Add support for more characters in links (#379)

src/syntax/lexer.rs

@@ -264,16 +264,35 @@ impl Lexer<'_> {
     }
 
     fn link(&mut self) -> SyntaxKind {
+        let mut bracket_stack = Vec::new();
         #[rustfmt::skip]
-        self.s.eat_while(|c: char| matches!(c,
+        self.s.eat_while(|c: char| {
-            | '0' ..= '9'
+            match c {
-            | 'a' ..= 'z'
+                | '0' ..= '9'
-            | 'A' ..= 'Z'
+                | 'a' ..= 'z'
-            | '~'  | '/' | '%' | '?' | '#' | '&' | '+' | '='
+                | 'A' ..= 'Z'
-            | '\'' | '.' | ',' | ';'
+                | '!' | '#' | '$' | '%' | '&' | '*' | '+'
-        ));
+                | ',' | '-' | '.' | '/' | ':' | ';' | '='
+                | '?' | '@' | '_' | '~' | '\'' => true,
+                '[' => {
+                    bracket_stack.push(SyntaxKind::LeftBracket);
+                    true
+                }
+                '(' => {
+                    bracket_stack.push(SyntaxKind::LeftParen);
+                    true
+                }
+                ']' => bracket_stack.pop() == Some(SyntaxKind::LeftBracket),
+                ')' => bracket_stack.pop() == Some(SyntaxKind::LeftParen),
+                _ => false,
+            }
+        });
+        if !bracket_stack.is_empty() {
+            return self.error_at_end("expected closing bracket in link");
+        }
 
-        if self.s.scout(-1) == Some('.') {
+        // Don't include the trailing characters likely to be part of another expression.
+        if matches!(self.s.scout(-1), Some('!' | ',' | '.' | ':' | ';' | '?' | '\'')) {
             self.s.uneat();
         }
 

tests/typ/meta/link.typ

@@ -22,6 +22,22 @@ Wahttp://link \
 Nohttps:\//link \
 Nohttp\://comment
 
+---
+// Verify that brackets are included in links.
+https://[::1]:8080/ \
+https://example.com/(paren) \
+https://example.com/#(((nested))) \
+
+---
+// Check that unbalanced brackets are not included in links.
+#[https://example.com/] \
+https://example.com/)
+
+---
+// Verify that opening brackets without closing brackets throw an error.
+// Error: 22-22 expected closing bracket in link
+https://exam(ple.com/
+
 ---
 // Styled with underline and color.
 #show link: it => underline(text(fill: rgb("283663"), it))