From e063d4c68513936e2eb9a7e6031d77aab32a71b3 Mon Sep 17 00:00:00 2001
From: Klesti Selimaj <klesti.selimay@icloud.com>
Date: Sun, 10 May 2026 17:55:08 +0200
Subject: [PATCH] Traits

---
 mist-test/src/logger.mist |  2 ++
 parser/src/ast.rs         | 15 ++++++++++++++-
 parser/src/grammar.pest   | 20 +++++++++++++++++++-
 parser/src/lib.rs         | 25 +++++++++++++++++++++++++
 4 files changed, 60 insertions(+), 2 deletions(-)

diff --git a/mist-test/src/logger.mist b/mist-test/src/logger.mist
index f6b55c5..a1c5631 100644
--- a/mist-test/src/logger.mist
+++ b/mist-test/src/logger.mist
@@ -1,5 +1,7 @@
 use <std::fmt>;
 
+public trait TestLogging: Display {}
+
 public enum LogLevel {
     Info,
     Warning,
diff --git a/parser/src/ast.rs b/parser/src/ast.rs
index 5f78fd4..18509dd 100644
--- a/parser/src/ast.rs
+++ b/parser/src/ast.rs
@@ -75,6 +75,13 @@ pub enum TopLevelKind {
     Import(Path),
     Mod(Identifier),
     ImplDecl(ImplDecl),
+    TraitDecl {
+        visibility: Visibility,
+        name: Identifier,
+        generics: Generics,
+        requirements: Vec<TypeExpr>,
+        items: Vec<TraitItem>,
+    },
     EnumDecl {
         visibility: Visibility,
         name: Identifier,
@@ -83,8 +90,8 @@ pub enum TopLevelKind {
     },
     StructDecl {
         visibility: Visibility,
-        generics: Generics,
         name: Identifier,
+        generics: Generics,
         fields: Vec<FieldDecl>,
     },
     FunctionDecl(FunctionDecl),
@@ -98,6 +105,12 @@ pub enum TopLevelKind {
     },
 }
 
+#[derive(Debug, Clone, Serialize)]
+pub enum TraitItem {
+    WithBody(FunctionDecl),
+    NoBody(FunctionDecl),
+}
+
 #[derive(Debug, Clone, Serialize)]
 pub enum ClassItem {
     Method(FunctionDecl),
diff --git a/parser/src/grammar.pest b/parser/src/grammar.pest
index afc0ea4..b9f3bfb 100644
--- a/parser/src/grammar.pest
+++ b/parser/src/grammar.pest
@@ -259,6 +259,24 @@ impl_decl = {
     "impl" ~ generics? ~ type_expr ~ "{" ~ method* ~ "}"
 }
 
+// ======================================================
+// Traits
+// ======================================================
+trait_requirements = { ":" ~ type_expr_param ~ ("+" ~ type_expr_param)* }
+
+method_no_body = {
+    export? ~ type_expr ~ identifier ~ generics? ~ "(" ~ self_param? ~ ("," ~ param_list?)? ~ ")"
+}
+
+trait_item = _{
+    method
+  | method_no_body
+}
+
+trait_decl = {
+    export? ~ "trait" ~ identifier ~ generics? ~ trait_requirements? ~ "{" ~ trait_item* ~ "}"
+}
+
 // ======================================================
 // FUNCTIONS
 // ======================================================
@@ -272,7 +290,7 @@ function_decl = {
 // ======================================================
 
 top_level = {
-    (attributes ~ (import | impl_for_decl | impl_decl | function_decl | struct_decl | enum_decl | class_decl | mod_package))
+    (attributes ~ (import | impl_for_decl | impl_decl | trait_decl | struct_decl | enum_decl | class_decl | mod_package | function_decl))
   | mod_attribute
 }
 
diff --git a/parser/src/lib.rs b/parser/src/lib.rs
index d3861e2..fb0343e 100644
--- a/parser/src/lib.rs
+++ b/parser/src/lib.rs
@@ -305,6 +305,31 @@ impl From<pest::iterators::Pair<'_, Rule>> for TopLevelKind {
 
             Rule::impl_for_decl | Rule::impl_decl => TopLevelKind::ImplDecl(ImplDecl::from(pair)),
 
+            Rule::trait_decl => TopLevelKind::TraitDecl {
+                visibility: Visibility::from(&mut inner),
+                name: Identifier::from(inner.next().unwrap()),
+                generics: consume_rule(&mut inner, Rule::generics)
+                    .map(Generics::from)
+                    .unwrap_or_default(),
+                requirements: consume_rule(&mut inner, Rule::trait_requirements)
+                    .map(|pair| pair.into_inner().map(TypeExpr::from).collect())
+                    .unwrap_or_default(),
+                items: inner.map(TraitItem::from).collect(),
+            },
+
+            _ => unimplemented!("{rule:#?}"),
+        }
+    }
+}
+
+impl From<pest::iterators::Pair<'_, Rule>> for TraitItem {
+    fn from(pair: pest::iterators::Pair<'_, Rule>) -> Self {
+        let rule = pair.as_rule();
+
+        match rule {
+            Rule::method => TraitItem::WithBody(FunctionDecl::from(pair)),
+            Rule::method_no_body => TraitItem::NoBody(FunctionDecl::from(pair)),
+
             _ => unimplemented!("{rule:#?}"),
         }
     }