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| 1 | +use proc_macro::TokenStream; |
| 2 | +use quote::quote; |
| 3 | +use syn::{parse_macro_input, parse_quote, Attribute, ItemStruct, LitStr, Meta, NestedMeta}; |
| 4 | + |
| 5 | +#[proc_macro_attribute] |
| 6 | +pub fn prefixed_args(attr: TokenStream, item: TokenStream) -> TokenStream { |
| 7 | + let prefix = parse_prefix(attr); |
| 8 | + let mut input = parse_macro_input!(item as ItemStruct); |
| 9 | + |
| 10 | + if let syn::Fields::Named(fields) = &mut input.fields { |
| 11 | + for field in fields.named.iter_mut() { |
| 12 | + let mut skip = false; |
| 13 | + let mut override_name: Option<String> = None; |
| 14 | + |
| 15 | + let mut next_attrs: Vec<Attribute> = Vec::with_capacity(field.attrs.len()); |
| 16 | + for attr in field.attrs.drain(..) { |
| 17 | + if attr.path().is_ident("prefixed_arg") { |
| 18 | + let _ = attr.parse_nested_meta(|meta| { |
| 19 | + if meta.path.is_ident("skip") { |
| 20 | + skip = true; |
| 21 | + return Ok(()); |
| 22 | + } |
| 23 | + if meta.path.is_ident("rename") { |
| 24 | + let value = meta.value()?; |
| 25 | + let lit: LitStr = value.parse()?; |
| 26 | + override_name = Some(lit.value()); |
| 27 | + return Ok(()); |
| 28 | + } |
| 29 | + Ok(()) |
| 30 | + }); |
| 31 | + continue; |
| 32 | + } |
| 33 | + |
| 34 | + next_attrs.push(attr); |
| 35 | + } |
| 36 | + field.attrs = next_attrs; |
| 37 | + |
| 38 | + if skip { |
| 39 | + continue; |
| 40 | + } |
| 41 | + |
| 42 | + if has_arg_long(&field.attrs) { |
| 43 | + continue; |
| 44 | + } |
| 45 | + |
| 46 | + let field_name = override_name |
| 47 | + .or_else(|| serde_rename(&field.attrs)) |
| 48 | + .or_else(|| field.ident.as_ref().map(|ident| ident.to_string())); |
| 49 | + |
| 50 | + let field_name = match field_name { |
| 51 | + Some(name) => name, |
| 52 | + None => continue, |
| 53 | + }; |
| 54 | + |
| 55 | + let long_value = format!("{}.{}", prefix, field_name); |
| 56 | + let long_lit = LitStr::new(&long_value, proc_macro2::Span::call_site()); |
| 57 | + let long_attr: Attribute = parse_quote!(#[arg(long = #long_lit)]); |
| 58 | + field.attrs.push(long_attr); |
| 59 | + } |
| 60 | + } |
| 61 | + |
| 62 | + TokenStream::from(quote!(#input)) |
| 63 | +} |
| 64 | + |
| 65 | +fn parse_prefix(attr: TokenStream) -> String { |
| 66 | + let meta = parse_macro_input!(attr as syn::AttributeArgs); |
| 67 | + for nested in meta { |
| 68 | + match nested { |
| 69 | + NestedMeta::Meta(Meta::NameValue(name_value)) if name_value.path.is_ident("prefix") => { |
| 70 | + if let syn::Expr::Lit(expr_lit) = name_value.value { |
| 71 | + if let syn::Lit::Str(lit_str) = expr_lit.lit { |
| 72 | + return lit_str.value(); |
| 73 | + } |
| 74 | + } |
| 75 | + } |
| 76 | + NestedMeta::Lit(syn::Lit::Str(lit_str)) => { |
| 77 | + return lit_str.value(); |
| 78 | + } |
| 79 | + _ => {} |
| 80 | + } |
| 81 | + } |
| 82 | + |
| 83 | + String::new() |
| 84 | +} |
| 85 | + |
| 86 | +fn has_arg_long(attrs: &[Attribute]) -> bool { |
| 87 | + for attr in attrs { |
| 88 | + if !attr.path().is_ident("arg") { |
| 89 | + continue; |
| 90 | + } |
| 91 | + let mut found = false; |
| 92 | + let _ = attr.parse_nested_meta(|meta| { |
| 93 | + if meta.path.is_ident("long") { |
| 94 | + found = true; |
| 95 | + } |
| 96 | + Ok(()) |
| 97 | + }); |
| 98 | + if found { |
| 99 | + return true; |
| 100 | + } |
| 101 | + } |
| 102 | + false |
| 103 | +} |
| 104 | + |
| 105 | +fn serde_rename(attrs: &[Attribute]) -> Option<String> { |
| 106 | + for attr in attrs { |
| 107 | + if !attr.path().is_ident("serde") { |
| 108 | + continue; |
| 109 | + } |
| 110 | + let mut rename_value = None; |
| 111 | + let _ = attr.parse_nested_meta(|meta| { |
| 112 | + if meta.path.is_ident("rename") { |
| 113 | + let value = meta.value()?; |
| 114 | + let lit: LitStr = value.parse()?; |
| 115 | + rename_value = Some(lit.value()); |
| 116 | + } |
| 117 | + Ok(()) |
| 118 | + }); |
| 119 | + if rename_value.is_some() { |
| 120 | + return rename_value; |
| 121 | + } |
| 122 | + } |
| 123 | + None |
| 124 | +} |
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