combine crates to workspace

btrfs_parse_derive/Cargo.toml

@@ -0,0 +1,14 @@
+[package]
+name = "btrfs_parse_derive"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]
+proc-macro2 = "1.0.66"
+quote = "1.0.32"
+syn = "2.0.27"
+
+[lib]
+proc-macro = true

btrfs_parse_derive/src/lib.rs

@@ -0,0 +1,184 @@
+extern crate proc_macro;
+extern crate syn;
+#[macro_use]
+extern crate quote;
+extern crate proc_macro2;
+
+use proc_macro2::Span;
+use proc_macro::TokenStream;
+use syn::{DeriveInput, Data::Enum, parse_macro_input};
+
+#[proc_macro_derive(AllVariants)]
+pub fn derive_all_variants(input: TokenStream) -> TokenStream {
+	let syn_item: DeriveInput = parse_macro_input!(input);
+
+	let variants = match syn_item.data {
+		Enum(enum_item) => {
+			enum_item.variants.into_iter().map(|v|v.ident)
+		},
+		_ => panic!("AllVariants only works on enums!"),
+	};
+	let enum_name = syn_item.ident;
+
+	let expanded = quote! {
+		impl #enum_name {
+			fn all_variants() -> &'static[#enum_name] {
+				&[ #(#enum_name::#variants),* ]
+			}
+		}
+	};
+
+	expanded.into()
+}
+
+#[proc_macro_derive(ParseBin, attributes(skip_bytes, len))]
+pub fn derive_parse_bin(input: TokenStream) -> TokenStream {
+	let syn_item: DeriveInput = parse_macro_input!(input);
+	let name = syn_item.ident;
+
+	match syn_item.data {
+		syn::Data::Struct(struct_item) => {
+			match struct_item.fields {
+				syn::Fields::Named(fields_named) => {
+					return derive_parse_bin_struct(&name, &fields_named.named);
+				},
+				syn::Fields::Unnamed(fields_unnamed) => {
+					if fields_unnamed.unnamed.len() != 1 {
+						panic!("ParseBin does not support tuple structs!");
+					}
+
+					let inner_type = fields_unnamed.unnamed.into_iter().next().unwrap().ty;
+					return derive_parse_bin_alias(name, inner_type);
+				},
+				_ => panic!("ParseBin on unit structs makes no sense!"),
+			}
+		},
+		_ => panic!("ParseBin only works on structs so far!"),
+	};
+}
+
+fn derive_parse_bin_alias(name: syn::Ident, ty: syn::Type) -> TokenStream {
+	quote! {
+		impl ParseBin for #name {
+			fn parse_len(bytes: &[u8]) -> Result<(Self, usize), ParseError> {
+				let (result, size) = <#ty>::parse_len(bytes)?;
+				Ok((#name(result), size))
+			}
+		}
+	}.into()
+}
+
+fn derive_parse_bin_struct<'a, T>(name: &syn::Ident, fields: T) -> TokenStream
+	where T: IntoIterator<Item = &'a syn::Field>
+{
+	let mut parsing_statements = Vec::new();
+	let mut combining_expressions = Vec::new();
+
+	for field in fields {
+		let field_name = field.ident.as_ref().unwrap();
+		let field_type = &field.ty;
+		let mut skip: Option<usize> = None;
+		let mut veclen: Option<String> = None;
+
+		// look for attributes
+		for at in &field.attrs {
+			if let syn::Meta::NameValue(nv) = &at.meta {
+				if nv.path.segments.len() == 1 {
+					let attr_name = nv.path.segments[0].ident.to_string();
+					if attr_name == "skip_bytes" {
+						if let syn::Expr::Lit(expr) = &nv.value {
+							if let syn::Lit::Int(nbytes) = &expr.lit {
+//								println!("reserved = {}", nbytes);
+								skip = nbytes.base10_parse::<usize>().ok()
+							}
+						}
+					} else if attr_name == "len" {
+						if let syn::Expr::Lit(expr) = &nv.value {
+							if let syn::Lit::Str(litstr) = &expr.lit {
+//								println!("len = {}", litstr.value());
+								veclen = Some(litstr.value());
+							}
+						}
+					}
+				}
+			}
+		}
+
+		if let Some(offset) = skip {
+			parsing_statements.push(quote!{
+				__parse_bin_derive_size += #offset;
+			});
+		}
+
+		if let Some(varname) = veclen {
+			let field_name_item = format_ident!("{}_item", field_name);
+
+			let field_type_item: &syn::Type = match &field_type {
+				syn::Type::Path(tp) => {
+					match tp.path.segments.iter().next() {
+						Some(single) => {
+							if &single.ident.to_string() == "Vec" {
+								match &single.arguments {
+									syn::PathArguments::AngleBracketed(args) => {
+										match args.args.iter().next() {
+											Some(firstarg) => {
+												match firstarg {
+													syn::GenericArgument::Type(ty) => {
+														Some(ty)
+													},
+													_ => None,
+												}
+											},
+											None => None,
+										}
+									},
+									_ => None,
+								}
+							} else {
+								None
+							}
+						},
+						None => None,
+					}
+				},
+				_ => None,
+			}.expect("The len attribute is only allowed on type Vec<_>");
+
+			let varname_ident = syn::Ident::new(&varname, Span::call_site());
+
+			parsing_statements.push(quote!{
+				let mut #field_name = Vec::new();
+				for i in 0 .. #varname_ident.0 as usize {
+					let #field_name_item = <#field_type_item>::parse_len(&bytes[__parse_bin_derive_size..])?;
+					__parse_bin_derive_size += #field_name_item.1;
+					#field_name.push(#field_name_item.0);
+				}
+			});
+
+			combining_expressions.push(quote!(#field_name: #field_name));
+		} else {
+			parsing_statements.push(quote!{
+				let #field_name = <#field_type>::parse_len(&bytes[__parse_bin_derive_size..])?;
+				__parse_bin_derive_size += #field_name.1;
+			});
+
+			combining_expressions.push(quote!(#field_name: #field_name.0));
+		}
+	}
+
+	quote! {
+		impl ParseBin for #name {
+			fn parse_len(bytes: &[u8]) -> Result<(Self, usize), ParseError> {
+				let mut __parse_bin_derive_size: usize = 0;
+
+				#(#parsing_statements)*
+
+				let result = #name {
+					#(#combining_expressions),*
+				};
+
+				Ok((result, __parse_bin_derive_size))
+			}
+		}
+	}.into()
+}