cgp-component-macro-lib 0.3.0

Context-generic programming core component macros implemented as a library.
Documentation 
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use alloc::format;

use proc_macro2::Span;
use quote::ToTokens;
use syn::parse::{Parse, ParseStream};
use syn::punctuated::Punctuated;
use syn::token::{Comma, Gt, Lt};
use syn::{Error, Ident};

use crate::derive_component::entry::Entries;

pub struct ComponentSpec {
    pub provider_name: Ident,
    pub context_type: Ident,
    pub component_name: Ident,
    pub component_params: Punctuated<Ident, Comma>,
}

pub struct ComponentNameSpec {
    pub component_name: Ident,
    pub component_params: Punctuated<Ident, Comma>,
}

static VALID_KEYS: [&str; 3] = ["context", "provider", "name"];

impl Parse for ComponentSpec {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        let Entries { entries } = input.parse()?;

        for key in entries.keys() {
            if !VALID_KEYS.iter().any(|valid| valid == key) {
                return Err(syn::Error::new(
                    Span::call_site(),
                    format!(
                        r#"invalid key in component spec: {key}. the following keys are valid: "context", "provider", "name"."#
                    ),
                ));
            }
        }

        let context_type: Ident = {
            let raw_context_type = entries.get("context");

            if let Some(context_type) = raw_context_type {
                syn::parse2(context_type.to_token_stream())?
            } else {
                Ident::new("Context", Span::call_site())
            }
        };

        let provider_name: Ident = {
            let raw_provider_name = entries
                .get("provider")
                .ok_or_else(|| Error::new(input.span(), "expect provider name to be given"))?;

            syn::parse2(raw_provider_name.to_token_stream())?
        };

        let (component_name, component_params) = {
            let raw_component_name = entries.get("name");

            if let Some(raw_component_name) = raw_component_name {
                let ComponentNameSpec {
                    component_name,
                    component_params,
                } = syn::parse2(raw_component_name.to_token_stream())?;
                (component_name, component_params)
            } else {
                (
                    Ident::new(&format!("{}Component", provider_name), provider_name.span()),
                    Punctuated::default(),
                )
            }
        };

        Ok(ComponentSpec {
            component_name,
            provider_name,
            context_type,
            component_params,
        })
    }
}

impl Parse for ComponentNameSpec {
    fn parse(input: ParseStream) -> syn::Result<Self> {
        let component_name: Ident = input.parse()?;

        let component_params = if input.peek(Lt) {
            let _: Lt = input.parse()?;

            let component_params: Punctuated<Ident, Comma> =
                Punctuated::parse_separated_nonempty(input)?;

            let _: Gt = input.parse()?;

            component_params
        } else {
            Punctuated::default()
        };

        Ok(Self {
            component_name,
            component_params,
        })
    }
}