bundle_derive/
lib.rs

1use proc_macro::TokenStream;
2use quote::quote;
3use syn::{parse_macro_input, Attribute, Data, DataEnum, DeriveInput, Fields, Ident, Lit, Meta};
4
5#[proc_macro_derive(Bundle, attributes(bundle))]
6pub fn strand_derive(input: TokenStream) -> TokenStream {
7    let input = parse_macro_input!(input as DeriveInput);
8    let name = &input.ident;
9
10    let state = extract_attr_ident(&input, "state");
11
12    let mut alternative = None;
13
14    let mut prefixes: Vec<_> = Vec::new();
15
16    let variants: Vec<_> = if let Data::Enum(DataEnum { variants, .. }) = &input.data {
17        variants.iter().filter_map(|variant| {
18            match &variant.fields {
19                Fields::Unnamed(fields) if fields.unnamed.len() == 1 => {
20                    let field_ty = &fields.unnamed[0].ty;
21
22                    if attr_exist(&variant.attrs, "other") {
23                        alternative = Some(field_ty);
24                        return None
25                    }
26
27                    if let Some(prefix) = extract_attr_name(&variant.attrs, "prefix") {
28                        prefixes.push((prefix, field_ty));
29                    }
30
31                    let scope_name = extract_attr_name(&variant.attrs, "name")?;
32
33                    Some((scope_name, field_ty))
34                }
35                _ => panic!("Strand derive only supports enums with tuple variants containing a single field"),
36            }
37        }).collect()
38    } else {
39        panic!("Strand derive only supports enums");
40    };
41    
42    let prefix_variants = prefixes.iter().map(|(prefix, field_ty)| {
43        quote! {
44            s if s.starts_with(#prefix) => return #field_ty::run(state, input.strip_prefix(#prefix).unwrap(), ws_chars),
45        }
46    });
47
48    let parse_variants = variants.iter().map(|(scope_name, field_ty)| {
49        quote! {
50            #scope_name => return #field_ty::run(state, residue, ws_chars),
51        }
52    });
53
54    let match_other = if alternative.is_none() {
55        quote!(
56            _ => return Err(format!("Invalid scope: {}", arg)),
57        )
58    } else {
59        let other = alternative.unwrap();
60        quote!(
61            _ => return #other::run(state, input, ws_chars),
62        )
63    };
64
65    let gen = quote! {
66        impl Bundle for #name {
67            type State = #state;
68
69            fn run(state: &mut Self::State, input: &str, ws_chars: &[char]) -> Result<(), String> {
70                fn split_at_char<'a>(input_raw: &'a str, splits: &[char]) -> (&'a str, &'a str) {
71                    fn trim_chars<'a>(input: &'a str, splits: &[char]) -> &'a str {
72                        let start_trimmed = input.trim_start_matches(|c| splits.contains(&c));
73                        let trimmed = start_trimmed.trim_end_matches(|c| splits.contains(&c));
74                        trimmed
75                    }
76
77                    let input = trim_chars(input_raw, splits);
78                
79                    let mut out = ("", input);
80                
81                    for (index, char) in input.char_indices() {
82                        if splits.contains(&char) {
83                            let (a, b) = input.split_at(index);
84                            out = (b, trim_chars(a, splits));
85                            break;
86                        }
87                    }
88                
89                    out
90                }
91
92                let (residue, arg) = split_at_char(input, ws_chars);
93                if arg == "" {
94                    return Err("Not enough arguments".into())
95                }
96
97                match arg {
98                    #( #parse_variants )*
99                    #( #prefix_variants)*
100                    #match_other
101                }
102            }
103        }
104    };
105
106    gen.into()
107}
108
109fn attr_exist(attrs: &Vec<Attribute>, ident: &str) -> bool {
110    for attr in attrs {
111        if attr.path.is_ident("bundle") {
112            if let Ok(Meta::List(meta_list)) = attr.parse_meta() {
113                for nested_meta in meta_list.nested {
114                    if let syn::NestedMeta::Meta(meta) = nested_meta {
115                        if let Meta::Path(path) = meta {
116                            if path.is_ident(ident) {
117                                return true
118                            }
119                        }
120                    }
121                }
122            }
123        }
124    }
125    
126    false
127}
128
129fn extract_attr_name(attrs: &Vec<Attribute>, ident: &str) -> Option<String> {
130    let mut action_function_name = attrs.iter().filter_map(|attr| {
131        if attr.path.is_ident("bundle") {
132            if let Ok(Meta::List(meta_list)) = attr.parse_meta() {
133                for nested_meta in meta_list.nested {
134                    if let syn::NestedMeta::Meta(meta) = nested_meta {
135                        if let Meta::NameValue(name_value) = meta {
136                            if name_value.path.is_ident(ident) {
137                                if let Lit::Str(s) = name_value.lit {
138                                    return Some(s.value());
139                                }
140                            }
141                        }
142                    }
143                }
144            }
145        }
146        None
147    });
148
149    action_function_name
150        .next()
151}
152
153fn extract_attr_ident(input: &DeriveInput, ident: &str) -> Ident {
154    let mut action_function_name = input.attrs.iter().filter_map(|attr| {
155        if attr.path.is_ident("bundle") {
156            if let Ok(Meta::List(meta_list)) = attr.parse_meta() {
157                for nested_meta in meta_list.nested {
158                    if let syn::NestedMeta::Meta(meta) = nested_meta {
159                        if let Meta::NameValue(name_value) = meta {
160                            if name_value.path.is_ident(ident) {
161                                if let Lit::Str(s) = name_value.lit {
162                                    return Some(Ident::new(&s.value(), s.span()));
163                                }
164                            }
165                        }
166                    }
167                }
168            }
169        }
170        None
171    });
172
173    action_function_name
174        .next()
175        .expect(&format!("Couldn't find attribute: {}", ident))
176}
bundle_derive/lib.rs

bundle_derive/
lib.rs
