGroup.processKey(editor, context, k)
+    val putData = PutData(textData, null, 1, insertTextBeforeCaret = true, rawIndent = true, caretAfterInsertedText = true)
-    }
+    injector.put.putText(editor, context, putData)
     return true
   }
   return false

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/EngineEditorHelper.kt

@@ -33,4 +33,11 @@ interface EngineEditorHelper {
   fun inlayAwareOffsetToVisualPosition(editor: VimEditor, offset: Int): VimVisualPosition
   fun getVisualLineLength(editor: VimEditor, line: Int): Int
   fun getLeadingWhitespace(editor: VimEditor, line: Int): String
+  fun anyNonWhitespace(editor: VimEditor, offset: Int, dir: Int): Boolean
+}
+
+fun VimEditor.endsWithNewLine(): Boolean {
+  val textLength = this.fileSize().toInt()
+  if (textLength == 0) return false
+  return this.text()[textLength - 1] == '\n'
 }

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/VimActionExecutor.kt

@@ -65,6 +65,7 @@ interface VimActionExecutor {
   )
 
   fun findVimAction(id: String): EditorActionHandlerBase?
+  fun findVimActionOrDie(id: String): EditorActionHandlerBase
 
   fun getAction(actionId: String): NativeAction?
   fun getActionIdList(idPrefix: String): List<String>

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/VimChangeGroupBase.kt

@@ -1,6 +1,7 @@
 package com.maddyhome.idea.vim.api
 
 import com.maddyhome.idea.vim.KeyHandler
+import com.maddyhome.idea.vim.command.Argument
 import com.maddyhome.idea.vim.command.Command
 import com.maddyhome.idea.vim.command.CommandFlags
 import com.maddyhome.idea.vim.command.CommandState
@@ -24,6 +25,8 @@ import com.maddyhome.idea.vim.listener.SelectionVimListenerSuppressor
 import com.maddyhome.idea.vim.mark.VimMarkConstants.MARK_CHANGE_END
 import com.maddyhome.idea.vim.mark.VimMarkConstants.MARK_CHANGE_POS
 import com.maddyhome.idea.vim.mark.VimMarkConstants.MARK_CHANGE_START
+import com.maddyhome.idea.vim.options.OptionConstants
+import com.maddyhome.idea.vim.options.OptionScope
 import com.maddyhome.idea.vim.register.RegisterConstants.LAST_INSERTED_TEXT_REGISTER
 import java.awt.event.KeyEvent
 import javax.swing.KeyStroke
@@ -798,6 +801,134 @@ abstract class VimChangeGroupBase : VimChangeGroup {
     }
   }
 
+  override fun getDeleteRangeAndType(
+    editor: VimEditor,
+    caret: VimCaret,
+    context: ExecutionContext,
+    argument: Argument,
+    isChange: Boolean,
+    operatorArguments: OperatorArguments,
+  ): Pair<TextRange, SelectionType>? {
+    val range = injector.motion.getMotionRange(editor, caret, context, argument, operatorArguments) ?: return null
+
+    // Delete motion commands that are not linewise become linewise if all the following are true:
+    // 1) The range is across multiple lines
+    // 2) There is only whitespace before the start of the range
+    // 3) There is only whitespace after the end of the range
+    var type: SelectionType = if (argument.motion.isLinewiseMotion()) {
+      SelectionType.LINE_WISE
+    } else {
+      SelectionType.CHARACTER_WISE
+    }
+    val motion = argument.motion
+    if (!isChange && !motion.isLinewiseMotion()) {
+      val start = editor.offsetToLogicalPosition(range.startOffset)
+      val end = editor.offsetToLogicalPosition(range.endOffset)
+      if (start.line != end.line) {
+        if (!injector.engineEditorHelper.anyNonWhitespace(editor, range.startOffset, -1) &&
+          !injector.engineEditorHelper.anyNonWhitespace(editor, range.endOffset, 1)
+        ) {
+          type = SelectionType.LINE_WISE
+        }
+      }
+    }
+    return Pair(range, type)
+  }
+
+  /**
+   * Delete the range of text.
+   *
+   * @param editor   The editor to delete the text from
+   * @param caret    The caret to be moved after deletion
+   * @param range    The range to delete
+   * @param type     The type of deletion
+   * @param isChange Is from a change action
+   * @return true if able to delete the text, false if not
+   */
+  override fun deleteRange(
+    editor: VimEditor,
+    caret: VimCaret,
+    range: TextRange,
+    type: SelectionType?,
+    isChange: Boolean,
+  ): Boolean {
+
+    // Update the last column before we delete, or we might be retrieving the data for a line that no longer exists
+    caret.vimLastColumn = caret.inlayAwareVisualColumn
+    val removeLastNewLine = removeLastNewLine(editor, range, type)
+    val res = deleteText(editor, range, type)
+    if (removeLastNewLine) {
+      val textLength = editor.fileSize().toInt()
+      editor.deleteString(TextRange(textLength - 1, textLength))
+    }
+    if (res) {
+      var pos = injector.engineEditorHelper.normalizeOffset(editor, range.startOffset, isChange)
+      if (type === SelectionType.LINE_WISE) {
+        pos = injector.motion
+          .moveCaretToLineWithStartOfLineOption(
+            editor, editor.offsetToLogicalPosition(pos).line,
+            caret
+          )
+      }
+      injector.motion.moveCaret(editor, caret, pos)
+    }
+    return res
+  }
+
+  private fun removeLastNewLine(editor: VimEditor, range: TextRange, type: SelectionType?): Boolean {
+    var endOffset = range.endOffset
+    val fileSize = editor.fileSize().toInt()
+    if (endOffset > fileSize) {
+      check(
+        !injector.optionService.isSet(
+          OptionScope.GLOBAL,
+          OptionConstants.ideastrictmodeName,
+          OptionConstants.ideastrictmodeName
+        )
+      ) { "Incorrect offset. File size: $fileSize, offset: $endOffset" }
+      endOffset = fileSize
+    }
+    return (type === SelectionType.LINE_WISE) && range.startOffset != 0 && editor.text()[endOffset - 1] != '\n' && endOffset == fileSize
+  }
+
+  /**
+   * Delete from the cursor to the end of count - 1 lines down and enter insert mode
+   *
+   * @param editor The editor to change
+   * @param caret  The caret to perform action on
+   * @param count  The number of lines to change
+   * @return true if able to delete count lines, false if not
+   */
+  override fun changeEndOfLine(editor: VimEditor, caret: VimCaret, count: Int): Boolean {
+    val res = deleteEndOfLine(editor, caret, count)
+    if (res) {
+      caret.moveToOffset(injector.motion.moveCaretToLineEnd(editor, caret))
+      editor.vimChangeActionSwitchMode = CommandState.Mode.INSERT
+    }
+    return res
+  }
+
+  /**
+   * Delete count characters and then enter insert mode
+   *
+   * @param editor The editor to change
+   * @param caret  The caret to be moved
+   * @param count  The number of characters to change
+   * @return true if able to delete count characters, false if not
+   */
+  override fun changeCharacters(editor: VimEditor, caret: VimCaret, count: Int): Boolean {
+    val len = injector.engineEditorHelper.getLineLength(editor)
+    val col = caret.getLogicalPosition().column
+    if (col + count >= len) {
+      return changeEndOfLine(editor, caret, 1)
+    }
+    val res = deleteCharacter(editor, caret, count, true)
+    if (res) {
+      editor.vimChangeActionSwitchMode = CommandState.Mode.INSERT
+    }
+    return res
+  }
+
   /**
    * Clears all the keystrokes from the current insert command
    *
@@ -871,6 +1002,24 @@ abstract class VimChangeGroupBase : VimChangeGroup {
   companion object {
     private const val MAX_REPEAT_CHARS_COUNT = 10000
     private val logger = vimLogger<VimChangeGroupBase>()
+
+    /**
+     * Counts number of lines in the visual block.
+     *
+     *
+     * The result includes empty and short lines which does not have explicit start position (caret).
+     *
+     * @param editor The editor the block was selected in
+     * @param range  The range corresponding to the selected block
+     * @return total number of lines
+     */
+    fun getLinesCountInVisualBlock(editor: VimEditor, range: TextRange): Int {
+      val startOffsets = range.startOffsets
+      if (startOffsets.isEmpty()) return 0
+      val firstStart = editor.offsetToLogicalPosition(startOffsets[0])
+      val lastStart = editor.offsetToLogicalPosition(startOffsets[range.size() - 1])
+      return lastStart.line - firstStart.line + 1
+    }
   }
 }
 

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/api/VimSearchHelper.kt

@@ -75,6 +75,15 @@ interface VimSearchHelper {
     bigWord: Boolean,
   ): Int
 
+  fun findNextWordEnd(
+    chars: CharSequence,
+    pos: Int,
+    size: Int,
+    count: Int,
+    bigWord: Boolean,
+    spaceWords: Boolean,
+  ): Int
+
   fun findNextWord(editor: VimEditor, searchFrom: Int, count: Int, bigWord: Boolean): Int
 
   fun findPattern(

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/put/VimPutBase.kt

@@ -12,6 +12,7 @@ import com.maddyhome.idea.vim.command.isChar
 import com.maddyhome.idea.vim.command.isLine
 import com.maddyhome.idea.vim.common.TextRange
 import com.maddyhome.idea.vim.helper.firstOrNull
+import com.maddyhome.idea.vim.helper.mode
 import com.maddyhome.idea.vim.mark.VimMarkConstants.MARK_CHANGE_POS
 import java.util.*
 import kotlin.math.abs
@@ -140,7 +141,9 @@ abstract class VimPutBase : VimPut {
       }
       "postEndOffset" -> caret.moveToOffset(endOffset + 1)
       "preLineEndOfEndOffset" -> {
-        val pos = min(endOffset, editor.getLineEndForOffset(endOffset - 1) - 1)
+        var rightestPosition = editor.getLineEndForOffset(endOffset - 1)
+        if (editor.mode != CommandState.Mode.INSERT) --rightestPosition // it's not possible to place a caret at the end of the line in any mode except insert
+        val pos = min(endOffset, rightestPosition)
         caret.moveToOffset(pos)
       }
     }

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/register/VimRegisterGroup.kt

@@ -48,6 +48,11 @@ interface VimRegisterGroup {
     isDelete: Boolean,
   ): Boolean
 
+  /**
+   * Stores text to any writable register (used for the let command)
+   */
+  fun storeText(register: Char, text: String): Boolean
+
   /**
    * Stores text, character wise, in the given special register
    *

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/register/VimRegisterGroupBase.kt

@@ -18,6 +18,7 @@ import com.maddyhome.idea.vim.register.RegisterConstants.RECORDABLE_REGISTERS
 import com.maddyhome.idea.vim.register.RegisterConstants.SMALL_DELETION_REGISTER
 import com.maddyhome.idea.vim.register.RegisterConstants.UNNAMED_REGISTER
 import com.maddyhome.idea.vim.register.RegisterConstants.VALID_REGISTERS
+import com.maddyhome.idea.vim.register.RegisterConstants.WRITABLE_REGISTERS
 import com.maddyhome.idea.vim.vimscript.model.datatypes.VimString
 import javax.swing.KeyStroke
 
@@ -292,6 +293,24 @@ abstract class VimRegisterGroupBase : VimRegisterGroup {
     return true
   }
 
+  override fun storeText(register: Char, text: String): Boolean {
+    if (!WRITABLE_REGISTERS.contains(register)) {
+      return false
+    }
+    logger.debug { "register '$register' contains: \"$text\"" }
+    val textToStore = if (register.isUpperCase()) {
+      (getRegister(register.lowercaseChar())?.rawText ?: "") + text
+    } else {
+      text
+    }
+    val reg = Register(register, SelectionType.CHARACTER_WISE, textToStore, ArrayList())
+    saveRegister(register, reg)
+    if (register == '/') {
+      injector.searchGroup.lastSearchPattern = text // todo we should not have this field if we have the "/" register
+    }
+    return true
+  }
+
   private fun guessSelectionType(text: String): SelectionType {
     return if (text.endsWith("\n")) SelectionType.LINE_WISE else SelectionType.CHARACTER_WISE
   }

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/vimscript/model/commands/LetCommand.kt

@@ -21,9 +21,11 @@ package com.maddyhome.idea.vim.vimscript.model.commands
 import com.maddyhome.idea.vim.api.ExecutionContext
 import com.maddyhome.idea.vim.api.VimEditor
 import com.maddyhome.idea.vim.api.injector
+import com.maddyhome.idea.vim.diagnostic.vimLogger
 import com.maddyhome.idea.vim.ex.ExException
 import com.maddyhome.idea.vim.ex.ranges.Ranges
 import com.maddyhome.idea.vim.options.OptionScope
+import com.maddyhome.idea.vim.register.RegisterConstants
 import com.maddyhome.idea.vim.vimscript.model.ExecutionResult
 import com.maddyhome.idea.vim.vimscript.model.Script
 import com.maddyhome.idea.vim.vimscript.model.VimLContext
@@ -56,8 +58,12 @@ data class LetCommand(
   val isSyntaxSupported: Boolean,
 ) : Command.SingleExecution(ranges) {
 
+  companion object {
+    private val logger = vimLogger<LetCommand>()
+  }
   override val argFlags = flags(RangeFlag.RANGE_FORBIDDEN, ArgumentFlag.ARGUMENT_OPTIONAL, Access.READ_ONLY)
 
+
   @Throws(ExException::class)
   override fun processCommand(editor: VimEditor, context: ExecutionContext): ExecutionResult {
     if (!isSyntaxSupported) return ExecutionResult.Error
@@ -194,13 +200,19 @@ data class LetCommand(
       is EnvVariableExpression -> TODO()
 
       is Register -> {
-        if (!(variable.char.isLetter() || variable.char.isDigit() || variable.char == '"')) {
+        if (RegisterConstants.WRITABLE_REGISTERS.contains(variable.char)) {
-          throw ExException("Let command supports only 0-9a-zA-Z\" registers at the moment")
+          val result = injector.registerGroup.storeText(variable.char, expression.evaluate(editor, context, vimContext).asString())
+          if (!result) {
+            logger.error("""
+              Error during `let ${variable.originalString} ${operator.value} ${expression.originalString}` command execution.
+              Could not set register value
+            """.trimIndent())
+          }
+        } else if (RegisterConstants.VALID_REGISTERS.contains(variable.char)) {
+          throw ExException("E354: Invalid register name: '${variable.char}'")
+        } else {
+          throw ExException("E18: Unexpected characters in :let")
         }
-
-        injector.registerGroup.startRecording(editor, variable.char)
-        injector.registerGroup.recordText(expression.evaluate(editor, context, vimContext).asString())
-        injector.registerGroup.finishRecording(editor)
       }
 
       else -> throw ExException("E121: Undefined variable")

vim-engine/src/main/kotlin/com/maddyhome/idea/vim/vimscript/model/functions/DefinedFunctionHandler.kt

@@ -61,7 +61,7 @@ data class DefinedFunctionHandler(val function: FunctionDeclaration) : FunctionH
         )
       )
     }
-    initializeFunctionVariables(argumentValues, editor, context)
+    initializeFunctionVariables(argumentValues, editor, context, vimContext)
 
     if (function.flags.contains(FunctionFlag.RANGE)) {
       val line = (injector.variableService.getNonNullVariableValue(Variable(Scope.FUNCTION_VARIABLE, "firstline"), editor, context, function) as VimInt).value
@@ -131,12 +131,12 @@ data class DefinedFunctionHandler(val function: FunctionDeclaration) : FunctionH
     return returnValue
   }
 
-  private fun initializeFunctionVariables(argumentValues: List<Expression>, editor: VimEditor, context: ExecutionContext) {
+  private fun initializeFunctionVariables(argumentValues: List<Expression>, editor: VimEditor, context: ExecutionContext, functionCallContext: VimLContext) {
     // non-optional function arguments
     for ((index, name) in function.args.withIndex()) {
       injector.variableService.storeVariable(
         Variable(Scope.FUNCTION_VARIABLE, name),
-        argumentValues[index].evaluate(editor, context, function.vimContext),
+        argumentValues[index].evaluate(editor, context, functionCallContext),
         editor,
         context,
         function
@@ -147,7 +147,7 @@ data class DefinedFunctionHandler(val function: FunctionDeclaration) : FunctionH
       val expressionToStore = if (index + function.args.size < argumentValues.size) argumentValues[index + function.args.size] else function.defaultArgs[index].second
       injector.variableService.storeVariable(
         Variable(Scope.FUNCTION_VARIABLE, function.defaultArgs[index].first),
-        expressionToStore.evaluate(editor, context, function.vimContext),
+        expressionToStore.evaluate(editor, context, functionCallContext),
         editor,
         context,
         function
@@ -158,7 +158,7 @@ data class DefinedFunctionHandler(val function: FunctionDeclaration) : FunctionH
       val remainingArgs = if (function.args.size + function.defaultArgs.size < argumentValues.size) {
         VimList(
           argumentValues.subList(function.args.size + function.defaultArgs.size, argumentValues.size)
-            .map { it.evaluate(editor, context, function.vimContext) }.toMutableList()
+            .map { it.evaluate(editor, context, functionCallContext) }.toMutableList()
         )
       } else {
         VimList(mutableListOf())