use syn::{
self, Attribute, Data, DeriveInput, Field as SynField, Fields as SynFields, Generics, Ident,
Type, Visibility,
};
use quote::ToTokens;
use proc_macro2::TokenStream;
use std::fmt::{self, Display};
mod field_map;
pub use self::field_map::FieldMap;
#[derive(Clone)]
pub struct DataStructure<'a> {
pub vis: &'a Visibility,
pub name: &'a Ident,
pub generics: &'a Generics,
pub attrs: &'a [Attribute],
pub data_variant: DataVariant,
pub variants: Vec<Struct<'a>>,
}
impl<'a> DataStructure<'a> {
pub fn new(ast: &'a DeriveInput) -> Self {
let name = &ast.ident;
let data_variant: DataVariant;
let mut variants = Vec::new();
match &ast.data {
Data::Enum(enum_) => {
for (variant, var) in enum_.variants.iter().enumerate() {
variants.push(Struct::new(
StructParams {
variant: variant,
attrs: &var.attrs,
name: &var.ident,
},
&var.fields,
));
}
data_variant = DataVariant::Enum;
}
Data::Struct(struct_) => {
variants.push(Struct::new(
StructParams {
variant: 0,
attrs: &[],
name: name,
},
&struct_.fields,
));
data_variant = DataVariant::Struct;
}
Data::Union(union_) => {
let fields = Some(&union_.fields.named);
let sk = StructKind::Braced;
let vari = Struct::with_fields(
StructParams {
variant: 0,
attrs: &[],
name: name,
},
sk,
fields,
);
variants.push(vari);
data_variant = DataVariant::Union;
}
}
Self {
vis: &ast.vis,
name,
attrs: &ast.attrs,
generics: &ast.generics,
data_variant,
variants,
}
}
}
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash)]
pub enum StructKind {
Tupled,
Braced,
}
#[derive(Debug, Copy, Clone, PartialEq, PartialOrd, Ord, Eq, Hash)]
pub enum DataVariant {
Struct,
Enum,
Union,
}
#[derive(Copy, Clone)]
pub struct FieldIndex {
pub variant: usize,
pub pos: usize,
}
#[derive(Copy, Clone)]
struct StructParams<'a> {
variant: usize,
attrs: &'a [Attribute],
name: &'a Ident,
}
#[derive(Clone)]
pub struct Struct<'a> {
pub attrs: &'a [Attribute],
pub name: &'a Ident,
pub kind: StructKind,
pub fields: Vec<Field<'a>>,
_priv: (),
}
impl<'a> Struct<'a> {
fn new(p: StructParams<'a>, fields: &'a SynFields) -> Self {
let kind = match *fields {
SynFields::Named { .. } => StructKind::Braced,
SynFields::Unnamed { .. } => StructKind::Tupled,
SynFields::Unit { .. } => StructKind::Braced,
};
let fields = match fields {
SynFields::Named(f) => Some(&f.named),
SynFields::Unnamed(f) => Some(&f.unnamed),
SynFields::Unit => None,
};
Self::with_fields(p, kind, fields)
}
fn with_fields<I>(p: StructParams<'a>, kind: StructKind, fields: Option<I>) -> Self
where
I: IntoIterator<Item = &'a SynField>,
{
let fields = match fields {
Some(x) => Field::from_iter(p, x),
None => Vec::new(),
};
Self {
attrs: p.attrs,
name: p.name,
kind,
fields,
_priv: (),
}
}
}
#[derive(Clone)]
pub struct Field<'a> {
pub index: FieldIndex,
pub attrs: &'a [Attribute],
pub ident: FieldIdent<'a>,
pub pattern_ident: Ident,
pub ty: &'a Type,
}
impl<'a> Field<'a> {
fn new(index: FieldIndex, field: &'a SynField) -> Self {
let span;
let ident = match field.ident.as_ref() {
Some(ident) => {
span = ident.span();
FieldIdent::Named(ident)
}
None => {
span = syn::spanned::Spanned::span(&field.ty);
FieldIdent::new_index(index.pos)
}
};
let pattern_ident = Ident::new(&format!("f{}_7ac4rtizw8q", ident), span);
Self {
index,
attrs: &field.attrs,
ident,
pattern_ident,
ty: &field.ty,
}
}
pub fn pattern_ident(&self) -> &Ident {
&self.pattern_ident
}
fn from_iter<I>(p: StructParams<'a>, fields: I) -> Vec<Self>
where
I: IntoIterator<Item = &'a SynField>,
{
fields
.into_iter()
.enumerate()
.map(|(pos, f)| {
let fi = FieldIndex {
variant: p.variant,
pos,
};
Field::new(fi, f)
})
.collect()
}
}
#[derive(Debug, Clone, PartialEq, Eq, Ord, PartialOrd, Hash)]
pub enum FieldIdent<'a> {
Index(usize),
Named(&'a Ident),
}
impl<'a> Display for FieldIdent<'a> {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
match self {
FieldIdent::Index(x) => Display::fmt(x, f),
FieldIdent::Named(x) => Display::fmt(x, f),
}
}
}
impl<'a> ToTokens for FieldIdent<'a> {
fn to_tokens(&self, tokens: &mut TokenStream) {
match *self {
FieldIdent::Index(ind) => syn::Index::from(ind).to_tokens(tokens),
FieldIdent::Named(name) => name.to_tokens(tokens),
}
}
}
impl<'a> FieldIdent<'a> {
fn new_index(index: usize) -> Self {
FieldIdent::Index(index)
}
}