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Second iteration on documenation.

This commit is contained in:
Sergey Pepyakin 2018-01-24 18:49:42 +03:00
parent f6f23accdd
commit 230abc6a91
2 changed files with 209 additions and 9 deletions
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121
src/host.rs
View File

@ -13,7 +13,6 @@ impl<'a> From<&'a [RuntimeValue]> for RuntimeArgs<'a> {
}
impl<'a> RuntimeArgs<'a> {
/// Extract argument by index `idx` returning error if cast is invalid or not enough arguments
pub fn nth<T>(&self, idx: usize) -> Result<T, Error> where RuntimeValue: TryInto<T, Error> {
Ok(self.nth_value(idx)?.try_into().map_err(|_| Error::Value("Invalid argument cast".to_owned()))?)
@ -33,7 +32,44 @@ impl<'a> RuntimeArgs<'a> {
}
}
/// Custom user error.
/// Trait that allows the host to return custom error.
///
/// It should be useful for representing custom traps,
/// troubles at instantiation time or other host specific conditions.
///
/// # Examples
///
/// ```rust
/// use std::fmt;
/// use wasmi::{Error, HostError};
///
/// #[derive(Debug)]
/// struct MyError {
/// code: u32,
/// }
///
/// impl fmt::Display for MyError {
/// fn fmt(&self, f: &mut fmt::Formatter) -> fmt::Result {
/// write!(f, "MyError, code={}", self.code)
/// }
/// }
///
/// impl HostError for MyError { }
///
/// fn failable_fn() -> Result<(), Error> {
/// let my_error = MyError { code: 1312 };
/// Err(Error::Host(Box::new(my_error)))
/// }
///
/// match failable_fn() {
/// Err(Error::Host(host_error)) => {
/// let my_error = host_error.downcast_ref::<MyError>().unwrap();
/// assert_eq!(my_error.code, 1312);
/// }
/// _ => panic!(),
/// }
/// ```
///
pub trait HostError: 'static + ::std::fmt::Display + ::std::fmt::Debug + Send + Sync {
#[doc(hidden)]
fn __private_get_type_id__(&self) -> TypeId {
@ -62,6 +98,77 @@ impl HostError {
}
}
/// Trait that allows to implement host functions.
///
/// # Examples
///
/// ```rust
/// use wasmi::{
/// Externals, RuntimeValue, RuntimeArgs, Error, ModuleImportResolver,
/// FuncRef, ValueType, Signature, FuncInstance
/// };
///
/// struct HostExternals {
/// counter: usize,
/// }
///
/// const ADD_FUNC_INDEX: usize = 0;
///
/// impl Externals for HostExternals {
/// fn invoke_index(
/// &mut self,
/// index: usize,
/// args: RuntimeArgs,
/// ) -> Result<Option<RuntimeValue>, Error> {
/// match index {
/// ADD_FUNC_INDEX => {
/// let a: u32 = args.nth(0).unwrap();
/// let b: u32 = args.nth(1).unwrap();
/// let result = a + b;
///
/// Ok(Some(RuntimeValue::I32(result as i32)))
/// }
/// _ => panic!("Unimplemented function at {}", index),
/// }
/// }
/// }
///
/// impl HostExternals {
/// fn check_signature(
/// &self,
/// index: usize,
/// signature: &Signature
/// ) -> bool {
/// let (params, ret_ty): (&[ValueType], Option<ValueType>) = match index {
/// ADD_FUNC_INDEX => (&[ValueType::I32, ValueType::I32], Some(ValueType::I32)),
/// _ => return false,
/// };
/// signature.params() == params && signature.return_type() == ret_ty
/// }
/// }
///
/// impl ModuleImportResolver for HostExternals {
/// fn resolve_func(
/// &self,
/// field_name: &str,
/// signature: &Signature
/// ) -> Result<FuncRef, Error> {
/// let index = match field_name {
/// "add" => ADD_FUNC_INDEX,
/// _ => {
/// return Err(Error::Instantiation(
/// format!("Export {} not found", field_name),
/// ))
/// }
/// };
///
/// Ok(FuncInstance::alloc_host(
/// Signature::new(&[ValueType::I32, ValueType::I32][..], Some(ValueType::I32)),
/// ADD_FUNC_INDEX,
/// ))
/// }
/// }
/// ```
pub trait Externals {
fn invoke_index(
&mut self,
@ -70,6 +177,10 @@ pub trait Externals {
) -> Result<Option<RuntimeValue>, Error>;
}
/// Implementation of [`Externals`] that just traps on [`invoke_index`].
///
/// [`Externals`]: trait.Externals.html
/// [`invoke_index`]: trait.Externals.html#tymethod.invoke_index
pub struct NopExternals;
impl Externals for NopExternals {
@ -86,7 +197,7 @@ impl Externals for NopExternals {
mod tests {
use value::RuntimeValue;
use super::RuntimeArgs;
use super::{RuntimeArgs, HostError};
#[test]
fn i32_runtime_args() {
@ -100,4 +211,8 @@ mod tests {
let args: RuntimeArgs = (&[RuntimeValue::I64(90534534545322)][..]).into();
assert!(args.nth::<i32>(0).is_err());
}
// Tests that `HostError` trait is object safe.
fn _host_error_is_object_safe(_: &HostError) {
}
}

97
src/imports.rs
View File

@ -7,36 +7,95 @@ use module::ModuleRef;
use types::{GlobalDescriptor, TableDescriptor, MemoryDescriptor};
use {Error, Signature};
/// Resolver of a module's dependencies.
///
/// A module have dependencies in a form of a list of imports (i.e.
/// tuple of a (`module_name`, `field_name`, `descriptor`)).
///
/// The job of implementations of this trait is to provide on each
/// import a corresponding concrete reference.
pub trait ImportResolver {
/// Resolve a function.
///
/// Returned function should match given `signature`, i.e. all parameter types and return value should have exact match.
/// Otherwise, link-time error will occur.
fn resolve_func(
&self,
module_name: &str,
_module_name: &str,
field_name: &str,
func_type: &Signature,
_signature: &Signature,
) -> Result<FuncRef, Error>;
/// Resolve a global variable.
///
/// Returned global should match given `descriptor`, i.e. type and mutability
/// should match. Otherwise, link-time error will occur.
fn resolve_global(
&self,
module_name: &str,
field_name: &str,
global_type: &GlobalDescriptor,
descriptor: &GlobalDescriptor,
) -> Result<GlobalRef, Error>;
/// Resolve a memory.
///
/// Returned memory should match requested memory (described by the `descriptor`),
/// i.e. initial size of a returned memory should be equal or larger than requested memory.
/// Furthermore, if requested memory have maximum size, returned memory either should have
/// equal or larger maximum size or have no maximum size at all.
/// If returned memory doesn't match the requested then link-time error will occur.
fn resolve_memory(
&self,
module_name: &str,
field_name: &str,
memory_type: &MemoryDescriptor,
descriptor: &MemoryDescriptor,
) -> Result<MemoryRef, Error>;
/// Resolve a table.
///
/// Returned table should match requested table (described by the `descriptor`),
/// i.e. initial size of a returned table should be equal or larger than requested table.
/// Furthermore, if requested memory have maximum size, returned memory either should have
/// equal or larger maximum size or have no maximum size at all.
/// If returned table doesn't match the requested then link-time error will occur.
fn resolve_table(
&self,
module_name: &str,
field_name: &str,
table_type: &TableDescriptor,
descriptor: &TableDescriptor,
) -> Result<TableRef, Error>;
}
/// Convenience builder of [`ImportResolver`].
///
/// With help of this builder, you can easily create [`ImportResolver`], just by
/// adding needed [resolvers][`ModuleImportResolver`] by names.
///
/// # Examples
///
/// ```rust
/// use wasmi::{load_from_buffer, ModuleInstance, ImportsBuilder};
/// #
/// # struct EnvModuleResolver;
/// # impl ::wasmi::ModuleImportResolver for EnvModuleResolver { }
/// # fn func() -> Result<(), ::wasmi::Error> {
/// # let module = load_from_buffer(&[0x00, 0x61, 0x73, 0x6d, 0x01, 0x00, 0x00, 0x00]).unwrap();
/// # let other_instance = ModuleInstance::new(&module, &ImportsBuilder::default())?.assert_no_start();
///
/// let imports = ImportsBuilder::new()
/// .with_resolver("env", &EnvModuleResolver)
/// // Note, that ModuleInstance can be a resolver too.
/// .with_resolver("other_instance", &other_instance);
/// let instance = ModuleInstance::new(&module, &imports)?.assert_no_start();
///
/// # Ok(())
/// # }
/// ```
///
/// [`ImportResolver`]: trait.ImportResolver.html
/// [`ModuleImportResolver`]: trait.ModuleImportResolver.html
pub struct ImportsBuilder<'a> {
modules: HashMap<String, &'a ModuleImportResolver>,
}
@ -48,10 +107,12 @@ impl<'a> Default for ImportsBuilder<'a> {
}
impl<'a> ImportsBuilder<'a> {
/// Create an empty `ImportsBuilder`.
pub fn new() -> ImportsBuilder<'a> {
ImportsBuilder { modules: HashMap::new() }
}
/// Register an resolver by a name.
pub fn with_resolver<N: Into<String>>(
mut self,
name: N,
@ -61,11 +122,12 @@ impl<'a> ImportsBuilder<'a> {
self
}
/// Register an resolver by a name.
pub fn push_resolver<N: Into<String>>(&mut self, name: N, resolver: &'a ModuleImportResolver) {
self.modules.insert(name.into(), resolver);
}
pub fn resolver(&self, name: &str) -> Option<&ModuleImportResolver> {
fn resolver(&self, name: &str) -> Option<&ModuleImportResolver> {
self.modules.get(name).cloned()
}
}
@ -116,7 +178,15 @@ impl<'a> ImportResolver for ImportsBuilder<'a> {
}
}
/// Version of [`ImportResolver`] specialized for a single module.
///
/// [`ImportResolver`]: trait.ImportResolver.html
pub trait ModuleImportResolver {
/// Resolve a function.
///
/// See [`ImportResolver::resolve_func`] for details.
///
/// [`ImportResolver::resolve_func`]: trait.ImportResolver.html#tymethod.resolve_func
fn resolve_func(
&self,
field_name: &str,
@ -127,6 +197,11 @@ pub trait ModuleImportResolver {
))
}
/// Resolve a global variable.
///
/// See [`ImportResolver::resolve_global`] for details.
///
/// [`ImportResolver::resolve_global`]: trait.ImportResolver.html#tymethod.resolve_global
fn resolve_global(
&self,
field_name: &str,
@ -137,6 +212,11 @@ pub trait ModuleImportResolver {
))
}
/// Resolve a memory.
///
/// See [`ImportResolver::resolve_memory`] for details.
///
/// [`ImportResolver::resolve_memory`]: trait.ImportResolver.html#tymethod.resolve_memory
fn resolve_memory(
&self,
field_name: &str,
@ -147,6 +227,11 @@ pub trait ModuleImportResolver {
))
}
/// Resolve a table.
///
/// See [`ImportResolver::resolve_table`] for details.
///
/// [`ImportResolver::resolve_table`]: trait.ImportResolver.html#tymethod.resolve_table
fn resolve_table(
&self,
field_name: &str,