/// <summary>
/// Verifies if the link is valid, before processing into a link, or plain text.
/// </summary>
/// <param name="element"> The parsed inline element to render. </param>
/// <param name="context"> Persistent state. </param>
protected void CheckRenderMarkdownLink(MarkdownLinkInline element, IRenderContext context)
{
// Avoid processing when link text is empty.
if (element.Inlines.Count == 0)
{
return;
}
// Attempt to resolve references.
element.ResolveReference(Document);
if (element.Url == null)
{
// The element couldn't be resolved, just render it as text.
RenderInlineChildren(element.Inlines, context);
return;
}
foreach (MarkdownInline inline in element.Inlines)
{
if (inline is ImageInline imageInline)
{
// this is an image, create Image.
if (!string.IsNullOrEmpty(imageInline.ReferenceId))
{
imageInline.ResolveReference(Document);
}
imageInline.Url = element.Url;
RenderImage(imageInline, context);
return;
}
}
RenderMarkdownLink(element, context);
}
static Common()
{
BoldItalicTextInline.AddTripChars(_triggerList);
BoldTextInline.AddTripChars(_triggerList);
ItalicTextInline.AddTripChars(_triggerList);
MarkdownLinkInline.AddTripChars(_triggerList);
HyperlinkInline.AddTripChars(_triggerList);
CommentInline.AddTripChars(_triggerList);
StrikethroughTextInline.AddTripChars(_triggerList);
SuperscriptTextInline.AddTripChars(_triggerList);
SubscriptTextInline.AddTripChars(_triggerList);
CodeInline.AddTripChars(_triggerList);
ImageInline.AddTripChars(_triggerList);
EmojiInline.AddTripChars(_triggerList);
LinkAnchorInline.AddTripChars(_triggerList);
// Create an array of characters to search against using IndexOfAny.
_tripCharacters = _triggerList.Select(trigger => trigger.FirstChar).Distinct().ToArray();
}
/// <summary>
/// Attempts to parse a markdown link e.g. "[](http://www.reddit.com)".
/// </summary>
/// <param name="markdown"> The markdown text. </param>
/// <param name="start"> The location to start parsing. </param>
/// <param name="maxEnd"> The location to stop parsing. </param>
/// <returns> A parsed markdown link, or <c>null</c> if this is not a markdown link. </returns>
internal static InlineParseResult Parse(string markdown, int start, int maxEnd)
{
// Expect a '[' character.
if (start == maxEnd || markdown[start] != '[')
{
return(null);
}
// Find the ']' character, keeping in mind that [test [0-9]](http://www.test.com) is allowed.
int linkTextOpen = start + 1;
int pos = linkTextOpen;
int linkTextClose;
int openSquareBracketCount = 0;
while (true)
{
linkTextClose = markdown.IndexOfAny(new char[] { '[', ']' }, pos, maxEnd - pos);
if (linkTextClose == -1)
{
return(null);
}
if (markdown[linkTextClose] == '[')
{
openSquareBracketCount++;
}
else if (openSquareBracketCount > 0)
{
openSquareBracketCount--;
}
else
{
break;
}
pos = linkTextClose + 1;
}
// Skip whitespace.
pos = linkTextClose + 1;
while (pos < maxEnd && ParseHelpers.IsMarkdownWhiteSpace(markdown[pos]))
{
pos++;
}
if (pos == maxEnd)
{
return(null);
}
// Expect the '(' character or the '[' character.
int linkOpen = pos;
if (markdown[pos] == '(')
{
// Skip whitespace.
linkOpen++;
while (linkOpen < maxEnd && ParseHelpers.IsMarkdownWhiteSpace(markdown[linkOpen]))
{
linkOpen++;
}
// Find the ')' character.
pos = linkOpen;
int linkClose = -1;
var openParenthesis = 0;
while (pos < maxEnd)
{
if (markdown[pos] == ')')
{
if (openParenthesis == 0)
{
linkClose = pos;
break;
}
else
{
openParenthesis--;
}
}
if (markdown[pos] == '(')
{
openParenthesis++;
}
pos++;
}
if (pos >= maxEnd)
{
return(null);
}
int end = linkClose + 1;
// Skip whitespace backwards.
while (linkClose > linkOpen && ParseHelpers.IsMarkdownWhiteSpace(markdown[linkClose - 1]))
{
linkClose--;
}
// If there is no text whatsoever, then this is not a valid link.
if (linkOpen == linkClose)
{
return(null);
}
// Check if there is tooltip text.
string url;
string tooltip = null;
bool lastUrlCharIsDoubleQuote = markdown[linkClose - 1] == '"';
int tooltipStart = Common.IndexOf(markdown, " \"", linkOpen, linkClose - 1);
if (tooltipStart == linkOpen)
{
return(null);
}
if (lastUrlCharIsDoubleQuote && tooltipStart != -1)
{
// Extract the URL (resolving any escape sequences).
url = TextRunInline.ResolveEscapeSequences(markdown, linkOpen, tooltipStart).TrimEnd(' ', '\t', '\r', '\n');
tooltip = markdown.Substring(tooltipStart + 2, (linkClose - 1) - (tooltipStart + 2));
}
else
{
// Extract the URL (resolving any escape sequences).
url = TextRunInline.ResolveEscapeSequences(markdown, linkOpen, linkClose);
}
// Check the URL is okay.
if (!url.IsEmail())
{
if (!Common.IsUrlValid(url))
{
return(null);
}
}
else
{
tooltip = url = $"mailto:{url}";
}
// We found a regular stand-alone link.
var result = new MarkdownLinkInline
{
Inlines = Common.ParseInlineChildren(markdown, linkTextOpen, linkTextClose, ignoreLinks: true),
Url = url.Replace(" ", "%20", StringComparison.Ordinal),
Tooltip = tooltip
};
return(new InlineParseResult(result, start, end));
}
else if (markdown[pos] == '[')
{
// Find the ']' character.
int linkClose = Common.IndexOf(markdown, ']', pos + 1, maxEnd);
if (linkClose == -1)
{
return(null);
}
// We found a reference-style link.
var result = new MarkdownLinkInline
{
Inlines = Common.ParseInlineChildren(markdown, linkTextOpen, linkTextClose, ignoreLinks: true),
ReferenceId = markdown.Substring(linkOpen + 1, linkClose - (linkOpen + 1))
};
if (string.IsNullOrEmpty(result.ReferenceId))
{
result.ReferenceId = markdown.Substring(linkTextOpen, linkTextClose - linkTextOpen);
}
return(new InlineParseResult(result, start, linkClose + 1));
}
return(null);
}
/// <summary>
/// Renders a link element
/// </summary>
/// <param name="element"> The parsed inline element to render. </param>
/// <param name="context"> Persistent state. </param>
protected override void RenderMarkdownLink(MarkdownLinkInline element, IRenderContext context)
{
var localContext = context as InlineRenderContext;
if (localContext == null)
{
throw new RenderContextIncorrectException();
}
// HACK: Superscript is not allowed within a hyperlink. But if we switch it around, so
// that the superscript is outside the hyperlink, then it will render correctly.
// This assumes that the entire hyperlink is to be rendered as superscript.
if (AllTextIsSuperscript(element) == false)
{
// Regular ol' hyperlink.
var link = new Hyperlink();
// Register the link
LinkRegister.RegisterNewHyperLink(link, element.Url);
// Remove superscripts.
RemoveSuperscriptRuns(element, insertCaret: true);
// Render the children into the link inline.
var childContext = new InlineRenderContext(link.Inlines, context)
{
Parent = link,
WithinHyperlink = true
};
if (localContext.OverrideForeground)
{
link.Foreground = localContext.Foreground;
}
else if (LinkForeground != null)
{
link.Foreground = LinkForeground;
}
RenderInlineChildren(element.Inlines, childContext);
context.TrimLeadingWhitespace = childContext.TrimLeadingWhitespace;
ToolTipService.SetToolTip(link, element.Tooltip ?? element.Url);
// Add it to the current inlines
localContext.InlineCollection.Add(link);
}
else
{
// THE HACK IS ON!
// Create a fake superscript element.
var fakeSuperscript = new SuperscriptTextInline
{
Inlines = new List <MarkdownInline>
{
element
}
};
// Remove superscripts.
RemoveSuperscriptRuns(element, insertCaret: false);
// Now render it.
RenderSuperscriptRun(fakeSuperscript, context);
}
}
/// <summary>
/// Finds the next inline element by matching trip chars and verifying the match.
/// </summary>
/// <param name="markdown"> The markdown text to parse. </param>
/// <param name="start"> The position to start parsing. </param>
/// <param name="end"> The position to stop parsing. </param>
/// <param name="ignoreLinks"> Indicates whether to parse links. </param>
/// <returns>Returns the next element</returns>
private static InlineParseResult FindNextInlineElement(string markdown, int start, int end, bool ignoreLinks)
{
// Search for the next inline sequence.
for (int pos = start; pos < end; pos++)
{
// IndexOfAny should be the fastest way to skip characters we don't care about.
pos = markdown.IndexOfAny(_tripCharacters, pos, end - pos);
if (pos < 0)
{
break;
}
// Find the trigger(s) that matched.
char currentChar = markdown[pos];
foreach (InlineTripCharHelper currentTripChar in _triggerList)
{
// Check if our current char matches the suffix char.
if (currentChar == currentTripChar.FirstChar)
{
// Don't match if the previous character was a backslash.
if (pos > start && markdown[pos - 1] == '\\')
{
continue;
}
// If we are here we have a possible match. Call into the inline class to verify.
InlineParseResult parseResult = null;
switch (currentTripChar.Method)
{
case InlineParseMethod.BoldItalic:
parseResult = BoldItalicTextInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.Comment:
parseResult = CommentInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.LinkReference:
parseResult = LinkAnchorInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.Bold:
parseResult = BoldTextInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.Italic:
parseResult = ItalicTextInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.MarkdownLink:
if (!ignoreLinks)
{
parseResult = MarkdownLinkInline.Parse(markdown, pos, end);
}
break;
case InlineParseMethod.AngleBracketLink:
if (!ignoreLinks)
{
parseResult = HyperlinkInline.ParseAngleBracketLink(markdown, pos, end);
}
break;
case InlineParseMethod.Url:
if (!ignoreLinks)
{
parseResult = HyperlinkInline.ParseUrl(markdown, pos, end);
}
break;
case InlineParseMethod.RedditLink:
if (!ignoreLinks)
{
parseResult = HyperlinkInline.ParseRedditLink(markdown, pos, end);
}
break;
case InlineParseMethod.PartialLink:
if (!ignoreLinks)
{
parseResult = HyperlinkInline.ParsePartialLink(markdown, pos, end);
}
break;
case InlineParseMethod.Email:
if (!ignoreLinks)
{
parseResult = HyperlinkInline.ParseEmailAddress(markdown, start, pos, end);
}
break;
case InlineParseMethod.Strikethrough:
parseResult = StrikethroughTextInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.Superscript:
parseResult = SuperscriptTextInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.Subscript:
parseResult = SubscriptTextInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.Code:
parseResult = CodeInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.Image:
parseResult = ImageInline.Parse(markdown, pos, end);
break;
case InlineParseMethod.Emoji:
parseResult = EmojiInline.Parse(markdown, pos, end);
break;
}
if (parseResult != null)
{
return(parseResult);
}
}
}
}
// If we didn't find any elements we have a normal text block.
// Let us consume the entire range.
return(new InlineParseResult(TextRunInline.Parse(markdown, start, end), start, end));
}
