From 14dfb3f63004d06d4ba1c34a24fff6686b6e5312 Mon Sep 17 00:00:00 2001
From: PgBiel <9021226+PgBiel@users.noreply.github.com>
Date: Mon, 24 Jun 2024 19:21:33 -0300
Subject: [PATCH] create DecoratorMarker and DecoratorName

---
 crates/typst-syntax/src/ast.rs       | 18 +++++++++++-
 crates/typst-syntax/src/highlight.rs |  2 ++
 crates/typst-syntax/src/kind.rs      |  7 +++++
 crates/typst-syntax/src/lexer.rs     | 43 ++++++++++++++++++----------
 tests/suite/syntax/decorator.typ     |  3 +-
 5 files changed, 56 insertions(+), 17 deletions(-)

diff --git a/crates/typst-syntax/src/ast.rs b/crates/typst-syntax/src/ast.rs
index 8380ae1c6..019ff4663 100644
--- a/crates/typst-syntax/src/ast.rs
+++ b/crates/typst-syntax/src/ast.rs
@@ -80,6 +80,22 @@ impl<'a> Markup<'a> {
     }
 }
 
+node! {
+    DecoratorName
+}
+
+impl<'a> DecoratorName<'a> {
+    /// Get the decorator name.
+    pub fn get(self) -> &'a EcoString {
+        self.0.text()
+    }
+
+    /// Get the decorator name as a string slice.
+    pub fn as_str(self) -> &'a str {
+        self.get()
+    }
+}
+
 node! {
     /// A decorator: `/! allow("warning")`.
     Decorator
@@ -87,7 +103,7 @@ node! {
 
 impl<'a> Decorator<'a> {
     /// The name of the decorator, e.g. `allow`.
-    pub fn name(self) -> Ident<'a> {
+    pub fn name(self) -> DecoratorName<'a> {
         self.0.cast_first_match().unwrap_or_default()
     }
 
diff --git a/crates/typst-syntax/src/highlight.rs b/crates/typst-syntax/src/highlight.rs
index 83c15b14b..c78ec6941 100644
--- a/crates/typst-syntax/src/highlight.rs
+++ b/crates/typst-syntax/src/highlight.rs
@@ -287,6 +287,8 @@ pub fn highlight(node: &LinkedNode) -> Option<Tag> {
         SyntaxKind::DestructAssignment => None,
 
         SyntaxKind::Decorator => None,
+        SyntaxKind::DecoratorMarker => None,
+        SyntaxKind::DecoratorName => None,
 
         SyntaxKind::LineComment => Some(Tag::Comment),
         SyntaxKind::BlockComment => Some(Tag::Comment),
diff --git a/crates/typst-syntax/src/kind.rs b/crates/typst-syntax/src/kind.rs
index 50d40960a..599806b57 100644
--- a/crates/typst-syntax/src/kind.rs
+++ b/crates/typst-syntax/src/kind.rs
@@ -280,6 +280,11 @@ pub enum SyntaxKind {
     Destructuring,
     /// A destructuring assignment expression: `(x, y) = (1, 2)`.
     DestructAssignment,
+
+    /// A decorator's marker: `/!`.
+    DecoratorMarker,
+    /// A decorator's name: `allow`.
+    DecoratorName,
 }
 
 impl SyntaxKind {
@@ -505,6 +510,8 @@ impl SyntaxKind {
             Self::FuncReturn => "`return` expression",
             Self::Destructuring => "destructuring pattern",
             Self::DestructAssignment => "destructuring assignment expression",
+            Self::DecoratorMarker => "decorator marker",
+            Self::DecoratorName => "decorator name",
         }
     }
 }
diff --git a/crates/typst-syntax/src/lexer.rs b/crates/typst-syntax/src/lexer.rs
index f8e8bbc21..9bfc64cb4 100644
--- a/crates/typst-syntax/src/lexer.rs
+++ b/crates/typst-syntax/src/lexer.rs
@@ -222,16 +222,18 @@ impl Lexer<'_> {
     /// `/! decorator-name("string argument1", "string argument2")`
     /// with optional whitespaces and comments between arguments.
     fn decorator(&mut self, start: usize) -> SyntaxNode {
-        // TODO: DecoratorMarker node
-        let current_start = start;
-        let mut subtree = vec![];
+        // Start by lexing the marker.
+        let marker = self.emit_token(SyntaxKind::DecoratorMarker, start);
+        let mut subtree = vec![marker];
+
+        let current_start = self.s.cursor();
 
         // Ignore initial non-newline whitespaces
         if !self.s.eat_while(is_inline_whitespace).is_empty() {
             subtree.push(self.emit_token(SyntaxKind::Space, current_start));
         }
 
-        // Decorator's name
+        // Lex the decorator name
         let current_start = self.s.cursor();
         if !self.s.eat_if(is_id_start) {
             self.s.eat_until(is_newline);
@@ -241,17 +243,8 @@ impl Lexer<'_> {
             return SyntaxNode::inner(SyntaxKind::Decorator, subtree);
         }
 
-        self.s.eat_while(is_id_continue);
-        let ident = self.s.from(current_start);
-
-        subtree.push(if ident == "allow" {
-            self.emit_token(SyntaxKind::Ident, current_start)
-        } else {
-            self.emit_error(
-                eco_format!("expected decorator name 'allow', found '{ident}'"),
-                current_start,
-            )
-        });
+        let decorator_name = self.decorator_name(current_start);
+        subtree.push(self.emit_token(decorator_name, current_start));
 
         // Left parenthesis before decorator arguments
         let current_start = self.s.cursor();
@@ -323,6 +316,26 @@ impl Lexer<'_> {
         SyntaxNode::inner(SyntaxKind::Decorator, subtree)
     }
 
+    /// Lexes a decorator name.
+    /// A decorator name is an identifier within a specific subset of allowed
+    /// identifiers.
+    /// Currently, `allow` is the only valid decorator name.
+    fn decorator_name(&mut self, start: usize) -> SyntaxKind {
+        self.s.eat_while(is_id_continue);
+        let ident = self.s.from(start);
+
+        if ident == "allow" {
+            SyntaxKind::DecoratorName
+        } else {
+            let error = self.error(eco_format!("invalid decorator name"));
+            self.hint("must be 'allow'");
+            error
+        }
+    }
+
+    /// Lexes a string in a decorator.
+    /// Currently, such strings only allow a very restricted set of characters.
+    /// These restrictions may be lifted in the future.
     fn decorator_string(&mut self) -> SyntaxKind {
         // TODO: Allow more characters in decorators' strings, perhaps allowing
         // newlines somehow.
diff --git a/tests/suite/syntax/decorator.typ b/tests/suite/syntax/decorator.typ
index e418eff08..d9de2b636 100644
--- a/tests/suite/syntax/decorator.typ
+++ b/tests/suite/syntax/decorator.typ
@@ -36,7 +36,8 @@ this is ok
 /! allow("@some/thing-there123")
 
 --- unknown-decorator ---
-// Error: 4-12 expected decorator name 'allow', found 'whatever'
+// Error: 4-12 invalid decorator name
+// Hint: 4-12 must be 'allow'
 /! whatever()
 
 --- invalid-decorator-syntax ---