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derive WIP
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@xlc
xlc committed Apr 18, 2020
1 parent 82d8635 commit 32d0668
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8 changes: 5 additions & 3 deletions Cargo.toml
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Expand Up @@ -14,16 +14,18 @@ categories = [
[dependencies]
lite-parser = { path = "parser", default-features = false }
num-traits = { version = "0.2", optional = true, default-features = false }
lite-json-derive = { path = "derive", default-features = false, optional = true }

[features]
default = ["std"]
std = [
"lite-parser/std"
]
# Enables converting values to floats in no-`std` environment
float = ["num-traits"]
float = ["num-traits"] # Enables converting values to floats in no-`std` environment
derive = ["lite-json-derive"]

[workspace]
members = [
"parser"
"parser",
"derive"
]
19 changes: 19 additions & 0 deletions derive/Cargo.toml
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[package]
name = "lite-json-derive"
description = "Serialization and deserialization derive macro for lite-json"
version = "0.1.0"
authors = ["Bryan Chen <[email protected]>"]
license = "Apache-2.0"
edition = "2018"

[lib]
proc-macro = true

[dependencies]
syn = { version = "1.0.8", features = [ "full", "visit" ] }
quote = "1.0.2"
proc-macro2 = "1.0.6"
proc-macro-crate = "0.1.4"

[dev-dependencies]
lite-json = { path = "..", version = "0.1.0" }
111 changes: 111 additions & 0 deletions derive/src/from_json.rs
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// Heavily inspred by http://github.com/paritytech/parity-scale-codec

use proc_macro2::{Ident, Span, TokenStream};
use syn::{spanned::Spanned, Data, Error, Field, Fields};

use crate::utils;

pub fn quote(data: &Data, type_name: &Ident, input: &TokenStream) -> TokenStream {
match *data {
Data::Struct(ref data) => match data.fields {
Fields::Named(_) | Fields::Unnamed(_) => {
create_instance(quote! { #type_name }, input, &data.fields)
}
Fields::Unit => {
quote_spanned! { data.fields.span() =>
Ok(#type_name)
}
}
},
Data::Enum(ref data) => {
let data_variants = || {
data.variants
.iter()
.filter(|variant| crate::utils::get_skip(&variant.attrs).is_none())
};

let recurse = data_variants().enumerate().map(|(i, v)| {
let name = &v.ident;
let index = utils::index(v, i);

let create = create_instance(quote! { #type_name :: #name }, input, &v.fields);

quote_spanned! { v.span() =>
x if x == #index as u8 => {
#create
},
}
});

// TODO: match string name

quote! {
match #input {
_lite_json::JsonValue::Number(_lite_json::NumberValue { integer, .. }) => match integer {
#( #recurse )*,
_ => None
},
_ => None,
}
}
}
Data::Union(_) => {
Error::new(Span::call_site(), "Union types are not supported.").to_compile_error()
}
}
}

fn create_decode_expr(field: &Field, _name: &str, input: &TokenStream) -> TokenStream {
let skip = utils::get_skip(&field.attrs).is_some();

if skip {
quote_spanned! { field.span() => Default::default() }
} else {
quote_spanned! { field.span() =>
_lite_json::FromJson::from_json(#input)?;
}
}
}

fn create_instance(name: TokenStream, input: &TokenStream, fields: &Fields) -> TokenStream {
match *fields {
Fields::Named(ref fields) => {
let recurse = fields.named.iter().map(|f| {
let name_ident = &f.ident;
let field = match name_ident {
Some(a) => format!("{}.{}", name, a),
None => format!("{}", name),
};
let decode = create_decode_expr(f, &field, input);

quote_spanned! { f.span() =>
#name_ident: #decode
}
});

quote_spanned! { fields.span() =>
Ok(#name {
#( #recurse, )*
})
}
}
Fields::Unnamed(ref fields) => {
let recurse = fields.unnamed.iter().enumerate().map(|(i, f)| {
let name = format!("{}.{}", name, i);

create_decode_expr(f, &name, input)
});

quote_spanned! { fields.span() =>
Ok(#name (
#( #recurse, )*
))
}
}
Fields::Unit => {
quote_spanned! { fields.span() =>
Ok(#name)
}
}
}
}
175 changes: 175 additions & 0 deletions derive/src/into_json.rs
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// Heavily inspred by http://github.com/paritytech/parity-scale-codec

use std::str::from_utf8;

use proc_macro2::{Ident, Span, TokenStream};
use syn::{punctuated::Punctuated, spanned::Spanned, token::Comma, Data, Error, Field, Fields};

use crate::utils;

type FieldsList = Punctuated<Field, Comma>;

fn encode_named_fields<F>(fields: &FieldsList, field_name: F) -> TokenStream
where
F: Fn(usize, &Option<Ident>) -> TokenStream,
{
let recurse = fields.iter().enumerate().map(|(i, f)| {
let skip = utils::get_skip(&f.attrs).is_some();
let field = field_name(i, &f.ident);

if skip {
quote! {}
} else {
quote_spanned! { f.span() =>
(
stringify!(f.indent.unwrap()).into_iter().collect(),
_lite_json::IntoJson::into_json(#field)
)
}
}
});

quote! {
_lite_json::JsonValue::Object( __core::vec![ #( #recurse, )* ] )
}
}

fn encode_unnamed_fields<F>(fields: &FieldsList, field_name: F) -> TokenStream
where
F: Fn(usize, &Option<Ident>) -> TokenStream,
{
let recurse = fields.iter().enumerate().map(|(i, f)| {
let skip = utils::get_skip(&f.attrs).is_some();
let field = field_name(i, &f.ident);

if skip {
quote! {}
} else {
quote_spanned! { f.span() =>
_lite_json::IntoJson::into_json(#field)
}
}
});

quote! {
_lite_json::JsonValue::Array( __core::vec![ #( #recurse, )* ] )
}
}

pub fn quote(data: &Data, type_name: &Ident) -> TokenStream {
let self_ = quote!(self);
let dest = &quote!(dest);
let encoding = match *data {
Data::Struct(ref data) => match data.fields {
Fields::Named(ref fields) => {
encode_named_fields(&fields.named, |_, name| quote!(&#self_.#name))
}
Fields::Unnamed(ref fields) => encode_unnamed_fields(&fields.unnamed, |i, _| {
let i = syn::Index::from(i);
quote!(&#self_.#i)
}),
Fields::Unit => quote! {
_lite_json::JsonValue::Object( __core::vec![] )
},
},
Data::Enum(ref data) => {
let data_variants = || {
data.variants
.iter()
.filter(|variant| crate::utils::get_skip(&variant.attrs).is_none())
};

// If the enum has no variants, make it null
if data_variants().count() == 0 {
return quote!(_lite_json::JsonValue::Null);
}

let recurse = data_variants().map(|f| {
let name = &f.ident;

match f.fields {
Fields::Named(ref fields) => {
let field_name = |_, ident: &Option<Ident>| quote!(#ident);
let names = fields.named
.iter()
.enumerate()
.map(|(i, f)| field_name(i, &f.ident));

let encode_fields = encode_named_fields(
&fields.named,
|a, b| field_name(a, b),
);

quote_spanned! { f.span() =>
#type_name :: #name { #( ref #names, )* } => {
_lite_json::JsonValue::Array(__core::vec![
_lite_json::JsonValue::String(stringify!(#name).into_iter().collect()),
#encode_fields
])
}
}
},
Fields::Unnamed(ref fields) => {
let field_name = |i, _: &Option<Ident>| {
let data = stringify(i as u8);
let ident = from_utf8(&data).expect("We never go beyond ASCII");
let ident = Ident::new(ident, Span::call_site());
quote!(#ident)
};
let names = fields.unnamed
.iter()
.enumerate()
.map(|(i, f)| field_name(i, &f.ident));

let encode_fields = encode_unnamed_fields(
&fields.unnamed,
|a, b| field_name(a, b),
);

quote_spanned! { f.span() =>
#type_name :: #name { #( ref #names, )* } => {
_lite_json::JsonValue::Array(__core::vec![
_lite_json::JsonValue::String(stringify!(#name).into_iter().collect()),
#encode_fields
])
}
}
},
Fields::Unit => {
quote_spanned! { f.span() =>
#type_name :: #name => {
_lite_json::JsonValue::String(stringify!(#name).into_iter().collect())
}
}
},
}
});

quote! {
match *#self_ {
#( #recurse )*,
_ => (),
}
}
}
Data::Union(ref data) => {
Error::new(data.union_token.span(), "Union types are not supported.").to_compile_error()
}
};

quote! {
fn encode_to<EncOut: _parity_scale_codec::Output>(&#self_, #dest: &mut EncOut) {
#encoding
}
}
}

pub fn stringify(id: u8) -> [u8; 2] {
const CHARS: &[u8] = b"abcdefghijklmnopqrstuvwxyz";
let len = CHARS.len() as u8;
let symbol = |id: u8| CHARS[(id % len) as usize];
let a = symbol(id);
let b = symbol(id / len);

[a, b]
}
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