ReplacingCallback

FindReplaceOptions.ReplacingCallback property

The user-defined method which is called before every replace occurrence.

public IReplacingCallback ReplacingCallback { get; set; }

Examples

Shows how to replace all occurrences of a regular expression pattern with another string, while tracking all such replacements.

public void ReplaceWithCallback()
{
    Document doc = new Document();
    DocumentBuilder builder = new DocumentBuilder(doc);

    builder.Writeln("Our new location in New York City is opening tomorrow. " +
                    "Hope to see all our NYC-based customers at the opening!");

    // We can use a "FindReplaceOptions" object to modify the find-and-replace process.
    FindReplaceOptions options = new FindReplaceOptions();

    // Set a callback that tracks any replacements that the "Replace" method will make.
    TextFindAndReplacementLogger logger = new TextFindAndReplacementLogger();
    options.ReplacingCallback = logger;

    doc.Range.Replace(new Regex("New York City|NYC"), "Washington", options);

    Assert.AreEqual("Our new location in (Old value:\"New York City\") Washington is opening tomorrow. " +
                    "Hope to see all our (Old value:\"NYC\") Washington-based customers at the opening!", doc.GetText().Trim());

    Assert.AreEqual("\"New York City\" converted to \"Washington\" 20 characters into a Run node.\r\n" +
                    "\"NYC\" converted to \"Washington\" 42 characters into a Run node.", logger.GetLog().Trim());
}

/// <summary>
/// Maintains a log of every text replacement done by a find-and-replace operation
/// and notes the original matched text's value.
/// </summary>
private class TextFindAndReplacementLogger : IReplacingCallback
{
    ReplaceAction IReplacingCallback.Replacing(ReplacingArgs args)
    {
        mLog.AppendLine($"\"{args.Match.Value}\" converted to \"{args.Replacement}\" " +
                        $"{args.MatchOffset} characters into a {args.MatchNode.NodeType} node.");

        args.Replacement = $"(Old value:\"{args.Match.Value}\") {args.Replacement}";
        return ReplaceAction.Replace;
    }

    public string GetLog()
    {
        return mLog.ToString();
    }

    private readonly StringBuilder mLog = new StringBuilder();
}

Shows how to apply a different font to new content via FindReplaceOptions.

public void ConvertNumbersToHexadecimal()
{
    Document doc = new Document();
    DocumentBuilder builder = new DocumentBuilder(doc);

    builder.Font.Name = "Arial";
    builder.Writeln("Numbers that the find-and-replace operation will convert to hexadecimal and highlight:\n" +
                    "123, 456, 789 and 17379.");

    // We can use a "FindReplaceOptions" object to modify the find-and-replace process.
    FindReplaceOptions options = new FindReplaceOptions();

    // Set the "HighlightColor" property to a background color that we want to apply to the operation's resulting text.
    options.ApplyFont.HighlightColor = Color.LightGray;

    NumberHexer numberHexer = new NumberHexer();
    options.ReplacingCallback = numberHexer;

    int replacementCount = doc.Range.Replace(new Regex("[0-9]+"), "", options);

    Console.WriteLine(numberHexer.GetLog());

    Assert.AreEqual(4, replacementCount);
    Assert.AreEqual("Numbers that the find-and-replace operation will convert to hexadecimal and highlight:\r" +
                    "0x7B, 0x1C8, 0x315 and 0x43E3.", doc.GetText().Trim());
    Assert.AreEqual(4, doc.GetChildNodes(NodeType.Run, true).OfType<Run>()
            .Count(r => r.Font.HighlightColor.ToArgb() == Color.LightGray.ToArgb()));
}

/// <summary>
/// Replaces numeric find-and-replacement matches with their hexadecimal equivalents.
/// Maintains a log of every replacement.
/// </summary>
private class NumberHexer : IReplacingCallback
{
    public ReplaceAction Replacing(ReplacingArgs args)
    {
        mCurrentReplacementNumber++;

        int number = Convert.ToInt32(args.Match.Value);

        args.Replacement = $"0x{number:X}";

        mLog.AppendLine($"Match #{mCurrentReplacementNumber}");
        mLog.AppendLine($"\tOriginal value:\t{args.Match.Value}");
        mLog.AppendLine($"\tReplacement:\t{args.Replacement}");
        mLog.AppendLine($"\tOffset in parent {args.MatchNode.NodeType} node:\t{args.MatchOffset}");

        mLog.AppendLine(string.IsNullOrEmpty(args.GroupName)
            ? $"\tGroup index:\t{args.GroupIndex}"
            : $"\tGroup name:\t{args.GroupName}");

        return ReplaceAction.Replace;
    }

    public string GetLog()
    {
        return mLog.ToString();
    }

    private int mCurrentReplacementNumber;
    private readonly StringBuilder mLog = new StringBuilder();
}

See Also

FindReplaceOptions.ReplacementFormat FindReplaceOptions.SmartParagraphBreakReplacement