From cde0ff5582c27caf15d7581bc42ff9a1e70a0eb8 Mon Sep 17 00:00:00 2001
From: Jooris Hadeler <jooris@hadeler.me>
Date: Thu, 12 Mar 2026 21:42:40 +0100
Subject: [PATCH] feat: Add support for compound statements.

This commit adds parsing logic for compound statements.
---
 src/ast.rs    |  9 +++++++++
 src/main.rs   |  5 +++++
 src/parser.rs | 40 ++++++++++++++++++++++++++++++++++++++--
 test.bky      |  5 ++++-
 4 files changed, 56 insertions(+), 3 deletions(-)

diff --git a/src/ast.rs b/src/ast.rs
index 7e73509..84f81d9 100644
--- a/src/ast.rs
+++ b/src/ast.rs
@@ -234,6 +234,15 @@ pub enum StatementKind<P: Phase> {
         value: Option<Expression<P>>,
     },
 
+    /// A braced block of statements, e.g. `{ let x = 1; f(x); }`.
+    ///
+    /// Compound statements introduce a new scope and can appear anywhere a
+    /// statement is expected.
+    Compound {
+        /// The statements contained within the block, in source order.
+        inner: Vec<Statement<P>>,
+    },
+
     /// A bare expression statement, e.g. `f(x);`.
     ///
     /// The trailing `;` is not stored in the node but is included in
diff --git a/src/main.rs b/src/main.rs
index 45e62f1..113626b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -34,5 +34,10 @@ fn main() {
             Ok(ast) => println!("{ast:#?}"),
             Err(diag) => diag.report(file, &content),
         }
+
+        parser
+            .errors
+            .into_iter()
+            .for_each(|diag| diag.report(file, &content));
     }
 }
diff --git a/src/parser.rs b/src/parser.rs
index 35c0d16..67bc36a 100644
--- a/src/parser.rs
+++ b/src/parser.rs
@@ -24,7 +24,7 @@ pub struct Parser<'src> {
     /// Diagnostics accumulated during parsing. Non-fatal errors are pushed here
     /// so that the parser can attempt to continue and surface multiple issues
     /// in a single pass.
-    errors: Vec<Diagnostic>,
+    pub errors: Vec<Diagnostic>,
 }
 
 impl<'src> Parser<'src> {
@@ -110,12 +110,14 @@ impl<'src> Parser<'src> {
     /// Dispatches to the appropriate specialised parser based on the leading
     /// token:
     /// - `let` → [`parse_let_statement`](Self::parse_let_statement)
+    /// - `{`   → [`parse_compound_statement`](Self::parse_compound_statement)
     /// - anything else → an expression followed by a mandatory `;`
     pub fn parse_statement(&mut self) -> Result<ast::ParsedStatement, Diagnostic> {
         let peek = self.peek_no_eof()?;
 
         match peek.kind {
             TokenKind::KwLet => self.parse_let_statement(),
+            TokenKind::LCurly => self.parse_compound_statement(),
 
             _ => {
                 let expr = self.parse_expression(0)?;
@@ -171,6 +173,36 @@ impl<'src> Parser<'src> {
         })
     }
 
+    /// Parses a braced block of statements: `{ <stmt>* }`.
+    ///
+    /// Each inner statement is parsed with [`parse_statement`](Self::parse_statement).
+    /// If a statement fails, the diagnostic is pushed onto [`errors`](Parser::errors)
+    /// and [`synchronize`](Self::synchronize) is called so that parsing can
+    /// continue with the next statement. The block span runs from `{` to `}`.
+    fn parse_compound_statement(&mut self) -> Result<ast::ParsedStatement, Diagnostic> {
+        let lcurly_token = self.expect(TokenKind::LCurly)?;
+        let mut inner = Vec::new();
+
+        while !self.is_at_eof() && !self.is_peek(TokenKind::RCurly) {
+            match self.parse_statement() {
+                Ok(stmt) => inner.push(stmt),
+                Err(diag) => {
+                    self.errors.push(diag);
+                    self.synchronize();
+                }
+            }
+        }
+
+        let rcurly_token = self.expect(TokenKind::RCurly)?;
+        let span = lcurly_token.span.extend(rcurly_token.span);
+
+        Ok(ast::ParsedStatement {
+            kind: ast::StatementKind::Compound { inner },
+            span,
+            extra: (),
+        })
+    }
+
     /// Parses a type annotation, e.g. `u8`, `i64`, `bool`, or a user-defined
     /// named type.
     ///
@@ -193,7 +225,11 @@ impl<'src> Parser<'src> {
 
             TokenKind::Identifier => ast::TypeKind::Named(peek.text.to_string()),
 
-            _ => return Err(Diagnostic::new(Severity::Error, "expected a type")),
+            _ => {
+                return Err(
+                    Diagnostic::new(Severity::Error, "expected a type").with_span(peek.span)
+                );
+            }
         };
 
         let span = self.advance().span;
diff --git a/test.bky b/test.bky
index d75e696..ce0d482 100644
--- a/test.bky
+++ b/test.bky
@@ -1 +1,4 @@
-let test: i32 = foo.bar - 5 as i32;
\ No newline at end of file
+{
+    let a : 0;
+    f();
+}
\ No newline at end of file