var decls

crates/parser/src/lib.rs

@@ -240,7 +240,7 @@ pub enum AstNode {
     VarDecl {
         mutable: bool,
         name: String,
-        var_type: Type,
+        var_type: Option<Type>,
     },
     Assignment {
         dest: Index,
@@ -414,6 +414,14 @@ impl PlaceOrValue {
             PlaceOrValue::Value(_) => PlaceOrValue::Value(index),
         }
     }
+
+    pub fn eq_placeness(&self, other: &Self) -> bool {
+        match (self, other) {
+            (PlaceOrValue::Place(_), PlaceOrValue::Place(_))
+            | (PlaceOrValue::Value(_), PlaceOrValue::Value(_)) => true,
+            _ => false,
+        }
+    }
 }
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Hash, Default)]
@@ -603,9 +611,48 @@ where
         self.function.clone()
     }
 
-    fn stmt(&self) -> impl Parser<'src, TokenInput<'src>, Index, ParserExtra> + Clone {
+    fn var_decl(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, Index, ParserExtra> + Clone + use<'src, 'b> {
+        let ident = select! {Token::Ident(ident) => ident};
+        just(Token::Let)
+            .ignored()
+            .then(select! {Token::Mutable => ()}.or_not())
+            .then(ident)
+            .then(
+                just(Token::Colon)
+                    .ignore_then(type_parser::<ParserExtra>())
+                    .or_not(),
+            )
+            .then(
+                just(Token::Equal)
+                    .ignore_then(self.expr().map_with(Self::into_value))
+                    .or_not(),
+            )
+            .then_ignore(just(Token::Semi))
+            .map_with(|((((_, mutable), ident), var_type), val), e: &mut E| {
+                let decl = e.state().push(AstNode::VarDecl {
+                    mutable: mutable.is_some(),
+                    name: ident.to_string(),
+                    var_type,
+                });
+                if let Some(expr) = val {
+                    e.state().push(AstNode::Assignment {
+                        dest: decl,
+                        expr: expr.index(),
+                    })
+                } else {
+                    decl
+                }
+            })
+    }
+
+    fn stmt(
+        &self,
+    ) -> impl Parser<'src, TokenInput<'src>, Index, ParserExtra> + Clone + use<'src, 'b> {
         choice((
             self.function.clone(),
+            self.var_decl(),
             self.expr
                 .clone()
                 .then_ignore(just(Token::Semi))
@@ -718,10 +765,7 @@ where
         &self,
     ) -> impl Parser<'src, TokenInput<'src>, PlaceOrValue, ParserExtra> + Clone + use<'src, 'b>
     {
-        self.expr
-            .clone()
-            .then_ignore(just(Token::Semi))
-            .map(PlaceOrValue::index)
+        self.stmt()
             .repeated()
             .collect::<Vec<_>>()
             .then(self.expr.clone().or_not())
@@ -1022,13 +1066,20 @@ where
             .then(self.expr())
             .then(else_expr.or_not())
             .map_with(|((condition, then), or), e: &mut E| {
-                // TODO: determine placeness from branches
+                use PlaceOrValue::*;
+                let (then, or) = match (then, or) {
+                    (Place(then), Some(Place(or))) => (Place(then), Some(Place(or))),
+                    _ => (
+                        Self::into_value(then, e),
+                        or.map(|or| Self::into_value(or, e)),
+                    ),
+                };
                 let node = AstNode::If {
                     condition,
                     then: then.index(),
                     r#else: or.map(PlaceOrValue::index),
                 };
-                e.state().push(node).as_value()
+                then.with_index(e.state().push(node))
             })
     }
 
@@ -1095,7 +1146,7 @@ mod symbols;
 
 #[cfg(test)]
 mod tests {
-    use chumsky::{Parser, extra::SimpleState};
+    use chumsky::{ParseResult, Parser, extra::SimpleState};
 
     use crate::{Ast, AstNode, ParserCtx, ParserExtra, new_token_input, pretty, type_parser};
 
@@ -1163,6 +1214,10 @@ mod tests {
     ) {
         let mut state = SimpleState(Ast::new());
         let out = parser.parse_with_state(tokens, &mut state);
+        for e in out.errors() {
+            eprintln!("Error: {}", e);
+            panic!("errors occured while parsing.")
+        }
         let ast = state.0;
         let mut pretty = pretty::PrettyPrint::new();
         pretty.print(&ast);
@@ -1184,6 +1239,7 @@ mod tests {
                 r#"
 /// docs!
 fn my_function(a: i32, b: *const u8) -> i32 {
+    let mut x: i32;
     x = a + 1;
     x
 }
@@ -1193,6 +1249,40 @@ fn my_function(a: i32, b: *const u8) -> i32 {
         );
     }
 
+    #[test]
+    fn parse_var_decl() {
+        let ctx = crate::ParserCtx::new();
+        print_ast(
+            new_token_input(
+                r#"
+let mut x: i32 = 10;
+"#,
+            ),
+            ctx.var_decl(),
+        );
+    }
+
+    #[test]
+    fn parse_stmts() {
+        let ctx = crate::ParserCtx::new();
+        print_ast(
+            new_token_input(
+                r#"
+let mut x: i32 = 10;
+"#,
+            ),
+            ctx.stmt(),
+        );
+        print_ast(
+            new_token_input(
+                r#"
+(if (true) {x} else {y}) = x + x;
+"#,
+            ),
+            ctx.stmt(),
+        );
+    }
+
     #[test]
     fn parse_if_expr() {
         let ctx = crate::ParserCtx::new();

crates/parser/src/pretty.rs

@@ -164,7 +164,15 @@ impl PrettyPrint {
                 mutable,
                 name,
                 var_type,
-            } => todo!(),
+            } => {
+                self.push_line(format!(
+                    "{} [{} {}: {}]",
+                    node_name(node),
+                    name,
+                    mutable.then_some(" mut").unwrap_or(""),
+                    var_type.map_or("?".to_string(), |ty| format!("{ty}"))
+                ));
+            }
             AstNode::Assignment { dest, expr } => {
                 self.push_line(format!("{}", node_name(node),));
                 self.indents.push(Indent::Vertical);
@@ -174,7 +182,7 @@ impl PrettyPrint {
                 });
                 *self.indents.last_mut().unwrap() = Indent::End;
                 self.push_line("EXPR".to_string());
-                self.with_indent(core::iter::once(*dest), |this, idx| {
+                self.with_indent(core::iter::once(*expr), |this, idx| {
                     this.stuff(ast, idx);
                 });
                 self.indents.pop();
@@ -182,8 +190,13 @@ impl PrettyPrint {
             AstNode::GlobalDecl {
                 name,
                 var_type,
-                expr: value,
-            } => todo!(),
+                expr,
+            } => {
+                self.push_line(format!("{} [{}: {}]", node_name(node), name, var_type));
+                self.with_indent(core::iter::once(*expr), |this, idx| {
+                    this.stuff(ast, idx);
+                });
+            }
             AstNode::StructDecl { name, fields } => todo!(),
             AstNode::FieldDecl { name, field_type } => todo!(),
             AstNode::FieldAccess { expr, field } => todo!(),
@@ -350,8 +363,8 @@ fn node_name(node: &AstNode) -> &'static str {
         AstNode::ExplicitCast { .. } => "AS",
         AstNode::Deref { .. } => "DEREF",
         AstNode::AddressOf { .. } => "ADDR_OF",
-        AstNode::PlaceToValue { .. } => "INTO_PLACE",
-        AstNode::ValueToPlace { .. } => "INTO_VALUE",
+        AstNode::PlaceToValue { .. } => "INTO_VALUE",
+        AstNode::ValueToPlace { .. } => "INTO_PLACE",
         AstNode::CallExpr { .. } => "CALL",
         AstNode::Argument { .. } => "ARG",
         AstNode::Not(_) => "NOT",