tidos_macro 0.7.5

Procedural macros for the Tidos component framework.
Documentation 
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//! Procedural macros for the [Tidos](https://docs.rs/tidos) SSR framework.
//!
//! This crate is an implementation detail. All macros are re-exported by the
//! `tidos` crate via `#[doc(inline)] pub use tidos_macro::*;`, so you should
//! depend on `tidos` directly rather than on this crate.
//!
//! For usage examples and full documentation see the
//! [`tidos` crate docs](https://docs.rs/tidos).

extern crate proc_macro;

use proc_macro::TokenStream;

use crate::page_wrapper::PageWrapper;
use quote::{format_ident, quote, ToTokens};
use syn::parse_macro_input;
use tokens::Component;
use uuid::Uuid;

mod code_generation;
mod i18n;
mod page_wrapper;
mod parsing;
mod tokens;

/// Renders an HTML template to a `String`.
///
/// Write HTML directly in Rust. Interpolate Rust expressions with `{ }` and
/// use the control-flow blocks below for loops, conditionals, and pattern
/// matching.
///
/// # Syntax summary
///
/// | Syntax | Meaning |
/// |---|---|
/// | `{expr}` | Interpolate a Rust expression |
/// | `{#for x in iter} … {/for}` | Loop |
/// | `{#if cond} … {:else if cond} … {:else} … {/if}` | Conditional |
/// | `{#match val} {:case Pat} … {/match}` | Pattern match |
/// | `<Component prop={expr} />` | Render a component |
///
/// # Examples
///
/// ## Inline expression
/// ```rust,no_run
/// use tidos_macro::view;
///
/// let name = "Alice";
/// view! {
///     <p>Hello {name}!</p>
/// }
/// ```
///
/// ## For loop
/// ```rust,no_run
/// use tidos_macro::view;
///
/// let names = vec!["Bob", "Alice"];
///
/// view! {
///     {#for name in names}
///         <p>{format!("Hello {}!", name)}</p>
///     {/for}
/// }
/// ```
///
/// ## If / else
/// ```rust,no_run
/// use tidos_macro::view;
///
/// let age = 18;
/// let is_american = false;
///
/// view! {
///     {#if age >= 18 && !is_american}
///         <p>User is allowed to drink.</p>
///     {:else if age >= 21 && is_american}
///         <p>User is allowed to drink.</p>
///     {:else if age >= 18 && age < 21 && is_american}
///         <p>User is probably the designated driver.</p>
///     {:else}
///         <p>User is not allowed to drink.</p>
///     {/if}
/// }
/// ```
///
/// ## Match statement
/// ```rust,no_run
/// use tidos_macro::view;
///
/// enum Pet { Fish, Dog, Cat, Other { name: String } }
/// use Pet::*;
///
/// let my_pet = Dog;
///
/// view! {
///     {#match my_pet}
///         {:case Fish}
///             <p>Blub!</p>
///         {:case Dog}
///             <p>{"Who's a good boy!"}</p>
///         {:case Cat}
///             <p>Give all mortal possessions to cat!</p>
///         {:case _}
///             <p>Is it a snake or a spider?</p>
///     {/match}
/// }
/// ```
#[allow(clippy::all)]
#[proc_macro]
pub fn view(input: TokenStream) -> TokenStream {
	let input = parse_macro_input!(input as Component);

	let expanded = input.to_token_stream();

	expanded.into()
}

/// Renders an HTML template and wraps it in a `Page`.
///
/// Use `page!` in a route handler instead of [`view!`] when you need to
/// return a full page. Internally it creates a `Page`, renders the template
/// into it, and returns the `Page` value.
///
/// Accepts exactly the same template syntax as [`view!`].
///
/// # Example
///
/// ```rust,no_run
/// use tidos::{page, Component, Page};
///
/// pub fn getting_started() -> Page {
///     let x: isize = Default::default();
///
///     page! {
///         <main>
///             <h1>Getting started</h1>
///             <p>{x.to_string()}</p>
///         </main>
///     }
/// }
/// ```
#[allow(clippy::all)]
#[proc_macro]
pub fn page(input: TokenStream) -> TokenStream {
	let input = parse_macro_input!(input as PageWrapper);

	let expanded = input.to_token_stream();

	expanded.into()
}

/// Injects HTML into the `<head>` of the current page.
///
/// Call `head!` inside `Component::to_render` to add elements such as
/// `<title>`, `<link>`, or `<meta>` tags to the page `<head>`. Each call is
/// deduplicated by a compile-time UUID, so it is safe to call from components
/// rendered inside a loop.
///
/// # Example
///
/// ```rust,no_run
/// use tidos::{head, Component, Page};
///
/// pub struct Title {
///     pub title: String,
/// }
///
/// impl Component for Title {
///     fn to_render(&self, page: &mut Page) -> String {
///         head! {
///             <title>{&self.title}</title>
///         }
///         String::new()
///     }
/// }
/// ```
#[allow(clippy::all)]
#[proc_macro]
pub fn head(input: TokenStream) -> TokenStream {
	let input = parse_macro_input!(input as Component);

	let x = Uuid::new_v4().to_string();
	// todo refactor it to &str when I'm comfortable with lifetime annontations
	let input = quote!(
		page.add_elements_to_head(#x, #input);
	);

	let expanded = input.to_token_stream();

	expanded.into()
}

/// Injects a scoped CSS file into the page `<head>` and returns the generated class name.
///
/// The path is resolved relative to the calling source file (like
/// `include_str!`). At compile time the macro generates a unique
/// `tidos-<uuid>` class name, wraps the CSS file content as
/// `.tidos-<uuid> { … }`, and injects a `<style>` tag into the page `<head>`
/// via `Page::add_elements_to_head`. Because injection is keyed by UUID,
/// calling `scoped_css!` inside a loop only injects the style once.
///
/// The macro returns a `&'static str` you can bind to a `class` attribute.
///
/// # Example
///
/// ```rust,no_run
/// use tidos::{scoped_css, view, Component, Page};
///
/// pub struct Card { pub title: String }
///
/// impl Component for Card {
///     fn to_render(&self, page: &mut Page) -> String {
///         view! {
///             <div class={scoped_css!("./card.css")}>
///                 <h2>{&self.title}</h2>
///             </div>
///         }
///     }
/// }
/// ```
#[allow(clippy::all)]
#[proc_macro]
pub fn scoped_css(input: TokenStream) -> TokenStream {
	let file_name = input.to_string().replace("\"", "");

	let x = format!("tidos-{}", Uuid::new_v4().to_string());
	// todo refactor it to &str when I'm comfortable with lifetime annontations
	let input = quote!(
		{
			page.add_elements_to_head(#x, String::from(concat!("<style>.", #x, " {", include_str!(#file_name), "}</style>")));
			#x
		}
	);

	let expanded = input.to_token_stream();

	expanded.into()
}

/// Derives [`Component`](tidos::Component) for a struct that wraps a native
/// [Custom Element](https://developer.mozilla.org/en-US/docs/Web/API/Web_components/Using_custom_elements).
///
/// Place `#[native_element]` on a struct to automatically generate a
/// `Component` implementation that:
///
/// 1. Injects `<script type="module" src="/dist/StructName.js"></script>` into
///    the page `<head>`
/// 2. Renders the kebab-case HTML tag derived from the struct name, forwarding
///    all fields as HTML attributes.
///
/// # Attribute mapping
///
/// Field names are converted from `snake_case` to `kebab-case`.
/// The struct name is converted from `PascalCase` to `kebab-case` for the
/// HTML tag, and used as-is for the JS filename.
///
/// # Example
///
/// ```rust,no_run
/// use tidos::native_element;
///
/// #[native_element]
/// pub struct GreetName {
///     pub name: String,
///     pub is_shiny: bool,
/// }
/// ```
///
/// Generates roughly:
///
/// ```rust,no_run
/// # use tidos::{Component, Page};
/// # pub struct GreetName { pub name: String, pub is_shiny: bool }
/// impl tidos::Component for GreetName {
///     fn to_render(&self, page: &mut tidos::Page) -> String {
///         tidos::head! { <script type="module" src="/dist/GreetName.js"> }
///         tidos::view! { <greet-name name="Alice" is-shiny></greet-name> }
///     }
/// }
/// ```
#[allow(clippy::all)]
#[proc_macro_attribute]
pub fn native_element(_args: TokenStream, input: TokenStream) -> TokenStream {
	let input_struct = parse_macro_input!(input as syn::ItemStruct);
	let struct_name = &input_struct.ident;
	let struct_name_str = struct_name.to_string();

	let kebab_name = pascal_to_kebab(&struct_name_str);
	if !kebab_name.contains('-') {
		return syn::Error::new_spanned(
			&input_struct.ident,
			format!(
				"#[native_element] generated the tag name '{}', which is not a valid custom \
				 element name — custom elements must contain at least one '-'. \
				 Use a multi-word struct name (e.g. 'App{}' → 'app-{}').",
				kebab_name, struct_name_str, kebab_name
			),
		)
		.to_compile_error()
		.into();
	}

	let tag_name: Vec<syn::Ident> = kebab_name
		.split("-")
		.map(|x| format_ident!("{}", x))
		.collect();
	let tag_name = quote! { #( #tag_name )-* };

	let script_src = format!("/dist/{}.js", struct_name_str);

	let fields: Vec<&syn::Field> = match &input_struct.fields {
		syn::Fields::Named(f) => f.named.iter().collect(),
		syn::Fields::Unit => vec![],
		_ => {
			return syn::Error::new_spanned(
				&input_struct.ident,
				"#[native_element] only supports structs with named fields or unit structs",
			)
			.to_compile_error()
			.into()
		}
	};

	let attr_stmts: Vec<proc_macro2::TokenStream> = fields
		.iter()
		.map(|field| {
			let field_ident = field.ident.as_ref().unwrap();
			let attr_parts: Vec<syn::Ident> = field_ident
				.to_string()
				.split("_")
				.map(|x| format_ident!("{}", x))
				.collect();
			let attr_name = quote! { #( #attr_parts )-* };

			if is_bool_type(&field.ty) {
				quote! {
					:#attr_name={self.#field_ident}
				}
			} else {
				quote! {
					#attr_name={self.#field_ident}
				}
			}
		})
		.collect();

	let expanded = quote! {
		#input_struct

		impl tidos::Component for #struct_name {
			fn to_render(&self, page: &mut tidos::Page) -> String {
				tidos::head!(<script r#type="module" src=#script_src></script>);
				tidos::view!(<#tag_name #( #attr_stmts )*></#tag_name>)
			}
		}
	};

	expanded.into()
}

fn pascal_to_kebab(s: &str) -> String {
	let mut result = String::new();
	for (i, c) in s.chars().enumerate() {
		if c.is_uppercase() && i > 0 {
			result.push('-');
		}
		result.push(c.to_ascii_lowercase());
	}
	result
}

fn is_bool_type(ty: &syn::Type) -> bool {
	if let syn::Type::Path(type_path) = ty {
		if let Some(segment) = type_path.path.segments.last() {
			return segment.ident == "bool";
		}
	}
	false
}