1 | use std::borrow::Cow; |
2 | |
3 | use doc_comment_from; |
4 | use proc_macro2::{Span, TokenStream}; |
5 | use quote::{ToTokens, TokenStreamExt}; |
6 | use syn; |
7 | use syn::spanned::Spanned; |
8 | use BuilderPattern; |
9 | use Initializer; |
10 | use DEFAULT_STRUCT_NAME; |
11 | |
12 | use crate::DefaultExpression; |
13 | |
14 | /// Initializer for the struct fields in the build method, implementing |
15 | /// `quote::ToTokens`. |
16 | /// |
17 | /// # Examples |
18 | /// |
19 | /// Will expand to something like the following (depending on settings): |
20 | /// |
21 | /// ```rust,ignore |
22 | /// # extern crate proc_macro2; |
23 | /// # #[macro_use ] |
24 | /// # extern crate quote; |
25 | /// # extern crate syn; |
26 | /// # #[macro_use (default_build_method)] |
27 | /// # extern crate derive_builder_core; |
28 | /// # use derive_builder_core::{BuildMethod, BuilderPattern}; |
29 | /// # fn main() { |
30 | /// # let build_method = default_build_method!(); |
31 | /// # |
32 | /// # assert_eq!(quote!(#build_method).to_string(), quote!( |
33 | /// pub fn build(&self) -> ::derive_builder::export::core::result::Result<Foo, FooBuilderError> { |
34 | /// Ok(Foo { |
35 | /// foo: self.foo, |
36 | /// }) |
37 | /// } |
38 | /// # ).to_string()); |
39 | /// # } |
40 | /// ``` |
41 | #[derive (Debug)] |
42 | pub struct BuildMethod<'a> { |
43 | /// Path to the root of the derive_builder crate. |
44 | pub crate_root: &'a syn::Path, |
45 | /// Enables code generation for this build method. |
46 | pub enabled: bool, |
47 | /// Name of this build fn. |
48 | pub ident: &'a syn::Ident, |
49 | /// Visibility of the build method, e.g. `syn::Visibility::Public`. |
50 | pub visibility: Cow<'a, syn::Visibility>, |
51 | /// How the build method takes and returns `self` (e.g. mutably). |
52 | pub pattern: BuilderPattern, |
53 | /// Type of the target field. |
54 | /// |
55 | /// The corresonding builder field will be `Option<field_type>`. |
56 | pub target_ty: &'a syn::Ident, |
57 | /// Type parameters and lifetimes attached to this builder struct. |
58 | pub target_ty_generics: Option<syn::TypeGenerics<'a>>, |
59 | /// Type of error. |
60 | pub error_ty: syn::Path, |
61 | /// Field initializers for the target type. |
62 | pub initializers: Vec<TokenStream>, |
63 | /// Doc-comment of the builder struct. |
64 | pub doc_comment: Option<syn::Attribute>, |
65 | /// Default value for the whole struct. |
66 | /// |
67 | /// This will be in scope for all initializers as `__default`. |
68 | pub default_struct: Option<&'a DefaultExpression>, |
69 | /// Validation function with signature `&FooBuilder -> Result<(), String>` |
70 | /// to call before the macro-provided struct buildout. |
71 | pub validate_fn: Option<&'a syn::Path>, |
72 | } |
73 | |
74 | impl<'a> ToTokens for BuildMethod<'a> { |
75 | fn to_tokens(&self, tokens: &mut TokenStream) { |
76 | let ident = &self.ident; |
77 | let vis = &self.visibility; |
78 | let target_ty = &self.target_ty; |
79 | let target_ty_generics = &self.target_ty_generics; |
80 | let initializers = &self.initializers; |
81 | let self_param = match self.pattern { |
82 | BuilderPattern::Owned => quote!(self), |
83 | BuilderPattern::Mutable | BuilderPattern::Immutable => quote!(&self), |
84 | }; |
85 | let doc_comment = &self.doc_comment; |
86 | let default_struct = self.default_struct.as_ref().map(|default_expr| { |
87 | let default_expr = default_expr.with_crate_root(self.crate_root); |
88 | let ident = syn::Ident::new(DEFAULT_STRUCT_NAME, Span::call_site()); |
89 | quote!(let #ident: #target_ty #target_ty_generics = #default_expr;) |
90 | }); |
91 | let validate_fn = self |
92 | .validate_fn |
93 | .as_ref() |
94 | .map(|vfn| quote_spanned!(vfn.span() => #vfn(&self)?;)); |
95 | let error_ty = &self.error_ty; |
96 | |
97 | if self.enabled { |
98 | let crate_root = &self.crate_root; |
99 | tokens.append_all(quote!( |
100 | #doc_comment |
101 | #vis fn #ident(#self_param) |
102 | -> #crate_root::export::core::result::Result<#target_ty #target_ty_generics, #error_ty> |
103 | { |
104 | #validate_fn |
105 | #default_struct |
106 | Ok(#target_ty { |
107 | #(#initializers)* |
108 | }) |
109 | } |
110 | )) |
111 | } |
112 | } |
113 | } |
114 | |
115 | impl<'a> BuildMethod<'a> { |
116 | /// Set a doc-comment for this item. |
117 | pub fn doc_comment(&mut self, s: String) -> &mut Self { |
118 | self.doc_comment = Some(doc_comment_from(s)); |
119 | self |
120 | } |
121 | |
122 | /// Populate the `BuildMethod` with appropriate initializers of the |
123 | /// underlying struct. |
124 | /// |
125 | /// For each struct field this must be called with the appropriate |
126 | /// initializer. |
127 | pub fn push_initializer(&mut self, init: Initializer) -> &mut Self { |
128 | self.initializers.push(quote!(#init)); |
129 | self |
130 | } |
131 | } |
132 | |
133 | // pub struct BuildMethodError { |
134 | // is_generated: bool, |
135 | // ident: syn::Ident, |
136 | // } |
137 | |
138 | /// Helper macro for unit tests. This is _only_ public in order to be accessible |
139 | /// from doc-tests too. |
140 | #[doc (hidden)] |
141 | #[macro_export ] |
142 | macro_rules! default_build_method { |
143 | () => { |
144 | BuildMethod { |
145 | // Deliberately don't use the default value here - make sure |
146 | // that all test cases are passing crate_root through properly. |
147 | crate_root: &parse_quote!(::db), |
148 | enabled: true, |
149 | ident: &syn::Ident::new("build" , ::proc_macro2::Span::call_site()), |
150 | visibility: ::std::borrow::Cow::Owned(syn::parse_quote!(pub)), |
151 | pattern: BuilderPattern::Mutable, |
152 | target_ty: &syn::Ident::new("Foo" , ::proc_macro2::Span::call_site()), |
153 | target_ty_generics: None, |
154 | error_ty: syn::parse_quote!(FooBuilderError), |
155 | initializers: vec![quote!(foo: self.foo,)], |
156 | doc_comment: None, |
157 | default_struct: None, |
158 | validate_fn: None, |
159 | } |
160 | }; |
161 | } |
162 | |
163 | #[cfg (test)] |
164 | mod tests { |
165 | #[allow (unused_imports)] |
166 | use super::*; |
167 | |
168 | #[test ] |
169 | fn std() { |
170 | let build_method = default_build_method!(); |
171 | |
172 | #[rustfmt::skip] |
173 | assert_eq!( |
174 | quote!(#build_method).to_string(), |
175 | quote!( |
176 | pub fn build(&self) -> ::db::export::core::result::Result<Foo, FooBuilderError> { |
177 | Ok(Foo { |
178 | foo: self.foo, |
179 | }) |
180 | } |
181 | ) |
182 | .to_string() |
183 | ); |
184 | } |
185 | |
186 | #[test ] |
187 | fn default_struct() { |
188 | let mut build_method = default_build_method!(); |
189 | let alt_default = |
190 | DefaultExpression::explicit::<syn::Expr>(parse_quote!(Default::default())); |
191 | build_method.default_struct = Some(&alt_default); |
192 | |
193 | #[rustfmt::skip] |
194 | assert_eq!( |
195 | quote!(#build_method).to_string(), |
196 | quote!( |
197 | pub fn build(&self) -> ::db::export::core::result::Result<Foo, FooBuilderError> { |
198 | let __default: Foo = { Default::default() }; |
199 | Ok(Foo { |
200 | foo: self.foo, |
201 | }) |
202 | } |
203 | ) |
204 | .to_string() |
205 | ); |
206 | } |
207 | |
208 | #[test ] |
209 | fn skip() { |
210 | let mut build_method = default_build_method!(); |
211 | build_method.enabled = false; |
212 | build_method.enabled = false; |
213 | |
214 | assert_eq!(quote!(#build_method).to_string(), quote!().to_string()); |
215 | } |
216 | |
217 | #[test ] |
218 | fn rename() { |
219 | let ident = syn::Ident::new("finish" , Span::call_site()); |
220 | let mut build_method: BuildMethod = default_build_method!(); |
221 | build_method.ident = &ident; |
222 | |
223 | #[rustfmt::skip] |
224 | assert_eq!( |
225 | quote!(#build_method).to_string(), |
226 | quote!( |
227 | pub fn finish(&self) -> ::db::export::core::result::Result<Foo, FooBuilderError> { |
228 | Ok(Foo { |
229 | foo: self.foo, |
230 | }) |
231 | } |
232 | ) |
233 | .to_string() |
234 | ); |
235 | } |
236 | |
237 | #[test ] |
238 | fn validation() { |
239 | let validate_path: syn::Path = parse_quote!(IpsumBuilder::validate); |
240 | |
241 | let mut build_method: BuildMethod = default_build_method!(); |
242 | build_method.validate_fn = Some(&validate_path); |
243 | |
244 | #[rustfmt::skip] |
245 | assert_eq!( |
246 | quote!(#build_method).to_string(), |
247 | quote!( |
248 | pub fn build(&self) -> ::db::export::core::result::Result<Foo, FooBuilderError> { |
249 | IpsumBuilder::validate(&self)?; |
250 | |
251 | Ok(Foo { |
252 | foo: self.foo, |
253 | }) |
254 | } |
255 | ) |
256 | .to_string() |
257 | ); |
258 | } |
259 | } |
260 | |