Add vm and compile modules

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

src/compile/mod.rs

@@ -0,0 +1,42 @@
+pub mod sym;
+
+use crate::{
+    syn::ast::Stmt,
+    compile::sym::SymStack,
+};
+
+pub trait Pass {
+    type Out;
+    fn pass(&self, ctx: &mut Ctx) -> Self::Out;
+}
+
+// * Desugar
+// * Collect names as symbols
+// * Create basic blocks
+
+pub struct Ctx {
+    sym_stack: SymStack,
+}
+
+impl Ctx {
+    pub fn sym_stack(&self) -> &SymStack {
+        &self.sym_stack
+    }
+
+    pub fn sym_stack_mut(&mut self) -> &mut SymStack {
+        &mut self.sym_stack
+    }
+}
+
+// no sugar in the syntax quite yet
+/*
+pub struct Desugar;
+
+impl Pass<Vec<Stmt>> for Desugar {
+    type Out = Vec<Stmt>;
+
+    fn pass(&mut self, input: Vec<Stmt>) -> Vec<Stmt> {
+        input
+    }
+}
+*/

src/compile/sym.rs

@@ -0,0 +1,16 @@
+use crate::obj::Sym;
+use std::collections::HashMap;
+
+pub struct SymStack {
+    syms: HashMap<String, Sym>,
+    stack: Vec<Vec<Sym>>,
+}
+
+impl SymStack {
+    pub fn new() -> Self {
+        SymStack {
+            syms: Default::default(),
+            stack: vec![Default::default()],
+        }
+    }
+}

src/main.rs

@@ -1,9 +1,11 @@
 #![allow(dead_code)]
 #![feature(new_uninit)]
 
+mod compile;
 mod syn;
 mod obj;
 mod mem;
+mod vm;
 
 use std::{
     convert::TryFrom,

src/mem/gc.rs

@@ -5,7 +5,6 @@ use crate::{
         intern::Intern,
     }
 };
-use std::ptr::NonNull;
 
 pub trait Gc: Intern {
     fn alloc<O: Obj + 'static>(&mut self, obj: O) -> ObjRef<O>;

src/mem/ptr.rs

@@ -1,6 +1,6 @@
 use crate::obj::Obj;
 use std::{
-    any,
+    any::{self, Any},
     cell::RefCell,
     fmt::{self, Debug, Formatter},
     ops::Deref,
@@ -10,13 +10,14 @@ use std::{
 pub type DynRef = ObjRef<dyn Obj>;
 
 pub struct ObjRef<O>
-    where O: Obj + ?Sized
+where O: Obj + ?Sized,
 {
     ptr: NonNull<ObjCell<O>>,
 }
 
 impl<O> ObjRef<O>
-    where O: Obj + ?Sized
+where
+    O: Obj + ?Sized,
 {
     pub fn new(ptr: NonNull<ObjCell<O>>) -> Self {
         ObjRef { ptr }
@@ -27,8 +28,16 @@ impl<O> ObjRef<O>
     }
 }
 
+impl<O: Obj + ?Sized> AsRef<ObjCell<O>> for ObjRef<O> {
+    fn as_ref(&self) -> &ObjCell<O> {
+        // safe because pointer should point at live data assuming GC is working appropriately
+        unsafe { &*self.as_ptr() }
+    }
+}
+
 impl<O> ObjRef<O>
-    where O: Obj
+where
+    O: Obj,
 {
     pub fn as_dyn(&self) -> ObjRef<dyn Obj> {
         let ptr = self.as_ptr() as *const ObjCell<dyn Obj>;
@@ -37,7 +46,8 @@ impl<O> ObjRef<O>
 }
 
 impl<O> Deref for ObjRef<O>
-    where O: Obj + ?Sized
+where
+    O: Obj + ?Sized,
 {
     type Target = RefCell<O>;
 
@@ -48,28 +58,37 @@ impl<O> Deref for ObjRef<O>
 }
 
 impl<O> Clone for ObjRef<O>
-    where O: Obj + ?Sized
+where
+    O: Obj + ?Sized,
 {
     fn clone(&self) -> Self {
         ObjRef { ptr: self.ptr }
     }
 }
 
-impl<O> Copy for ObjRef<O>
-    where O: Obj + ?Sized
-{}
+impl<O> Copy for ObjRef<O> where O: Obj + ?Sized {}
 
 impl<O> Debug for ObjRef<O>
-    where O: Obj + Debug + ?Sized
+where
+    O: Obj + Debug + ?Sized,
 {
     fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
-        write!(fmt, "<{} object at {:#x}>", any::type_name::<O>(), self.as_ptr() as *const () as usize)
+        write!(
+            fmt,
+            "<{} object at {:#x}>",
+            any::type_name::<O>(),
+            self.as_ptr() as *const () as usize
+        )
     }
 }
 
 impl Debug for ObjRef<dyn Obj> {
     fn fmt(&self, fmt: &mut Formatter) -> fmt::Result {
-        write!(fmt, "<? object at {:#x}>", self.as_ptr() as *const () as usize)
+        write!(
+            fmt,
+            "<? object at {:#x}>",
+            self.as_ptr() as *const () as usize
+        )
     }
 }
 

src/obj/attrs.rs

@@ -104,7 +104,7 @@ impl<'ctx> AttrsBuilder<'ctx> {
         }
     }
 
-    pub fn attr(mut self, symbol_name: &str, value: DynRef) -> Self {
+    pub fn attr(self, symbol_name: &str, value: DynRef) -> Self {
         let sym = self.ctx.gc_mut().add_sym(symbol_name);
         self.attr_sym(sym, value)
     }

src/obj/fun.rs

@@ -0,0 +1,92 @@
+use crate::{obj::prelude::*, vm::op::Op};
+use std::{any::Any, cell::Cell, rc::Rc};
+
+pub type NativeFunPtr = fn(argv: Vec<DynRef>);
+
+pub struct NativeFun {
+    attrs: ObjRef<Attrs>,
+    fn_ptr: NativeFunPtr,
+}
+
+impl NativeFun {
+    pub fn new(ctx: &mut ObjCtx, name: StrRef, fn_ptr: NativeFunPtr) -> Self {
+        let attrs = Attrs::new(ctx, Default::default());
+        NativeFun {
+            attrs,
+            fn_ptr,
+        }
+    }
+
+    pub fn call(&self, argv: Vec<DynRef>) {
+        (self.fn_ptr)(argv)
+    }
+}
+
+impl Obj for NativeFun {
+    fn attrs(&self) -> ObjRef<Attrs> {
+        self.attrs
+    }
+
+    fn is_marked(&self) -> bool {
+        // native functions are always available
+        true
+    }
+
+    fn mark(&self) {}
+
+    fn unmark(&self) {}
+
+    fn as_any(&self) -> &dyn std::any::Any {
+        self
+    }
+}
+
+pub struct Fun {
+    attrs: ObjRef<Attrs>,
+    code: Rc<Vec<Op>>,
+    marked: Cell<bool>,
+}
+
+impl Fun {
+    pub fn new(attrs: ObjRef<Attrs>, code: Rc<Vec<Op>>) -> Self {
+        Fun {
+            attrs,
+            code,
+            marked: Cell::new(false),
+        }
+    }
+
+    pub fn code(&self) -> Rc<Vec<Op>> {
+        Rc::clone(&self.code)
+    }
+}
+
+impl Obj for Fun {
+    fn attrs(&self) -> ObjRef<Attrs> {
+        self.attrs
+    }
+
+    fn is_marked(&self) -> bool {
+        self.marked.get()
+    }
+
+    fn mark(&self) {
+        if self.is_marked() {
+            return;
+        }
+        self.marked.set(true);
+        self.attrs.borrow().mark();
+    }
+
+    fn unmark(&self) {
+        if !self.is_marked() {
+            return;
+        }
+        self.marked.set(false);
+        self.attrs.borrow().unmark();
+    }
+
+    fn as_any(&self) -> &dyn Any {
+        self
+    }
+}

src/obj/mod.rs

@@ -2,7 +2,7 @@ pub mod attrs;
 pub mod ctx;
 pub mod dict;
 pub mod error;
-//pub mod native_fun;
+pub mod fun;
 //pub mod num;
 pub mod str;
 pub mod sym {
@@ -13,7 +13,7 @@ pub mod sym {
 pub mod prelude {
     pub use crate::{
         obj::{
-            Attrs, Dict, DictRef, Str, StrRef, Sym, ObjCtx, Obj,
+            Attrs, Dict, DictRef, Fun, NativeFun, Str, StrRef, Sym, ObjCtx, Obj,
         },
         mem::{
             ptr::{ObjRef, DynRef},
@@ -25,8 +25,9 @@ pub mod prelude {
 
 pub use self::{
     attrs::Attrs,
-    dict::{Dict, DictRef},
     ctx::ObjCtx,
+    dict::{Dict, DictRef},
+    fun::{NativeFun, Fun},
     str::{Str, StrRef},
     sym::Sym,
 };

src/obj/native_fun.rs

@@ -1,27 +0,0 @@
-use crate::obj::prelude::*;
-
-pub type NativeFunPtr = *const fn();
-
-pub struct NativeFun {
-    attrs: Attrs,
-    fn_ptr: NativeFunPtr,
-}
-
-impl NativeFun {
-    pub fn new(ctx: &mut ObjCtx, name: StrRef, fn_ptr: NativeFunPtr) -> Self {
-        todo!()
-        /*
-        let attrs = Attrs::default();
-        NativeFun {
-            attrs,
-            fn_ptr,
-        }
-        */
-    }
-}
-/*
-
-impl Obj for NativeFun {
-    fn get_attr(&self, key: &DynRef) -> Option<DynRef>
-}
-*/

src/obj/str.rs

@@ -1,6 +1,6 @@
-use crate::obj::{attrs::AttrsBuilder, prelude::*};
+use crate::obj::prelude::*;
 use derivative::Derivative;
-use std::{any::Any, cell::Cell, collections::BTreeMap};
+use std::{any::Any, cell::Cell};
 
 pub type StrRef = ObjRef<Str>;
 

src/vm/frame.rs

@@ -0,0 +1,49 @@
+use crate::obj::prelude::*;
+use std::collections::BTreeMap;
+
+#[derive(Default)]
+pub struct Frame {
+    stack: Vec<DynRef>,
+    ip: usize,
+    return_value: Option<DynRef>,
+    locals: BTreeMap<Sym, DynRef>,
+}
+
+impl Frame {
+    pub fn new() -> Self {
+        Default::default()
+    }
+
+    pub fn push(&mut self, obj_ref: DynRef) {
+        self.stack.push(obj_ref)
+    }
+    
+    pub fn pop(&mut self) -> Option<DynRef> {
+        self.stack.pop()
+    }
+
+    pub fn ip(&self) -> usize {
+        self.ip
+    }
+
+    pub fn set_ip(&mut self, ip: usize) {
+        self.ip = ip;
+    }
+
+    pub fn return_value(&self) -> Option<DynRef> {
+        self.return_value
+    }
+
+    pub fn set_return_value(&mut self, obj_ref: DynRef) {
+        self.return_value = Some(obj_ref);
+    }
+
+    pub fn get_local(&self, sym: Sym) -> Option<DynRef> {
+        self.locals.get(&sym).copied()
+    }
+
+    pub fn set_local(&mut self, sym: Sym, obj_ref: DynRef) -> Option<DynRef> {
+        self.locals.insert(sym, obj_ref)
+    }
+}
+

src/vm/mod.rs

@@ -0,0 +1,131 @@
+pub mod op;
+pub mod frame;
+
+use crate::{
+    obj::prelude::*,
+    vm::{
+        op::Op,
+        frame::Frame,
+    }
+};
+use std::rc::Rc;
+
+pub struct State {
+    frames: Vec<Frame>,
+}
+
+impl State {
+    pub fn new() -> Self {
+        State { frames: Default::default(), }
+    }
+
+    fn frame(&self) -> &Frame {
+        self.frames
+            .last()
+            .unwrap()
+    }
+
+    fn frame_mut(&mut self) -> &mut Frame {
+        self.frames
+            .last_mut()
+            .unwrap()
+    }
+
+    fn push_stack(&mut self, value: DynRef) {
+        self.frame_mut()
+            .push(value);
+    }
+
+    fn pop_stack(&mut self) -> Option<DynRef> {
+        self.frame_mut()
+            .pop()
+    }
+
+    fn ip(&self) -> usize {
+        self.frame().ip()
+    }
+
+    fn set_ip(&mut self, ip: usize) {
+        self.frame_mut().set_ip(ip);
+    }
+
+    fn get_local(&self, sym: Sym) -> Option<DynRef> {
+        self.frame().get_local(sym)
+    }
+
+    fn set_local(&mut self, sym: Sym, obj_ref: DynRef) -> Option<DynRef> {
+        self.frame_mut().set_local(sym, obj_ref)
+    }
+
+    pub fn run(&mut self, ops: Rc<Vec<Op>>) {
+        self.frames.push(Default::default());
+        while self.ip() < ops.len() {
+            let mut next_ip = self.ip() + 1;
+            match &ops[self.ip()] {
+                Op::Push(sym) => {
+                    // TODO - local not found
+                    let obj_ref = self.get_local(*sym)
+                        .expect("TODO - local not found");
+                    self.push_stack(obj_ref);
+                }
+                Op::Pop(sym) => {
+                    // stack should not underflow
+                    let obj_ref = self.pop_stack()
+                        .expect("misaligned stack for pop");
+                    if let Some(sym) = *sym {
+                        self.set_local(sym, obj_ref);
+                    }
+                }
+                Op::GetAttr(sym) => {
+                    let top = self.pop_stack()
+                        .expect("misaligned stack for getattrs");
+                    let obj_ref = {
+                        let top_ref = top.borrow();
+                        let attrs = top_ref.attrs();
+                        let attrs_ref = attrs.borrow();
+                        // TODO - local not found
+                        attrs_ref.get(*sym)
+                            .expect("TODO - local not found")
+                    };
+                    self.push_stack(obj_ref);
+                }
+                Op::Call(argc) => {
+                    let fun = self.pop_stack()
+                        .expect("misaligned stack for function call");
+                    let mut argv = Vec::with_capacity(*argc);
+                    for i in 0 .. *argc {
+                        let arg = self.pop_stack()
+                            .expect("misaligned stack for argv");
+                        argv.push(arg);
+                    }
+                    // reverse since arguments are pushed in order of being passed
+                    argv.reverse();
+
+                    // call function
+                    // TODO - call the function indirectly?
+                    //
+                    // problem: downcast_ref returns a reference bound by the lifetime of the
+                    // function (because of the ref cell). This keeps the fun object borrowed,
+                    // which means any attempts to modify the function while it is running will
+                    // cause the VM to panic.
+                    //
+                    // possible solution:
+                    //  pop the function object, and then determine which function to call on the
+                    //  object (possibly after downcasting?)
+                    // 
+                    // TODO
+                    // Figure out a way to either call a native function with NativeFun::call, or
+                    // call a user function with Fun::code()
+                    if let Some(fun) = fun.borrow().as_any().downcast_ref::<Fun>() {
+                    } else if let Some(fun) = fun.borrow().as_any().downcast_ref::<NativeFun>() {
+                    } else {
+                        todo!("TODO - not a function")
+                    }
+                    todo!()
+                }
+            }
+            self.set_ip(next_ip);
+        }
+        self.frames.pop();
+    }
+}

src/vm/op.rs

@@ -0,0 +1,22 @@
+use crate::obj::Sym;
+
+// VM execution model:
+// * every function call has its own stack frame
+// * stack frames keep track of locals
+// * ops deal with symbols directly
+// * stack values are either obj references or symbols
+
+pub enum Op {
+    /// Push a value from a symbol
+    Push(Sym),
+    
+    /// Pop the top stack value into a local (if supplied)
+    Pop(Option<Sym>),
+
+    /// Pop the top stack value, getting an attribute and replacing pushing that value to the
+    /// stack.
+    GetAttr(Sym),
+
+    /// Pop the top stack value and the number of arguments, and attempt to call the function.
+    Call(usize),
+}