public async Task <string> EvaluateBlockAsync(RCodeBlock block, CancellationToken ct)
{
block.State = CodeBlockState.Created;
await TaskUtilities.SwitchToBackgroundThread();
try {
ct.ThrowIfCancellationRequested();
var session = await EvalSession.StartSessionAsync(ct);
var callback = EvalSession.SessionCallback;
session.Output += OnSessionOutput;
await ExecuteAndCaptureOutputAsync(session, block.Text, ct);
if (callback.PlotResult != null)
{
block.Result = Invariant($"<img src='data:image/gif;base64, {Convert.ToBase64String(callback.PlotResult)}' style='display:block; margin: 0 auto; text-align: center;' />");
callback.PlotResult = null;
}
else if (_output != null && _output.Length > 0)
{
block.Result = block.DisplayMessages ? HtmlFormatter.FormatCode(_output.ToString()) : string.Empty;
}
else if (_errors != null && _errors.Length > 0)
{
block.Result = block.DisplayMessages && block.DisplayErrors ? FormatError(_errors.ToString()) : string.Empty;
}
} catch (Exception ex) when(!ex.IsCriticalException())
{
_output = _errors = null;
block.Result = FormatError(ex.Message);
} finally {
if (EvalSession.RSession != null)
{
EvalSession.RSession.Output -= OnSessionOutput;
}
SignalActivity();
}
block.State = CodeBlockState.Evaluated;
return(block.Result);
}
protected override void Write(HtmlRenderer renderer, CodeBlock codeBlock)
{
renderer.EnsureLine();
var fencedCodeBlock = codeBlock as FencedCodeBlock;
if (codeBlock.Column > 0 || fencedCodeBlock?.Info == null)
{
if (codeBlock.Span.Length > 0)
{
var text = new string(' ', codeBlock.Column) + _documentText.Substring(codeBlock.Span.Start, codeBlock.Span.Length);
renderer.Write(HtmlFormatter.FormatCode(text, "background-color: rgba(0, 0, 0, 0.04);"));
}
return;
}
// For R blocks indent count must be zero (no whitespace before ```{r}
if (MarkdownUtility.GetRCodeBlockSeparatorLength(fencedCodeBlock.Info, out int start))
{
var text = fencedCodeBlock.GetText();
var rCodeBlock = new RCodeBlock(_blockNumber, text, fencedCodeBlock.Arguments);
var result = GetCachedResult(_blockNumber, rCodeBlock.Hash, fencedCodeBlock);
if (result != null)
{
renderer.Write(result);
}
else
{
var elementId = rCodeBlock.HtmlElementId;
_blocks.Add(rCodeBlock);
// Write placeholder first. We will insert actual data when the evaluation is done.
renderer.Write(GetBlockPlaceholder(elementId, text));
}
_blockNumber++;
}
}
private string FormatError(string error) => HtmlFormatter.FormatCode(error, "color: red;");
private static string GetCodeHtml(string code) => HtmlFormatter.FormatCode(code, "background-color: rgba(0, 0, 0, 0.04);");
