From 4c297eb957a5beb05b6d3dff94bfaf7545181887 Mon Sep 17 00:00:00 2001
From: mars <mars@tebibyte.media>
Date: Wed, 2 Mar 2022 10:21:10 -0700
Subject: [PATCH] Parse mutable interface functions

---
 src/parse.rs | 92 +++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 62 insertions(+), 30 deletions(-)

diff --git a/src/parse.rs b/src/parse.rs
index 7dac029..ee65e2a 100644
--- a/src/parse.rs
+++ b/src/parse.rs
@@ -23,7 +23,8 @@ impl<'a> ParseTree<'a> {
                 }
 
                 declarations.push(Definition::build_function(
-                    Some((struct_name, mutable)),
+                    mutable,
+                    Some(struct_name),
                     lexer,
                 ));
 
@@ -31,7 +32,9 @@ impl<'a> ParseTree<'a> {
             } else {
                 match tok {
                     Token::Struct => declarations.push(Definition::build_structure(lexer)),
-                    Token::Function => declarations.push(Definition::build_function(None, lexer)),
+                    Token::Function => {
+                        declarations.push(Definition::build_function(false, None, lexer))
+                    }
                     Token::Interface => declarations.push(Definition::build_interface(lexer)),
                     Token::Impl => declarations.push(Definition::build_impl(lexer)),
                     Token::Identifier => associated_struct = Some(lexer.slice()),
@@ -51,12 +54,12 @@ pub enum Definition<'a> {
         members: Vec<StructMember<'a>>,
     },
     Function {
-        associated_struct: Option<(&'a str, bool)>,
+        associated_struct: Option<&'a str>,
         implementation: FnImpl<'a>,
     },
     Interface {
         name: &'a str,
-        functions: Vec<(&'a str, FnSig<'a>)>,
+        functions: Vec<FnDef<'a>>,
     },
     Impl {
         structure: &'a str,
@@ -91,10 +94,11 @@ impl<'a> Definition<'a> {
     }
 
     pub fn build_function(
-        associated_struct: Option<(&'a str, bool)>,
+        mutable: bool,
+        associated_struct: Option<&'a str>,
         lexer: &mut Lexer<'a>,
     ) -> Self {
-        let implementation = FnImpl::build(lexer);
+        let implementation = FnImpl::build(mutable, lexer);
 
         Self::Function {
             associated_struct,
@@ -109,17 +113,13 @@ impl<'a> Definition<'a> {
         let mut functions = Vec::new();
         loop {
             match lexer.next().unwrap() {
-                Token::Function => {
-                    let name = lexer.eat_expect_id();
-                    let (signature, next) = FnSig::build(lexer);
-                    if next != Token::Semicolon {
-                        lexer.panic_message("Expected semicolon");
-                    }
-
-                    functions.push((name, signature));
+                Token::Function => functions.push(FnDef::eat_with_semicolon(false, lexer)),
+                Token::Mut => {
+                    lexer.eat_expect(Token::Function);
+                    functions.push(FnDef::eat_with_semicolon(true, lexer));
                 }
                 Token::BraceClose => break,
-                _ => lexer.panic_message("Expected fn or closing bracket"),
+                _ => lexer.panic_message("Expected function definition or closing bracket"),
             }
         }
 
@@ -142,7 +142,11 @@ impl<'a> Definition<'a> {
         loop {
             match lexer.next().unwrap() {
                 Token::BraceClose => break,
-                Token::Function => functions.push(FnImpl::build(lexer)),
+                Token::Function => functions.push(FnImpl::build(false, lexer)),
+                Token::Mut => {
+                    lexer.eat_expect(Token::Function);
+                    functions.push(FnImpl::build(true, lexer));
+                }
                 _ => lexer.panic_message("Expected function implementation or closing brace"),
             }
         }
@@ -157,27 +161,55 @@ impl<'a> Definition<'a> {
 
 #[derive(Debug)]
 pub struct FnImpl<'a> {
-    pub name: &'a str,
-    pub signature: FnSig<'a>,
+    pub def: FnDef<'a>,
     pub body: BranchBody<'a>,
 }
 
 impl<'a> FnImpl<'a> {
-    pub fn build(lexer: &mut Lexer<'a>) -> Self {
-        let name = lexer.eat_expect_id();
-        let (signature, tok) = FnSig::build(lexer);
-
-        if tok != Token::BraceOpen {
-            lexer.panic_message("Expected open brace");
-        }
-
+    pub fn build(mutable: bool, lexer: &mut Lexer<'a>) -> Self {
+        let def = FnDef::eat_with_brace(mutable, lexer);
         let body = BranchBody::build(lexer);
+        Self { def, body }
+    }
+}
 
-        Self {
-            name,
-            signature,
-            body,
+#[derive(Debug)]
+pub struct FnDef<'a> {
+    pub mutable: bool,
+    pub name: &'a str,
+    pub signature: FnSig<'a>,
+}
+
+impl<'a> FnDef<'a> {
+    pub fn build(mutable: bool, lexer: &mut Lexer<'a>) -> (Self, Token) {
+        let name = lexer.eat_expect_id();
+        let (signature, tail) = FnSig::build(lexer);
+        (
+            Self {
+                mutable,
+                name,
+                signature,
+            },
+            tail,
+        )
+    }
+
+    pub fn eat_with_semicolon(mutable: bool, lexer: &mut Lexer<'a>) -> Self {
+        let (fn_def, tail) = Self::build(mutable, lexer);
+        if tail != Token::Semicolon {
+            lexer.panic_message("Expected semicolon");
         }
+
+        fn_def
+    }
+
+    pub fn eat_with_brace(mutable: bool, lexer: &mut Lexer<'a>) -> Self {
+        let (fn_def, tail) = Self::build(mutable, lexer);
+        if tail != Token::BraceOpen {
+            lexer.panic_message("Expected opening brace");
+        }
+
+        fn_def
     }
 }