narrative-macros 0.5.0

Procedural macros for the narrative crate
Documentation 
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// &self in these methods are not necessary but it's for future extensibility and friendly API.

use proc_macro2::TokenStream;
use quote::{format_ident, quote};

use crate::{
    item_story::{story_const::StoryConst, ItemStory},
    story_attr_syntax::StoryAttr,
};

pub(crate) fn generate(attr: &StoryAttr, input: &ItemStory) -> TokenStream {
    let title = &attr.title;
    let ident = &input.ident;
    let steps = input.steps().map(|step| {
        let step_name = &step.inner.sig.ident;
        quote! {
            #[inline]
            pub fn #step_name(&self) -> Step {
                Step::#step_name
            }
        }
    });
    let step_names = input.steps().map(|step| &step.inner.sig.ident);
    let consts = input.consts().map(|item| &item.raw.ident);
    let consts_defs = input.consts().map(
        |StoryConst {
             raw,
             default: (eq, default),
         }| {
            let ident = &raw.ident;
            let ty = &raw.ty;
            Some(quote! {
                pub const #ident: #ty #eq #default;
            })
        },
    );
    quote! {
        #[derive(Default)]
        pub struct StoryContext;
        impl StoryContext {
            #(#consts_defs)*
            #(#steps)*
        }
        impl narrative::story::StoryContext for StoryContext {
            type Step = Step;
            type Const = StoryConst;
            type StepIter = std::slice::Iter<'static, Self::Step>;
            type ConstIter = std::slice::Iter<'static, Self::Const>;
            #[inline]
            fn story_title(&self) -> String {
                #title.to_string()
            }
            #[inline]
            fn story_id(&self) -> &'static str {
                stringify!(#ident)
            }
            #[inline]
            fn steps(&self) -> Self::StepIter {
                [#(Step::#step_names),*].iter()
            }
            #[inline]
            fn consts(&self) -> Self::ConstIter {
                [#(StoryConst::#consts),*].iter()
            }
        }
    }
}

pub(crate) fn generate_ext(input: &ItemStory) -> TokenStream {
    let ident = &input.ident;
    let async_ident = format_ident!("Async{}", input.ident);
    quote! {
        pub trait ContextExt {
            fn context() -> StoryContext;
            fn get_context(&self) -> StoryContext;
        }
        pub trait AsyncContextExt {
            fn context() -> StoryContext;
            fn get_context(&self) -> StoryContext;
        }
        impl <T: #ident> ContextExt for T {
            #[inline]
            fn context() -> StoryContext {
                StoryContext::default()
            }
            #[inline]
            fn get_context(&self) -> StoryContext {
                StoryContext::default()
            }
        }
        impl <T: #async_ident> AsyncContextExt for T {
            #[inline]
            fn context() -> StoryContext {
                StoryContext::default()
            }
            #[inline]
            fn get_context(&self) -> StoryContext {
                StoryContext::default()
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use pretty_assertions::assert_eq;

    #[test]
    fn test_generate() {
        let attr = syn::parse_quote! {
            "Story Title"
        };
        let story_syntax = syn::parse_quote! {
            trait UserStory {
                const NAME: &str = "Ryo";
                const AGE: u32 = 20;

                #[step("step1")]
                fn step1();
                #[step("step2: {name}", name = "ryo")]
                fn step2(name: &str);
            }
        };
        let actual = generate(&attr, &story_syntax);
        let expected = quote! {
            #[derive(Default)]
            pub struct StoryContext;
            impl StoryContext {
                pub const NAME: &str = "Ryo";
                pub const AGE: u32 = 20;

                #[inline]
                pub fn step1(&self) -> Step {
                    Step::step1
                }
                #[inline]
                pub fn step2(&self) -> Step {
                    Step::step2
                }
            }
            impl narrative::story::StoryContext for StoryContext {
                type Step = Step;
                type Const = StoryConst;
                type StepIter = std::slice::Iter<'static, Self::Step>;
                type ConstIter = std::slice::Iter<'static, Self::Const>;
                #[inline]
                fn story_title(&self) -> String {
                    "Story Title".to_string()
                }
                #[inline]
                fn story_id(&self) -> &'static str {
                    stringify!(UserStory)
                }
                #[inline]
                fn steps(&self) -> Self::StepIter {
                    [Step::step1, Step::step2].iter()
                }
                #[inline]
                fn consts(&self) -> Self::ConstIter {
                    [StoryConst::NAME, StoryConst::AGE].iter()
                }
            }
        };
        assert_eq!(actual.to_string(), expected.to_string());
    }
}