Add regex for title text version of links

* Add regex for title text version of links

Original parser matched:
  [name](http:://link)

Add match for:
  [name](http:://link "title text")

* Add tests and improve regex's
* Several new tests in test_maddy_linkparser.cpp  (Some with paths for future improvement, and one to ensure an overzealous future update doesn't disallow actually-used special characters like o-umlaut).
* URLs now ignore leading/trailing spaces.
* URLs now don't match on internal spaces or quotes.
* Small grammar fix in CONTRIBUTING.md
* Updated changelog.

AUTHORS

@@ -11,3 +11,4 @@ Andrew Mettlach (dmmettlach@gmail.com)
 Evan Klitzke (evan@eklitzke.org)
 Albert Schwarzkopf (dev-maddy@quitesimple.org)
 Ivans Saponenko (ivans.saponenko+maddy@gmail.com)
+Lucian Smith (lpsmith@uw.edu)

CHANGELOG.md

@@ -13,6 +13,10 @@ maddy uses [semver versioning](https://semver.org/).
 * ![**REMOVED**](https://img.shields.io/badge/-REMOVED-%23900) for now removed features.
 
 ## Upcoming
+* ![**ADDED**](https://img.shields.io/badge/-ADDED-%23099) Correctly parse links with title text, i.e. `[link](http://example.com "example")`.
+* ![**FIXED**](https://img.shields.io/badge/-FIXED-%23090) Do not create invalid URLs from links with spaces, i.e. `[link](/ABC/some file)`.
+* ![**FIXED**](https://img.shields.io/badge/-FIXED-%23090) Do not create invalid HTML from links with quotes, i.e. `[link](/ABC/some"file)`.
+
 
 ## version 1.4.0 2025-03-28
 

CONTRIBUTING.md

@@ -16,4 +16,4 @@ improve the code? Then [create a GitHub issue](https://github.com/progsource/mad
 * Explain for what your PR is for - like providing a use-case or something similar.
 * Update documentation of the Markdown syntax if anything changed there. (`docs/definitions.md`)
 * Add a changelog entry at "Upcoming" inside of `CHANGELOG.md`
-* Make sure, that the tests are successful and if you wrote a bugfix, to have a test, that highlights the issue.
+* Make sure that the tests are successful and if you wrote a bugfix, to have a test that highlights the issue.

docs/definitions.md

@@ -41,6 +41,14 @@ results in
 <a href="http://example.com">Text of the link</a>
 ```
 
+```
+[Text of the link](http://example.com "title text")
+```
+results in
+```html
+<a href="http://example.com" title="title text">Text of the link</a>
+```
+
 ## Lists
 
 ### unordered

include/maddy/linkparser.h

@@ -40,10 +40,17 @@ public:
    */
   void Parse(std::string& line) override
   {
-    static std::regex re(R"(\[([^\]]*)\]\(([^)]*)\))");
+    // Match [name](http:://link "title text")
-    static std::string replacement = "<a href=\"$2\">$1</a>";
+    // NOTE:  the 'no quote' bit at the beginning (^") is a hack for now:
-
+    // there should eventually be something that replaces it with '%22'.
+    static std::regex re(R"(\[([^\]]*)\]\( *([^)^ ^"]*) *\"([^\"]*)\" *\))");
+    static std::string replacement = "<a href=\"$2\" title=\"$3\">$1</a>";
     line = std::regex_replace(line, re, replacement);
+
+    // Match [name](http:://link)
+    static std::regex re2(R"(\[([^\]]*)\]\( *([^)^ ^"]*) *\))");
+    static std::string replacement2 = "<a href=\"$2\">$1</a>";
+    line = std::regex_replace(line, re2, replacement2);
   }
 }; // class LinkParser
 

tests/maddy/test_maddy_linkparser.cpp

@@ -37,14 +37,47 @@ TEST(MADDY_LINKPARSER, ItReplacesMarkdownWithLinks)
   ASSERT_EQ(expected, text);
 }
 
+TEST(MADDY_LINKPARSER, ItReplacesMarkdownWithSpacesAfterLink)
+{
+  std::string text =
+    "Some text [Link Title](http://example.com    ) bla [Link "
+    "Title](http://example.com)";
+  std::string expected =
+    "Some text <a href=\"http://example.com\">Link Title</a> bla <a "
+    "href=\"http://example.com\">Link Title</a>";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(expected, text);
+}
+
+TEST(MADDY_LINKPARSER, ItHandlesURLsWithOfficiallyIllegalCharacters)
+{
+  // Some links in the real world have characters that are not
+  // 'official' characters that are supposedly allowed in URLs.
+  std::string text =
+    "Wikipedia's [Möbius strip]"
+    "(https://en.wikipedia.org/wiki/Möbius_strip) link.";
+  std::string expected =
+    "Wikipedia's <a "
+    "href=\"https://en.wikipedia.org/wiki/Möbius_strip\">"
+    "Möbius strip</a> link.";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(expected, text);
+}
+
 TEST(
   MADDY_LINKPARSER, ItReplacesMarkdownProperlyEvenWithMultipleParenthesisInLine
 )
 {
   std::string text =
-    "(This is a [link](/ABC/some file) (the URL will include this).)";
+    "(This is a [link](/ABC/some_file) (the URL will not include this).)";
   std::string expected =
-    "(This is a <a href=\"/ABC/some file\">link</a> (the URL will include "
+    "(This is a <a href=\"/ABC/some_file\">link</a> (the URL will not include "
     "this).)";
   auto linkParser = std::make_shared<maddy::LinkParser>();
 
@@ -53,6 +86,99 @@ TEST(
   ASSERT_EQ(expected, text);
 }
 
+TEST(MADDY_LINKPARSER, ItDoesntReplaceMarkdownWithSpaceInURL)
+{
+  // Spaces are not allowed in URLs, so don't match them.
+  std::string text = "This is an invalid [link](/ABC/some file)";
+  std::string expected = "This is an invalid [link](/ABC/some file)";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(expected, text);
+}
+
+TEST(MADDY_LINKPARSER, ItReplacesMarkdownWithTitleText)
+{
+  std::string text = "Link to [name](http:://example.com \"title text\")";
+  std::string expected =
+    "Link to <a href=\"http:://example.com\" title=\"title text\">name</a>";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(expected, text);
+}
+
+TEST(MADDY_LINKPARSER, ItReplacesMarkdownWithSpacesWithTitleText)
+{
+  std::string text = "Link to [name](http:://example.com     \"title text\")";
+  std::string expected =
+    "Link to <a href=\"http:://example.com\" title=\"title text\">name</a>";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(expected, text);
+}
+
+TEST(MADDY_LINKPARSER, ItReplacesMarkdownWithMoreSpacesWithTitleText)
+{
+  std::string text =
+    "Link to [name](http:://example.com     \"title text\"    )";
+  std::string expected =
+    "Link to <a href=\"http:://example.com\" title=\"title text\">name</a>";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(expected, text);
+}
+
+TEST(MADDY_LINKPARSER, ItReplacesMarkdownWithParentheticalText)
+{
+  std::string text = "Link to [name](http:://example.com \"title (text)\")";
+  std::string expected =
+    "Link to <a href=\"http:://example.com\" title=\"title (text)\">name</a>";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(expected, text);
+}
+
+TEST(MADDY_LINKPARSER, ItDoesntReplaceMarkdownWithTooManyQuotes)
+{
+  // If you have too many quotation marks, don't match:
+  std::string text =
+    "This is an invalid [link](/ABC/some_file \"title \" text \")";
+  std::string expected =
+    "This is an invalid [link](/ABC/some_file \"title \" text \")";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(expected, text);
+}
+
+TEST(MADDY_LINKPARSER, ItDoesntReplaceMarkdownWithQuoteInLink)
+{
+  // This is actually legal markdown, but hard to parse with regexes;
+  // See disabled 'ItReplacesMarkdownWithQuoteInLink' below.
+  //
+  // For now, don't try to translate it; it would produce invalid HTML.
+
+  std::string text = "Some text [Link Title](http://example.com/\"foo ) bla.";
+  std::string current_expected =
+    "Some text [Link Title](http://example.com/\"foo ) bla.";
+  std::string correct_expected =
+    "Some text <a href=\"http://example.com/%22foo\">Link Title</a> bla.";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(current_expected, text);
+}
 // -----------------------------------------------------------------------------
 
 class DISABLED_MADDY_LINKPARSER : public ::testing::Test
@@ -70,3 +196,17 @@ TEST_F(DISABLED_MADDY_LINKPARSER, ItReplacesNoImageMarkdownWithLinks)
 
   ASSERT_EQ(expected, text);
 }
+
+TEST(DISABLED_MADDY_LINKPARSER, ItReplacesMarkdownWithQuoteInLink)
+{
+  // This is legal markdown, but hard to parse with regexes; dropping it
+  // here for a future update.
+  std::string text = "Some text [Link Title](http://example.com/\"foo ) bla.";
+  std::string expected =
+    "Some text <a href=\"http://example.com/%22foo\">Link Title</a> bla.";
+  auto linkParser = std::make_shared<maddy::LinkParser>();
+
+  linkParser->Parse(text);
+
+  ASSERT_EQ(expected, text);
+}