Vendor things

third-party/vendor/bindgen/codegen/dyngen.rs

@@ -0,0 +1,201 @@
+use crate::codegen;
+use crate::ir::context::BindgenContext;
+use crate::ir::function::ClangAbi;
+use proc_macro2::Ident;
+
+/// Used to build the output tokens for dynamic bindings.
+#[derive(Default)]
+pub struct DynamicItems {
+    /// Tracks the tokens that will appears inside the library struct -- e.g.:
+    /// ```ignore
+    /// struct Lib {
+    ///    __library: ::libloading::Library,
+    ///    pub x: Result<unsafe extern ..., ::libloading::Error>, // <- tracks these
+    ///    ...
+    /// }
+    /// ```
+    struct_members: Vec<proc_macro2::TokenStream>,
+
+    /// Tracks the tokens that will appear inside the library struct's implementation, e.g.:
+    ///
+    /// ```ignore
+    /// impl Lib {
+    ///     ...
+    ///     pub unsafe fn foo(&self, ...) { // <- tracks these
+    ///         ...
+    ///     }
+    /// }
+    /// ```
+    struct_implementation: Vec<proc_macro2::TokenStream>,
+
+    /// Tracks the initialization of the fields inside the `::new` constructor of the library
+    /// struct, e.g.:
+    /// ```ignore
+    /// impl Lib {
+    ///
+    ///     pub unsafe fn new<P>(path: P) -> Result<Self, ::libloading::Error>
+    ///     where
+    ///         P: AsRef<::std::ffi::OsStr>,
+    ///     {
+    ///         ...
+    ///         let foo = __library.get(...) ...; // <- tracks these
+    ///         ...
+    ///     }
+    ///
+    ///     ...
+    /// }
+    /// ```
+    constructor_inits: Vec<proc_macro2::TokenStream>,
+
+    /// Tracks the information that is passed to the library struct at the end of the `::new`
+    /// constructor, e.g.:
+    /// ```ignore
+    /// impl LibFoo {
+    ///     pub unsafe fn new<P>(path: P) -> Result<Self, ::libloading::Error>
+    ///     where
+    ///         P: AsRef<::std::ffi::OsStr>,
+    ///     {
+    ///         ...
+    ///         Ok(LibFoo {
+    ///             __library: __library,
+    ///             foo,
+    ///             bar, // <- tracks these
+    ///             ...
+    ///         })
+    ///     }
+    /// }
+    /// ```
+    init_fields: Vec<proc_macro2::TokenStream>,
+}
+
+impl DynamicItems {
+    pub fn new() -> Self {
+        Self::default()
+    }
+
+    pub fn get_tokens(
+        &self,
+        lib_ident: Ident,
+        ctx: &BindgenContext,
+    ) -> proc_macro2::TokenStream {
+        let struct_members = &self.struct_members;
+        let constructor_inits = &self.constructor_inits;
+        let init_fields = &self.init_fields;
+        let struct_implementation = &self.struct_implementation;
+
+        let from_library = if ctx.options().wrap_unsafe_ops {
+            quote!(unsafe { Self::from_library(library) })
+        } else {
+            quote!(Self::from_library(library))
+        };
+
+        quote! {
+            extern crate libloading;
+
+            pub struct #lib_ident {
+                __library: ::libloading::Library,
+                #(#struct_members)*
+            }
+
+            impl #lib_ident {
+                pub unsafe fn new<P>(
+                    path: P
+                ) -> Result<Self, ::libloading::Error>
+                where P: AsRef<::std::ffi::OsStr> {
+                    let library = ::libloading::Library::new(path)?;
+                    #from_library
+                }
+
+                pub unsafe fn from_library<L>(
+                    library: L
+                ) -> Result<Self, ::libloading::Error>
+                where L: Into<::libloading::Library> {
+                    let __library = library.into();
+                    #( #constructor_inits )*
+                    Ok(#lib_ident {
+                        __library,
+                        #( #init_fields ),*
+                    })
+                }
+
+                #( #struct_implementation )*
+            }
+        }
+    }
+
+    #[allow(clippy::too_many_arguments)]
+    pub(crate) fn push(
+        &mut self,
+        ident: Ident,
+        abi: ClangAbi,
+        is_variadic: bool,
+        is_required: bool,
+        args: Vec<proc_macro2::TokenStream>,
+        args_identifiers: Vec<proc_macro2::TokenStream>,
+        ret: proc_macro2::TokenStream,
+        ret_ty: proc_macro2::TokenStream,
+        attributes: Vec<proc_macro2::TokenStream>,
+        ctx: &BindgenContext,
+    ) {
+        if !is_variadic {
+            assert_eq!(args.len(), args_identifiers.len());
+        }
+
+        let signature = quote! { unsafe extern #abi fn ( #( #args),* ) #ret };
+        let member = if is_required {
+            signature
+        } else {
+            quote! { Result<#signature, ::libloading::Error> }
+        };
+
+        self.struct_members.push(quote! {
+            pub #ident: #member,
+        });
+
+        // N.B: If the signature was required, it won't be wrapped in a Result<...>
+        //      and we can simply call it directly.
+        let fn_ = if is_required {
+            quote! { self.#ident }
+        } else {
+            quote! { self.#ident.as_ref().expect("Expected function, got error.") }
+        };
+        let call_body = if ctx.options().wrap_unsafe_ops {
+            quote!(unsafe { (#fn_)(#( #args_identifiers ),*) })
+        } else {
+            quote!((#fn_)(#( #args_identifiers ),*) )
+        };
+
+        // We can't implement variadic functions from C easily, so we allow to
+        // access the function pointer so that the user can call it just fine.
+        if !is_variadic {
+            self.struct_implementation.push(quote! {
+                #(#attributes)*
+                pub unsafe fn #ident ( &self, #( #args ),* ) -> #ret_ty {
+                    #call_body
+                }
+            });
+        }
+
+        // N.B: Unwrap the signature upon construction if it is required to be resolved.
+        let ident_str = codegen::helpers::ast_ty::cstr_expr(ident.to_string());
+        let library_get = if ctx.options().wrap_unsafe_ops {
+            quote!(unsafe { __library.get(#ident_str) })
+        } else {
+            quote!(__library.get(#ident_str))
+        };
+
+        self.constructor_inits.push(if is_required {
+            quote! {
+                let #ident = #library_get.map(|sym| *sym)?;
+            }
+        } else {
+            quote! {
+                let #ident = #library_get.map(|sym| *sym);
+            }
+        });
+
+        self.init_fields.push(quote! {
+            #ident
+        });
+    }
+}