rusteal-macros 0.8.0

Proc macros (#[uclass], #[ufunction], #[uproperty]) for rusteal
Documentation 
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use quote::ToTokens;

use crate::prop_type;

pub(crate) fn hash<I: IntoIterator<Item = String>>(declarations: I) -> u64 {
    let mut declarations: Vec<String> = declarations.into_iter().collect();
    declarations.sort();
    prop_type::fnv1a_hash(&declarations.join("\u{1f}"))
}

pub(crate) fn declaration(
    attributes: &[syn::Attribute],
    attrs: &[&str],
    item: &impl ToTokens,
) -> String {
    let mut out = String::new();

    for attr in attributes
        .iter()
        .filter(|a| attrs.iter().any(|name| a.path().is_ident(name)))
    {
        out.push_str(&attr.to_token_stream().to_string());
        out.push(' ');
    }

    out.push_str(&item.to_token_stream().to_string());
    out
}

pub(crate) fn field(field: &syn::Field, attrs: &[&str]) -> Option<String> {
    if !field
        .attrs
        .iter()
        .any(|a| attrs.iter().any(|name| a.path().is_ident(name)))
    {
        return None;
    }

    let ident = field.ident.as_ref()?;
    let ty = &field.ty;

    Some(declaration(
        &field.attrs,
        attrs,
        &quote::quote! { #ident: #ty },
    ))
}

#[cfg(test)]
mod tests {
    use super::*;
    use syn::parse_quote;

    fn fields(item: syn::ItemStruct) -> Vec<String> {
        item.fields
            .iter()
            .filter_map(|f| field(f, &["uproperty", "component"]))
            .collect()
    }

    #[test]
    fn ue_fields_make_the_shape() {
        let before = fields(parse_quote! {
            struct Platform {
                #[uproperty(EditAnywhere)]
                speed: f32,
                timer: f64,
            }
        });

        let same = fields(parse_quote! {
            struct Platform {
                #[doc = "A comment changes nothing."]
                #[uproperty(EditAnywhere)]
                speed:   f32,
                timer: f32,
                elapsed: f64,
            }
        });

        let added = fields(parse_quote! {
            struct Platform {
                #[uproperty(EditAnywhere)]
                speed: f32,
                #[uproperty(EditAnywhere)]
                distance: f32,
            }
        });

        let flags = fields(parse_quote! {
            struct Platform {
                #[uproperty(VisibleAnywhere)]
                speed: f32,
            }
        });

        assert_eq!(hash(before.clone()), hash(same));
        assert_ne!(hash(before.clone()), hash(added));
        assert_ne!(hash(before), hash(flags));
    }

    #[test]
    fn order_does_not_matter() {
        let a = vec!["a".to_string(), "b".to_string()];
        let b = vec!["b".to_string(), "a".to_string()];
        assert_eq!(hash(a), hash(b));
    }

    #[test]
    fn a_method_body_is_not_part_of_it() {
        let shape =
            |method: syn::ImplItemFn| declaration(&method.attrs, &["ufunction"], &method.sig);

        let before = shape(parse_quote! {
            #[ufunction(BlueprintCallable)]
            fn jump(&mut self, height: f32) { let _ = height; }
        });

        let body = shape(parse_quote! {
            #[ufunction(BlueprintCallable)]
            fn jump(&mut self, height: f32) { println!("{height}"); }
        });

        let params = shape(parse_quote! {
            #[ufunction(BlueprintCallable)]
            fn jump(&mut self, height: f64) {}
        });

        assert_eq!(before, body);
        assert_ne!(before, params);
    }
}