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//! Identifiers used within generated code.
8
9use proc_macro2::Span;
10use syn::*;
11
12use crate::types::ref_ty;
13
14/// Container struct for various identifiers used throughout the parser code.
15///
16/// This struct is passed around from the [`crate::compound::Compound`]
17/// downward to the code generators in order to ensure that everyone is on the
18/// same page about which identifiers are used for what.
19///
20/// The recommended usage is to bind the names which are needed into the local
21/// scope like this:
22///
23/// ```text
24/// # let scope = FromEventsScope::new();
25/// let FromEventsScope {
26/// ref attrs,
27/// ..
28/// } = scope;
29/// ```
30pub(crate) struct FromEventsScope {
31 /// Accesses the `AttrMap` from code in
32 /// [`crate::field::FieldBuilderPart::Init`].
33 pub(crate) attrs: Ident,
34
35 /// Accesses the `String` of a `rxml::Event::Text` event from code in
36 /// [`crate::field::FieldBuilderPart::Text`].
37 pub(crate) text: Ident,
38
39 /// Accesses the builder data during parsing.
40 ///
41 /// This should not be used directly outside [`crate::compound`]. Most of
42 /// the time, using [`Self::access_field`] is the correct way to access
43 /// the builder data.
44 pub(crate) builder_data_ident: Ident,
45}
46
47impl FromEventsScope {
48 /// Create a fresh scope with all necessary identifiers.
49 pub(crate) fn new() -> Self {
50 // Sadly, `Ident::new` is not `const`, so we have to create even the
51 // well-known identifiers from scratch all the time.
52 Self {
53 attrs: Ident::new("attrs", Span::call_site()),
54 text: Ident::new("__xso_proc_macro_text_data", Span::call_site()),
55 builder_data_ident: Ident::new("__xso_proc_macro_builder_data", Span::call_site()),
56 }
57 }
58
59 /// Generate an expression which accesses the temporary value for the
60 /// given `member` during parsing.
61 pub(crate) fn access_field(&self, member: &Member) -> Expr {
62 Expr::Field(ExprField {
63 attrs: Vec::new(),
64 base: Box::new(Expr::Path(ExprPath {
65 attrs: Vec::new(),
66 qself: None,
67 path: self.builder_data_ident.clone().into(),
68 })),
69 dot_token: syn::token::Dot {
70 spans: [Span::call_site()],
71 },
72 member: Member::Named(mangle_member(member)),
73 })
74 }
75}
76
77/// Container struct for various identifiers used throughout the generator
78/// code.
79///
80/// This struct is passed around from the [`crate::compound::Compound`]
81/// downward to the code generators in order to ensure that everyone is on the
82/// same page about which identifiers are used for what.
83///
84/// See [`FromEventsScope`] for recommendations on the usage.
85pub(crate) struct AsItemsScope {
86 /// Lifetime for data borrowed by the implementation.
87 pub(crate) lifetime: Lifetime,
88}
89
90impl AsItemsScope {
91 /// Create a fresh scope with all necessary identifiers.
92 pub(crate) fn new(lifetime: &Lifetime) -> Self {
93 Self {
94 lifetime: lifetime.clone(),
95 }
96 }
97
98 /// Create a reference to `ty`, borrowed for the lifetime of the AsXml
99 /// impl.
100 pub(crate) fn borrow(&self, ty: Type) -> Type {
101 ref_ty(ty, self.lifetime.clone())
102 }
103}
104
105pub(crate) fn mangle_member(member: &Member) -> Ident {
106 match member {
107 Member::Named(member) => quote::format_ident!("f{}", member),
108 Member::Unnamed(member) => quote::format_ident!("f_u{}", member.index),
109 }
110}