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use proc_macro2::{Ident, Span, TokenStream};
use quote::{quote, TokenStreamExt};
use syn::{Attribute, Data, DeriveInput, Error, Expr, ExprLit, Fields, Lit, LitInt, Result, Type};
pub fn stream_parse(input: DeriveInput) -> Result<TokenStream> {
let name = &input.ident;
let attrs = input.attrs;
match input.data {
Data::Struct(v) => {
// iterate through struct fields
let (w, r, new_reads) = impl_named_fields(v.fields);
let writes = quote!(#(#w)*);
let reads = quote!(#(#r),*);
// get the visibility etc on each field
// return a quote for block impl
Ok(quote! {
#[automatically_derived]
impl Streamable<#name> for #name {
fn parse(&self) -> Result<Vec<u8>, ::binary_util::error::BinaryError> {
use ::binary_util::interfaces::{Reader, Writer};
use ::binary_util::io::ByteWriter;
let mut writer = ByteWriter::new();
#writes
Ok(writer.as_slice().to_vec())
}
fn compose(s: &[u8], position: &mut usize) -> Result<Self, ::binary_util::error::BinaryError> {
use ::binary_util::interfaces::{Reader, Writer};
use ::std::io::Read;
let mut source = ::binary_util::io::ByteReader::from(s);
Ok(Self {
#reads
})
}
}
impl ::binary_util::interfaces::Writer for #name {
fn write(&self, writer: &mut ::binary_util::io::ByteWriter) -> Result<(), ::std::io::Error> {
use ::binary_util::interfaces::{Reader, Writer};
#writes
Ok(())
}
}
impl ::binary_util::interfaces::Reader<#name> for #name {
fn read(source: &mut ::binary_util::io::ByteReader) -> Result<Self, ::std::io::Error> {
use ::binary_util::interfaces::{Reader, Writer};
// get the repr type and read it
Ok(Self {
#new_reads
})
}
}
})
}
Data::Enum(data) => {
let representation =
find_one_attr("repr", attrs).expect("Enums must have a #[repr] attribute");
let enum_ty = representation
.parse_args::<Ident>()
.expect("Enums can only have types as attributes");
if !enum_ty
.to_string()
.starts_with(|v| v == 'u' || v == 'i' || v == 'f')
{
return Err(Error::new_spanned(
representation,
"Representation must be a primitive number",
));
}
let (mut writers, mut readers) = (Vec::<TokenStream>::new(), Vec::<TokenStream>::new());
let mut new_writers = Vec::<TokenStream>::new();
if !data.variants.iter().all(|v| match v.fields.clone() {
Fields::Unit => true,
Fields::Unnamed(_) => true,
_ => false,
}) {
return Err(Error::new_spanned(
data.variants,
"Enum Fields must be Uninitialized or Named",
));
}
let mut last_field: Option<Expr> = None;
for variant in &data.variants {
// for each field...
// get the value of the last field.
match &variant.fields {
Fields::Unit => {
if let Some(da) = variant.discriminant.as_ref() {
let discrim = da.1.clone();
let var_name = variant.ident.clone();
// writers
writers.push(
quote!(Self::#var_name => Ok((#discrim as #enum_ty).write_to_bytes().unwrap().as_slice().to_vec()),),
);
new_writers.push(
quote!{
Self::#var_name => {
source.write((#discrim as #enum_ty).write_to_bytes()?.as_slice())?;
Ok(())
}
}
);
// readers
readers.push(quote!(#discrim => Ok(Self::#var_name),));
last_field = Some(discrim.clone());
} else {
if last_field.is_some() {
// The discriminant exists, but the variant is unit.
// However there was a previous discriminant.
// We need to add a literal "one" to the discriminant.
// This is a bit tricky so bare with the hacks here.
match last_field.unwrap() {
Expr::Lit(v) => {
// get the literal value of the last field.
let lit = v.lit.clone();
match lit {
Lit::Int(literal_value) => {
let next =
literal_value.base10_parse::<u64>().unwrap()
+ 1;
// If last field is none, then this is the first field.
// In this case, we will just write the discriminant as 0.
last_field = Some(Expr::Lit(ExprLit {
lit: Lit::Int(LitInt::new(
&format!("{}", next),
Span::call_site(),
)),
attrs: Vec::new(),
}));
let discrim = last_field.clone().unwrap();
let var_name = variant.ident.clone();
// writers
writers.push(quote!(Self::#var_name => Ok((#discrim as #enum_ty).write_to_bytes()?),));
new_writers.push(
quote!{
Self::#var_name => {
source.write((#discrim as #enum_ty).write_to_bytes()?.as_slice())?;
Ok(())
}
}
);
// readers
readers
.push(quote!(#discrim => Ok(Self::#var_name),));
}
_ => {
return Err(Error::new_spanned(variant, "Enum discriminant must be a literal but the previous field was not a literal"));
}
}
}
_ => {
return Err(Error::new_spanned(variant, "Enum discriminant must be a literal but the previous field was not a literal"));
}
}
} else {
// If last field is none, then this is the first field.
// In this case, we will just write the discriminant as 0.
last_field = Some(Expr::Lit(ExprLit {
lit: Lit::Int(LitInt::new(&"0", Span::call_site())),
attrs: Vec::new(),
}));
let discrim = last_field.clone().unwrap();
let var_name = variant.ident.clone();
// writers
writers.push(
quote!(Self::#var_name => Ok((#discrim as #enum_ty).write_to_bytes()?),),
);
new_writers.push(
quote!{
Self::#var_name => {
source.write((#discrim as #enum_ty).write_to_bytes()?.as_slice())?;
Ok(())
}
}
);
// readers
readers.push(quote!(#discrim => Ok(Self::#var_name),));
}
}
}
Fields::Unnamed(_fields) => {
return Err(Error::new_spanned(
variant,
"Variant fields are not explicitly supported yet.",
));
// for field in fields.unnamed.iter() {
// dbg!("I am here 2\n\n\\nn\n\n");
// }
}
_ => return Err(Error::new_spanned(variant.clone(), "Variant invalid")),
}
}
Ok(quote! {
#[automatically_derived]
impl ::binary_util::interfaces::Streamable<#name> for #name {
fn parse(&self) -> Result<Vec<u8>, ::binary_util::error::BinaryError> {
use ::binary_util::interfaces::{Reader, Writer};
match self {
#(#writers)*
}
}
fn compose(source: &[u8], offset: &mut usize) -> Result<Self, ::binary_util::error::BinaryError> {
use ::binary_util::interfaces::{Reader, Writer};
// get the repr type and read it
let v = <#enum_ty>::read(&mut ::binary_util::io::ByteReader::from(source))?;
match v {
#(#readers)*
_ => panic!("Will not fit in enum!")
}
}
}
impl ::binary_util::interfaces::Writer for #name {
fn write(&self, source: &mut ::binary_util::io::ByteWriter) -> Result<(), ::std::io::Error> {
use ::binary_util::interfaces::{Reader, Writer};
match self {
#(#new_writers)*
}
}
}
impl ::binary_util::interfaces::Reader<#name> for #name {
fn read(source: &mut ::binary_util::io::ByteReader) -> Result<Self, ::std::io::Error> {
use ::binary_util::interfaces::{Reader, Writer};
// get the repr type and read it
let v = <#enum_ty>::read(source)?;
match v {
#(#readers)*
_ => panic!("Will not fit in enum!")
}
}
}
})
}
Data::Union(_) => Err(syn::Error::new(
name.span(),
"BinaryStream does not support Type Unions. Use Enums instead.",
)),
}
}
pub fn impl_named_fields(fields: Fields) -> (Vec<TokenStream>, Vec<TokenStream>, TokenStream) {
let mut writers = Vec::<TokenStream>::new();
let mut readers = Vec::<TokenStream>::new();
let mut new_reads = TokenStream::new();
match fields {
Fields::Named(v) => {
for field in &v.named {
let field_id = field.ident.as_ref().unwrap();
let (writer, reader, nw) = impl_streamable_lazy(field_id, &field.ty);
writers.push(writer);
readers.push(reader);
new_reads.append_all(nw);
}
}
Fields::Unnamed(_v) => {
panic!("Can not parse un-named fields at this current point in time.")
}
Fields::Unit => {
panic!("Can not use uninitalized data values.")
}
}
(writers, readers, new_reads)
}
// pub fn impl_unnamed_fields(_fields: FieldsUnnamed) -> (TokenStream, TokenStream) {
// todo!()
// }
pub fn impl_streamable_lazy(name: &Ident, ty: &Type) -> (TokenStream, TokenStream, TokenStream) {
(
quote! { writer.write(&self.#name.write_to_bytes().unwrap().as_slice()[..])?; },
quote!(#name: <#ty>::read(&mut source)?),
quote! { #name: <#ty>::read(source)?, },
)
}
fn find_one_attr(name: &str, attrs: Vec<Attribute>) -> Option<Attribute> {
let mut iter = attrs.iter().filter(|a| a.path().is_ident(name));
match (iter.next(), iter.next()) {
(Some(v), None) => Some(v.clone()),
_ => None,
}
}