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support attrs in struct

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This commit is contained in:
Guillaume Pinot 2017-02-06 01:00:27 +01:00
parent 1196571909
commit edc9d69f03
2 changed files with 38 additions and 25 deletions
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2
examples/basic.rs
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@ -8,12 +8,12 @@
extern crate structopt;
#[macro_use]
extern crate structopt_derive;
#[macro_use]
extern crate clap;
use structopt::StructOpt;
#[derive(StructOpt, Debug)]
#[structopt(name = "basic", about = "A basic example")]
struct Opt {
#[structopt(short = "d", long = "debug", help = "Activate debug mode")]
debug: bool,

61
structopt-derive/src/lib.rs
View file

@ -11,6 +11,7 @@ extern crate syn;
extern crate quote;
use proc_macro::TokenStream;
use syn::{Attribute, Body, VariantData, MetaItem, NestedMetaItem, Ident, Lit, StrStyle};
#[proc_macro_derive(StructOpt, attributes(structopt))]
pub fn structopt(input: TokenStream) -> TokenStream {
@ -42,14 +43,39 @@ fn ty(t: &syn::Ty) -> Ty {
}
}
fn extract_attrs<'a>(attrs: &'a [Attribute]) -> Box<Iterator<Item = (&'a Ident, &'a Lit)> + 'a> {
let iter = attrs.iter()
.filter_map(|attr| match attr.value {
MetaItem::List(ref i, ref v) if i.as_ref() == "structopt" => Some(v),
_ => None,
}).flat_map(|v| v.iter().filter_map(|mi| match *mi {
NestedMetaItem::MetaItem(MetaItem::NameValue(ref i, ref l)) => Some((i, l)),
_ => None,
}));
Box::new(iter)
}
fn from_attr_or(attrs: &[(&Ident, &Lit)], key: &str, default: &str) -> Lit {
attrs.iter()
.find(|&&(i, _)| i.as_ref() == key)
.map(|&(_, l)| l.clone())
.unwrap_or_else(|| Lit::Str(default.into(), StrStyle::Cooked))
}
fn impl_structopt(ast: &syn::DeriveInput) -> quote::Tokens {
use syn::{Body, VariantData, MetaItem, NestedMetaItem};
let name = &ast.ident;
let struct_name = &ast.ident;
let s = if let Body::Struct(VariantData::Struct(ref s)) = ast.body {
s
} else {
panic!("Only struct is supported")
};
let struct_attrs: Vec<_> = extract_attrs(&ast.attrs).collect();
let name = from_attr_or(&struct_attrs, "name", env!("CARGO_PKG_NAME"));
let version = from_attr_or(&struct_attrs, "version", env!("CARGO_PKG_VERSION"));
let author = from_attr_or(&struct_attrs, "author", env!("CARGO_PKG_AUTHORS"));
let about = from_attr_or(&struct_attrs, "about", env!("CARGO_PKG_DESCRIPTION"));
let args = s.iter().map(|f| {
let ident = f.ident.as_ref().unwrap();
let modifier = match ty(&f.ty) {
@ -78,21 +104,7 @@ fn impl_structopt(ast: &syn::DeriveInput) -> quote::Tokens {
.required(true)
},
};
let from_attr = f.attrs.iter()
.filter_map(|attr| {
if let MetaItem::List(ref i, ref v) = attr.value {
if i.as_ref() == "structopt" {
return Some(v)
}
}
None
}).flat_map(|v| v.iter().filter_map(|mi| {
if let NestedMetaItem::MetaItem(MetaItem::NameValue(ref i, ref l)) = *mi {
Some(quote!(.#i(#l)))
} else {
None
}
}));
let from_attr = extract_attrs(&f.attrs).map(|(i, l)| quote!(.#i(#l)));
quote! {
.arg(Arg::with_name(stringify!(#ident))
#modifier
@ -122,21 +134,22 @@ fn impl_structopt(ast: &syn::DeriveInput) -> quote::Tokens {
.unwrap()
},
};
quote! {
#ident: matches.#convert,
}
quote!( #ident: matches.#convert, )
});
quote! {
impl StructOpt for #name {
impl StructOpt for #struct_name {
fn clap<'a, 'b>() -> clap::App<'a, 'b> {
use ::clap::Arg;
app_from_crate!()
use clap::{App, Arg};
App::new(#name)
.version(#version)
.author(#author)
.about(#about)
#( #args )*
}
fn from_clap(app: clap::App) -> Self {
let matches = app.get_matches();
#name {
#struct_name {
#( #fields )*
}
}