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use syn;
#[derive(Debug, Clone, PartialEq)]
pub enum Argument {
VarArgsSeparator,
VarArgs(syn::Ident),
KeywordArgs(syn::Ident),
Arg(syn::Ident, Option<String>),
Kwarg(syn::Ident, String),
}
pub fn parse_arguments(items: &[syn::NestedMeta]) -> Vec<Argument> {
let mut arguments = Vec::new();
let mut has_kw = false;
let mut has_varargs = false;
let mut has_kwargs = false;
let args_str = quote! {
#(#items),*
}
.to_string();
for item in items.iter() {
match item {
syn::NestedMeta::Meta(syn::Meta::Word(ref ident)) => {
if has_kwargs {
println!("syntax error, keyword arguments is defined: {:?}", args_str);
return Vec::new();
}
if has_kw {
println!(
"syntax error, argument is not allowed after keyword argument: {:?}",
args_str
);
return Vec::new();
}
arguments.push(Argument::Arg(ident.clone(), None))
}
syn::NestedMeta::Meta(syn::Meta::NameValue(ref nv)) => {
match nv.lit {
syn::Lit::Str(ref litstr) => {
if litstr.value() == "*" {
if has_kwargs {
println!(
"* - syntax error, keyword arguments is defined: {:?}",
args_str
);
return Vec::new();
}
if has_varargs {
println!("*(var args) is defined: {:?}", args_str);
return Vec::new();
}
has_varargs = true;
arguments.push(Argument::VarArgs(nv.ident.clone()));
} else if litstr.value() == "**" {
if has_kwargs {
println!("arguments already define ** (kw args): {:?}", args_str);
return Vec::new();
}
has_kwargs = true;
arguments.push(Argument::KeywordArgs(nv.ident.clone()));
} else {
if has_varargs {
arguments
.push(Argument::Kwarg(nv.ident.clone(), litstr.value().clone()))
} else {
if has_kwargs {
println!(
"syntax error, keyword arguments is defined: {:?}",
args_str
);
return Vec::new();
}
has_kw = true;
arguments.push(Argument::Arg(
nv.ident.clone(),
Some(litstr.value().clone()),
))
}
}
}
syn::Lit::Int(ref litint) => {
if has_varargs {
arguments.push(Argument::Kwarg(
nv.ident.clone(),
format!("{}", litint.value()),
));
} else {
if has_kwargs {
println!(
"syntax error, keyword arguments is defined: {:?}",
args_str
);
return Vec::new();
}
has_kw = true;
arguments.push(Argument::Arg(
nv.ident.clone(),
Some(format!("{}", litint.value())),
));
}
}
syn::Lit::Bool(ref litb) => {
if has_varargs {
arguments
.push(Argument::Kwarg(nv.ident.clone(), format!("{}", litb.value)));
} else {
if has_kwargs {
println!(
"syntax error, keyword arguments is defined: {:?}",
args_str
);
return Vec::new();
}
has_kw = true;
arguments.push(Argument::Arg(
nv.ident.clone(),
Some(format!("{}", litb.value)),
));
}
}
_ => {
println!("Only string literal is supported, got: {:?}", nv.lit);
return Vec::new();
}
}
}
syn::NestedMeta::Literal(ref lit) => {
match lit {
&syn::Lit::Str(ref lits) => {
if lits.value() == "*" {
if has_kwargs {
println!(
"syntax error, keyword arguments is defined: {:?}",
args_str
);
return Vec::new();
}
if has_varargs {
println!("arguments already define * (var args): {:?}", args_str);
return Vec::new();
}
has_varargs = true;
arguments.push(Argument::VarArgsSeparator);
} else {
println!(
"Unknown string literal, got: {:?} args: {:?}",
lits.value(),
args_str
);
return Vec::new();
}
}
_ => {
println!(
"Only string literal is supported, got: {:?} args: {:?}",
lit, args_str
);
return Vec::new();
}
}
}
_ => {
println!("Unknown argument, got: {:?} args: {:?}", item, args_str);
return Vec::new();
}
}
}
arguments
}
#[cfg(test)]
mod test {
use args::{parse_arguments, Argument};
use proc_macro2::TokenStream;
use syn;
fn items(s: TokenStream) -> Vec<syn::NestedMeta> {
let dummy: syn::ItemFn = parse_quote!{#s fn dummy() {}};
match dummy.attrs[0].interpret_meta() {
Some(syn::Meta::List(syn::MetaList { nested, .. })) => {
nested.iter().map(Clone::clone).collect()
}
_ => unreachable!(),
}
}
#[test]
fn test_errs() {
assert!(parse_arguments(&items(quote!{#[args(test="1", test2)]})).is_empty());
assert!(parse_arguments(&items(quote!{#[args(test=1, "*", args="*")]})).is_empty());
assert!(parse_arguments(&items(quote!{#[args(test=1, kwargs="**", args="*")]})).is_empty());
assert!(parse_arguments(&items(quote!{#[args(test=1, kwargs="**", args)]})).is_empty());
}
#[test]
fn test_simple_args() {
let args = parse_arguments(&items(quote!{#[args(test1, test2, test3="None")]}));
assert!(
args == vec![
Argument::Arg(parse_quote!{test1}, None),
Argument::Arg(parse_quote!{test2}, None),
Argument::Arg(parse_quote!{test3}, Some("None".to_owned())),
]
);
}
#[test]
fn test_varargs() {
let args = parse_arguments(&items(
quote!{#[args(test1, test2="None", "*", test3="None")]},
));
assert!(
args == vec![
Argument::Arg(parse_quote!{test1}, None),
Argument::Arg(parse_quote!{test2}, Some("None".to_owned())),
Argument::VarArgsSeparator,
Argument::Kwarg(parse_quote!{test3}, "None".to_owned()),
]
);
}
#[test]
fn test_all() {
let args = parse_arguments(&items(
quote!{#[args(test1, test2="None", args="*", test3="None", kwargs="**")]},
));
assert!(
args == vec![
Argument::Arg(parse_quote!{test1}, None),
Argument::Arg(parse_quote!{test2}, Some("None".to_owned())),
Argument::VarArgs(parse_quote!{args}),
Argument::Kwarg(parse_quote!{test3}, "None".to_owned()),
Argument::KeywordArgs(parse_quote!{kwargs}),
]
);
}
}