1// Copyright (c) 2024 Jonas Schäfer <jonas@zombofant.net>
2//
3// This Source Code Form is subject to the terms of the Mozilla Public
4// License, v. 2.0. If a copy of the MPL was not distributed with this
5// file, You can obtain one at http://mozilla.org/MPL/2.0/.
6
7#![forbid(unsafe_code)]
8#![warn(missing_docs)]
9#![allow(rustdoc::private_intra_doc_links)]
10#![cfg_attr(docsrs, feature(doc_auto_cfg))]
11/*!
12# Macros for parsing XML into Rust structs, and vice versa
13
14**If you are a user of `xso_proc` or `xso`, please
15return to `xso` for more information**. The documentation of
16`xso_proc` is geared toward developers of `…_macros` and `…_core`.
17
18**You have been warned.**
19*/
20
21// Wondering about RawTokenStream vs. TokenStream?
22// syn mostly works with proc_macro2, while the proc macros themselves use
23// proc_macro.
24use proc_macro::TokenStream as RawTokenStream;
25use proc_macro2::{Span, TokenStream};
26use quote::quote;
27use syn::*;
28
29mod common;
30mod compound;
31mod enums;
32mod error_message;
33mod field;
34mod meta;
35mod scope;
36mod state;
37mod structs;
38mod types;
39
40use common::{AsXmlParts, FromXmlParts, ItemDef};
41
42/// Convert an [`syn::Item`] into the parts relevant for us.
43///
44/// If the item is of an unsupported variant, an appropriate error is
45/// returned.
46fn parse_struct(item: Item) -> Result<(Visibility, Ident, Box<dyn ItemDef>)> {
47 match item {
48 Item::Struct(item) => {
49 let meta = meta::XmlCompoundMeta::parse_from_attributes(&item.attrs)?;
50 let def = structs::StructDef::new(&item.ident, meta, &item.fields)?;
51 Ok((item.vis, item.ident, Box::new(def)))
52 }
53 Item::Enum(item) => {
54 let meta = meta::XmlCompoundMeta::parse_from_attributes(&item.attrs)?;
55 let def = enums::EnumDef::new(&item.ident, meta, &item.variants)?;
56 Ok((item.vis, item.ident, Box::new(def)))
57 }
58 other => Err(Error::new_spanned(other, "cannot derive on this item")),
59 }
60}
61
62/// Generate a `xso::FromXml` implementation for the given item, or fail with
63/// a proper compiler error.
64fn from_xml_impl(input: Item) -> Result<TokenStream> {
65 let (vis, ident, def) = parse_struct(input)?;
66
67 let name_ident = Ident::new("name", Span::call_site());
68 let attrs_ident = Ident::new("attrs", Span::call_site());
69
70 let FromXmlParts {
71 defs,
72 from_events_body,
73 builder_ty_ident,
74 } = def.make_from_events_builder(&vis, &name_ident, &attrs_ident)?;
75
76 #[cfg_attr(not(feature = "minidom"), allow(unused_mut))]
77 let mut result = quote! {
78 #defs
79
80 impl ::xso::FromXml for #ident {
81 type Builder = #builder_ty_ident;
82
83 fn from_events(
84 name: ::xso::exports::rxml::QName,
85 attrs: ::xso::exports::rxml::AttrMap,
86 ctx: &::xso::Context<'_>,
87 ) -> ::core::result::Result<Self::Builder, ::xso::error::FromEventsError> {
88 #from_events_body
89 }
90 }
91 };
92
93 #[cfg(feature = "minidom")]
94 result.extend(quote! {
95 impl ::core::convert::TryFrom<::xso::exports::minidom::Element> for #ident {
96 type Error = ::xso::error::FromElementError;
97
98 fn try_from(other: ::xso::exports::minidom::Element) -> ::core::result::Result<Self, Self::Error> {
99 ::xso::try_from_element(other)
100 }
101 }
102 });
103
104 if def.debug() {
105 println!("{}", result);
106 }
107
108 Ok(result)
109}
110
111/// Macro to derive a `xso::FromXml` implementation on a type.
112///
113/// The user-facing documentation for this macro lives in the `xso` crate.
114#[proc_macro_derive(FromXml, attributes(xml))]
115pub fn from_xml(input: RawTokenStream) -> RawTokenStream {
116 // Shim wrapper around `from_xml_impl` which converts any errors into
117 // actual compiler errors within the resulting token stream.
118 let item = syn::parse_macro_input!(input as Item);
119 match from_xml_impl(item) {
120 Ok(v) => v.into(),
121 Err(e) => e.into_compile_error().into(),
122 }
123}
124
125/// Generate a `xso::AsXml` implementation for the given item, or fail with
126/// a proper compiler error.
127fn as_xml_impl(input: Item) -> Result<TokenStream> {
128 let (vis, ident, def) = parse_struct(input)?;
129
130 let AsXmlParts {
131 defs,
132 as_xml_iter_body,
133 item_iter_ty_lifetime,
134 item_iter_ty,
135 } = def.make_as_xml_iter(&vis)?;
136
137 #[cfg_attr(not(feature = "minidom"), allow(unused_mut))]
138 let mut result = quote! {
139 #defs
140
141 impl ::xso::AsXml for #ident {
142 type ItemIter<#item_iter_ty_lifetime> = #item_iter_ty;
143
144 fn as_xml_iter(&self) -> ::core::result::Result<Self::ItemIter<'_>, ::xso::error::Error> {
145 #as_xml_iter_body
146 }
147 }
148 };
149
150 #[cfg(all(feature = "minidom", feature = "panicking-into-impl"))]
151 result.extend(quote! {
152 impl ::core::convert::From<#ident> for ::xso::exports::minidom::Element {
153 fn from(other: #ident) -> Self {
154 ::xso::transform(&other).expect("seamless conversion into minidom::Element")
155 }
156 }
157
158 impl ::core::convert::From<&#ident> for ::xso::exports::minidom::Element {
159 fn from(other: &#ident) -> Self {
160 ::xso::transform(other).expect("seamless conversion into minidom::Element")
161 }
162 }
163 });
164
165 #[cfg(all(feature = "minidom", not(feature = "panicking-into-impl")))]
166 result.extend(quote! {
167 impl ::core::convert::TryFrom<#ident> for ::xso::exports::minidom::Element {
168 type Error = ::xso::error::Error;
169
170 fn try_from(other: #ident) -> ::core::result::Result<Self, Self::Error> {
171 ::xso::transform(&other)
172 }
173 }
174 impl ::core::convert::TryFrom<&#ident> for ::xso::exports::minidom::Element {
175 type Error = ::xso::error::Error;
176
177 fn try_from(other: &#ident) -> ::core::result::Result<Self, Self::Error> {
178 ::xso::transform(other)
179 }
180 }
181 });
182
183 if def.debug() {
184 println!("{}", result);
185 }
186
187 Ok(result)
188}
189
190/// Macro to derive a `xso::AsXml` implementation on a type.
191///
192/// The user-facing documentation for this macro lives in the `xso` crate.
193#[proc_macro_derive(AsXml, attributes(xml))]
194pub fn as_xml(input: RawTokenStream) -> RawTokenStream {
195 // Shim wrapper around `as_xml_impl` which converts any errors into
196 // actual compiler errors within the resulting token stream.
197 let item = syn::parse_macro_input!(input as Item);
198 match as_xml_impl(item) {
199 Ok(v) => v.into(),
200 Err(e) => e.into_compile_error().into(),
201 }
202}