Parse `break`, `continue` and `return` expression

7 files changed, 140 insertions, 2 deletions

diff --git a/src/eval/mod.rs b/src/eval/mod.rs
index 2023004f..a8c6c688 100644
--- a/src/eval/mod.rs
+++ b/src/eval/mod.rs
@@ -390,6 +390,9 @@ impl Eval for Expr {
             Self::For(v) => v.eval(ctx),
             Self::Import(v) => v.eval(ctx),
             Self::Include(v) => v.eval(ctx),
+            Self::Break(v) => v.eval(ctx),
+            Self::Continue(v) => v.eval(ctx),
+            Self::Return(v) => v.eval(ctx),
         }
     }
 }
@@ -905,6 +908,30 @@ impl Eval for IncludeExpr {
     }
 }
 
+impl Eval for BreakExpr {
+    type Output = Value;
+
+    fn eval(&self, _: &mut EvalContext) -> TypResult<Self::Output> {
+        Err("break is not yet implemented").at(self.span())
+    }
+}
+
+impl Eval for ContinueExpr {
+    type Output = Value;
+
+    fn eval(&self, _: &mut EvalContext) -> TypResult<Self::Output> {
+        Err("continue is not yet implemented").at(self.span())
+    }
+}
+
+impl Eval for ReturnExpr {
+    type Output = Value;
+
+    fn eval(&self, _: &mut EvalContext) -> TypResult<Self::Output> {
+        Err("return is not yet implemented").at(self.span())
+    }
+}
+
 /// Try to mutably access the value an expression points to.
 ///
 /// This only works if the expression is a valid lvalue.
diff --git a/src/parse/incremental.rs b/src/parse/incremental.rs
index 2edb84ba..9dd5bec1 100644
--- a/src/parse/incremental.rs
+++ b/src/parse/incremental.rs
@@ -548,7 +548,10 @@ impl NodeKind {
             | Self::ShowExpr
             | Self::WrapExpr
             | Self::ImportExpr
-            | Self::IncludeExpr => SuccessionRule::AtomicPrimary,
+            | Self::IncludeExpr
+            | Self::BreakExpr
+            | Self::ContinueExpr
+            | Self::ReturnExpr => SuccessionRule::AtomicPrimary,
 
             // This element always has to remain in the same column so better
             // reparse the whole parent.
diff --git a/src/parse/mod.rs b/src/parse/mod.rs
index 67e35a5a..a9839ed6 100644
--- a/src/parse/mod.rs
+++ b/src/parse/mod.rs
@@ -405,6 +405,9 @@ fn primary(p: &mut Parser, atomic: bool) -> ParseResult {
         Some(NodeKind::For) => for_expr(p),
         Some(NodeKind::Import) => import_expr(p),
         Some(NodeKind::Include) => include_expr(p),
+        Some(NodeKind::Break) => break_expr(p),
+        Some(NodeKind::Continue) => continue_expr(p),
+        Some(NodeKind::Return) => return_expr(p),
 
         Some(NodeKind::Error(_, _)) => {
             p.eat();
@@ -833,6 +836,33 @@ fn include_expr(p: &mut Parser) -> ParseResult {
     })
 }
 
+/// Parse a break expression.
+fn break_expr(p: &mut Parser) -> ParseResult {
+    p.perform(NodeKind::BreakExpr, |p| {
+        p.eat_assert(&NodeKind::Break);
+        Ok(())
+    })
+}
+
+/// Parse a continue expression.
+fn continue_expr(p: &mut Parser) -> ParseResult {
+    p.perform(NodeKind::ContinueExpr, |p| {
+        p.eat_assert(&NodeKind::Continue);
+        Ok(())
+    })
+}
+
+/// Parse a return expression.
+fn return_expr(p: &mut Parser) -> ParseResult {
+    p.perform(NodeKind::ReturnExpr, |p| {
+        p.eat_assert(&NodeKind::Return);
+        if !p.eof() {
+            expr(p)?;
+        }
+        Ok(())
+    })
+}
+
 /// Parse an identifier.
 fn ident(p: &mut Parser) -> ParseResult {
     match p.peek() {
diff --git a/src/syntax/ast.rs b/src/syntax/ast.rs
index 6732aa40..13c639f9 100644
--- a/src/syntax/ast.rs
+++ b/src/syntax/ast.rs
@@ -231,6 +231,12 @@ pub enum Expr {
     Import(ImportExpr),
     /// An include expression: `include "chapter1.typ"`.
     Include(IncludeExpr),
+    /// A break expression: `break`.
+    Break(BreakExpr),
+    /// A continue expression: `continue`.
+    Continue(ContinueExpr),
+    /// A return expression: `return`.
+    Return(ReturnExpr),
 }
 
 impl TypedNode for Expr {
@@ -256,6 +262,9 @@ impl TypedNode for Expr {
             NodeKind::ForExpr => node.cast().map(Self::For),
             NodeKind::ImportExpr => node.cast().map(Self::Import),
             NodeKind::IncludeExpr => node.cast().map(Self::Include),
+            NodeKind::BreakExpr => node.cast().map(Self::Break),
+            NodeKind::ContinueExpr => node.cast().map(Self::Continue),
+            NodeKind::ReturnExpr => node.cast().map(Self::Return),
             _ => node.cast().map(Self::Lit),
         }
     }
@@ -283,6 +292,9 @@ impl TypedNode for Expr {
             Self::For(v) => v.as_red(),
             Self::Import(v) => v.as_red(),
             Self::Include(v) => v.as_red(),
+            Self::Break(v) => v.as_red(),
+            Self::Continue(v) => v.as_red(),
+            Self::Return(v) => v.as_red(),
         }
     }
 }
@@ -1042,6 +1054,28 @@ impl IncludeExpr {
 }
 
 node! {
+    /// A break expression: `break`.
+    BreakExpr
+}
+
+node! {
+    /// A continue expression: `continue`.
+    ContinueExpr
+}
+
+node! {
+    /// A return expression: `return x + 1`.
+    ReturnExpr
+}
+
+impl ReturnExpr {
+    /// The expression to return.
+    pub fn body(&self) -> Option<Expr> {
+        self.0.cast_last_child()
+    }
+}
+
+node! {
     /// An identifier.
     Ident: NodeKind::Ident(_)
 }
diff --git a/src/syntax/highlight.rs b/src/syntax/highlight.rs
index c399b487..315e8f17 100644
--- a/src/syntax/highlight.rs
+++ b/src/syntax/highlight.rs
@@ -223,6 +223,9 @@ impl Category {
             NodeKind::ImportExpr => None,
             NodeKind::ImportItems => None,
             NodeKind::IncludeExpr => None,
+            NodeKind::BreakExpr => None,
+            NodeKind::ContinueExpr => None,
+            NodeKind::ReturnExpr => None,
         }
     }
 
diff --git a/src/syntax/mod.rs b/src/syntax/mod.rs
index 74a642ca..9b606e0e 100644
--- a/src/syntax/mod.rs
+++ b/src/syntax/mod.rs
@@ -689,6 +689,12 @@ pub enum NodeKind {
     ImportItems,
     /// An include expression: `include "chapter1.typ"`.
     IncludeExpr,
+    /// A break expression: `break`.
+    BreakExpr,
+    /// A continue expression: `continue`.
+    ContinueExpr,
+    /// A return expression: `return x + 1`.
+    ReturnExpr,
     /// A line comment, two slashes followed by inner contents, terminated with
     /// a newline: `//<str>\n`.
     LineComment,
@@ -755,7 +761,7 @@ impl NodeKind {
         }
     }
 
-    /// Whether this token appears in Markup.
+    /// Which mode this token can appear in, in both if `None`.
     pub fn mode(&self) -> Option<TokenMode> {
         match self {
             Self::Markup(_)
@@ -780,6 +786,9 @@ impl NodeKind {
             | Self::Block
             | Self::Ident(_)
             | Self::LetExpr
+            | Self::SetExpr
+            | Self::ShowExpr
+            | Self::WrapExpr
             | Self::IfExpr
             | Self::WhileExpr
             | Self::ForExpr
@@ -897,6 +906,9 @@ impl NodeKind {
             Self::ImportExpr => "`import` expression",
             Self::ImportItems => "import items",
             Self::IncludeExpr => "`include` expression",
+            Self::BreakExpr => "`break` expression",
+            Self::ContinueExpr => "`continue` expression",
+            Self::ReturnExpr => "`return` expression",
             Self::LineComment => "line comment",
             Self::BlockComment => "block comment",
             Self::Error(_, _) => "parse error",
diff --git a/src/syntax/pretty.rs b/src/syntax/pretty.rs
index f8285f0c..e8110262 100644
--- a/src/syntax/pretty.rs
+++ b/src/syntax/pretty.rs
@@ -234,6 +234,9 @@ impl Pretty for Expr {
             Self::For(v) => v.pretty(p),
             Self::Import(v) => v.pretty(p),
             Self::Include(v) => v.pretty(p),
+            Self::Break(v) => v.pretty(p),
+            Self::Continue(v) => v.pretty(p),
+            Self::Return(v) => v.pretty(p),
         }
     }
 }
@@ -547,6 +550,28 @@ impl Pretty for IncludeExpr {
     }
 }
 
+impl Pretty for BreakExpr {
+    fn pretty(&self, p: &mut Printer) {
+        p.push_str("break");
+    }
+}
+
+impl Pretty for ContinueExpr {
+    fn pretty(&self, p: &mut Printer) {
+        p.push_str("continue");
+    }
+}
+
+impl Pretty for ReturnExpr {
+    fn pretty(&self, p: &mut Printer) {
+        p.push_str("return");
+        if let Some(body) = self.body() {
+            p.push(' ');
+            body.pretty(p);
+        }
+    }
+}
+
 impl Pretty for Ident {
     fn pretty(&self, p: &mut Printer) {
         p.push_str(self);
@@ -681,5 +706,9 @@ mod tests {
         roundtrip("#for k, x in y {z}");
         roundtrip("#import * from \"file.typ\"");
         roundtrip("#include \"chapter1.typ\"");
+        roundtrip("{break}");
+        roundtrip("{continue}");
+        roundtrip("{return}");
+        roundtrip("{return x + 1}");
     }
 }