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// Copyright (c) the JPEG XL Project Authors. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
extern crate proc_macro;
use proc_macro::TokenStream;
use proc_macro_error2::{abort, proc_macro_error};
use proc_macro2::TokenStream as TokenStream2;
use quote::quote;
use syn::{DeriveInput, Meta, parse_macro_input};
fn get_bits(expr_call: &syn::ExprCall) -> syn::Expr {
if let syn::Expr::Path(ep) = &*expr_call.func {
if !ep.path.is_ident("Bits") {
abort!(
expr_call,
"Unexpected function name in coder: {}",
ep.path.get_ident().unwrap()
);
}
if expr_call.args.len() != 1 {
abort!(
expr_call,
"Unexpected number of arguments for Bits() in coder: {}",
expr_call.args.len()
);
}
return expr_call.args[0].clone();
}
abort!(expr_call, "Unexpected function call in coder");
}
fn parse_single_coder(input: &syn::Expr, extra_lit: Option<&syn::ExprLit>) -> TokenStream2 {
match &input {
syn::Expr::Lit(lit) => match extra_lit {
None => quote! {U32::Val(#lit)},
Some(elit) => quote! {U32::Val(#lit + #elit)},
},
syn::Expr::Call(expr_call) => {
let bits = get_bits(expr_call);
match extra_lit {
None => quote! {U32::Bits(#bits)},
Some(elit) => quote! {U32::BitsOffset{n: #bits, off: #elit}},
}
}
syn::Expr::Binary(syn::ExprBinary {
attrs: _,
left,
op: syn::BinOp::Add(_),
right,
}) => {
let (left, right) = if let syn::Expr::Lit(_) = **left {
(right, left)
} else {
(left, right)
};
match (&**left, &**right) {
(syn::Expr::Call(expr_call), syn::Expr::Lit(lit)) => {
let bits = get_bits(expr_call);
match extra_lit {
None => quote! {U32::BitsOffset{n: #bits, off: #lit}},
Some(elit) => quote! {U32::BitsOffset{n: #bits, off: #lit + #elit}},
}
}
_ => abort!(
input,
"Unexpected expression in coder, must be Bits(a) + b, Bits(a), or b"
),
}
}
_ => abort!(
input,
"Unexpected expression in coder, must be Bits(a) + b, Bits(a), or b"
),
}
}
fn parse_coder(input: &syn::Expr) -> TokenStream2 {
let parse_u2s = |expr_call: &syn::ExprCall, lit: Option<&syn::ExprLit>| {
if let syn::Expr::Path(ep) = &*expr_call.func {
if !ep.path.is_ident("u2S") {
let coder = parse_single_coder(input, None);
return quote! {U32Coder::Direct(#coder)};
}
if expr_call.args.len() != 4 {
abort!(
input,
"Unexpected number of arguments for U32() in coder: {}",
expr_call.args.len()
);
}
let args = vec![
parse_single_coder(&expr_call.args[0], lit),
parse_single_coder(&expr_call.args[1], lit),
parse_single_coder(&expr_call.args[2], lit),
parse_single_coder(&expr_call.args[3], lit),
];
return quote! {U32Coder::Select(#(#args),*)};
}
abort!(input, "Unexpected function call in coder");
};
match &input {
syn::Expr::Call(expr_call) => parse_u2s(expr_call, None),
syn::Expr::Binary(syn::ExprBinary {
attrs: _,
left,
op: syn::BinOp::Add(_),
right,
}) => {
let (left, right) = if let syn::Expr::Lit(_) = **left {
(right, left)
} else {
(left, right)
};
match (&**left, &**right) {
(syn::Expr::Call(expr_call), syn::Expr::Lit(lit)) => {
parse_u2s(expr_call, Some(lit))
}
_ => abort!(
input,
"Unexpected expression in coder, must be (u2S|Bits)(a) + b, (u2S|Bits)(a), or b"
),
}
}
_ => parse_single_coder(input, None),
}
}
fn parse_size_coder(mut input: syn::Expr) -> TokenStream2 {
match input {
syn::Expr::Call(syn::ExprCall {
ref func,
ref mut args,
..
}) => {
if args.len() != 1 {
abort!(input, "Expected 1 argument in sized_coder inner call");
}
match &**func {
syn::Expr::Path(expr_path) if expr_path.path.is_ident("implicit") => {
let arg = args.first().unwrap().clone();
parse_coder(&arg)
}
syn::Expr::Path(expr_path) if expr_path.path.is_ident("explicit") => {
quote! { U32Coder::Direct(U32::Val(#args)) }
}
_ => abort!(
input,
"Unexpected expression in size_coder, must be 'implicit()' or 'explicit()'"
),
}
}
_ => abort!(
input,
"Unexpected expression in size_coder, must be 'implicit()' or 'explicit()'"
),
}
}
fn prettify_condition(cond: &syn::Expr) -> String {
(quote! {#cond})
.to_string()
.replace(" . ", ".")
.replace("! ", "!")
.replace(" :: ", "::")
}
#[derive(Debug)]
struct Condition {
expr: Option<syn::Expr>,
has_all_default: bool,
pretty: String,
}
impl Condition {
fn get_expr(&self, all_default_field: &Option<syn::Ident>) -> Option<TokenStream2> {
if self.has_all_default {
let all_default = all_default_field.as_ref().unwrap();
match &self.expr {
Some(expr) => Some(quote! { !#all_default && (#expr) }),
None => Some(quote! { !#all_default }),
}
} else {
self.expr.as_ref().map(|expr| quote! {#expr})
}
}
fn get_pretty(&self, all_default_field: &Option<syn::Ident>) -> String {
if self.has_all_default {
let all_default = all_default_field.as_ref().unwrap();
let all_default = "!".to_owned() + "e! {#all_default}.to_string();
match &self.expr {
Some(_) => all_default + " && (" + &self.pretty + ")",
None => all_default,
}
} else {
self.pretty.clone()
}
}
}
#[derive(Debug, Clone)]
struct U32 {
coder: TokenStream2,
}
#[derive(Debug)]
#[allow(clippy::large_enum_variant)]
enum Coder {
WithoutConfig,
U32(U32),
Select(Condition, U32, U32),
Vector(U32, Box<Coder>),
}
impl Coder {
fn ty(&self) -> TokenStream2 {
match self {
Coder::WithoutConfig => quote! {()},
Coder::U32(..) => quote! {U32Coder},
Coder::Select(..) => quote! {U32Coder},
Coder::Vector(_, value_coder) => {
let value_coder_ty = value_coder.ty();
quote! {VectorCoder<#value_coder_ty>}
}
}
}
fn config(&self, all_default_field: &Option<syn::Ident>) -> TokenStream2 {
match self {
Coder::WithoutConfig => quote! { () },
Coder::U32(U32 { coder }) => quote! { #coder },
Coder::Select(condition, U32 { coder: coder_true }, U32 { coder: coder_false }) => {
let cnd = condition.get_expr(all_default_field).unwrap();
quote! {
if #cnd { #coder_true } else { #coder_false }
}
}
Coder::Vector(U32 { coder }, value_coder) => {
let value_coder = value_coder.config(all_default_field);
quote! {VectorCoder{size_coder: #coder, value_coder: #value_coder}}
}
}
}
}
#[derive(Debug)]
enum FieldKind {
Unconditional(Coder),
Conditional(Condition, Coder),
Defaulted(Condition, Coder),
}
#[derive(Debug)]
struct Field {
name: proc_macro2::Ident,
kind: FieldKind,
ty: syn::Type,
default: Option<TokenStream2>,
default_element: Option<TokenStream2>,
nonserialized_inits: Vec<TokenStream2>,
}
impl Field {
fn parse(f: &syn::Field, num: usize, all_default_field: &mut Option<syn::Ident>) -> Field {
let mut condition = None;
let mut default = None;
let mut coder = None;
let mut select_coder = None;
let mut coder_true = None;
let mut coder_false = None;
let mut is_all_default = false;
let mut size_coder = None;
let mut nonserialized = vec![];
let mut default_element = None;
// Parse attributes.
for a in &f.attrs {
match a.path().get_ident().map(syn::Ident::to_string).as_deref() {
Some("coder") => {
if coder.is_some() {
abort!(f, "Repeated coder");
}
let coder_ast = a.parse_args::<syn::Expr>().unwrap();
coder = Some(Coder::U32(U32 {
coder: parse_coder(&coder_ast),
}));
}
Some("default") => {
if default.is_some() {
abort!(f, "Repeated default");
}
let default_expr = a.parse_args::<syn::Expr>().unwrap();
default = Some(quote! {#default_expr});
}
Some("default_element") => {
if default_element.is_some() {
abort!(f, "Repeated default_element")
}
let default_element_expr = a.parse_args::<syn::Expr>().unwrap();
default_element = Some(quote! { #default_element_expr })
}
Some("condition") => {
if condition.is_some() {
abort!(f, "Repeated condition");
}
let condition_ast = a.parse_args::<syn::Expr>().unwrap();
let pretty_cond = prettify_condition(&condition_ast);
condition = Some(Condition {
expr: Some(condition_ast),
has_all_default: all_default_field.is_some(),
pretty: pretty_cond,
});
}
Some("all_default") => {
if num != 0 {
abort!(f, "all_default is not the first field");
}
if default.is_some() {
abort!(f, "all_default has an implicit default");
}
is_all_default = true;
default = Some(quote! { true });
}
Some("select_coder") => {
if select_coder.is_some() {
abort!(f, "Repeated select_coder");
}
let condition_ast = a.parse_args::<syn::Expr>().unwrap();
let pretty_cond = prettify_condition(&condition_ast);
select_coder = Some(Condition {
expr: Some(condition_ast),
has_all_default: false,
pretty: pretty_cond,
});
}
Some("coder_false") => {
if coder_false.is_some() {
abort!(f, "Repeated coder_false");
}
let coder_ast = a.parse_args::<syn::Expr>().unwrap();
coder_false = Some(U32 {
coder: parse_coder(&coder_ast),
});
}
Some("coder_true") => {
if coder_true.is_some() {
abort!(f, "Repeated coder_true");
}
let coder_ast = a.parse_args::<syn::Expr>().unwrap();
coder_true = Some(U32 {
coder: parse_coder(&coder_ast),
});
}
Some("size_coder") => {
if size_coder.is_some() {
abort!(f, "Repeated size_coder");
}
let coder_ast = a.parse_args::<syn::Expr>().unwrap();
size_coder = Some(U32 {
coder: parse_size_coder(coder_ast),
});
}
Some("nonserialized") => {
let Meta::List(ns) = &a.meta else {
abort!(a, "Invalid attribute");
};
let stream = &ns.tokens;
nonserialized.push(quote! {#stream});
}
_ => {}
}
}
if default.is_some() && default_element.is_some() {
abort!(f, "default is incompatible with default_element");
}
if let Some(select_coder) = select_coder {
if coder_true.is_none() || coder_false.is_none() {
abort!(
f,
"Invalid field, select_coder is set but coder_true or coder_false are not"
)
}
if coder.is_some() {
abort!(f, "Invalid field, select_coder and coder are both present")
}
coder = Some(Coder::Select(
select_coder,
coder_true.unwrap(),
coder_false.unwrap(),
))
}
let condition = if condition.is_some() || all_default_field.is_none() {
condition
} else {
Some(Condition {
expr: None,
has_all_default: true,
pretty: String::new(),
})
};
// Assume nested field if no coder.
let mut coder = coder.unwrap_or_else(|| Coder::WithoutConfig);
if let Some(c) = size_coder {
if default.is_none() {
default = Some(quote! { Vec::new() });
}
coder = Coder::Vector(c, Box::new(coder))
}
let ident = f.ident.as_ref().unwrap();
let kind = match (condition, default.is_some()) {
(None, _) => FieldKind::Unconditional(coder),
(Some(cond), false) => FieldKind::Conditional(cond, coder),
(Some(cond), true) => FieldKind::Defaulted(cond, coder),
};
if is_all_default {
*all_default_field = Some(f.ident.as_ref().unwrap().clone());
}
Field {
name: ident.clone(),
kind,
ty: f.ty.clone(),
default,
default_element,
nonserialized_inits: nonserialized,
}
}
// Produces reading code (possibly with tracing).
fn read_fun(&self, all_default_field: &Option<syn::Ident>) -> TokenStream2 {
let ident = &self.name;
let ty = &self.ty;
let nonserialized_inits = &self.nonserialized_inits;
match &self.kind {
FieldKind::Unconditional(coder) => {
let cfg_ty = coder.ty();
let cfg = coder.config(all_default_field);
let trc = quote! {
crate::util::tracing_wrappers::trace!("Setting {} to {:?}. total_bits_read: {}, peek: {:08b}", stringify!(#ident), #ident, br.total_bits_read(), br.peek(8));
};
quote! {
let #ident = {
let cfg = #cfg;
type NS = <#ty as UnconditionalCoder<#cfg_ty>>::Nonserialized;
let nonserialized = NS { #(#nonserialized_inits),* };
<#ty>::read_unconditional(&cfg, br, &nonserialized)?
};
#trc
}
}
FieldKind::Conditional(condition, coder) => {
let cfg_ty = coder.ty();
let cfg = coder.config(all_default_field);
let cnd = condition.get_expr(all_default_field).unwrap();
let pretty_cnd = condition.get_pretty(all_default_field);
let trc = quote! {
crate::util::tracing_wrappers::trace!("{} is {}, setting {} to {:?}. total_bits_read: {}, peek {:08b}", #pretty_cnd, #cnd, stringify!(#ident), #ident, br.total_bits_read(), br.peek(8));
};
quote! {
let #ident = {
let cond = #cnd;
let cfg = #cfg;
type NS = <#ty as ConditionalCoder<#cfg_ty>>::Nonserialized;
let nonserialized = NS { #(#nonserialized_inits),* };
<#ty>::read_conditional(&cfg, cond, br, &nonserialized)?
};
#trc
}
}
FieldKind::Defaulted(condition, coder) => {
let cfg_ty = coder.ty();
let cfg = coder.config(all_default_field);
let cnd = condition.get_expr(all_default_field).unwrap();
let pretty_cnd = condition.get_pretty(all_default_field);
let default = &self.default;
let trc = quote! {
crate::util::tracing_wrappers::trace!("{} is {}, setting {} to {:?}. total_bits_read: {}, peek {:08b}", #pretty_cnd, #cnd, stringify!(#ident), #ident, br.total_bits_read(), br.peek(8));
};
let (read_fn, default) = if let Some(def) = &self.default_element {
(quote! { read_defaulted_element }, Some(def))
} else {
(quote! { read_defaulted }, default.as_ref())
};
quote! {
let #ident = {
let cond = #cnd;
let cfg = #cfg;
type NS = <#ty as DefaultedCoder<#cfg_ty>>::Nonserialized;
let field_nonserialized = NS { #(#nonserialized_inits),* };
let default = #default;
<#ty>::#read_fn(&cfg, cond, default, br, &field_nonserialized)?
};
#trc
}
}
}
}
// Produces default code.
fn default_code(&self) -> TokenStream2 {
let ident = &self.name;
let ty = &self.ty;
let nonserialized_inits = &self.nonserialized_inits;
let default = &self.default;
match &self.kind {
FieldKind::Defaulted(_, coder) => {
let cfg_ty = coder.ty();
let default = &self.default;
quote! {
let #ident = {
type NS = <#ty as DefaultedCoder<#cfg_ty>>::Nonserialized;
let field_nonserialized = NS { #(#nonserialized_inits),* };
#default
};
}
}
_ => quote! { let #ident = #default; },
}
}
}
fn derive_struct(input: &DeriveInput) -> TokenStream2 {
let name = &input.ident;
let validate = input.attrs.iter().any(|a| a.path().is_ident("validate"));
let nonserialized: Vec<_> = input
.attrs
.iter()
.filter_map(|a| {
if a.path().is_ident("nonserialized") {
Some(a.parse_args::<syn::Expr>().unwrap())
} else {
None
}
})
.collect();
if nonserialized.len() > 1 {
abort!(input, "repeated nonserialized");
}
let nonserialized = if nonserialized.is_empty() {
quote! {Empty}
} else {
let v = &nonserialized[0];
quote! {#v}
};
let data = if let syn::Data::Struct(struct_data) = &input.data {
struct_data
} else {
abort!(input, "derive_struct didn't get a struct");
};
let fields = if let syn::Fields::Named(syn::FieldsNamed {
brace_token: _,
named,
}) = &data.fields
{
named
} else {
abort!(data.fields, "only named fields are supported (for now?)");
};
let mut all_default_field = None;
let fields: Vec<_> = fields
.iter()
.enumerate()
.map(|(n, f)| Field::parse(f, n, &mut all_default_field))
.collect();
let fields_read = fields.iter().map(|x| x.read_fun(&all_default_field));
let fields_names = fields.iter().map(|x| &x.name);
let impl_default = if fields.iter().all(|x| x.default.is_some()) {
let field_init = fields.iter().map(Field::default_code);
let struct_init = fields.iter().map(|f| {
let ident = &f.name;
quote! { #ident }
});
quote! {
impl #name {
pub fn default(nonserialized: &#nonserialized) -> #name {
#(#field_init)*
#name {
#(#struct_init),*
}
}
}
}
} else {
quote! {}
};
let impl_validate = if validate {
quote! { return_value.check(nonserialized)?; }
} else {
quote! {}
};
let align = match input.attrs.iter().any(|a| a.path().is_ident("aligned")) {
true => quote! { br.jump_to_byte_boundary()?; },
false => quote! {},
};
quote! {
#impl_default
impl crate::headers::encodings::UnconditionalCoder<()> for #name {
type Nonserialized = #nonserialized;
#[cold]
#[inline(never)]
fn read_unconditional(_: &(), br: &mut BitReader, nonserialized: &Self::Nonserialized) -> Result<#name, Error> {
use crate::headers::encodings::UnconditionalCoder;
use crate::headers::encodings::ConditionalCoder;
use crate::headers::encodings::DefaultedCoder;
use crate::headers::encodings::DefaultedElementCoder;
#align
#(#fields_read)*
let return_value = #name {
#(#fields_names),*
};
#impl_validate
Ok(return_value)
}
}
}
}
fn derive_enum(input: &DeriveInput) -> TokenStream2 {
let name = &input.ident;
quote! {
impl crate::headers::encodings::UnconditionalCoder<U32Coder> for #name {
type Nonserialized = Empty;
fn read_unconditional(config: &U32Coder, br: &mut BitReader, _: &Empty) -> Result<#name, Error> {
use num_traits::FromPrimitive;
let u = u32::read_unconditional(config, br, &Empty{})?;
if let Some(e) = #name::from_u32(u) {
Ok(e)
} else {
Err(Error::InvalidEnum(u, stringify!(#name).to_string()))
}
}
}
impl crate::headers::encodings::UnconditionalCoder<()> for #name {
type Nonserialized = Empty;
fn read_unconditional(config: &(), br: &mut BitReader, nonserialized: &Empty) -> Result<#name, Error> {
#name::read_unconditional(
&U32Coder::Select(
U32::Val(0), U32::Val(1),
U32::BitsOffset{n: 4, off: 2},
U32::BitsOffset{n: 6, off: 18}), br, nonserialized)
}
}
}
}
#[proc_macro_error]
#[proc_macro_derive(
UnconditionalCoder,
attributes(
coder,
condition,
default,
default_element,
all_default,
select_coder,
coder_true,
coder_false,
validate,
size_coder,
nonserialized,
aligned,
)
)]
pub fn derive_jxl_headers(input: TokenStream) -> TokenStream {
let input = parse_macro_input!(input as DeriveInput);
match &input.data {
syn::Data::Struct(_) => derive_struct(&input).into(),
syn::Data::Enum(_) => derive_enum(&input).into(),
_ => abort!(input, "Only implemented for struct"),
}
}
#[proc_macro_attribute]
pub fn noop(_attr: TokenStream, item: TokenStream) -> TokenStream {
item
}
#[cfg(feature = "test")]
#[proc_macro]
pub fn for_each_test_file(input: TokenStream) -> TokenStream {
use std::{fs, path::Path};
use syn::Ident;
let fn_name = parse_macro_input!(input as Ident);
let root_test_dir = Path::new(env!("CARGO_MANIFEST_DIR"))
.join("..")
.join("jxl")
.join("resources")
.join("test");
let conformance_test_dir = root_test_dir.join("conformance_test_images");
let mut tests = vec![];
for test_dir in [root_test_dir, conformance_test_dir] {
for entry in fs::read_dir(&test_dir).unwrap() {
let entry = entry.unwrap();
let path = entry.path();
if path.extension().is_some_and(|ext| ext == "jxl") {
let pathname = path.to_string_lossy();
let relative_path = path
.strip_prefix(&test_dir)
.unwrap()
.to_string_lossy()
.replace('/', "_slash_");
let test_name = format!(
"{}_{}",
fn_name,
relative_path.strip_suffix(".jxl").unwrap()
);
let test_name = Ident::new(&test_name, fn_name.span());
tests.push(quote! {
#[test]
fn #test_name() {
#fn_name(&Path::new(#pathname)).unwrap()
}
});
}
}
}
quote! {
#(#tests)*
}
.into()
}