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use crate::{attr, bound};
use proc_macro2::{Span, TokenStream};
use quote::quote;
use syn::{
parse_quote, Data, DataEnum, DataStruct, DeriveInput, Error, Fields, FieldsNamed, Result,
};
pub fn derive(input: DeriveInput) -> Result<TokenStream> {
match &input.data {
Data::Struct(DataStruct {
fields: Fields::Named(fields),
..
}) => derive_struct(&input, fields),
Data::Enum(enumeration) => derive_enum(&input, enumeration),
Data::Struct(_) => Err(Error::new(
Span::call_site(),
"currently only structs with named fields are supported",
)),
Data::Union(_) => Err(Error::new(
Span::call_site(),
"currently only structs and enums are supported by this derive",
)),
}
}
fn derive_struct(input: &DeriveInput, fields: &FieldsNamed) -> Result<TokenStream> {
let info = attr::container_info(&input.attrs)?;
let ident = &input.ident;
let literal = ident.to_string();
let (impl_generics, ty_generics, _where_clause) = input.generics.split_for_impl();
let placements = fields
.named
.iter()
.map(attr::field_info)
.collect::<Result<Vec<_>>>()?;
let needs_default = placements.iter().any(|f| f.skip);
let field_names = placements
.iter()
.filter_map(|f| {
if f.skip || f.flatten {
None
} else {
Some(f.name.to_string())
}
})
.collect::<Vec<_>>();
// If any of the fields are flattened, then we don't have enough
// structure in the FromDynamic interface to know precisely which
// fields were legitimately used by any recursively flattened item,
// or, in the recursive item, to know which of the fields were used
// by the parent.
// We need to disable warning or raising errors for unknown fields
// in that case to avoid false positives.
let adjust_options = if placements.iter().any(|f| f.flatten) {
quote!(let options = options.flatten();)
} else {
quote!()
};
let field_names = quote!(
&[ #( #field_names, )* ]
);
let placements = placements
.into_iter()
.map(|f| f.from_dynamic(&literal))
.collect::<Vec<_>>();
let bound = parse_quote!(wezterm_dynamic::FromDynamic);
let bounded_where_clause = bound::where_clause_with_bound(&input.generics, bound);
let obj = if needs_default {
quote!(
Ok(Self {
#(
#placements
)*
.. Self::default()
})
)
} else {
quote!(
Ok(Self {
#(
#placements
)*
})
)
};
let from_dynamic = match info.try_from {
Some(try_from) => {
quote!(
use std::convert::TryFrom;
let target = <#try_from>::from_dynamic(value, options)?;
<#ident>::try_from(target).map_err(|e| wezterm_dynamic::Error::Message(format!("{:#}", e)))
)
}
None => {
quote!(
match value {
Value::Object(obj) => {
wezterm_dynamic::Error::raise_unknown_fields(options, #literal, &obj, Self::possible_field_names())?;
#obj
}
other => Err(wezterm_dynamic::Error::NoConversion {
source_type: other.variant_name().to_string(),
dest_type: #literal
}),
}
)
}
};
let tokens = quote! {
impl #impl_generics wezterm_dynamic::FromDynamic for #ident #ty_generics #bounded_where_clause {
fn from_dynamic(value: &wezterm_dynamic::Value, options: wezterm_dynamic::FromDynamicOptions) -> std::result::Result<Self, wezterm_dynamic::Error> {
use wezterm_dynamic::{Value, BorrowedKey, ObjectKeyTrait};
#adjust_options
#from_dynamic
}
}
impl #impl_generics #ident #ty_generics #bounded_where_clause {
pub const fn possible_field_names() -> &'static [&'static str] {
#field_names
}
}
};
if info.debug {
eprintln!("{}", tokens);
}
Ok(tokens)
}
fn derive_enum(input: &DeriveInput, enumeration: &DataEnum) -> Result<TokenStream> {
if input.generics.lt_token.is_some() || input.generics.where_clause.is_some() {
return Err(Error::new(
Span::call_site(),
"Enums with generics are not supported",
));
}
let info = attr::container_info(&input.attrs)?;
let ident = &input.ident;
let literal = ident.to_string();
let variant_names = enumeration
.variants
.iter()
.map(|variant| variant.ident.to_string())
.collect::<Vec<_>>();
let from_dynamic = match info.try_from {
Some(try_from) => {
quote!(
use std::convert::TryFrom;
let target = <#try_from>::from_dynamic(value, options)?;
<#ident>::try_from(target).map_err(|e| wezterm_dynamic::Error::Message(format!("{:#}", e)))
)
}
None => {
let units = enumeration
.variants
.iter()
.filter_map(|variant| match &variant.fields {
Fields::Unit => {
let ident = &variant.ident;
let literal = ident.to_string();
Some(quote!(
#literal => {
return Ok(Self::#ident);
}
))
}
_ => None,
})
.collect::<Vec<_>>();
let variants = enumeration.variants.iter().map(|variant| {
let ident = &variant.ident;
let literal = ident.to_string();
match &variant.fields {
Fields::Unit => {
// Already handled separately
quote!()
}
Fields::Named(fields) => {
let var_fields = fields
.named
.iter()
.map(|f| {
let info = attr::field_info(f).unwrap();
info.from_dynamic(&literal)
})
.collect::<Vec<_>>();
quote!(
#literal => {
match value {
Value::Object(obj) => {
Ok(Self::#ident {
#( #var_fields )*
})
}
other => return Err(wezterm_dynamic::Error::NoConversion {
source_type: other.variant_name().to_string(),
dest_type: "Object",
}),
}
}
)
}
Fields::Unnamed(fields) => {
if fields.unnamed.len() == 1 {
let ty = fields.unnamed.iter().map(|f| &f.ty).next().unwrap();
quote!(
#literal => {
Ok(Self::#ident(<#ty>::from_dynamic(value, options)?))
}
)
} else {
let var_fields = fields
.unnamed
.iter()
.enumerate()
.map(|(idx, f)| {
let ty = &f.ty;
quote!(
<#ty>::from_dynamic(
arr.get(#idx)
.ok_or_else(|| wezterm_dynamic::Error::Message(
format!("missing idx {} of enum struct {}", #idx, #literal)))?,
options
)?,
)
})
.collect::<Vec<_>>();
quote!(
#literal => {
match value {
Value::Array(arr) => {
Ok(Self::#ident (
#( #var_fields )*
))
}
other => return Err(wezterm_dynamic::Error::NoConversion {
source_type: other.variant_name().to_string(),
dest_type: "Array",
}),
}
}
)
}
}
}
}).collect::<Vec<_>>();
quote!(
match value {
Value::String(s) => {
match s.as_str() {
#( #units )*
_ => Err(wezterm_dynamic::Error::InvalidVariantForType {
variant_name: s.clone(),
type_name: #literal,
possible: #ident::variants(),
})
}
}
Value::Object(place) => {
if place.len() == 1 {
let (name, value) : (&Value, &Value) = place.iter().next().unwrap();
match name {
Value::String(name) => {
match name.as_str() {
#( #variants )*
_ => Err(wezterm_dynamic::Error::InvalidVariantForType {
variant_name: name.to_string(),
type_name: #literal,
possible: #ident::variants(),
})
}
}
_ => Err(wezterm_dynamic::Error::InvalidVariantForType {
variant_name: name.variant_name().to_string(),
type_name: #literal,
possible: #ident::variants(),
})
}
} else {
Err(wezterm_dynamic::Error::IncorrectNumberOfEnumKeys {
type_name: #literal,
num_keys: place.len(),
})
}
}
other => Err(wezterm_dynamic::Error::NoConversion {
source_type: other.variant_name().to_string(),
dest_type: #literal
}),
}
)
}
};
let tokens = quote! {
impl wezterm_dynamic::FromDynamic for #ident {
fn from_dynamic(value: &wezterm_dynamic::Value, options: wezterm_dynamic::FromDynamicOptions) -> std::result::Result<Self, wezterm_dynamic::Error> {
use wezterm_dynamic::{Value, BorrowedKey, ObjectKeyTrait};
#from_dynamic
}
}
impl #ident {
pub fn variants() -> &'static [&'static str] {
&[
#( #variant_names, )*
]
}
}
};
if info.debug {
eprintln!("{}", tokens);
}
Ok(tokens)
}