Interpret two backticks as single-backtick block ✅

src/parse/tokens.rs

@@ -227,6 +227,11 @@ impl<'s> Tokens<'s> {
             backticks += 1;
         }
 
+        // Special case for empty inline block.
+        if backticks == 2 {
+            return Token::Raw(TokenRaw { text: "", backticks: 1, terminated: true });
+        }
+
         let start = self.s.index();
 
         let mut found = 0;
@@ -723,21 +728,25 @@ mod tests {
 
     #[test]
     fn test_tokenize_raw_blocks() {
+        let empty = Raw("", 1, true);
+
         // Test basic raw block.
+        t!(Markup: "``"     => empty);
         t!(Markup: "`raw`"  => Raw("raw", 1, true));
         t!(Markup[""]: "`]" => Raw("]", 1, false));
 
         // Test special symbols in raw block.
-        t!(Markup: "`[func]`"   => Raw("[func]", 1, true));
-        t!(Markup[""]: r"`\`` " => Raw(r"\", 1, true), Raw(" ", 1, false));
-
-        // Test more backticks.
-        t!(Markup: "````🚀````"           => Raw("🚀", 4, true));
-        t!(Markup[""]: "````👩‍🚀``noend"    => Raw("👩‍🚀``noend", 4, false));
-        t!(Markup[""]: "````raw``````new" => Raw("raw", 4, true), Raw("new", 2, false));
+        t!(Markup: "`[brackets]`" => Raw("[brackets]", 1, true));
+        t!(Markup[""]: r"`\`` "   => Raw(r"\", 1, true), Raw(" ", 1, false));
 
         // Test separated closing backticks.
         t!(Markup: "```not `y`e`t```" => Raw("not `y`e`t", 3, true));
+
+        // Test more backticks.
+        t!(Markup: "``nope``"             => empty, Text("nope"), empty);
+        t!(Markup: "````🚀````"           => Raw("🚀", 4, true));
+        t!(Markup[""]: "`````👩‍🚀````noend" => Raw("👩‍🚀````noend", 5, false));
+        t!(Markup[""]: "````raw``````"    => Raw("raw", 4, true), empty);
     }
 
     #[test]

src/syntax/mod.rs

@@ -63,9 +63,10 @@ mod tests {
         roundtrip("= *Ok*");
 
         // Raw.
+        roundtrip("``");
         roundtrip("`lang 1`");
-        test("`` hi``", "`hi`");
-        test("`` ` ``", "```");
+        test("``` hi```", "`hi`");
+        test("``` ` ```", "```");
     }
 
     #[test]

src/syntax/node.rs

@@ -66,11 +66,11 @@ impl Pretty for NodeHeading {
 
 /// A raw block with optional syntax highlighting: `` `raw` ``.
 ///
-/// Raw blocks start with an arbitrary number of backticks and end with the same
-/// number of backticks. If you want to include a sequence of backticks in a raw
-/// block, simply surround the block with more backticks.
+/// Raw blocks start with 1 or 3+ backticks and end with the same number of
+/// backticks. If you want to include a sequence of backticks in a raw block,
+/// simply surround the block with more backticks.
 ///
-/// When using at least two backticks, an optional language tag may follow
+/// When using at least three backticks, an optional language tag may follow
 /// directly after the backticks. This tag defines which language to
 /// syntax-highlight the text in. Apart from the language tag and some
 /// whitespace trimming discussed below, everything inside a raw block is
@@ -82,22 +82,21 @@ impl Pretty for NodeHeading {
 ///   `raw`
 ///   ```
 /// - An optional language tag may follow directly at the start when the block
-///   is surrounded by at least two backticks.
-///   ```typst
-///   ``rust println!("hello!")``;
-///   ```
-/// - Blocks can span multiple lines. Two backticks suffice to be able to
-///   specify the language tag, but three are fine, too.
-///   ```typst
-///   ``rust
+///   is surrounded by at least three backticks.
+///   ````typst
+///   ```rust println!("hello!")```;
+///   ````
+///   - Blocks can span multiple lines.
+///   ````typst
+///   ```rust
 ///   loop {
 ///      find_yak().shave();
 ///   }
-///   ``
 ///   ```
-/// - Start with a space to omit the language tag (the space will be trimmed
-///   from the output) and use more backticks to allow backticks in the raw
-///   text.
+///   ````
+///   - Start with a space to omit the language tag (the space will be trimmed
+///     from the output) and use more backticks to allow backticks in the raw
+///     text.
 ///   `````typst
 ///   ```` This contains ```backticks``` and has no leading & trailing spaces. ````
 ///   `````
@@ -107,24 +106,22 @@ impl Pretty for NodeHeading {
 ///   given, a few things would become problematic or even impossible:
 ///   - Typical multiline code blocks (like in the example above) would have an
 ///     additional newline before and after the code.
-///   - Raw text wrapped in more than one backtick could not exist without
-///     leading whitespace since the first word would be interpreted as a
-///     language tag.
+///   - The first word of text wrapped in more than three backticks would always
+///     be interpreted as a language tag which means that text without leading
+///     space would be impossible.
 ///   - A single backtick without surrounding spaces could not exist as raw text
 ///     since it would be interpreted as belonging to the opening or closing
 ///     backticks.
 ///
-///   To fix these problems, we trim text in multi-backtick blocks as follows:
-///   - We trim a single space or a sequence of whitespace followed by a newline
-///     at the start.
-///   - We trim a single space or a newline followed by a sequence of whitespace
-///     at the end.
+///   To fix these problems, we trim blocks with 3+ backticks as follows:
+///   - A single space or a sequence of whitespace followed by a newline at the start.
+///   - A single space or a newline followed by a sequence of whitespace at the end.
 ///
 ///   With these rules, a single raw backtick can be produced by the sequence
-///   ``` `` ` `` ```, ``` `` unhighlighted text `` ``` has no surrounding
-///   spaces and multiline code blocks don't have extra empty lines. Note that
-///   you can always force leading or trailing whitespace simply by adding more
-///   spaces.
+///   ```` ``` ` ``` ````, ```` ``` unhighlighted text ``` ```` has no
+///   surrounding spaces and multiline code blocks don't have extra empty lines.
+///   Note that you can always force leading or trailing whitespace simply by
+///   adding more spaces.
 #[derive(Debug, Clone, PartialEq)]
 pub struct NodeRaw {
     /// An optional identifier specifying the language to syntax-highlight in.

tests/lang/typ/raw.typ

@@ -1,22 +1,27 @@
 #[font 8pt]
 
+// No extra space.
+`A``B`
+
 // Typst syntax inside.
-`#let x = 1``[f 1]`
+`#let x = 1` \
+`#[f 1]`
 
 // Space between "rust" and "let" is trimmed.
-The keyword ``rust let``.
+The keyword ```rust let```.
 
 // Trimming depends on number backticks.
+<``> \
 <` untrimmed `> \
-<`` trimmed ``>
+<``` trimmed ```>
 
 // Multiline trimming.
-``py
+```py
 import this
 
 def say_hi():
     print("Hi!")
-``
+```
 
 // Lots of backticks inside.
 ````