Add AttrsBuidler, change Attrs struct around some

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

src/mem/basic.rs

@@ -8,6 +8,7 @@ use crate::{
 };
 use std::{collections::HashMap, ptr::NonNull};
 
+#[derive(Default)]
 pub struct BasicGc {
     objects: Vec<Box<ObjCell<dyn Obj>>>,
     strs: HashMap<String, ObjRef<Str>>,
@@ -69,3 +70,33 @@ impl Intern for BasicGc {
             .or_insert_with(|| len)
     }
 }
+
+// TODO object cloning
+// implementing `clone` is difficult without an ObjCtx, since Attrs has a pointer to itself. This
+// pointer would need to be updated.
+//
+// This will probably require a custom `ObjClone` trait to achieve the desired behavior with a ctx
+// object
+
+/*
+#[test]
+fn test_gc_clone() {
+    use crate::{obj::{attrs::AttrsBuilder, ctx::DefaultGc, Attrs, ObjCtx}};
+    
+    let mut ctx = ObjCtx::new(DefaultGc::default());
+
+    let empty_attrs = Attrs::new(&mut ctx, Default::default());
+
+    let empty_sym = ctx.gc_mut().add_sym("empty");
+    let attrs_source = AttrsBuilder::new(&mut ctx)
+        .attr_sym(empty_sym, empty_attrs.as_dyn())
+        .finish();
+
+    let attrs_clone = ctx.gc_mut().cloned(attrs_source.borrow());
+
+
+    assert!(!std::ptr::eq(attrs_source.as_ptr(), attrs_clone.as_ptr()));
+
+    let empty1 = attrs_source.borrow().get(empty_sym).unwrap();
+}
+*/

src/mem/gc.rs

@@ -5,18 +5,14 @@ use crate::{
         intern::Intern,
     }
 };
+use std::ptr::NonNull;
 
 pub trait Gc: Intern {
     fn alloc<O: Obj + 'static>(&mut self, obj: O) -> ObjRef<O>;
 
     fn add_obj<O: Obj + 'static>(&mut self, owned: Box<ObjCell<O>>);
 
-    fn mark(&mut self, alive: &[DynRef]) {
-        for obj in alive.iter() {
-            obj.borrow_mut().mark();
-        }
-    }
+    fn mark(&mut self, alive: &[DynRef]);
 
     fn sweep(&mut self);
 }
-

src/obj/attrs.rs

@@ -4,19 +4,21 @@ use crate::{
 };
 use std::{
     cell::Cell,
+    collections::BTreeMap,
     mem::MaybeUninit,
     ptr::{self, NonNull},
 };
 
-#[derive(Clone)]
+pub type AttrsMap = BTreeMap<Sym, DynRef>;
+
 pub struct Attrs {
-    attrs: Vec<(Sym, DynRef)>,
+    attrs: AttrsMap,
     marked: Cell<bool>,
     this: ObjRef<Attrs>,
 }
 
 impl Attrs {
-    pub fn new(ctx: &mut ObjCtx) -> Self {
+    pub fn new(ctx: &mut ObjCtx, attrs: BTreeMap<Sym, DynRef>) -> ObjRef<Self> {
         let obj: Box<ObjCell<Attrs>> = unsafe {
             let mut obj: Box<MaybeUninit<ObjCell<Attrs>>> = Box::new_uninit();
             // maybe UB? taking away the uninit right before it's initialized may be bad
@@ -31,19 +33,27 @@ impl Attrs {
             obj.assume_init()
         };
 
-        let attrs = {
+        let obj_ref = {
             let obj_ref: &Attrs = &obj.borrow();
             assert!(
                 ptr::eq(&*obj as *const _, obj_ref.this.as_ptr()),
                 "Attr 'this' member does not point to itself"
             );
-            obj_ref.clone()
+            obj_ref.this
         };
 
         // Add the object to the allocator pool
         ctx.gc_mut().add_obj(obj);
+        obj_ref
+    }
 
-        attrs
+    pub fn insert(&mut self, sym: Sym, value: DynRef) -> Option<DynRef> {
+        self.attrs.insert(sym, value)
+    }
+
+    pub fn get(&self, sym: Sym) -> Option<DynRef> {
+        dbg!(&self.attrs);
+        self.attrs.get(&dbg!(sym)).copied()
     }
 }
 
@@ -77,11 +87,59 @@ impl Obj for Attrs {
     }
 }
 
+pub struct AttrsBuilder<'ctx> {
+    ctx: &'ctx mut ObjCtx,
+    attrs: AttrsMap,
+}
+
+impl<'ctx> AttrsBuilder<'ctx> {
+    pub fn new(ctx: &'ctx mut ObjCtx) -> Self {
+        Self::with_base(ctx, Default::default())
+    }
+
+    pub fn with_base(ctx: &'ctx mut ObjCtx, attrs: AttrsMap) -> Self {
+        AttrsBuilder {
+            attrs,
+            ctx,
+        }
+    }
+
+    pub fn attr(mut self, symbol_name: &str, value: DynRef) -> Self {
+        let sym = self.ctx.gc_mut().add_sym(symbol_name);
+        self.attr_sym(sym, value)
+    }
+
+    pub fn attr_sym(mut self, sym: Sym, value: DynRef) -> Self {
+        self.attrs.insert(sym, value);
+        self
+    }
+
+    pub fn finish(self) -> ObjRef<Attrs> {
+        let Self { ctx, attrs } = self;
+        Attrs::new(ctx, attrs)
+    }
+}
+
 #[test]
 fn test_attrs_new() {
     use crate::mem::BasicGc;
 
     let mut ctx = ObjCtx::new(BasicGc::default());
     
-    let attrs = Attrs::new(&mut ctx);
+    let attrs_ref = Attrs::new(&mut ctx, Default::default());
+
+    {
+        let mut attrs = attrs_ref.borrow_mut();
+        let sym = ctx.gc_mut().add_sym("symbol");
+        attrs.insert(sym, attrs_ref.as_dyn());
+
+        assert!(
+            ptr::eq(
+                dbg!(attrs.get(sym).unwrap().as_ptr()),
+                dbg!(attrs_ref.as_dyn().as_ptr())
+                //               ^ as_dyn() is important here - this will cause the test to fail
+                //               otherwise
+            ),
+        );
+    }
 }

src/obj/ctx.rs

@@ -1,12 +1,17 @@
-use crate::mem::{gc::Gc, BasicGc};
+use crate::{
+    mem::{gc::Gc, ptr::DynRef, BasicGc},
+    obj::Sym,
+};
+use std::collections::BTreeMap;
 
 pub type DefaultGc = BasicGc;
 
-pub struct ObjCtx<G=DefaultGc>
+pub struct ObjCtx<G = DefaultGc>
 where
     G: Gc,
 {
     gc: G,
+    globals: BTreeMap<Sym, DynRef>,
 }
 
 impl<G> ObjCtx<G>
@@ -14,13 +19,22 @@ where
     G: Gc,
 {
     pub fn new(gc: G) -> Self {
-        ObjCtx { gc }
+        ObjCtx { gc, globals: Default::default() }
     }
-    
+
     pub fn gc(&self) -> &G {
         &self.gc
     }
+
     pub fn gc_mut(&mut self) -> &mut G {
         &mut self.gc
     }
+
+    pub fn globals(&self) -> &BTreeMap<Sym, DynRef> {
+        &self.globals
+    }
+
+    pub fn globals_mut(&mut self) -> &mut BTreeMap<Sym, DynRef> {
+        &mut self.globals
+    }
 }

src/obj/str.rs

@@ -1,6 +1,6 @@
-use crate::obj::prelude::*;
+use crate::obj::{attrs::AttrsBuilder, prelude::*};
 use derivative::Derivative;
-use std::{any::Any, cell::Cell};
+use std::{any::Any, cell::Cell, collections::BTreeMap};
 
 pub type StrRef = ObjRef<Str>;
 
@@ -18,14 +18,17 @@ pub struct Str {
 
 impl Str {
     pub fn new(ctx: &mut ObjCtx, contents: String) -> Self {
-        todo!()
-        /*
         Str {
-            attrs: Default::default(),
+            attrs: Self::type_attrs(ctx),
             contents,
             marked: Cell::new(false),
         }
-        */
+    }
+
+    fn type_attrs(ctx: &mut ObjCtx) -> ObjRef<Attrs> {
+        // TODO need global namespace
+        // TODO need upcast from dyn to static
+        todo!()
     }
 
     pub fn contents(&self) -> &String {

src/obj/ty.rs

@@ -1,9 +1,9 @@
-use crate::obj::prelude::*;
+use crate::obj::{attrs::AttrsBuilder, prelude::*};
 use std::cell::Cell;
 
 pub struct Ty {
     marked: Cell<bool>,
-    this: ObjRef<Ty>,
+    attrs: ObjRef<Attrs>,
 }
 
 impl Ty {