mocktopus_macros 0.3.6

Mocktopus procedural macros
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use header_builder::FnHeaderBuilder;
use syn::{ArgCaptured, Attribute, Block, FnArg, FnDecl, Ident, ImplItem, ImplItemMethod, Item, ItemFn, ItemImpl,
          ItemMod, ItemTrait, MethodSig, Pat, PatIdent, TraitItem, TraitItemMethod};
use syn::punctuated::Punctuated;
use syn::token::{Comma, Const, Unsafe};

pub fn inject_item(item: &mut Item) {
    match *item {
        Item::Fn(ref mut item_fn)       => inject_fn(item_fn),
        Item::Mod(ref mut item_mod)     => inject_mod(item_mod),
        Item::Trait(ref mut item_trait) => inject_trait(item_trait),
        Item::Impl(ref mut item_impl)   => inject_impl(item_impl),
        _                               => (),
    }
}

fn inject_fn(item_fn: &mut ItemFn) {
    inject_any_fn(&FnHeaderBuilder::StaticFn, &item_fn.attrs, &item_fn.constness, &item_fn.unsafety, &item_fn.ident,
                  &mut item_fn.decl, &mut *item_fn.block);
}

fn inject_mod(item_mod: &mut ItemMod) {
    if is_not_mockable(&item_mod.attrs) {
        return
    }
    item_mod.content.iter_mut()
        .flat_map(|c| &mut c.1)
        .for_each(inject_item)
}

fn inject_trait(item_trait: &mut ItemTrait) {
    if is_not_mockable(&item_trait.attrs) {
        return
    }
    for item in &mut item_trait.items {
        if let TraitItem::Method(TraitItemMethod {
            ref attrs,
            ref mut sig,
            default: Some(ref mut block),
            ..
        }) = *item {
            inject_any_method(&FnHeaderBuilder::TraitDefault, attrs, sig, block);
        }
    }
}

fn inject_impl(item_impl: &mut ItemImpl) {
    if is_not_mockable(&item_impl.attrs) {
        return
    }
    let builder = match item_impl.trait_ {
        Some((_, ref path, _)) => FnHeaderBuilder::TraitImpl(&path.segments),
        None => FnHeaderBuilder::StructImpl,
    };
    for impl_item in &mut item_impl.items {
        if let ImplItem::Method(ref mut item_method) = *impl_item {
            if is_impl_fn_mockabile(&builder, item_method) {
                inject_any_method(&builder, &item_method.attrs, &mut item_method.sig, &mut item_method.block);
            }
        }
    }
}

fn is_impl_fn_mockabile(builder: &FnHeaderBuilder, item_method: &ImplItemMethod) -> bool {
    if let FnHeaderBuilder::TraitImpl(ref segments) = *builder {
        if let Some(pair) = segments.last() {
            let segment = pair.value();
            if segment.arguments.is_empty() && segment.ident.as_ref() == "Drop" {
                if item_method.sig.ident.as_ref() == "drop" {
                    return false
                }
            }
        }
    }
    true
}


fn inject_any_method(builder: &FnHeaderBuilder, attrs: &Vec<Attribute>, sig: &mut MethodSig, block: &mut Block) {
    inject_any_fn(builder, attrs, &sig.constness, &sig.unsafety, &sig.ident, &mut sig.decl, block)
}

fn inject_any_fn(builder: &FnHeaderBuilder, attrs: &Vec<Attribute>, constness: &Option<Const>,
                 unsafety: &Option<Unsafe>, fn_name: &Ident, fn_decl: &mut FnDecl, block: &mut Block) {
    if constness.is_some() || unsafety.is_some() || fn_decl.variadic.is_some() || is_not_mockable(attrs) {
        return
    }
    unignore_fn_args(&mut fn_decl.inputs);
    let header_stmt = builder.build(fn_name, fn_decl, block.brace_token.0);
    block.stmts.insert(0, header_stmt);
}

fn unignore_fn_args(inputs: &mut Punctuated<FnArg, Comma>) {
    for (i, fn_arg) in inputs.iter_mut().enumerate() {
        if let FnArg::Captured(
            ArgCaptured {
                ref mut pat,
                ..
            }
        ) = *fn_arg {
            let span = match *pat {
                Pat::Wild(ref pat_wild) => pat_wild.underscore_token.0[0],
                _ => continue,
            };
            *pat = Pat::Ident(
                PatIdent {
                    by_ref: None,
                    mutability: None,
                    ident: Ident::new(&format!("__mocktopus_unignored_argument_{}__", i), span),
                    subpat: None,
                }
            )
        }
    }
}

const INJECTOR_STOPPER_ATTRS: [&str; 2] = ["mockable", "not_mockable"];

fn is_not_mockable(attrs: &Vec<Attribute>) -> bool {
    attrs.iter()
        .filter_map(|a| a.path.segments.last())
        .map(|s| s.value().ident.as_ref())
        .any(|i| INJECTOR_STOPPER_ATTRS.contains(&i))
}