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use prelude::*;
use super::common::*;
use std::iter;
use tyhandlers::{Direction};
use idents;
use model;
extern crate proc_macro;
use self::proc_macro::TokenStream;
/// Expands the `com_impl` attribute.
///
/// The attribute expansion results in the following items:
///
/// - Implementation for the delegating methods when calling the Rust methods
/// from COM.
/// - Virtual table instance for the COM type.
pub fn expand_com_impl(
_attr_tokens: &TokenStream,
item_tokens: TokenStream,
) -> Result<TokenStream, model::ParseError>
{
// Parse the attribute.
let mut output = vec![] ;
let imp = model::ComImpl::parse( &item_tokens.to_string() )?;
let struct_ident = imp.struct_name();
let itf_ident = imp.interface_name();
for ( _, impl_variant ) in imp.variants() {
let itf_unique_ident = impl_variant.interface_unique_name();
let vtable_struct_ident = idents::vtable_struct( &itf_unique_ident );
let vtable_instance_ident = idents::vtable_instance( &struct_ident, &itf_unique_ident );
let vtable_offset = idents::vtable_offset( &struct_ident, &itf_unique_ident );
/////////////////////
// #itf::QueryInterface, AddRef & Release
//
// Note that the actual methods implementation for these bits differs from
// the primary IUnknown methods. When the methods are being called through
// this vtable, the self_vtable pointer will point to this vtable and not
// the start of the CoClass instance.
//
// We can convert these to the ComBox references by offsetting the pointer
// by the known vtable offset.
// QueryInterface
let calling_convetion = get_calling_convetion();
let query_interface_ident = idents::method_impl(
&struct_ident, &itf_unique_ident, "query_interface" );
output.push( quote!(
#[allow(non_snake_case)]
#[doc(hidden)]
unsafe extern #calling_convetion fn #query_interface_ident(
self_vtable : ::intercom::RawComPtr,
riid : ::intercom::REFIID,
out : *mut ::intercom::RawComPtr
) -> ::intercom::raw::HRESULT
{
// Get the primary iunk interface by offsetting the current
// self_vtable with the vtable offset. Once we have the primary
// pointer we can delegate the call to the primary implementation.
::intercom::ComBox::< #struct_ident >::query_interface(
&mut *(( self_vtable as usize - #vtable_offset() ) as *mut _ ),
riid,
out )
}
) );
// AddRef
let add_ref_ident = idents::method_impl(
&struct_ident, &itf_unique_ident, "add_ref" );
output.push( quote!(
#[allow(non_snake_case)]
#[allow(dead_code)]
#[doc(hidden)]
unsafe extern #calling_convetion fn #add_ref_ident(
self_vtable : ::intercom::RawComPtr
) -> u32 {
::intercom::ComBox::< #struct_ident >::add_ref(
&mut *(( self_vtable as usize - #vtable_offset() ) as *mut _ ) )
}
) );
// Release
let release_ident = idents::method_impl(
&struct_ident, &itf_unique_ident, "release" );
output.push( quote!(
#[allow(non_snake_case)]
#[allow(dead_code)]
#[doc(hidden)]
unsafe extern #calling_convetion fn #release_ident(
self_vtable : ::intercom::RawComPtr
) -> u32 {
::intercom::ComBox::< #struct_ident >::release_ptr(
( self_vtable as usize - #vtable_offset() ) as *mut _ )
}
) );
// Start the definition fo the vtable fields. The base interface is always
// IUnknown at this point. We might support IDispatch later, but for now
// we only support IUnknown.
let mut vtable_fields = vec![
quote!(
__base : ::intercom::IUnknownVtbl {
query_interface_Automation : #query_interface_ident,
add_ref_Automation : #add_ref_ident,
release_Automation : #release_ident,
},
) ];
// Process the impl items. This gathers all COM-visible methods and defines
// delegating calls for them. These delegating calls are the ones that are
// invoked by the clients. The calls then convert everything to the RUST
// interface.
//
// The impl may have various kinds of items - we only support the ones that
// seem okay. So in case we encounter any errors we'll just skip the method
// silently. This is done by breaking out of the 'catch' before adding the
// method to the vtable fields.
for method_info in impl_variant.methods() {
let method_ident = &method_info.unique_name;
let method_rust_ident = &method_info.display_name;
let method_impl_ident = idents::method_impl(
&struct_ident, &itf_unique_ident, &method_ident.to_string() );
let in_out_args = method_info.raw_com_args()
.into_iter()
.map( |com_arg| {
let name = &com_arg.name;
let com_ty = &com_arg.handler.com_ty( com_arg.dir );
let dir = match com_arg.dir {
Direction::In => quote!(),
Direction::Out | Direction::Retval => quote!( *mut )
};
quote!( #name : #dir #com_ty )
} );
let self_arg = quote!( self_vtable : ::intercom::RawComPtr );
let args = iter::once( self_arg ).chain( in_out_args );
// Format the in and out parameters for the Rust call.
let ( in_temporaries, in_params ) : ( Vec<_>, Vec<_> ) = method_info.args
.iter()
.map( |ca| {
let conversion = ca.handler.com_to_rust( &ca.name, Direction::In );
( conversion.temporary, conversion.value )
} )
.unzip();
let return_ident = Ident::new( "__result", Span::call_site() );
let return_statement = method_info
.returnhandler
.rust_to_com_return( &return_ident );
// Define the delegating method implementation.
//
// Note the self_vtable here will be a pointer to the start of the
// vtable for the current interface. To get the coclass and thus
// the actual 'data' struct, we'll need to offset the self_vtable
// with the vtable offset.
let ret_ty = method_info.returnhandler.com_ty();
let self_struct_stmt = if method_info.is_const {
quote!( let self_struct : &#itf_ident = &**self_combox )
} else {
quote!( let self_struct : &mut #itf_ident = &mut **self_combox )
};
output.push( quote!(
#[allow(non_snake_case)]
#[allow(dead_code)]
#[doc(hidden)]
unsafe extern #calling_convetion fn #method_impl_ident(
#( #args ),*
) -> #ret_ty {
let result : Result< #ret_ty, ::intercom::ComError > = ( || {
// Acquire the reference to the ComBox. For this we need
// to offset the current 'self_vtable' vtable pointer.
let self_combox = ( self_vtable as usize - #vtable_offset() )
as *mut ::intercom::ComBox< #struct_ident >;
#( #in_temporaries )*
#self_struct_stmt;
let #return_ident = self_struct.#method_rust_ident( #( #in_params ),* );
Ok( { #return_statement } )
} )();
use ::intercom::ErrorValue;
match result {
Ok( v ) => v,
Err( err ) => < #ret_ty as ErrorValue >::from_error(
::intercom::store_error( err ) ),
}
}
) );
// Include the delegating method in the virtual table fields.
vtable_fields.push( quote!( #method_ident : #method_impl_ident, ) );
}
// Now that we've gathered all the virtual table fields, we can finally
// emit the virtual table instance.
output.push( quote!(
#[allow(non_upper_case_globals)]
const #vtable_instance_ident : #vtable_struct_ident
= #vtable_struct_ident { #( #vtable_fields )* };
) );
}
output.push( quote!(
impl ::intercom::HasInterface< #itf_ident > for #struct_ident {}
) );
Ok( tokens_to_tokenstream( item_tokens, output ) )
}