How to use com.intellij.openapi.editor.highlighter

  @Override
  public boolean isOpeningQuote(HighlighterIterator highlighterIterator, int offset) {
    boolean isOpeningQuote = false;

    if (OPENING_QUOTES.contains(highlighterIterator.getTokenType())){
      int start = highlighterIterator.getStart();
      isOpeningQuote = offset == start;
    }

    return isOpeningQuote;
  }
}

/**
 *
 * @param highlighterIterator
 * @param offset the current offset in the file of the {@code highlighterIterator}
 * @return {@code true} if {@link HighlighterIterator#getTokenType()} is one of {@link #CLOSING_QUOTES} and
 *   {@code offset} is {@link HighlighterIterator#getStart()}
 */
@Override
public boolean isClosingQuote(HighlighterIterator highlighterIterator, int offset) {
  boolean isClosingQuote = false;
  if (CLOSING_QUOTES.contains(highlighterIterator.getTokenType())) {
    int start = highlighterIterator.getStart();
    int end = highlighterIterator.getEnd();
    isClosingQuote = end - start >= 1 && offset == end - 1;
  }
  return isClosingQuote;
}

 @Nullable
 @Override
 public BracePair findPair(boolean left, HighlighterIterator iterator, CharSequence fileText, FileType fileType) {
  BracePair pair = super.findPair(left, iterator, fileText, fileType);

  if (pair == Paired.DO_END || pair == Paired.FN_END) {
   iterator.advance();

   if (!iterator.atEnd()) {
    IElementType tokenType = iterator.getTokenType();

    if (tokenType == ElixirTypes.KEYWORD_PAIR_COLON) {
     pair = null;
    }
   }

   iterator.retreat();
  }

  return pair;
 }
}

@Nullable
private IElementType getNonWhitespaceElementType(final HighlighterIterator iterator, int curLineStart, final int prevLineStartOffset) {
 while (!iterator.atEnd() && iterator.getEnd() >= curLineStart && iterator.getStart() >= prevLineStartOffset) {
  final IElementType tokenType = iterator.getTokenType();
  if (!MathematicaElementTypes.WHITE_SPACE_OR_COMMENTS.contains(tokenType)) {
   return tokenType;
  }
  iterator.retreat();
 }
 return null;
}

@Nullable
@Override
public CharSequence getClosingQuote(HighlighterIterator highlighterIterator, int offset) {
  CharSequence closingQuote = null;
  if (highlighterIterator.getStart() > 0) {
    highlighterIterator.retreat();
    try {
      IElementType tokenType = highlighterIterator.getTokenType();
      if (CLOSING_QUOTE_BY_OPENING_QUOTE.get(tokenType) != null) {
        Document document = highlighterIterator.getDocument();
        if (document != null) {
          String promoter = document.getText(
              new TextRange(highlighterIterator.getStart(), highlighterIterator.getEnd())
          );
          String terminator = StackFrame.TERMINATOR_BY_PROMOTER.get(promoter);
          if (terminator != null) {
            if (terminator.length() >= 3) {
              closingQuote = "\n" + terminator;
            } else {
              closingQuote = terminator;
            }
          }
        }
      }
    } finally {
      highlighterIterator.advance();
    }
  }
  return closingQuote;
}

/**
 * @return previous non-space token type
 */
@Nullable
public static IElementType getPreviousTokenType(@NotNull HighlighterIterator iterator) {
 moveToPreviousMeaningfulToken(iterator);
 return iterator.atEnd() ? null : iterator.getTokenType();
}

/**
 * Iterates forward until atEnd or non-space token
 */
@NotNull
public static HighlighterIterator moveToNextMeaningfulToken(@NotNull HighlighterIterator iterator) {
 iterator.advance();
 while (!iterator.atEnd()) {
  IElementType tokenType = iterator.getTokenType();
  if (tokenType != TokenType.WHITE_SPACE) {
   break;
  }
  iterator.advance();
 }
 return iterator;
}

/**
 * Iterates back until atEnd or non-space token
 */
@NotNull
public static HighlighterIterator moveToPreviousMeaningfulToken(@NotNull HighlighterIterator iterator) {
 while (!iterator.atEnd()) {
  IElementType tokenType = iterator.getTokenType();
  if (tokenType != TokenType.WHITE_SPACE) {
   break;
  }
  iterator.retreat();
 }
 return iterator;
}

HighlighterIterator iterator = highlighter.createIterator(caret - 2);
IElementType tokenType = iterator.getTokenType();
HighlighterIterator iterator = highlighter.createIterator(caret - 1);
IElementType tokenType = iterator.getTokenType();
HighlighterIterator iterator = highlighter.createIterator(caret - 2);
if (iterator.getTokenType() == ElixirTypes.OPENING_BIT) {
  editor.getDocument().insertString(caret, ">>");
  result = Result.STOP;
HighlighterIterator iterator = highlighter.createIterator(caret - 1);
IElementType tokenType = iterator.getTokenType();
HighlighterIterator iterator = highlighter.createIterator(caret - 1);
IElementType tokenType = iterator.getTokenType();

@Override
public boolean isInsideLiteral(HighlighterIterator highlighterIterator) {
  return LITERALS.contains(highlighterIterator.getTokenType());
}

public Brace(IElementType elementType, HighlighterIterator iterator) {
  this.elementType = elementType;
  this.offset = iterator.getStart();
  Document document = iterator.getDocument();
  this.text = document.getText(new TextRange(iterator.getStart(),
      iterator.getEnd()));
}

  private boolean isLBraceTokenBrace() {
    int offset = myFixture.getCaretOffset();
    Editor editor = myFixture.getEditor();
    CharSequence text = editor.getDocument().getCharsSequence();
    FileType fileType = ElixirFileType.INSTANCE;
    HighlighterIterator iterator = ((EditorEx) editor).getHighlighter().createIterator(offset);

    return BraceMatchingUtil.isLBraceToken(iterator, text, fileType);
  }
}

  @Override
  public EditorHighlighter getEditorHighlighter(@Nullable Project project, @NotNull FileType fileType, @Nullable VirtualFile virtualFile, @NotNull EditorColorsScheme colors) {
    return EditorHighlighterFactory.getInstance().createEditorHighlighter(CsvSyntaxHighlighterFactory.getSyntaxHighlighter(CsvLanguage.INSTANCE, project, virtualFile), colors);
  }
}

@Nullable
private IElementType getNonWhitespaceElementType(final HighlighterIterator iterator, int curLineStart, final int prevLineStartOffset) {
 while (!iterator.atEnd() && iterator.getEnd() >= curLineStart && iterator.getStart() >= prevLineStartOffset) {
  final IElementType tokenType = iterator.getTokenType();
  if (!MathematicaElementTypes.WHITE_SPACE_OR_COMMENTS.contains(tokenType)) {
   return tokenType;
  }
  iterator.retreat();
 }
 return null;
}

/**
 * Should return true if the current offset is the closing quote of the string. Unfortunately, I'm not quite sure
 * anymore why I had to make the calculations but I remember that something with the removal of an empty string did
 * not work.
 *
 * @param iterator
 *     the iterator to move through the token stream. Here, only used to get the current token type
 * @param offset
 *     current character offset
 * @return true, if the current offset is a closing quote
 */
@Override
public boolean isClosingQuote(HighlighterIterator iterator, int offset) {
 final IElementType tokenType = iterator.getTokenType();
 if (tokenType.equals(STRING_LITERAL_END)) {
  int start = iterator.getStart();
  int end = iterator.getEnd();
  return end - start >= 1 && offset == end - 1;
 }
 return false;
}

/**
 * @return next non-space token type; NB: current token is skipped
 */
@Nullable
public static IElementType getNextTokenType(@NotNull HighlighterIterator iterator) {
 moveToNextMeaningfulToken(iterator);
 return iterator.atEnd() ? null : iterator.getTokenType();
}

/**
 * Finds out whether the current offset is an opening quote element.
 *
 * @param iterator
 *     the iterator to move through the token stream. Here, only used to get the current token type
 * @param offset
 *     current character offset
 * @return true, if the current offset is an opening quote
 */
@Override
public boolean isOpeningQuote(HighlighterIterator iterator, int offset) {
 if (iterator.getTokenType().equals(STRING_LITERAL_BEGIN)) {
  int start = iterator.getStart();
  return offset == start;
 }
 return false;
}

/**
 * Should return true, when you are inside a string literal.
 *
 * @param iterator
 *     the iterator to move through the token stream. Here, only used to get the token type
 * @return true, if the iterator is currently inside a string
 */
@Override
public boolean isInsideLiteral(HighlighterIterator iterator) {
 return iterator.getTokenType().equals(STRING_LITERAL);
}

@Override
public boolean isClosingQuote(HighlighterIterator iterator, int offset) {
 return TemplateToolkitParserUtil.CLOSE_QUOTES.contains(iterator.getTokenType());
}

 @Override
 public boolean isOpeningQuote(HighlighterIterator iterator, int offset) {
  return TemplateToolkitParserUtil.OPEN_QUOTES.contains(iterator.getTokenType());
 }
}