/// <summary>
/// This function can be called by any element parsing. Given a start and stopping point this will
/// parse all found elements out of the range.
/// </summary>
/// <returns> A list of parsed inlines. </returns>
public static List <MarkdownInline> ParseInlineChildren(string markdown, int startingPos, int maxEndingPos, bool ignoreLinks = false)
{
int currentParsePosition = startingPos;
var inlines = new List <MarkdownInline>();
while (currentParsePosition < maxEndingPos)
{
// Find the next inline element.
var parseResult = FindNextInlineElement(markdown, currentParsePosition, maxEndingPos, ignoreLinks);
// If the element we found doesn't start at the position we are looking for there
// is text between the element and the start of the parsed element. We need to wrap
// it into a text run.
if (parseResult.Start != currentParsePosition)
{
var textRun = TextRunInline.Parse(markdown, currentParsePosition, parseResult.Start);
inlines.Add(textRun);
}
// Add the parsed element.
inlines.Add(parseResult.ParsedElement);
// Update the current position.
currentParsePosition = parseResult.End;
}
return(inlines);
}
private Run InternalRenderTextRun(TextRunInline element, IRenderContext context)
{
if (!(context is InlineRenderContext localContext))
{
throw new RenderContextIncorrectException();
}
var inlineCollection = localContext.InlineCollection;
// Create the text run
Run textRun = new Run
{
Text = CollapseWhitespace(context, element.Text)
};
// Add it
inlineCollection.Add(textRun);
return(textRun);
}
/// <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 text run element.
/// </summary>
/// <param name="element"> The parsed inline element to render. </param>
/// <param name="context"> Persistent state. </param>
protected override void RenderTextRun(TextRunInline element, IRenderContext context)
{
InternalRenderTextRun(element, context);
}
/// <summary>
/// Attempts to parse an image e.g. "".
/// </summary>
/// <param name="markdown"> The markdown text. </param>
/// <param name="start"> The location to start parsing. </param>
/// <param name="end"> The location to stop parsing. </param>
/// <returns> A parsed markdown image, or <c>null</c> if this is not a markdown image. </returns>
internal static InlineParseResult Parse(string markdown, int start, int end)
{
// Expect a '!' character.
if (start >= end || markdown[start] != '!')
{
return(null);
}
int pos = start + 1;
// Then a '[' character
if (pos >= end || markdown[pos] != '[')
{
return(null);
}
pos++;
// Find the ']' character
while (pos < end)
{
if (markdown[pos] == ']')
{
break;
}
pos++;
}
if (pos == end)
{
return(null);
}
// Extract the alt.
string tooltip = markdown.Substring(start + 2, pos - (start + 2));
// Expect the '(' character.
pos++;
string reference = string.Empty;
string url = string.Empty;
int imageWidth = 0;
int imageHeight = 0;
if (pos < end && markdown[pos] == '[')
{
int refstart = pos;
// Find the reference ']' character
while (pos < end)
{
if (markdown[pos] == ']')
{
break;
}
pos++;
}
reference = markdown.Substring(refstart + 1, pos - refstart - 1);
}
else if (pos < end && markdown[pos] == '(')
{
while (pos < end && ParseHelpers.IsMarkdownWhiteSpace(markdown[pos]))
{
pos++;
}
// Extract the URL.
int urlStart = pos;
while (pos < end && markdown[pos] != ')')
{
pos++;
}
var imageDimensionsPos = markdown.IndexOf(" =", urlStart, pos - urlStart, StringComparison.Ordinal);
url = imageDimensionsPos > 0
? TextRunInline.ResolveEscapeSequences(markdown, urlStart + 1, imageDimensionsPos)
: TextRunInline.ResolveEscapeSequences(markdown, urlStart + 1, pos);
if (imageDimensionsPos > 0)
{
// trying to find 'x' which separates image width and height
var dimensionsSepatorPos = markdown.IndexOf("x", imageDimensionsPos + 2, pos - imageDimensionsPos - 1, StringComparison.Ordinal);
// didn't find separator, trying to parse value as imageWidth
if (dimensionsSepatorPos == -1)
{
var imageWidthStr = markdown.Substring(imageDimensionsPos + 2, pos - imageDimensionsPos - 2);
int.TryParse(imageWidthStr, out imageWidth);
}
else
{
var dimensions = markdown.Substring(imageDimensionsPos + 2, pos - imageDimensionsPos - 2).Split('x');
// got width and height
if (dimensions.Length == 2)
{
int.TryParse(dimensions[0], out imageWidth);
int.TryParse(dimensions[1], out imageHeight);
}
}
}
}
if (pos == end)
{
return(null);
}
// We found something!
var result = new ImageInline
{
Tooltip = tooltip,
RenderUrl = url,
ReferenceId = reference,
Url = url,
Text = markdown.Substring(start, pos + 1 - start),
ImageWidth = imageWidth,
ImageHeight = imageHeight
};
return(new InlineParseResult(result, start, pos + 1));
}
/// <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));
}