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use std::str::FromStr;
use syn::Token;
use syn::parse::{Parse, ParseStream};
use crate::create_syn_error;
use crate::parsing::types::{get_bits_from_type, is_supported_bitfield_type};
/// Represents the `#[bitfield]` attribute.
#[derive(Clone)]
pub(crate) struct BitfieldAttribute {
/// The integer type of the bitfield.
pub(crate) ty: syn::Type,
/// The number of bits of the bitfield.
pub(crate) bits: u8,
/// The order of the bits in the bitfield.
pub(crate) bit_order: BitOrder,
/// The endianness of the `from_bits` input.
pub(crate) from_endian: Endian,
/// The endianness of the `into_bits` output.
pub(crate) into_endian: Endian,
/// Whether to generate the `new` or `new_without_defaults` function.
pub(crate) generate_new_func: bool,
/// Whether to generate the `into_bits` function.
pub(crate) generate_into_bits_func: bool,
/// Whether to generate the `from_bits` function.
pub(crate) generate_from_bits_func: bool,
/// Whether to generate the from trait functions.
pub(crate) generate_from_trait_funcs: bool,
/// Whether to generate the `default` implementation.
pub(crate) generate_default_impl: bool,
/// Whether to generate the builder.
pub(crate) generate_builder: bool,
/// Whether to generate the `debug_impl` function.
pub(crate) generate_debug_impl: bool,
/// Whether to generate the bit operations.
pub(crate) generate_bit_ops: bool,
/// Whether to generate the set bits implementation.
pub(crate) generate_set_bits_impl: bool,
/// Whether to generate the clear bits implementation.
pub(crate) generate_clear_bits_impl: bool,
/// Whether to generate the `to_builder` function.
pub(crate) generate_to_builder: bool,
/// Whether to generate the `neg` function.
pub(crate) generate_neg_func: bool,
}
/// The order of the bits in the bitfield.
///
/// If the order is `Lsb`, the top most field will be the least significant bit
/// and the bottom most field is the most significant bit. If the order is
/// `Msb`, the top most field will be the most significant bit and the bottom
/// most field is the least significant bit.
#[derive(Copy, Clone, PartialEq, Eq)]
pub(crate) enum BitOrder {
Lsb,
Msb,
}
impl FromStr for BitOrder {
type Err = ();
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s.to_ascii_lowercase().as_str() {
"lsb" => Ok(BitOrder::Lsb),
"msb" => Ok(BitOrder::Msb),
_ => Err(()),
}
}
}
/// The endianness of the bytes.
#[derive(Clone, PartialEq)]
pub(crate) enum Endian {
Little,
Big,
}
impl FromStr for Endian {
type Err = ();
fn from_str(s: &str) -> Result<Self, Self::Err> {
match s.to_ascii_lowercase().as_str() {
"little" => Ok(Endian::Little),
"big" => Ok(Endian::Big),
_ => Err(()),
}
}
}
impl Parse for BitfieldAttribute {
fn parse(input: ParseStream) -> syn::Result<Self> {
// Get the type of the bitfield.
let ty = match input.parse() {
Ok(ty) => ty,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'bitfield' attribute field type: {}. The 'bitfield' attribute must have an unsigned integer type as its first argument.",
err
),
));
}
};
if !is_supported_bitfield_type(&ty) {
return Err(create_syn_error(
input.span(),
"The 'bitfield' attribute must have an unsigned integer type as its first argument.",
));
}
let bits = get_bits_from_type(&ty)?;
// Move to the next argument.
if !input.is_empty() {
<Token![,]>::parse(input)?;
}
let mut bit_order = BitOrder::Lsb;
let mut from_endian = Endian::Big;
let mut into_endian = Endian::Big;
let mut generate_new_func = true;
let mut generate_into_bits_func = true;
let mut generate_from_bits_func = true;
let mut generate_from_trait_funcs = true;
let mut generate_default_impl = true;
let mut generate_builder = true;
let mut generate_debug_impl = true;
let mut generate_bit_ops = false;
let mut generate_set_bits_impl = true;
let mut generate_clear_bits_impl = true;
let mut generate_to_builder = false;
let mut generate_neg_func = false;
// Parse the remaining arguments which is in the form of `[key] = [val]`.
while !input.is_empty() {
// Parse the argument key.
let arg_ident = syn::Ident::parse(input)?;
// Move to the key part of the argument.
<Token![=]>::parse(input)?;
match arg_ident.to_string().as_str() {
"order" => {
let order_str = match input.parse::<syn::Ident>() {
Ok(order) => order.to_string(),
Err(err) => {
return Err(create_syn_error(
input.span(),
format!("Failed to parse the 'order' arg '{}'.", err),
));
}
};
bit_order = match BitOrder::from_str(&order_str) {
Ok(order) => order,
Err(_) => {
return Err(create_syn_error(
input.span(),
format!(
"Invalid order: '{}', must be either 'lsb' or 'msb'.",
order_str
),
));
}
};
}
// Doesn't apply to user passed functions.
"from_endian" => {
let from_endian_str = match input.parse::<syn::Ident>() {
Ok(from_endian) => from_endian.to_string(),
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'from_endian' arg '{}', must be either 'little' or 'big'.",
err
),
));
}
};
from_endian = match Endian::from_str(&from_endian_str) {
Ok(endian) => endian,
Err(_) => {
return Err(create_syn_error(
input.span(),
format!(
"Invalid endian: '{}', must be either 'little' or 'big'.",
from_endian_str
),
));
}
};
}
// Doesn't apply to user passed functions.
"into_endian" => {
let into_endian_str = match input.parse::<syn::Ident>() {
Ok(into_endian) => into_endian.to_string(),
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'into_endian' arg '{}', must be either 'little' or 'big'.",
err
),
));
}
};
into_endian = match Endian::from_str(&into_endian_str) {
Ok(endian) => endian,
Err(_) => {
return Err(create_syn_error(
input.span(),
format!(
"Invalid endian: '{}', must be either 'little' or 'big'.",
into_endian_str
),
));
}
};
}
"new" => {
generate_new_func = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'new' arg '{}', must be either 'true' or 'false'.",
err
),
));
}
};
}
"into_bits" => {
generate_into_bits_func = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'into_bits' arg '{}', must be either 'true' or 'false'.",
err
),
));
}
};
}
"from_bits" => {
generate_from_bits_func = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'from_bits' arg '{}', must be either 'true' or 'false'.",
err
),
));
}
};
}
"from" => {
generate_from_trait_funcs = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'from_type' arg '{}', must be either 'true' or 'false'.",
err
),
));
}
}
}
"default" => {
generate_default_impl = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'default' arg '{}', must be either 'true' or 'false'.",
err
),
));
}
};
}
"builder" => {
generate_builder = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'builder' arg '{}', must be either 'true' or 'false'.",
err
),
));
}
}
}
"to_builder" => {
generate_to_builder = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'builder' arg '{}', must be either 'true' or 'false'.",
err
),
));
}
}
}
"debug" => {
generate_debug_impl = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'debug' arg '{}', must be either 'true', or 'false'.",
err
),
));
}
};
}
"bit_ops" => {
generate_bit_ops = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'big_ops' arg '{}', must be either 'true', or 'false'.",
err
),
));
}
};
}
"set_bits" => {
generate_set_bits_impl = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'set_bits' arg '{}', must be either 'true', or 'false'.",
err
),
));
}
};
}
"clear_bits" => {
generate_clear_bits_impl = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'set_bits' arg '{}', must be either 'true', or 'false'.",
err
),
));
}
};
}
"neg" => {
generate_neg_func = match input.parse::<syn::LitBool>() {
Ok(val) => val.value,
Err(err) => {
return Err(create_syn_error(
input.span(),
format!(
"Failed to parse the 'neg' arg '{}', must be either 'true', or 'false'.",
err
),
));
}
};
}
_ => {
return Err(create_syn_error(
arg_ident.span(),
format!("Unknown 'bitfield' argument: {}", arg_ident),
));
}
}
// Move to the next argument.
if !input.is_empty() {
<Token![,]>::parse(input)?;
}
}
Ok(Self {
ty,
bits,
bit_order,
from_endian,
into_endian,
generate_new_func,
generate_into_bits_func,
generate_from_bits_func,
generate_default_impl,
generate_debug_impl,
generate_builder,
generate_from_trait_funcs,
generate_bit_ops,
generate_set_bits_impl,
generate_clear_bits_impl,
generate_to_builder,
generate_neg_func,
})
}
}
#[cfg(test)]
mod tests {
use quote::quote;
use super::*;
#[test]
fn test_parse_bitfield_no_args_returns_error() {
let args = quote!();
let args = syn::parse2::<BitfieldAttribute>(args);
assert!(args.is_err());
assert!(args.err().unwrap().to_string().contains(
"The 'bitfield' attribute must have an unsigned integer type as its first argument"
));
}
#[test]
fn test_parse_bitfield_invalid_type_arg_returns_error() {
let args = quote!(eff);
let args = syn::parse2::<BitfieldAttribute>(args);
assert!(args.is_err());
assert!(args.err().unwrap().to_string().contains(
"The 'bitfield' attribute must have an unsigned integer type as its first argument."
));
let args = quote!(i32);
let args = syn::parse2::<BitfieldAttribute>(args);
assert!(args.is_err());
assert!(args.err().unwrap().to_string().contains(
"The 'bitfield' attribute must have an unsigned integer type as its first argument."
));
}
#[test]
fn test_parse_bitfield_unsigned_integer_types() {
let args = quote!(u8);
let args = syn::parse2::<BitfieldAttribute>(args);
assert!(args.is_ok());
assert_eq!(args.unwrap().bits, 8);
let args = quote!(u16);
let args = syn::parse2::<BitfieldAttribute>(args);
assert!(args.is_ok());
assert_eq!(args.unwrap().bits, 16);
let args = quote!(u32);
let args = syn::parse2::<BitfieldAttribute>(args);
assert!(args.is_ok());
assert_eq!(args.unwrap().bits, 32);
let args = quote!(u64);
let args = syn::parse2::<BitfieldAttribute>(args);
assert!(args.is_ok());
assert_eq!(args.unwrap().bits, 64);
let args = quote!(u128);
let args = syn::parse2::<BitfieldAttribute>(args);
assert!(args.is_ok());
assert_eq!(args.unwrap().bits, 128);
}
}