Host module sketch

src/interpreter/host.rs

@@ -0,0 +1,139 @@
+use std::any::Any;
+use std::marker::PhantomData;
+use std::collections::HashMap;
+use elements::{FunctionType, ValueType};
+use interpreter::store::{Store, ExternVal};
+use interpreter::value::RuntimeValue;
+use interpreter::Error;
+
+pub struct HostModuleBuilder<'a, St> {
+	store: &'a mut Store,
+	exports: HashMap<String, ExternVal>,
+	_marker: PhantomData<St>,
+}
+
+impl<'a, St: 'static> HostModuleBuilder<'a, St> {
+	pub fn new(store: &'a mut Store) -> Self {
+		HostModuleBuilder {
+			store: store,
+			exports: HashMap::new(),
+			_marker: PhantomData,
+		}
+	}
+
+	pub fn push_func1<
+		Cl: Fn(&mut St, P1) -> Result<Option<Ret>, Error> + 'static,
+		Ret: AsReturn + 'static,
+		P1: FromArg + 'static,
+		F: Into<Func1<Cl, St, Ret, P1>>,
+	>(
+		&mut self,
+		name: &str,
+		f: F,
+	) {
+		let func_type = Func1::<Cl, St, Ret, P1>::derive_func_type();
+		let type_id = self.store.alloc_func_type(func_type);
+
+		let anyfunc = Box::new(f.into()) as Box<AnyFunc>;
+
+		let func_id = self.store.alloc_host_func(type_id, anyfunc);
+		let extern_val = ExternVal::Func(func_id);
+
+		self.exports.insert(name.to_owned(), extern_val);
+	}
+}
+
+pub trait AnyFunc {
+	fn call_as_any(
+		&self,
+		state: &mut Any,
+		args: &[RuntimeValue],
+	) -> Result<Option<RuntimeValue>, Error>;
+}
+
+pub trait FromArg {
+	fn from_arg(arg: &RuntimeValue) -> Self;
+	fn value_type() -> ValueType;
+}
+
+impl FromArg for i32 {
+	fn from_arg(arg: &RuntimeValue) -> Self {
+		match arg {
+			&RuntimeValue::I32(v) => v,
+			unexpected => panic!("Unexpected runtime value {:?}", unexpected)
+		}
+	}
+
+	fn value_type() -> ValueType {
+		ValueType::I32
+	}
+}
+
+pub trait AsReturn {
+	fn as_return_val(self) -> Option<RuntimeValue>;
+	fn value_type() -> Option<ValueType>;
+}
+
+impl AsReturn for i32 {
+	fn as_return_val(self) -> Option<RuntimeValue> {
+		Some(self.into())
+	}
+
+	fn value_type() -> Option<ValueType> {
+		Some(ValueType::I32)
+	}
+}
+
+impl AsReturn for () {
+	fn as_return_val(self) -> Option<RuntimeValue> {
+		None
+	}
+
+	fn value_type() -> Option<ValueType> {
+		None
+	}
+}
+
+pub struct Func1<Cl: Fn(&mut St, P1) -> Result<Option<Ret>, Error>, St, Ret: AsReturn, P1: FromArg> {
+	closure: Cl,
+	_marker: PhantomData<(St, Ret, P1)>,
+}
+
+impl<
+	St: 'static,
+	Ret: AsReturn,
+	P1: FromArg,
+	Cl: Fn(&mut St, P1) -> Result<Option<Ret>, Error>,
+> AnyFunc for Func1<Cl, St, Ret, P1> {
+	fn call_as_any(
+		&self,
+		state: &mut Any,
+		args: &[RuntimeValue],
+	) -> Result<Option<RuntimeValue>, Error> {
+		let state = state.downcast_mut::<St>().unwrap();
+		let p1 = P1::from_arg(&args[0]);
+		let result = (self.closure)(state, p1);
+		result.map(|r| r.and_then(|r| r.as_return_val()))
+	}
+}
+
+impl<St: 'static, Ret: AsReturn, P1: FromArg, Cl: Fn(&mut St, P1) -> Result<Option<Ret>, Error>> From<Cl>
+	for Func1<Cl, St, Ret, P1> {
+	fn from(cl: Cl) -> Self {
+		Func1 {
+			closure: cl,
+			_marker: PhantomData,
+		}
+	}
+}
+
+impl<
+	St: 'static,
+	Ret: AsReturn,
+	P1: FromArg,
+	Cl: Fn(&mut St, P1) -> Result<Option<Ret>, Error>,
+> Func1<Cl, St, Ret, P1> {
+	fn derive_func_type() -> FunctionType {
+		FunctionType::new(vec![P1::value_type()], Ret::value_type())
+	}
+}

src/interpreter/mod.rs

@@ -140,6 +140,7 @@ mod table;
 mod value;
 mod variable;
 mod store;
+mod host;
 
 #[cfg(test)]
 mod tests;

src/interpreter/program.rs

@@ -4,6 +4,7 @@ use elements::Module;
 use interpreter::Error;
 use interpreter::module::{ExecutionParams};
 use interpreter::store::{Store, ModuleId};
+use interpreter::host::HostModuleBuilder;
 
 /// Program instance. Program is a set of instantiated modules.
 pub struct ProgramInstance {
@@ -42,6 +43,10 @@ impl ProgramInstance {
 		Ok(module_id)
 	}
 
+	pub fn with_host_module<St: 'static>(&mut self, name: &str) -> HostModuleBuilder<St> {
+		HostModuleBuilder::new(&mut self.store)
+	}
+
 	/// Get one of the modules by name
 	pub fn module(&self, name: &str) -> Option<ModuleId> {
 		self.modules.get(name).cloned()

src/interpreter/runner.rs

@@ -1,5 +1,6 @@
 use std::mem;
 use std::ops;
+use std::sync::Arc;
 use std::{u32, usize};
 use std::fmt::{self, Display};
 use std::iter::repeat;
@@ -31,7 +32,7 @@ pub struct FunctionContext {
 	/// Function return type.
 	pub return_type: BlockType,
 	/// Local variables.
-	pub locals: Vec<VariableInstance>,
+	pub locals: Vec<RuntimeValue>,
 	/// Values stack.
 	pub value_stack: StackWithLimit<RuntimeValue>,
 	/// Blocks frames stack.
@@ -78,31 +79,24 @@ impl<'store> Interpreter<'store> {
 			let mut function_context = function_stack.pop_back().expect("on loop entry - not empty; on loop continue - checking for emptiness; qed");
 			let function_ref = function_context.function;
 			let function_return = {
-				let function_body = function_ref.resolve(self.store).body();
+				let func_instance = function_ref.resolve(self.store).clone();
+
+				match func_instance {
+					FuncInstance::Defined { body, .. } => {
+						let function_body = body;
 
-				match function_body {
-					Some(function_body) => {
 						if !function_context.is_initialized() {
 							let return_type = function_context.return_type;
-							function_context.initialize(&function_body.locals)?;
+							function_context.initialize(&function_body.locals);
 							function_context.push_frame(&function_body.labels, BlockFrameType::Function, return_type)?;
 						}
 
 						self.do_run_function(&mut function_context, function_body.opcodes.elements(), &function_body.labels)?
 					},
-					None => {
-						// move locals back to the stack
-						let locals_to_move: Vec<_> = function_context.locals.drain(..).collect();
-						for local in locals_to_move {
-							function_context.value_stack_mut().push(local.get())?;
-						}
-						let nested_context = CallerContext::nested(&mut function_context);
-
-						// TODO: Call host functions
-						// let result = function_ref.module.call_internal_function(nested_context, function_ref.internal_index)?;
-						// RunResult::Return(result)
-
-						panic!()
+					FuncInstance::Host { host_func, .. } => {
+						let args: Vec<_> = function_context.locals.drain(..).collect();
+						let result = self.store.invoke_host(host_func, args)?;
+						RunResult::Return(result)
 					},
 				}
 			};
@@ -977,7 +971,7 @@ impl<'store> Interpreter<'store> {
 }
 
 impl<'a> FunctionContext {
-	pub fn new<'store>(store: &'store Store, function: FuncId, value_stack_limit: usize, frame_stack_limit: usize, function_type: &FunctionSignature, args: Vec<VariableInstance>) -> Self {
+	pub fn new<'store>(store: &'store Store, function: FuncId, value_stack_limit: usize, frame_stack_limit: usize, function_type: &FunctionSignature, args: Vec<RuntimeValue>) -> Self {
 		let func_instance = function.resolve(store);
 		let module = match *func_instance {
 			FuncInstance::Defined { module, .. } => module,
@@ -1026,16 +1020,15 @@ impl<'a> FunctionContext {
 		self.is_initialized
 	}
 
-	pub fn initialize(&mut self, locals: &[Local]) -> Result<(), Error> {
+	pub fn initialize(&mut self, locals: &[Local]) {
 		debug_assert!(!self.is_initialized);
 		self.is_initialized = true;
 
 		let locals = locals.iter()
 			.flat_map(|l| repeat(l.value_type().into()).take(l.count() as usize))
-			.map(|vt| VariableInstance::new(true, vt, RuntimeValue::default(vt)))
-			.collect::<Result<Vec<_>, _>>()?;
+			.map(|vt| RuntimeValue::default(vt))
+			.collect::<Vec<_>>();
 		self.locals.extend(locals);
-		Ok(())
 	}
 
 	pub fn module(&self) -> ModuleId {
@@ -1043,16 +1036,17 @@ impl<'a> FunctionContext {
 	}
 
 	pub fn set_local(&mut self, index: usize, value: RuntimeValue) -> Result<InstructionOutcome, Error> {
-		self.locals.get_mut(index)
-			.ok_or(Error::Local(format!("expected to have local with index {}", index)))
-			.and_then(|l| l.set(value))
-			.map(|_| InstructionOutcome::RunNextInstruction)
+		let l = self.locals.get_mut(index)
+			.ok_or(Error::Local(format!("expected to have local with index {}", index)))?;
+
+		*l = value;
+		Ok(InstructionOutcome::RunNextInstruction)
 	}
 
 	pub fn get_local(&mut self, index: usize) -> Result<RuntimeValue, Error> {
 		self.locals.get(index)
+			.cloned()
 			.ok_or(Error::Local(format!("expected to have local with index {}", index)))
-			.map(|l| l.get())
 	}
 
 	pub fn value_stack(&self) -> &StackWithLimit<RuntimeValue> {
@@ -1136,7 +1130,7 @@ fn effective_address(address: u32, offset: u32) -> Result<u32, Error> {
 	}
 }
 
-pub fn prepare_function_args(function_type: &FunctionSignature, caller_stack: &mut StackWithLimit<RuntimeValue>) -> Result<Vec<VariableInstance>, Error> {
+pub fn prepare_function_args(function_type: &FunctionSignature, caller_stack: &mut StackWithLimit<RuntimeValue>) -> Result<Vec<RuntimeValue>, Error> {
 	let mut args = function_type.params().iter().rev().map(|param_type| {
 		let param_value = caller_stack.pop()?;
 		let actual_type = param_value.variable_type();
@@ -1145,7 +1139,7 @@ pub fn prepare_function_args(function_type: &FunctionSignature, caller_stack: &m
 			return Err(Error::Function(format!("invalid parameter type {:?} when expected {:?}", actual_type, expected_type)));
 		}
 
-		VariableInstance::new(true, expected_type, param_value)
+		Ok(param_value)
 	}).collect::<Result<Vec<_>, _>>()?;
 	args.reverse();
 	Ok(args)

src/interpreter/store.rs

@@ -7,6 +7,7 @@ use elements::{FunctionType, GlobalEntry, GlobalType, InitExpr, MemoryType, Modu
                Opcode, Opcodes, Local, TableType, Type, Internal};
 use interpreter::{Error, RuntimeValue, MemoryInstance, TableInstance, ExecutionParams, CallerContext, FunctionSignature};
 use interpreter::runner::{FunctionContext, prepare_function_args, Interpreter};
+use interpreter::host::AnyFunc;
 use validation::validate_module;
 use common::{DEFAULT_MEMORY_INDEX, DEFAULT_TABLE_INDEX, DEFAULT_FRAME_STACK_LIMIT, DEFAULT_VALUE_STACK_LIMIT};
 use common::stack::StackWithLimit;
@@ -118,6 +119,7 @@ pub enum ExternVal {
 	Global(GlobalId),
 }
 
+#[derive(Clone, Debug)]
 pub enum FuncInstance {
 	Defined {
 		func_type: TypeId,
@@ -138,15 +140,9 @@ impl FuncInstance {
 			}
 		}
 	}
-
-	pub fn body(&self) -> Option<Arc<FuncBody>> {
-		match *self {
-			FuncInstance::Defined { ref body, .. } => Some(Arc::clone(body)),
-			FuncInstance::Host { .. } => None,
-		}
-	}
 }
 
+#[derive(Clone, Debug)]
 pub struct FuncBody {
 	pub locals: Vec<Local>,
 	pub opcodes: Opcodes,
@@ -197,6 +193,7 @@ pub struct Store {
 	// However, they can be referenced in several places, so it is handy to have it here.
 	modules: Vec<ModuleInstance>,
 	types: Vec<FunctionType>,
+	host_funcs: Vec<Box<AnyFunc>>,
 }
 
 impl Store {
@@ -216,7 +213,7 @@ impl Store {
 			.expect("ID should always be a valid index")
 	}
 
-	fn alloc_func_type(&mut self, func_type: FunctionType) -> TypeId {
+	pub fn alloc_func_type(&mut self, func_type: FunctionType) -> TypeId {
 		self.types.push(func_type);
 		let type_id = self.types.len() - 1;
 		TypeId(type_id as u32)
@@ -233,7 +230,18 @@ impl Store {
 		FuncId(func_id as u32)
 	}
 
-	// TODO: alloc_host_func
+	pub fn alloc_host_func(&mut self, func_type: TypeId, anyfunc: Box<AnyFunc>) -> FuncId {
+		self.host_funcs.push(anyfunc);
+		let host_func_id = self.host_funcs.len() - 1;
+
+		let func = FuncInstance::Host {
+			func_type,
+			host_func: HostFuncId(host_func_id as u32),
+		};
+		self.funcs.push(func);
+		let func_id = self.funcs.len() - 1;
+		FuncId(func_id as u32)
+	}
 
 	fn alloc_table(&mut self, table_type: &TableType) -> Result<TableId, Error> {
 		let table = TableInstance::new(table_type)?;
@@ -453,6 +461,10 @@ impl Store {
 		interpreter.run_function(inner)
 	}
 
+	pub fn invoke_host(&mut self, host_func: HostFuncId, args: Vec<RuntimeValue>) -> Result<Option<RuntimeValue>, Error> {
+		panic!()
+	}
+
 	pub fn write_global(&mut self, global: GlobalId, val: RuntimeValue) -> Result<(), Error> {
 		let global_instance = self.globals.get_mut(global.0 as usize).expect("ID should be always valid");
 		if !global_instance.mutable {