/// <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 Helpers.Common.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 && Helpers.Common.IsWhiteSpace(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 && Helpers.Common.IsWhiteSpace(markdown[linkOpen])) { linkOpen++; } // Find the ')' character. pos = linkOpen; int linkClose = -1; while (pos < maxEnd) { linkClose = Helpers.Common.IndexOf(markdown, ')', pos, maxEnd); if (linkClose == -1) { return(null); } if (markdown[linkClose - 1] != '\\') { break; } pos = linkClose + 1; } if (pos >= maxEnd) { return(null); } int end = linkClose + 1; // Skip whitespace backwards. while (linkClose > linkOpen && Helpers.Common.IsWhiteSpace(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 = Helpers.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 (!IsUrlValid(url)) { return(null); } // We found a regular stand-alone link. var result = new MarkdownLinkInline(); result.Inlines = Helpers.Common.ParseInlineChildren(markdown, linkTextOpen, linkTextClose, ignoreLinks: true); result.Url = url.Replace(" ", "%20"); result.Tooltip = tooltip; return(new Helpers.Common.InlineParseResult(result, start, end)); } else if (markdown[pos] == '[') { // Find the ']' character. int linkClose = Helpers.Common.IndexOf(markdown, ']', pos + 1, maxEnd); if (linkClose == -1) { return(null); } // We found a reference-style link. var result = new MarkdownLinkInline(); result.Inlines = Helpers.Common.ParseInlineChildren(markdown, linkTextOpen, linkTextClose, ignoreLinks: true); result.ReferenceId = markdown.Substring(linkOpen + 1, linkClose - (linkOpen + 1)); if (result.ReferenceId == string.Empty) { result.ReferenceId = markdown.Substring(linkTextOpen, linkTextClose - linkTextOpen); } return(new Helpers.Common.InlineParseResult(result, start, linkClose + 1)); } return(null); }
/// <summary> /// Attempts to parse a reference e.g. "[example]: http://www.reddit.com 'title'". /// </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 link, or <c>null</c> if this is not a markdown link. </returns> internal static LinkReferenceBlock Parse(string markdown, int start, int end) { // Expect a '[' character. if (start >= end || markdown[start] != '[') { return(null); } // Find the ']' character int pos = start + 1; while (pos < end) { if (markdown[pos] == ']') { break; } pos++; } if (pos == end) { return(null); } // Extract the ID. string id = markdown.Substring(start + 1, pos - (start + 1)); // Expect the ':' character. pos++; if (pos == end || markdown[pos] != ':') { return(null); } // Skip whitespace pos++; while (pos < end && Helpers.Common.IsWhiteSpace(markdown[pos])) { pos++; } if (pos == end) { return(null); } // Extract the URL. int urlStart = pos; while (pos < end && !Helpers.Common.IsWhiteSpace(markdown[pos])) { pos++; } string url = TextRunInline.ResolveEscapeSequences(markdown, urlStart, pos); // Ignore leading '<' and trailing '>'. url = url.TrimStart('<').TrimEnd('>'); // Skip whitespace. pos++; while (pos < end && Helpers.Common.IsWhiteSpace(markdown[pos])) { pos++; } string tooltip = null; if (pos < end) { // Extract the tooltip. char tooltipEndChar; switch (markdown[pos]) { case '(': tooltipEndChar = ')'; break; case '"': case '\'': tooltipEndChar = markdown[pos]; break; default: return(null); } pos++; int tooltipStart = pos; while (pos < end && markdown[pos] != tooltipEndChar) { pos++; } if (pos == end) { return(null); // No end character. } tooltip = markdown.Substring(tooltipStart, pos - tooltipStart); // Check there isn't any trailing text. pos++; while (pos < end && Helpers.Common.IsWhiteSpace(markdown[pos])) { pos++; } if (pos < end) { return(null); } } // We found something! var result = new LinkReferenceBlock(); result.Id = id; result.Url = url; result.Tooltip = tooltip; return(result); }