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use std::fmt;
use {quote, syn};
use failure::Error;
use MacroError;
use arguments::KnownArgumentType;
pub fn extract_func_info(
item: &syn::Item,
) -> Result<(&syn::Item, &syn::FnDecl, &syn::Block), MacroError> {
match item.node {
syn::ItemKind::Fn(ref decleration, _, _, _, _, ref block) => {
Ok((item, &**decleration, block))
}
ref kind => Err(MacroError::InvalidItemKind { kind: kind.clone() })?,
}
}
pub fn get_argument_types(decl: &syn::FnDecl) -> Result<Vec<KnownArgumentType>, MacroError> {
Ok(decl.inputs
.iter()
.map(|input| match *input {
syn::FnArg::SelfRef(_, _) | syn::FnArg::SelfValue(_) => {
Err(MacroError::InvalidArgument { arg: input.clone() })
}
syn::FnArg::Captured(_, ref ty) | syn::FnArg::Ignored(ref ty) => Ok(ty.clone()),
})
.map(|ty_result| {
ty_result.and_then(|ty| KnownArgumentType::new(&ty))
})
.collect::<Result<_, _>>()?)
}
pub struct JsFnInfo {
pub rust_name: String,
pub args_ty: Vec<KnownArgumentType>,
pub ret_ty: syn::Ty,
}
impl JsFnInfo {
pub fn try_from(item: &syn::Item) -> Result<Self, Error> {
let (item, decl, _) = extract_func_info(item)?;
let argument_types = get_argument_types(decl)?;
let ret_ty = match decl.output {
syn::FunctionRetTy::Default => syn::Ty::Tup(Vec::new()),
syn::FunctionRetTy::Ty(ref ty) => ty.clone(),
};
Ok(JsFnInfo {
rust_name: item.ident.to_string(),
args_ty: argument_types,
ret_ty: ret_ty,
})
}
}
static TRANSFORMED_FUNC_PREFX: &'static str = "__js_fn_";
#[derive(Debug, Clone)]
pub struct TransformedRustIdent<T> {
name: T,
}
impl<T> TransformedRustIdent<T> {
pub fn new(name: T) -> TransformedRustIdent<T> {
TransformedRustIdent { name }
}
}
impl<T: fmt::Display> quote::ToTokens for TransformedRustIdent<T> {
fn to_tokens(&self, tokens: &mut quote::Tokens) {
tokens.append(format!("{}{}", TRANSFORMED_FUNC_PREFX, self.name));
}
}
impl<T: fmt::Display> fmt::Display for TransformedRustIdent<T> {
fn fmt(&self, f: &mut fmt::Formatter) -> Result<(), fmt::Error> {
write!(f, "{}{}", TRANSFORMED_FUNC_PREFX, self.name)
}
}