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 ) -> ::core::result::Result<Self::Builder, ::xso::error::FromEventsError> {
87 #from_events_body
88 }
89 }
90 };
91
92 #[cfg(feature = "minidom")]
93 result.extend(quote! {
94 impl ::core::convert::TryFrom<::xso::exports::minidom::Element> for #ident {
95 type Error = ::xso::error::FromElementError;
96
97 fn try_from(other: ::xso::exports::minidom::Element) -> ::core::result::Result<Self, Self::Error> {
98 ::xso::try_from_element(other)
99 }
100 }
101 });
102
103 if def.debug() {
104 println!("{}", result);
105 }
106
107 Ok(result)
108}
109
110/// Macro to derive a `xso::FromXml` implementation on a type.
111///
112/// The user-facing documentation for this macro lives in the `xso` crate.
113#[proc_macro_derive(FromXml, attributes(xml))]
114pub fn from_xml(input: RawTokenStream) -> RawTokenStream {
115 // Shim wrapper around `from_xml_impl` which converts any errors into
116 // actual compiler errors within the resulting token stream.
117 let item = syn::parse_macro_input!(input as Item);
118 match from_xml_impl(item) {
119 Ok(v) => v.into(),
120 Err(e) => e.into_compile_error().into(),
121 }
122}
123
124/// Generate a `xso::AsXml` implementation for the given item, or fail with
125/// a proper compiler error.
126fn as_xml_impl(input: Item) -> Result<TokenStream> {
127 let (vis, ident, def) = parse_struct(input)?;
128
129 let AsXmlParts {
130 defs,
131 as_xml_iter_body,
132 item_iter_ty_lifetime,
133 item_iter_ty,
134 } = def.make_as_xml_iter(&vis)?;
135
136 #[cfg_attr(not(feature = "minidom"), allow(unused_mut))]
137 let mut result = quote! {
138 #defs
139
140 impl ::xso::AsXml for #ident {
141 type ItemIter<#item_iter_ty_lifetime> = #item_iter_ty;
142
143 fn as_xml_iter(&self) -> ::core::result::Result<Self::ItemIter<'_>, ::xso::error::Error> {
144 #as_xml_iter_body
145 }
146 }
147 };
148
149 #[cfg(all(feature = "minidom", feature = "panicking-into-impl"))]
150 result.extend(quote! {
151 impl ::core::convert::From<#ident> for ::xso::exports::minidom::Element {
152 fn from(other: #ident) -> Self {
153 ::xso::transform(other).expect("seamless conversion into minidom::Element")
154 }
155 }
156 });
157
158 #[cfg(all(feature = "minidom", not(feature = "panicking-into-impl")))]
159 result.extend(quote! {
160 impl ::core::convert::TryFrom<#ident> for ::xso::exports::minidom::Element {
161 type Error = ::xso::error::Error;
162
163 fn try_from(other: #ident) -> ::core::result::Result<Self, Self::Error> {
164 ::xso::transform(other)
165 }
166 }
167 });
168
169 if def.debug() {
170 println!("{}", result);
171 }
172
173 Ok(result)
174}
175
176/// Macro to derive a `xso::AsXml` implementation on a type.
177///
178/// The user-facing documentation for this macro lives in the `xso` crate.
179#[proc_macro_derive(AsXml, attributes(xml))]
180pub fn as_xml(input: RawTokenStream) -> RawTokenStream {
181 // Shim wrapper around `as_xml_impl` which converts any errors into
182 // actual compiler errors within the resulting token stream.
183 let item = syn::parse_macro_input!(input as Item);
184 match as_xml_impl(item) {
185 Ok(v) => v.into(),
186 Err(e) => e.into_compile_error().into(),
187 }
188}