Bracket MatchingBracketToken

/// <summary>
/// Returns the TokenKey that corresponds to <paramref name="key"/> and
/// sets the value of <paramref name="isStartToken"/> to indicate if
/// <paramref name="key"/> is the first key in the pair.
/// </summary>
public string GetMatchingTokenKey(string key, ref bool isStartToken)
{
    // Simply 'switch' between the various keys and return it's opposite
    isStart = false;
    switch (key)
    {
        case "OpenParenthesisToken":
            isStart = true;
            return "CloseParenthesisToken";
        case "CloseParenthesisToken":
            return "OpenParenthesisToken";
        case "StringStartToken":
            isStart = true;
            return "StringEndToken";
        case "StringEndToken":
            return "StringStartToken";
    }
    return null;
}

/// <summary>
/// Returns the Token that corresponds to <paramref name="initialToken"/>.
/// </summary>
public Token FindMatchingToken(ActiproSoftware.SyntaxEditor.Document document, Token initialToken)
{
    bool readForward = true; // direction of read
    string openKey = null; // TokenKey of token that starts a pair
    string closeKey = null; // TokenKey of token that ends a pair 
    string keyToFind = null; // TokenKey of token we're looking for (either openKey or closeKey)
    int groupLevel = 0; // counter to determine nested level
    
    // Determine search criteria
    keyToFind = GetMatchingTokenId(initialToken.Key, ref readForward);
    if (keyToFind == null)
        return null; // Token does not support matching pairs
    if (readForward)
    {
        openKey = initialToken.Key;
        closeKey = keyToFind;
    }
    else
    {
        openKey = keyToFind;
        closeKey = initialToken.Key;
    }

    // Open a Token Stream to look for the desired token
    TokenStream stream = document.GetTokenStream(document.Tokens.IndexOf(initialToken.StartOffset));
    Token token = initialToken;

    while (token != null)
    {
        // Adjust group level if current token key is either the Open or Close key
        if (token.Key == openKey)
            groupLevel++;
        else if (token.Key == closeKey)
            groupLevel--;

        // Check if we found the Token we want
        if (token.Key == keyToFind && groupLevel == 0)
            return token;

        // Check for end of stream
        if ((stream.Position == 0 && readForward == false) || (strea.IsPastEnd && readForward))
            break; // end of stream reached

        // Advance to next token
        if (readForward)
        {
            token = stream.Read();
            if (token.StartOffset == initialToken.StartOffset)
                token = stream.Read(); // first forward read on a new stream returns the same token we started with
        }
        else
        {
            token = stream.ReadReverse();
        }
    }
    return null; // no match found
}

// Get Current Token
Token currentToken = editor.Document.Tokens.GetTokenAtOffset(editor.SelectedView.Selection.FirstOffset);
this.WriteLine("Index of Current Token = '" + editor.Document.Tokens.IndexOf(currentToken.StartOffset) + "'");
// Create two streams that start with this token
TokenStream forwardStream = editor.Document.GetTokenStream(editor.Document.Tokens.IndexOf(currentToken.StartOffset));
TokenStream reverseStream = editor.Document.GetTokenStream(editor.Document.Tokens.IndexOf(currentToken.StartOffset));
// Return the index of the token returned from a read operation in both directions on the stream
try
{
    this.WriteLine("Index of Stream.Read Token = '" + editor.Document.Tokens.IndexOf(forwardStream.Read().StartOffset) + "'");
}
catch
{
    this.WriteLine("Unable to perform Stream.Read at this location");
}
try
{
    this.WriteLine("Index of Stream.ReadReverse Token = '" + editor.Document.Tokens.IndexOf(reverseStream.ReadReverse().StartOffset) + "'");
}
catch
{
    this.WriteLine("Unable to perform Stream.ReadReverse at this location");
}

Index of Current Token = '57'
Index of Stream.Read Token = '57'
Index of Stream.ReadReverse Token = '56'

public Token Read() {
    Token token = tokens[position];
    this.Seek(1);
    return token;
}

public Token ReadReverse() {
    this.Seek(-1);
    return tokens[position];
}