CustomUserError -> UserError

spec/src/run.rs

@@ -14,7 +14,7 @@ use parity_wasm::interpreter::{
     DefaultProgramInstance, DefaultModuleInstance, 
     ItemIndex, ExportEntryType,
     Error as InterpreterError,
-    DummyCustomUserError,
+    DummyUserError,
 };
 
 fn spec_test_module() -> elements::Module {
@@ -58,7 +58,7 @@ fn try_deserialize(base_dir: &str, module_path: &str) -> Result<elements::Module
     parity_wasm::deserialize_file(&wasm_path)
 }
 
-fn try_load(base_dir: &str, module_path: &str) -> Result<(), parity_wasm::interpreter::Error<DummyCustomUserError>> {
+fn try_load(base_dir: &str, module_path: &str) -> Result<(), parity_wasm::interpreter::Error<DummyUserError>> {
     let module = try_deserialize(base_dir, module_path).map_err(|e| parity_wasm::interpreter::Error::Program(format!("{:?}", e)))?;
     let program = DefaultProgramInstance::new().expect("Failed creating program");
     program.add_module("try_load", module, None).map(|_| ())
@@ -91,7 +91,7 @@ fn runtime_values(test_vals: &[test::RuntimeValue]) -> Vec<parity_wasm::RuntimeV
 }
 
 fn run_action(program: &DefaultProgramInstance, action: &test::Action) 
-    -> Result<Option<parity_wasm::RuntimeValue>, InterpreterError<DummyCustomUserError>> 
+    -> Result<Option<parity_wasm::RuntimeValue>, InterpreterError<DummyUserError>> 
 {
     match *action {
         test::Action::Invoke { ref module, ref field, ref args } => {

src/interpreter/env.rs

@@ -3,7 +3,7 @@ use std::collections::HashMap;
 use builder::module;
 use elements::{Module, ExportEntry, Internal, GlobalEntry, GlobalType,
 	ValueType, InitExpr, Opcode, Opcodes};
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::env_native::NATIVE_INDEX_FUNC_MIN;
 use interpreter::module::{ModuleInstanceInterface, ModuleInstance, ExecutionParams,
 	ItemIndex, CallerContext, ExportEntryType, InternalFunctionReference, InternalFunction, FunctionSignature};
@@ -78,12 +78,12 @@ pub struct EnvParams {
 	pub allow_memory_growth: bool,
 }
 
-pub struct EnvModuleInstance<E: CustomUserError> {
+pub struct EnvModuleInstance<E: UserError> {
 	_params: EnvParams,
 	instance: ModuleInstance<E>,
 }
 
-impl<E> EnvModuleInstance<E> where E: CustomUserError {
+impl<E> EnvModuleInstance<E> where E: UserError {
 	pub fn new(params: EnvParams, module: Module) -> Result<Self, Error<E>> {
 		let mut instance = ModuleInstance::new(Weak::default(), "env".into(), module)?;
 		instance.instantiate(None)?;
@@ -95,7 +95,7 @@ impl<E> EnvModuleInstance<E> where E: CustomUserError {
 	}
 }
 
-impl<E> ModuleInstanceInterface<E> for EnvModuleInstance<E> where E: CustomUserError {
+impl<E> ModuleInstanceInterface<E> for EnvModuleInstance<E> where E: UserError {
 	fn execute_index(&self, index: u32, params: ExecutionParams<E>) -> Result<Option<RuntimeValue>, Error<E>> {
 		self.instance.execute_index(index, params)
 	}
@@ -167,7 +167,7 @@ impl<E> ModuleInstanceInterface<E> for EnvModuleInstance<E> where E: CustomUserE
 	}
 }
 
-pub fn env_module<E: CustomUserError>(params: EnvParams) -> Result<EnvModuleInstance<E>, Error<E>> {
+pub fn env_module<E: UserError>(params: EnvParams) -> Result<EnvModuleInstance<E>, Error<E>> {
 	debug_assert!(params.total_stack < params.total_memory);
 	debug_assert!((params.total_stack % LINEAR_MEMORY_PAGE_SIZE) == 0);
 	debug_assert!((params.total_memory % LINEAR_MEMORY_PAGE_SIZE) == 0);

src/interpreter/env_native.rs

@@ -3,7 +3,7 @@ use std::collections::HashMap;
 use std::borrow::Cow;
 use parking_lot::RwLock;
 use elements::{Internal, ValueType};
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::module::{ModuleInstanceInterface, ExecutionParams, ItemIndex,
 	CallerContext, ExportEntryType, InternalFunctionReference, InternalFunction, FunctionSignature};
 use interpreter::memory::MemoryInstance;
@@ -17,7 +17,7 @@ pub const NATIVE_INDEX_FUNC_MIN: u32 = 10001;
 pub const NATIVE_INDEX_GLOBAL_MIN: u32 = 20001;
 
 /// User functions executor.
-pub trait UserFunctionExecutor<E: CustomUserError> {
+pub trait UserFunctionExecutor<E: UserError> {
 	/// Execute function with given name.
 	fn execute(&mut self, name: &str, context: CallerContext<E>) -> Result<Option<RuntimeValue>, Error<E>>;
 }
@@ -68,7 +68,7 @@ impl UserFunctionDescriptor {
 }
 
 /// Set of user-defined module elements.
-pub struct UserDefinedElements<'a, E: 'a + CustomUserError> {
+pub struct UserDefinedElements<'a, E: 'a + UserError> {
 	/// User globals list.
 	pub globals: HashMap<String, Arc<VariableInstance<E>>>,
 	/// User functions list.
@@ -78,7 +78,7 @@ pub struct UserDefinedElements<'a, E: 'a + CustomUserError> {
 }
 
 /// Native module instance.
-pub struct NativeModuleInstance<'a, E: 'a + CustomUserError> {
+pub struct NativeModuleInstance<'a, E: 'a + UserError> {
 	/// Underllying module reference.
 	env: Arc<ModuleInstanceInterface<E>>,
 	/// User function executor.
@@ -93,7 +93,7 @@ pub struct NativeModuleInstance<'a, E: 'a + CustomUserError> {
 	globals: Vec<Arc<VariableInstance<E>>>,
 }
 
-impl<'a, E> NativeModuleInstance<'a, E> where E: CustomUserError {
+impl<'a, E> NativeModuleInstance<'a, E> where E: UserError {
 	/// Create new native module
 	pub fn new(env: Arc<ModuleInstanceInterface<E>>, elements: UserDefinedElements<'a, E>) -> Result<Self, Error<E>> {
 		if !elements.functions.is_empty() && elements.executor.is_none() {
@@ -111,7 +111,7 @@ impl<'a, E> NativeModuleInstance<'a, E> where E: CustomUserError {
 	}
 }
 
-impl<'a, E> ModuleInstanceInterface<E> for NativeModuleInstance<'a, E> where E: CustomUserError {
+impl<'a, E> ModuleInstanceInterface<E> for NativeModuleInstance<'a, E> where E: UserError {
 	fn execute_index(&self, index: u32, params: ExecutionParams<E>) -> Result<Option<RuntimeValue>, Error<E>> {
 		self.env.execute_index(index, params)
 	}
@@ -218,7 +218,7 @@ impl<'a, E> ModuleInstanceInterface<E> for NativeModuleInstance<'a, E> where E:
 }
 
 /// Create wrapper for env module with given native user functions.
-pub fn env_native_module<'a, E: CustomUserError>(env: Arc<ModuleInstanceInterface<E>>, user_elements: UserDefinedElements<'a, E>) -> Result<NativeModuleInstance<E>, Error<E>> {
+pub fn env_native_module<'a, E: UserError>(env: Arc<ModuleInstanceInterface<E>>, user_elements: UserDefinedElements<'a, E>) -> Result<NativeModuleInstance<E>, Error<E>> {
 	NativeModuleInstance::new(env, user_elements)
 }
 

src/interpreter/imports.rs

@@ -1,7 +1,7 @@
 use std::sync::{Arc, Weak};
 use std::collections::HashMap;
 use elements::{ImportSection, ImportEntry, External, Internal};
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::memory::MemoryInstance;
 use interpreter::module::{ModuleInstanceInterface, ItemIndex, ExportEntryType, FunctionSignature};
 use interpreter::program::ProgramInstanceEssence;
@@ -9,7 +9,7 @@ use interpreter::table::TableInstance;
 use interpreter::variable::{VariableInstance, VariableType};
 
 /// Module imports.
-pub struct ModuleImports<E: CustomUserError> {
+pub struct ModuleImports<E: UserError> {
 	/// Program instance.
 	program: Weak<ProgramInstanceEssence<E>>,
 	/// External functions.
@@ -22,7 +22,7 @@ pub struct ModuleImports<E: CustomUserError> {
 	globals: Vec<usize>,
 }
 
-impl<E> ModuleImports<E> where E: CustomUserError {
+impl<E> ModuleImports<E> where E: UserError {
 	/// Create new imports for given import section.
 	pub fn new(program: Weak<ProgramInstanceEssence<E>>, import_section: Option<&ImportSection>) -> Self {
 		let mut functions = Vec::new();

src/interpreter/memory.rs

@@ -2,7 +2,7 @@ use std::u32;
 use std::sync::Arc;
 use parking_lot::RwLock;
 use elements::MemoryType;
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::module::check_limits;
 
 /// Linear memory page size.
@@ -11,7 +11,7 @@ pub const LINEAR_MEMORY_PAGE_SIZE: u32 = 65536;
 const LINEAR_MEMORY_MAX_PAGES: u32 = 65536;
 
 /// Linear memory instance.
-pub struct MemoryInstance<E: CustomUserError> {
+pub struct MemoryInstance<E: UserError> {
 	/// Linear memory buffer.
 	buffer: RwLock<Vec<u8>>,
 	/// Maximum buffer size.
@@ -36,7 +36,7 @@ impl<'a, B: 'a> CheckedRegion<'a, B> where B: ::std::ops::Deref<Target=Vec<u8>>
 	}
 }
 
-impl<E> MemoryInstance<E> where E: CustomUserError {
+impl<E> MemoryInstance<E> where E: UserError {
 	/// Create new linear memory instance.
 	pub fn new(memory_type: &MemoryType) -> Result<Arc<Self>, Error<E>> {
 		check_limits(memory_type.limits())?;

src/interpreter/mod.rs

@@ -1,12 +1,12 @@
 //! WebAssembly interpreter module.
 
 /// Custom user error.
-pub trait CustomUserError: 'static + ::std::fmt::Display + ::std::fmt::Debug + Clone + PartialEq {
+pub trait UserError: 'static + ::std::fmt::Display + ::std::fmt::Debug + Clone + PartialEq {
 }
 
 /// Internal interpreter error.
 #[derive(Debug, Clone, PartialEq)]
-pub enum Error<E> where E: CustomUserError {
+pub enum Error<E> where E: UserError {
 	/// Program-level error.
 	Program(String),
 	/// Validation error.
@@ -41,7 +41,7 @@ pub enum Error<E> where E: CustomUserError {
 	User(E),
 }
 
-impl<E> Into<String> for Error<E> where E: CustomUserError {
+impl<E> Into<String> for Error<E> where E: UserError {
 	fn into(self) -> String {
 		match self {
 			Error::Program(s) => s,
@@ -66,11 +66,11 @@ impl<E> Into<String> for Error<E> where E: CustomUserError {
 
 /// Dummy user error.
 #[derive(Debug, Clone, PartialEq)]
-pub struct DummyCustomUserError;
+pub struct DummyUserError;
 
-impl CustomUserError for DummyCustomUserError {}
+impl UserError for DummyUserError {}
 
-impl ::std::fmt::Display for DummyCustomUserError {
+impl ::std::fmt::Display for DummyUserError {
 	fn fmt(&self, _f: &mut ::std::fmt::Formatter) -> Result<(), ::std::fmt::Error> { Ok(()) }
 }
 
@@ -102,12 +102,12 @@ pub use self::env::EnvParams;
 
 /// Default type of ProgramInstance if you do not need any custom user errors.
 /// To work with custom user errors or interpreter internals, use CustomProgramInstance.
-pub type DefaultProgramInstance = self::program::ProgramInstance<DummyCustomUserError>;
+pub type DefaultProgramInstance = self::program::ProgramInstance<DummyUserError>;
 
 /// Default type of ModuleInstance if you do not need any custom user errors.
 /// To work with custom user errors or interpreter internals, use CustomModuleInstance.
-pub type DefaultModuleInstance = self::module::ModuleInstance<DummyCustomUserError>;
+pub type DefaultModuleInstance = self::module::ModuleInstance<DummyUserError>;
 
 /// Default type of ModuleInstanceInterface if you do not need any custom user errors.
 /// To work with custom user errors or interpreter internals, use CustomModuleInstanceInterface.
-pub type DefaultModuleInstanceInterface = self::module::ModuleInstanceInterface<DummyCustomUserError>;
+pub type DefaultModuleInstanceInterface = self::module::ModuleInstanceInterface<DummyUserError>;

src/interpreter/module.rs

@@ -3,7 +3,7 @@ use std::iter::repeat;
 use std::sync::{Arc, Weak};
 use std::fmt;
 use elements::{Module, InitExpr, Opcode, Type, FunctionType, Internal, External, BlockType, ResizableLimits, Local, ValueType};
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::env_native::UserFunctionDescriptor;
 use interpreter::imports::ModuleImports;
 use interpreter::memory::MemoryInstance;
@@ -22,7 +22,7 @@ const DEFAULT_FRAME_STACK_LIMIT: usize = 1024;
 
 /// Execution context.
 #[derive(Clone)]
-pub struct ExecutionParams<'a, E: CustomUserError> {
+pub struct ExecutionParams<'a, E: UserError> {
 	/// Arguments.
 	pub args: Vec<RuntimeValue>,
 	/// Execution-local external modules.
@@ -50,7 +50,7 @@ pub enum FunctionSignature<'a> {
 }
 
 /// Module instance API.
-pub trait ModuleInstanceInterface<E: CustomUserError> {
+pub trait ModuleInstanceInterface<E: UserError> {
 	/// Execute function with the given index.
 	fn execute_index(&self, index: u32, params: ExecutionParams<E>) -> Result<Option<RuntimeValue>, Error<E>>;
 	/// Execute function with the given export name.
@@ -89,7 +89,7 @@ pub enum ItemIndex {
 }
 
 /// Module instance.
-pub struct ModuleInstance<E: CustomUserError> {
+pub struct ModuleInstance<E: UserError> {
 	/// Module name.
 	name: String,
 	/// Module.
@@ -109,7 +109,7 @@ pub struct ModuleInstance<E: CustomUserError> {
 }
 
 /// Caller context.
-pub struct CallerContext<'a, E: 'a + CustomUserError> {
+pub struct CallerContext<'a, E: 'a + UserError> {
 	/// Value stack limit
 	pub value_stack_limit: usize,
 	/// Frame stack limit
@@ -122,14 +122,14 @@ pub struct CallerContext<'a, E: 'a + CustomUserError> {
 
 /// Internal function reference.
 #[derive(Clone)]
-pub struct InternalFunctionReference<'a, E: CustomUserError> {
+pub struct InternalFunctionReference<'a, E: UserError> {
 	/// Module reference.
 	pub module: Arc<ModuleInstanceInterface<E> + 'a>,
 	/// Internal function index.
 	pub internal_index: u32,
 }
 
-impl<'a, E> fmt::Debug for InternalFunctionReference<'a, E> where E: CustomUserError {
+impl<'a, E> fmt::Debug for InternalFunctionReference<'a, E> where E: UserError {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		write!(f, "InternalFunctionReference")
 	}
@@ -145,7 +145,7 @@ pub struct InternalFunction<'a> {
 	pub labels: &'a HashMap<usize, usize>,
 }
 
-impl<'a, E> ExecutionParams<'a, E> where E: CustomUserError {
+impl<'a, E> ExecutionParams<'a, E> where E: UserError {
 	/// Create new execution params with given externa; module override.
 	pub fn with_external(name: String, module: Arc<ModuleInstanceInterface<E> + 'a>) -> Self {
 		let mut externals = HashMap::new();
@@ -163,7 +163,7 @@ impl<'a, E> ExecutionParams<'a, E> where E: CustomUserError {
 	}
 }
 
-impl<'a, E> Default for ExecutionParams<'a, E> where E: CustomUserError {
+impl<'a, E> Default for ExecutionParams<'a, E> where E: UserError {
 	fn default() -> Self {
 		ExecutionParams {
 			args: Vec::default(),
@@ -172,7 +172,7 @@ impl<'a, E> Default for ExecutionParams<'a, E> where E: CustomUserError {
 	}
 }
 
-impl<'a, E> From<Vec<RuntimeValue>> for ExecutionParams<'a, E> where E: CustomUserError {
+impl<'a, E> From<Vec<RuntimeValue>> for ExecutionParams<'a, E> where E: UserError {
 	fn from(args: Vec<RuntimeValue>) -> ExecutionParams<'a, E> {
 		ExecutionParams {
 			args: args,
@@ -181,7 +181,7 @@ impl<'a, E> From<Vec<RuntimeValue>> for ExecutionParams<'a, E> where E: CustomUs
 	}
 }
 
-impl<E> ModuleInstance<E> where E: CustomUserError {
+impl<E> ModuleInstance<E> where E: UserError {
 	/// Instantiate given module within program context.
 	pub fn new<'a>(program: Weak<ProgramInstanceEssence<E>>, name: String, module: Module) -> Result<Self, Error<E>> {
 		// load entries from import section
@@ -429,7 +429,7 @@ impl<E> ModuleInstance<E> where E: CustomUserError {
 	}
 }
 
-impl<E> ModuleInstanceInterface<E> for ModuleInstance<E> where E: CustomUserError {
+impl<E> ModuleInstanceInterface<E> for ModuleInstance<E> where E: UserError {
 	fn execute_index(&self, index: u32, params: ExecutionParams<E>) -> Result<Option<RuntimeValue>, Error<E>> {
 		let ExecutionParams { args, externals } = params;
 		let mut args = StackWithLimit::with_data(args, DEFAULT_VALUE_STACK_LIMIT);
@@ -609,7 +609,7 @@ impl<E> ModuleInstanceInterface<E> for ModuleInstance<E> where E: CustomUserErro
 	}
 }
 
-impl<'a, E> CallerContext<'a, E> where E: CustomUserError {
+impl<'a, E> CallerContext<'a, E> where E: UserError {
 	/// Top most args
 	pub fn topmost(args: &'a mut StackWithLimit<RuntimeValue, E>, externals: &'a HashMap<String, Arc<ModuleInstanceInterface<E> + 'a>>) -> Self {
 		CallerContext {
@@ -631,7 +631,7 @@ impl<'a, E> CallerContext<'a, E> where E: CustomUserError {
 	}
 }
 
-pub fn check_limits<E: CustomUserError>(limits: &ResizableLimits) -> Result<(), Error<E>> {
+pub fn check_limits<E: UserError>(limits: &ResizableLimits) -> Result<(), Error<E>> {
 	if let Some(maximum) = limits.maximum() {
 		if maximum < limits.initial() {
 			return Err(Error::Validation(format!("maximum limit {} is lesser than minimum {}", maximum, limits.initial())));
@@ -641,7 +641,7 @@ pub fn check_limits<E: CustomUserError>(limits: &ResizableLimits) -> Result<(),
 	Ok(())
 }
 
-fn get_initializer<E: CustomUserError>(expr: &InitExpr, module: &Module, imports: &ModuleImports<E>, expected_type: VariableType) -> Result<RuntimeValue, Error<E>> {
+fn get_initializer<E: UserError>(expr: &InitExpr, module: &Module, imports: &ModuleImports<E>, expected_type: VariableType) -> Result<RuntimeValue, Error<E>> {
 	let first_opcode = match expr.code().len() {
 		1 => &expr.code()[0],
 		2 if expr.code().len() == 2 && expr.code()[1] == Opcode::End => &expr.code()[0],

src/interpreter/program.rs

@@ -2,23 +2,23 @@ use std::sync::Arc;
 use std::collections::HashMap;
 use parking_lot::RwLock;
 use elements::Module;
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::env::{self, env_module};
 use interpreter::module::{ModuleInstance, ModuleInstanceInterface};
 
 /// Program instance. Program is a set of instantiated modules.
-pub struct ProgramInstance<E: CustomUserError> {
+pub struct ProgramInstance<E: UserError> {
 	/// Shared data reference.
 	essence: Arc<ProgramInstanceEssence<E>>,
 }
 
 /// Program instance essence.
-pub struct ProgramInstanceEssence<E: CustomUserError> {
+pub struct ProgramInstanceEssence<E: UserError> {
 	/// Loaded modules.
 	modules: RwLock<HashMap<String, Arc<ModuleInstanceInterface<E>>>>,
 }
 
-impl<E> ProgramInstance<E> where E: CustomUserError {
+impl<E> ProgramInstance<E> where E: UserError {
 	/// Create new program instance.
 	pub fn new() -> Result<Self, Error<E>> {
 		ProgramInstance::with_env_params(env::EnvParams::default())
@@ -55,7 +55,7 @@ impl<E> ProgramInstance<E> where E: CustomUserError {
 	}
 }
 
-impl<E> ProgramInstanceEssence<E> where E: CustomUserError {
+impl<E> ProgramInstanceEssence<E> where E: UserError {
 	/// Create new program essence.
 	pub fn new() -> Result<Self, Error<E>> {
 		ProgramInstanceEssence::with_env_params(env::EnvParams::default())

src/interpreter/runner.rs

@@ -6,7 +6,7 @@ use std::fmt::{self, Display};
 use std::iter::repeat;
 use std::collections::{HashMap, VecDeque};
 use elements::{Opcode, BlockType, Local};
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::module::{ModuleInstanceInterface, CallerContext, ItemIndex, InternalFunctionReference, FunctionSignature};
 use interpreter::stack::StackWithLimit;
 use interpreter::value::{
@@ -22,12 +22,12 @@ pub const DEFAULT_MEMORY_INDEX: u32 = 0;
 pub const DEFAULT_TABLE_INDEX: u32 = 0;
 
 /// Function interpreter.
-pub struct Interpreter<E: CustomUserError> {
+pub struct Interpreter<E: UserError> {
 	_dummy: ::std::marker::PhantomData<E>,
 }
 
 /// Function execution context.
-pub struct FunctionContext<'a, E: 'a + CustomUserError> {
+pub struct FunctionContext<'a, E: 'a + UserError> {
 	/// Is context initialized.
 	pub is_initialized: bool,
 	/// Internal function reference.
@@ -48,7 +48,7 @@ pub struct FunctionContext<'a, E: 'a + CustomUserError> {
 
 /// Interpreter action to execute after executing instruction.
 #[derive(Debug)]
-pub enum InstructionOutcome<'a, E: CustomUserError> {
+pub enum InstructionOutcome<'a, E: UserError> {
 	/// Continue with next instruction.
 	RunNextInstruction,
 	/// Branch to given frame.
@@ -62,14 +62,14 @@ pub enum InstructionOutcome<'a, E: CustomUserError> {
 }
 
 /// Function run result.
-enum RunResult<'a, E: 'a + CustomUserError> {
+enum RunResult<'a, E: 'a + UserError> {
 	/// Function has returned (optional) value.
 	Return(Option<RuntimeValue>),
 	/// Function is calling other function.
 	NestedCall(FunctionContext<'a, E>),
 }
 
-impl<E> Interpreter<E> where E: CustomUserError {
+impl<E> Interpreter<E> where E: UserError {
 	pub fn run_function(function_context: FunctionContext<E>) -> Result<Option<RuntimeValue>, Error<E>> {
 		let mut function_stack = VecDeque::new();
 		function_stack.push_back(function_context);
@@ -935,7 +935,7 @@ impl<E> Interpreter<E> where E: CustomUserError {
 	}
 }
 
-impl<'a, E> FunctionContext<'a, E> where E: CustomUserError {
+impl<'a, E> FunctionContext<'a, E> where E: UserError {
 	pub fn new(function: InternalFunctionReference<'a, E>, externals: &'a HashMap<String, Arc<ModuleInstanceInterface<E> + 'a>>, value_stack_limit: usize, frame_stack_limit: usize, function_type: &FunctionSignature, args: Vec<VariableInstance<E>>) -> Self {
 		FunctionContext {
 			is_initialized: false,
@@ -1075,20 +1075,20 @@ impl<'a, E> FunctionContext<'a, E> where E: CustomUserError {
 	}
 }
 
-impl<'a, E> fmt::Debug for FunctionContext<'a, E> where E: CustomUserError {
+impl<'a, E> fmt::Debug for FunctionContext<'a, E> where E: UserError {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		write!(f, "FunctionContext")
 	}
 }
 
-fn effective_address<E: CustomUserError>(address: u32, offset: u32) -> Result<u32, Error<E>> {
+fn effective_address<E: UserError>(address: u32, offset: u32) -> Result<u32, Error<E>> {
 	match offset.checked_add(address) {
 		None => Err(Error::Memory(format!("invalid memory access: {} + {}", offset, address))),
 		Some(address) => Ok(address),
 	}
 }
 
-pub fn prepare_function_args<E: CustomUserError>(function_type: &FunctionSignature, caller_stack: &mut StackWithLimit<RuntimeValue, E>) -> Result<Vec<VariableInstance<E>>, Error<E>> {
+pub fn prepare_function_args<E: UserError>(function_type: &FunctionSignature, caller_stack: &mut StackWithLimit<RuntimeValue, E>) -> Result<Vec<VariableInstance<E>>, Error<E>> {
 	let mut args = function_type.params().iter().rev().map(|param_type| {
 		let param_value = caller_stack.pop()?;
 		let actual_type = param_value.variable_type();

src/interpreter/stack.rs

@@ -1,10 +1,10 @@
 use std::collections::VecDeque;
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::value::{RuntimeValue, TryInto};
 
 /// Stack with limit.
 #[derive(Debug)]
-pub struct StackWithLimit<T, E> where T: Clone, E: CustomUserError {
+pub struct StackWithLimit<T, E> where T: Clone, E: UserError {
 	/// Stack values.
 	values: VecDeque<T>,
 	/// Stack limit (maximal stack len).
@@ -13,7 +13,7 @@ pub struct StackWithLimit<T, E> where T: Clone, E: CustomUserError {
 	_dummy: ::std::marker::PhantomData<E>,
 }
 
-impl<T, E> StackWithLimit<T, E> where T: Clone, E: CustomUserError {
+impl<T, E> StackWithLimit<T, E> where T: Clone, E: UserError {
 	pub fn with_data(data: Vec<T>, limit: usize) -> Self {
 		StackWithLimit {
 			values: data.into_iter().collect(),
@@ -100,7 +100,7 @@ impl<T, E> StackWithLimit<T, E> where T: Clone, E: CustomUserError {
 	}
 }
 
-impl<E> StackWithLimit<RuntimeValue, E> where E: CustomUserError {
+impl<E> StackWithLimit<RuntimeValue, E> where E: UserError {
 	pub fn pop_as<T>(&mut self) -> Result<T, Error<E>>
 		where RuntimeValue: TryInto<T, Error<E>> {
 		self.pop().and_then(TryInto::try_into)

src/interpreter/table.rs

@@ -2,13 +2,13 @@ use std::u32;
 use std::sync::Arc;
 use parking_lot::RwLock;
 use elements::TableType;
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::module::check_limits;
 use interpreter::variable::{VariableInstance, VariableType};
 use interpreter::value::RuntimeValue;
 
 /// Table instance.
-pub struct TableInstance<E: CustomUserError> {
+pub struct TableInstance<E: UserError> {
 	/// Table variables type.
 	variable_type: VariableType,
 	/// Table memory buffer.
@@ -16,11 +16,11 @@ pub struct TableInstance<E: CustomUserError> {
 }
 
 /// Table element. Cloneable wrapper around VariableInstance.
-struct TableElement<E: CustomUserError> {
+struct TableElement<E: UserError> {
 	pub var: VariableInstance<E>,
 }
 
-impl<E> TableInstance<E> where E: CustomUserError {
+impl<E> TableInstance<E> where E: UserError {
 	/// New instance of the table
 	pub fn new(table_type: &TableType) -> Result<Arc<Self>, Error<E>> {
 		check_limits(table_type.limits())?;
@@ -70,7 +70,7 @@ impl<E> TableInstance<E> where E: CustomUserError {
 	}
 }
 
-impl<E> TableElement<E> where E: CustomUserError {
+impl<E> TableElement<E> where E: UserError {
 	pub fn new(var: VariableInstance<E>) -> Self {
 		TableElement {
 			var: var,
@@ -78,7 +78,7 @@ impl<E> TableElement<E> where E: CustomUserError {
 	}
 }
 
-impl<E> Clone for TableElement<E> where E: CustomUserError {
+impl<E> Clone for TableElement<E> where E: UserError {
 	fn clone(&self) -> Self {
 		TableElement::new(VariableInstance::new(self.var.is_mutable(), self.var.variable_type(), self.var.get())
 			.expect("it only fails when variable_type() != passed variable value; both are read from already constructed var; qed"))

src/interpreter/tests/basics.rs

@@ -5,7 +5,7 @@ use std::collections::HashMap;
 use builder::module;
 use elements::{ExportEntry, Internal, ImportEntry, External, GlobalEntry, GlobalType,
 	InitExpr, ValueType, BlockType, Opcodes, Opcode, FunctionType};
-use interpreter::{Error, CustomUserError, ProgramInstance, DefaultProgramInstance, DefaultModuleInstance};
+use interpreter::{Error, UserError, ProgramInstance, DefaultProgramInstance, DefaultModuleInstance};
 use interpreter::env_native::{env_native_module, UserDefinedElements, UserFunctionExecutor, UserFunctionDescriptor};
 use interpreter::memory::MemoryInstance;
 use interpreter::module::{ModuleInstanceInterface, CallerContext, ItemIndex, ExecutionParams, ExportEntryType, FunctionSignature};
@@ -128,12 +128,12 @@ struct MeasuredVariable {
 	pub val: i32,
 }
 
-impl ExternalVariableValue<UserError> for MeasuredVariable {
+impl ExternalVariableValue<UserErrorWithCode> for MeasuredVariable {
 	fn get(&self) -> RuntimeValue {
 		RuntimeValue::I32(self.val)
 	}
 
-	fn set(&mut self, val: RuntimeValue) -> Result<(), Error<UserError>> {
+	fn set(&mut self, val: RuntimeValue) -> Result<(), Error<UserErrorWithCode>> {
 		self.val = val.try_into()?;
 		Ok(())
 	}
@@ -141,26 +141,26 @@ impl ExternalVariableValue<UserError> for MeasuredVariable {
 
 // custom user error
 #[derive(Debug, Clone, PartialEq)]
-struct UserError {
+struct UserErrorWithCode {
 	error_code: i32,
 }
 
-impl ::std::fmt::Display for UserError {
+impl ::std::fmt::Display for UserErrorWithCode {
 	fn fmt(&self, f: &mut ::std::fmt::Formatter) -> Result<(), ::std::fmt::Error> {
 		write!(f, "{}", self.error_code)
 	}
 }
 
-impl CustomUserError for UserError {}
+impl UserError for UserErrorWithCode {}
 
 // user function executor
 struct FunctionExecutor {
-	pub memory: Arc<MemoryInstance<UserError>>,
+	pub memory: Arc<MemoryInstance<UserErrorWithCode>>,
 	pub values: Vec<i32>,
 }
 
-impl UserFunctionExecutor<UserError> for FunctionExecutor {
-	fn execute(&mut self, name: &str, context: CallerContext<UserError>) -> Result<Option<RuntimeValue>, Error<UserError>> {
+impl UserFunctionExecutor<UserErrorWithCode> for FunctionExecutor {
+	fn execute(&mut self, name: &str, context: CallerContext<UserErrorWithCode>) -> Result<Option<RuntimeValue>, Error<UserErrorWithCode>> {
 		match name {
 			"add" => {
 				let memory_value = self.memory.get(0, 1).unwrap()[0];
@@ -185,7 +185,7 @@ impl UserFunctionExecutor<UserError> for FunctionExecutor {
 				Ok(Some(RuntimeValue::I32(diff as i32)))
 			},
 			"err" => {
-				Err(Error::User(UserError { error_code: 777 }))
+				Err(Error::User(UserErrorWithCode { error_code: 777 }))
 			},
 			_ => Err(Error::Trap("not implemented".into()).into()),
 		}
@@ -332,9 +332,9 @@ fn native_custom_error() {
 
 	let module_instance = program.add_module("main", module, Some(&params.externals)).unwrap();
 	assert_eq!(module_instance.execute_index(0, params.clone().add_argument(RuntimeValue::I32(7)).add_argument(RuntimeValue::I32(0))),
-		Err(Error::User(UserError { error_code: 777 })));
+		Err(Error::User(UserErrorWithCode { error_code: 777 })));
 	assert_eq!(module_instance.execute_index(1, params.clone().add_argument(RuntimeValue::I32(7)).add_argument(RuntimeValue::I32(0))),
-		Err(Error::User(UserError { error_code: 777 })));
+		Err(Error::User(UserErrorWithCode { error_code: 777 })));
 }
 
 #[test]

src/interpreter/tests/wabt.rs

@@ -3,7 +3,7 @@
 use std::sync::Arc;
 use builder::module;
 use elements::{ValueType, Opcodes, Opcode, BlockType, Local};
-use interpreter::{Error, DummyCustomUserError, DefaultProgramInstance, DefaultModuleInstanceInterface, ModuleInstanceInterface, ItemIndex};
+use interpreter::{Error, DummyUserError, DefaultProgramInstance, DefaultModuleInstanceInterface, ModuleInstanceInterface, ItemIndex};
 use interpreter::value::{RuntimeValue, TryInto};
 
 fn make_function_i32(body: Opcodes) -> (DefaultProgramInstance, Arc<DefaultModuleInstanceInterface>) {
@@ -22,7 +22,7 @@ fn make_function_i32(body: Opcodes) -> (DefaultProgramInstance, Arc<DefaultModul
 	(program, module)
 }
 
-fn run_function_i32(module: &Arc<DefaultModuleInstanceInterface>, arg: i32) -> Result<i32, Error<DummyCustomUserError>> {
+fn run_function_i32(module: &Arc<DefaultModuleInstanceInterface>, arg: i32) -> Result<i32, Error<DummyUserError>> {
 	module
 		.execute_index(0, vec![RuntimeValue::I32(arg)].into())
 		.and_then(|r| r.unwrap().try_into())

src/interpreter/validator.rs

@@ -2,7 +2,7 @@ use std::u32;
 use std::sync::Arc;
 use std::collections::HashMap;
 use elements::{Opcode, BlockType, ValueType};
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::runner::{DEFAULT_MEMORY_INDEX, DEFAULT_TABLE_INDEX};
 use interpreter::module::{ModuleInstance, ModuleInstanceInterface, ItemIndex, FunctionSignature};
 use interpreter::stack::StackWithLimit;
@@ -12,7 +12,7 @@ use interpreter::variable::VariableType;
 const NATURAL_ALIGNMENT: u32 = 0xFFFFFFFF;
 
 /// Function validation context.
-pub struct FunctionValidationContext<'a, E: 'a + CustomUserError> {
+pub struct FunctionValidationContext<'a, E: 'a + UserError> {
 	/// Wasm module instance (in process of instantiation).
 	module_instance: &'a ModuleInstance<E>,
 	/// Native externals.
@@ -75,7 +75,7 @@ pub enum BlockFrameType {
 }
 
 /// Function validator.
-pub struct Validator<E: CustomUserError> {
+pub struct Validator<E: UserError> {
 	_dummy: ::std::marker::PhantomData<E>,
 }
 
@@ -88,7 +88,7 @@ pub enum InstructionOutcome {
 	Unreachable,
 }
 
-impl<E> Validator<E> where E: CustomUserError {
+impl<E> Validator<E> where E: UserError {
 	pub fn validate_function(context: &mut FunctionValidationContext<E>, block_type: BlockType, body: &[Opcode]) -> Result<(), Error<E>> {
 		context.push_label(BlockFrameType::Function, block_type)?;
 		Validator::validate_function_block(context, body)?;
@@ -571,7 +571,7 @@ impl<E> Validator<E> where E: CustomUserError {
 	}
 }
 
-impl<'a, E> FunctionValidationContext<'a, E> where E: CustomUserError {
+impl<'a, E> FunctionValidationContext<'a, E> where E: UserError {
 	pub fn new(
 		module_instance: &'a ModuleInstance<E>, 
 		externals: Option<&'a HashMap<String, Arc<ModuleInstanceInterface<E> + 'a>>>,

src/interpreter/value.rs

@@ -1,7 +1,7 @@
 use std::{i32, i64, u32, u64, f32};
 use std::io;
 use byteorder::{LittleEndian, ReadBytesExt, WriteBytesExt};
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::variable::VariableType;
 
 /// Runtime value.
@@ -52,7 +52,7 @@ pub trait TransmuteInto<T> {
 }
 
 /// Convert from and to little endian.
-pub trait LittleEndianConvert<E: CustomUserError> where Self: Sized {
+pub trait LittleEndianConvert<E: UserError> where Self: Sized {
 	/// Convert to little endian buffer.
 	fn into_little_endian(self) -> Vec<u8>;
 	/// Convert from little endian buffer.
@@ -60,7 +60,7 @@ pub trait LittleEndianConvert<E: CustomUserError> where Self: Sized {
 }
 
 /// Arithmetic operations.
-pub trait ArithmeticOps<T, E: CustomUserError> {
+pub trait ArithmeticOps<T, E: UserError> {
 	/// Add two values.
 	fn add(self, other: T) -> T;
 	/// Subtract two values.
@@ -72,7 +72,7 @@ pub trait ArithmeticOps<T, E: CustomUserError> {
 }
 
 /// Integer value.
-pub trait Integer<T, E: CustomUserError>: ArithmeticOps<T, E> {
+pub trait Integer<T, E: UserError>: ArithmeticOps<T, E> {
 	/// Counts leading zeros in the bitwise representation of the value.
 	fn leading_zeros(self) -> T;
 	/// Counts trailing zeros in the bitwise representation of the value.
@@ -88,7 +88,7 @@ pub trait Integer<T, E: CustomUserError>: ArithmeticOps<T, E> {
 }
 
 /// Float-point value.
-pub trait Float<T, E: CustomUserError>: ArithmeticOps<T, E> {
+pub trait Float<T, E: UserError>: ArithmeticOps<T, E> {
 	/// Get absolute value.
 	fn abs(self) -> T;
 	/// Returns the largest integer less than or equal to a number.
@@ -178,7 +178,7 @@ impl From<f64> for RuntimeValue {
 	}
 }
 
-impl<E> TryInto<bool, Error<E>> for RuntimeValue where E: CustomUserError {
+impl<E> TryInto<bool, Error<E>> for RuntimeValue where E: UserError {
 	fn try_into(self) -> Result<bool, Error<E>> {
 		match self {
 			RuntimeValue::I32(val) => Ok(val != 0),
@@ -187,7 +187,7 @@ impl<E> TryInto<bool, Error<E>> for RuntimeValue where E: CustomUserError {
 	}
 }
 
-impl<E> TryInto<i32, Error<E>> for RuntimeValue where E: CustomUserError {
+impl<E> TryInto<i32, Error<E>> for RuntimeValue where E: UserError {
 	fn try_into(self) -> Result<i32, Error<E>> {
 		match self {
 			RuntimeValue::I32(val) => Ok(val),
@@ -196,7 +196,7 @@ impl<E> TryInto<i32, Error<E>> for RuntimeValue where E: CustomUserError {
 	}
 }
 
-impl<E> TryInto<i64, Error<E>> for RuntimeValue where E: CustomUserError {
+impl<E> TryInto<i64, Error<E>> for RuntimeValue where E: UserError {
 	fn try_into(self) -> Result<i64, Error<E>> {
 		match self {
 			RuntimeValue::I64(val) => Ok(val),
@@ -205,7 +205,7 @@ impl<E> TryInto<i64, Error<E>> for RuntimeValue where E: CustomUserError {
 	}
 }
 
-impl<E> TryInto<f32, Error<E>> for RuntimeValue where E: CustomUserError {
+impl<E> TryInto<f32, Error<E>> for RuntimeValue where E: UserError {
 	fn try_into(self) -> Result<f32, Error<E>> {
 		match self {
 			RuntimeValue::F32(val) => Ok(val),
@@ -214,7 +214,7 @@ impl<E> TryInto<f32, Error<E>> for RuntimeValue where E: CustomUserError {
 	}
 }
 
-impl<E> TryInto<f64, Error<E>> for RuntimeValue where E: CustomUserError {
+impl<E> TryInto<f64, Error<E>> for RuntimeValue where E: UserError {
 	fn try_into(self) -> Result<f64, Error<E>> {
 		match self {
 			RuntimeValue::F64(val) => Ok(val),
@@ -223,7 +223,7 @@ impl<E> TryInto<f64, Error<E>> for RuntimeValue where E: CustomUserError {
 	}
 }
 
-impl<E> TryInto<u32, Error<E>> for RuntimeValue where E: CustomUserError {
+impl<E> TryInto<u32, Error<E>> for RuntimeValue where E: UserError {
 	fn try_into(self) -> Result<u32, Error<E>> {
 		match self {
 			RuntimeValue::I32(val) => Ok(val as u32),
@@ -232,7 +232,7 @@ impl<E> TryInto<u32, Error<E>> for RuntimeValue where E: CustomUserError {
 	}
 }
 
-impl<E> TryInto<u64, Error<E>> for RuntimeValue where E: CustomUserError {
+impl<E> TryInto<u64, Error<E>> for RuntimeValue where E: UserError {
 	fn try_into(self) -> Result<u64, Error<E>> {
 		match self {
 			RuntimeValue::I64(val) => Ok(val as u64),
@@ -265,7 +265,7 @@ impl_wrap_into!(f64, f32);
 
 macro_rules! impl_try_truncate_into {
 	($from: ident, $into: ident) => {
-		impl<E> TryTruncateInto<$into, Error<E>> for $from where E: CustomUserError {
+		impl<E> TryTruncateInto<$into, Error<E>> for $from where E: UserError {
 			fn try_truncate_into(self) -> Result<$into, Error<E>> {
 				// Casting from a float to an integer will round the float towards zero
 				// NOTE: currently this will cause Undefined Behavior if the rounded value cannot be represented by the
@@ -373,7 +373,7 @@ impl TransmuteInto<f64> for i64 {
 	fn transmute_into(self) -> f64 { f64_from_bits(self as _) }
 }
 
-impl<E> LittleEndianConvert<E> for i8 where E: CustomUserError {
+impl<E> LittleEndianConvert<E> for i8 where E: UserError {
 	fn into_little_endian(self) -> Vec<u8> {
 		vec![self as u8]
 	}
@@ -385,7 +385,7 @@ impl<E> LittleEndianConvert<E> for i8 where E: CustomUserError {
 	}
 }
 
-impl<E> LittleEndianConvert<E> for u8 where E: CustomUserError {
+impl<E> LittleEndianConvert<E> for u8 where E: UserError {
 	fn into_little_endian(self) -> Vec<u8> {
 		vec![self]
 	}
@@ -397,7 +397,7 @@ impl<E> LittleEndianConvert<E> for u8 where E: CustomUserError {
 	}
 }
 
-impl<E> LittleEndianConvert<E> for i16 where E: CustomUserError {
+impl<E> LittleEndianConvert<E> for i16 where E: UserError {
 	fn into_little_endian(self) -> Vec<u8> {
 		let mut vec = Vec::with_capacity(2);
 		vec.write_i16::<LittleEndian>(self)
@@ -411,7 +411,7 @@ impl<E> LittleEndianConvert<E> for i16 where E: CustomUserError {
 	}
 }
 
-impl<E> LittleEndianConvert<E> for u16 where E: CustomUserError {
+impl<E> LittleEndianConvert<E> for u16 where E: UserError {
 	fn into_little_endian(self) -> Vec<u8> {
 		let mut vec = Vec::with_capacity(2);
 		vec.write_u16::<LittleEndian>(self)
@@ -425,7 +425,7 @@ impl<E> LittleEndianConvert<E> for u16 where E: CustomUserError {
 	}
 }
 
-impl<E> LittleEndianConvert<E> for i32 where E: CustomUserError {
+impl<E> LittleEndianConvert<E> for i32 where E: UserError {
 	fn into_little_endian(self) -> Vec<u8> {
 		let mut vec = Vec::with_capacity(4);
 		vec.write_i32::<LittleEndian>(self)
@@ -439,7 +439,7 @@ impl<E> LittleEndianConvert<E> for i32 where E: CustomUserError {
 	}
 }
 
-impl<E> LittleEndianConvert<E> for u32 where E: CustomUserError {
+impl<E> LittleEndianConvert<E> for u32 where E: UserError {
 	fn into_little_endian(self) -> Vec<u8> {
 		let mut vec = Vec::with_capacity(4);
 		vec.write_u32::<LittleEndian>(self)
@@ -453,7 +453,7 @@ impl<E> LittleEndianConvert<E> for u32 where E: CustomUserError {
 	}
 }
 
-impl<E> LittleEndianConvert<E> for i64 where E: CustomUserError {
+impl<E> LittleEndianConvert<E> for i64 where E: UserError {
 	fn into_little_endian(self) -> Vec<u8> {
 		let mut vec = Vec::with_capacity(8);
 		vec.write_i64::<LittleEndian>(self)
@@ -467,7 +467,7 @@ impl<E> LittleEndianConvert<E> for i64 where E: CustomUserError {
 	}
 }
 
-impl<E> LittleEndianConvert<E> for f32 where E: CustomUserError {
+impl<E> LittleEndianConvert<E> for f32 where E: UserError {
 	fn into_little_endian(self) -> Vec<u8> {
 		let mut vec = Vec::with_capacity(4);
 		vec.write_f32::<LittleEndian>(self)
@@ -482,7 +482,7 @@ impl<E> LittleEndianConvert<E> for f32 where E: CustomUserError {
 	}
 }
 
-impl<E> LittleEndianConvert<E> for f64 where E: CustomUserError {
+impl<E> LittleEndianConvert<E> for f64 where E: UserError {
 	fn into_little_endian(self) -> Vec<u8> {
 		let mut vec = Vec::with_capacity(8);
 		vec.write_f64::<LittleEndian>(self)
@@ -535,7 +535,7 @@ fn f64_from_bits(mut v: u64) -> f64 {
 
 macro_rules! impl_integer_arithmetic_ops {
 	($type: ident) => {
-		impl<E> ArithmeticOps<$type, E> for $type where E: CustomUserError {
+		impl<E> ArithmeticOps<$type, E> for $type where E: UserError {
 			fn add(self, other: $type) -> $type { self.wrapping_add(other) }
 			fn sub(self, other: $type) -> $type { self.wrapping_sub(other) }
 			fn mul(self, other: $type) -> $type { self.wrapping_mul(other) }
@@ -561,7 +561,7 @@ impl_integer_arithmetic_ops!(u64);
 
 macro_rules! impl_float_arithmetic_ops {
 	($type: ident) => {
-		impl<E> ArithmeticOps<$type, E> for $type where E: CustomUserError {
+		impl<E> ArithmeticOps<$type, E> for $type where E: UserError {
 			fn add(self, other: $type) -> $type { self + other }
 			fn sub(self, other: $type) -> $type { self - other }
 			fn mul(self, other: $type) -> $type { self * other }
@@ -575,7 +575,7 @@ impl_float_arithmetic_ops!(f64);
 
 macro_rules! impl_integer {
 	($type: ident) => {
-		impl<E> Integer<$type, E> for $type where E: CustomUserError {
+		impl<E> Integer<$type, E> for $type where E: UserError {
 			fn leading_zeros(self) -> $type { self.leading_zeros() as $type }
 			fn trailing_zeros(self) -> $type { self.trailing_zeros() as $type }
 			fn count_ones(self) -> $type { self.count_ones() as $type }
@@ -596,7 +596,7 @@ impl_integer!(u64);
 
 macro_rules! impl_float {
 	($type: ident, $int_type: ident) => {
-		impl<E> Float<$type, E> for $type where E: CustomUserError {
+		impl<E> Float<$type, E> for $type where E: UserError {
 			fn abs(self) -> $type { self.abs() }
 			fn floor(self) -> $type { self.floor() }
 			fn ceil(self) -> $type { self.ceil() }

src/interpreter/variable.rs

@@ -1,7 +1,7 @@
 use std::fmt;
 use parking_lot::RwLock;
 use elements::{GlobalType, ValueType, TableElementType};
-use interpreter::{Error, CustomUserError};
+use interpreter::{Error, UserError};
 use interpreter::value::RuntimeValue;
 
 /// Variable type.
@@ -20,7 +20,7 @@ pub enum VariableType {
 }
 
 /// Externally stored variable value.
-pub trait ExternalVariableValue<E: CustomUserError> {
+pub trait ExternalVariableValue<E: UserError> {
 	/// Get variable value.
 	fn get(&self) -> RuntimeValue;
 	/// Set variable value.
@@ -29,7 +29,7 @@ pub trait ExternalVariableValue<E: CustomUserError> {
 
 /// Variable instance.
 #[derive(Debug)]
-pub struct VariableInstance<E: CustomUserError> {
+pub struct VariableInstance<E: UserError> {
 	/// Is mutable?
 	is_mutable: bool,
 	/// Variable type.
@@ -39,14 +39,14 @@ pub struct VariableInstance<E: CustomUserError> {
 }
 
 /// Enum variable value.
-enum VariableValue<E: CustomUserError> {
+enum VariableValue<E: UserError> {
 	/// Internal value.
 	Internal(RuntimeValue),
 	/// External value.
 	External(Box<ExternalVariableValue<E>>),
 }
 
-impl<E> VariableInstance<E> where E: CustomUserError {
+impl<E> VariableInstance<E> where E: UserError {
 	/// New variable instance
 	pub fn new(is_mutable: bool, variable_type: VariableType, value: RuntimeValue) -> Result<Self, Error<E>> {
 		// TODO: there is nothing about null value in specification + there is nothing about initializing missing table elements? => runtime check for nulls
@@ -109,7 +109,7 @@ impl<E> VariableInstance<E> where E: CustomUserError {
 	}
 }
 
-impl<E> VariableValue<E> where E: CustomUserError {
+impl<E> VariableValue<E> where E: UserError {
 	fn get(&self) -> RuntimeValue {
 		match *self {
 			VariableValue::Internal(ref value) => value.clone(),
@@ -147,7 +147,7 @@ impl From<TableElementType> for VariableType {
 	}
 }
 
-impl<E> fmt::Debug for VariableValue<E> where E: CustomUserError {
+impl<E> fmt::Debug for VariableValue<E> where E: UserError {
 	fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
 		match *self {
 			VariableValue::Internal(ref value) => write!(f, "Variable.Internal({:?})", value),