Rust Quasi-Quoting macro with pretty template-engine like syntax

This crate provides quasi-quoting macros like quote. This crate has backward-compatibility with original quote! macro and also provides new template-engine like syntax.

This crate is get some inspiration from proc-quote.

Using this crate

This crate is useful for developing proc-macro. Usually an proc-macro crate using template_quote is placed with following Cargo.toml:

[package]
name = "your_crate_name"
version = "0.0.0"
edition = "2021"

[lib]
proc-macro = true

[dependencies]
template-quote = "0.1"
proc-macro2 = "1.0"

and with following src/lib.rs code:

extern crate proc_macro;
extern crate proc_macro2;
extern crate template_quote;

use template_quote::quote;
use proc_macro::TokenStream;
use proc_macro2::TokenStream as TokenStream2;

#[proc_macro]
pub fn my_macro(_: TokenStream) -> TokenStream {
	quote! { /* something here */ }.into()
}

then you will be able to use it like:

extern crate your_crate_name;
use your_crate_name::my_macro;

my_macro!()

Original syntax

Original quote! macro syntax is fully supported. See quote's doc.

Template-engine like syntax

Conditional blocks

template_quote supports if, else, else if, for .. in .., while .., while let ..., loop syntax like following:

let tokens = quote! {
	#(
		#(if v >= &10){
			#v
		}
		#(else){
			-#v
		}
	)*
};
assert_eq!("-1i32 10i32 -2i32 13i32 -4i32 19i32", tokens.to_string());

You can also set an separater for for, while, loop, placing a separater between #(..) and {..}.

Inline statements / expressions

You can use inline expression by syntax #{ ... }.

let v = vec![1, 2, 3];
let tokens = quote! {
	#(
		#v => #{ format!("{}", v).as_str() }
	)*
};
assert_eq!(
	"1i32 => \"1\" 2i32 => \"2\" 3i32 => \"3\"",
	tokens.to_string()
);

Limitation

• Let binding in #{ ... } within traditional repetition syntax #( .. )* does not work.
• If the punct token before '#' in the macro body has Spacing::Join, then the emitting punct also has same spacing, whether the '#' token is processed by the macro or not.