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use proc_macro2::{Ident, TokenStream};
use quote::{format_ident, quote};
use syn::parse::Parse;
use syn::punctuated::Punctuated;
use syn::{bracketed, parse_macro_input, LitInt, LitStr, Token};
struct DslInstructionInput {
opcode: LitInt,
name: Ident,
args: Punctuated<Ident, Token![,]>,
description: LitStr,
}
impl Parse for DslInstructionInput {
fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
let args_content;
Ok(Self {
opcode: input.parse()?,
name: input.parse()?,
args: {
bracketed!(args_content in input);
args_content.parse_terminated(Ident::parse, Token![,])?
},
description: input.parse()?,
})
}
}
struct DslInstructionsInput {
name: Ident,
instructions: Punctuated<DslInstructionInput, Token![,]>,
}
impl Parse for DslInstructionsInput {
fn parse(input: syn::parse::ParseStream) -> syn::Result<Self> {
Ok(Self {
name: input.parse()?,
instructions: {
input.parse::<Token![;]>()?;
input.parse_terminated(DslInstructionInput::parse, Token![,])?
},
})
}
}
fn into_enum_field(instruction: &DslInstructionInput) -> TokenStream {
let DslInstructionInput {
opcode,
name,
args,
description,
} = instruction;
let args = args.iter();
quote! {
#[doc = #description]
#name ( #( #args ),* ) = #opcode
}
}
fn into_bytecode_parser(instruction: &DslInstructionInput) -> TokenStream {
let DslInstructionInput {
opcode,
name,
args,
description: _,
} = instruction;
let args = args.iter().map(|arg| {
let read_ident = format_ident!("read_{}", arg);
let _chunk_codes = arg;
quote! {
{
let a: #arg = (chunk.code[*offset] << 56) + (chunk)
cursor . #read_ident ::<byteorder::LittleEndian>().unwrap()
}
}
});
quote! {
#opcode => {
Self:: #name (
#( #args ),*
)
}
}
}
#[proc_macro]
pub fn instructions(input: proc_macro::TokenStream) -> proc_macro::TokenStream {
let input = parse_macro_input!(input as DslInstructionsInput);
// Getting values to construct the enum
let enum_name = input.name;
let enum_fields = input
.instructions
.iter()
.map(into_enum_field)
.collect::<Vec<_>>();
// Getting the values to parse bytecode
let bytecode_parsers = input
.instructions
.iter()
.map(into_bytecode_parser)
.collect::<Vec<_>>();
// Building out the expanded code
let expanded = quote! {
#[repr(u8)]
#[derive(Clone, Debug)]
enum #enum_name {
#( #enum_fields ),*
}
impl #enum_name {
fn disassemble(chunk: &Chunk, offset: &mut usize) -> #enum_name {
let opcode = chunk.code[*offset];
*offset += 1;
let instruction = match opcode {
#( #bytecode_parsers ),*
_ => panic!("Unknown bytecode encountered"),
};
instruction
}
fn assemble(chunk: &mut Chunk) {
//
}
}
// impl #enum_name {
// fn from_bytecode(cursor: &mut Cursor<Vec<u8>>) -> Self {
// let bytecode = cursor.read_u8().unwrap();
//
// let instruction = match bytecode {
// #( #bytecode_parsers ),*
// _ => panic!("Unknown bytecode encountered"),
// };
//
// instruction
// }
// }
};
// Returning the proc_macro version of TokenStream
expanded.into()
}
|
