1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104
// Copyright 2016 The Rust Project Developers. See the COPYRIGHT // file at the top-level directory of this distribution and at // http://rust-lang.org/COPYRIGHT. // // Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or // http://www.apache.org/licenses/LICENSE-2.0> or the MIT license // <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your // option. This file may not be copied, modified, or distributed // except according to those terms. //! # Proc_Macro //! //! A library for procedural macro writers. //! //! ## Usage //! This crate provides the `qquote!` macro for syntax creation. //! //! The `qquote!` macro uses the crate `syntax`, so users must declare `extern crate syntax;` //! at the crate root. This is a temporary solution until we have better hygiene. //! //! ## Quasiquotation //! //! The quasiquoter creates output that, when run, constructs the tokenstream specified as //! input. For example, `qquote!(5 + 5)` will produce a program, that, when run, will //! construct the TokenStream `5 | + | 5`. //! //! ### Unquoting //! //! Unquoting is currently done as `unquote`, and works by taking the single next //! TokenTree in the TokenStream as the unquoted term. Ergonomically, `unquote(foo)` works //! fine, but `unquote foo` is also supported. //! //! A simple example might be: //! //!``` //!fn double(tmp: TokenStream) -> TokenStream { //! qquote!(unquote(tmp) * 2) //!} //!``` //! //! ### Large Example: Implementing Scheme's `cond` //! //! Below is the full implementation of Scheme's `cond` operator. //! //! ``` //! fn cond_rec(input: TokenStream) -> TokenStream { //! if input.is_empty() { return quote!(); } //! //! let next = input.slice(0..1); //! let rest = input.slice_from(1..); //! //! let clause : TokenStream = match next.maybe_delimited() { //! Some(ts) => ts, //! _ => panic!("Invalid input"), //! }; //! //! // clause is ([test]) [rhs] //! if clause.len() < 2 { panic!("Invalid macro usage in cond: {:?}", clause) } //! //! let test: TokenStream = clause.slice(0..1); //! let rhs: TokenStream = clause.slice_from(1..); //! //! if ident_eq(&test[0], str_to_ident("else")) || rest.is_empty() { //! quote!({unquote(rhs)}) //! } else { //! quote!({if unquote(test) { unquote(rhs) } else { cond!(unquote(rest)) } }) //! } //! } //! ``` //! #![crate_name = "proc_macro_plugin"] #![unstable(feature = "rustc_private", issue = "27812")] #![feature(plugin_registrar)] #![crate_type = "dylib"] #![crate_type = "rlib"] #![doc(html_logo_url = "https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png", html_favicon_url = "https://doc.rust-lang.org/favicon.ico", html_root_url = "https://doc.rust-lang.org/nightly/")] #![deny(warnings)] #![feature(staged_api)] #![feature(rustc_diagnostic_macros)] #![feature(rustc_private)] extern crate rustc_plugin; extern crate syntax; extern crate syntax_pos; mod qquote; use qquote::qquote; use rustc_plugin::Registry; use syntax::ext::base::SyntaxExtension; use syntax::symbol::Symbol; // ____________________________________________________________________________________________ // Main macro definition #[plugin_registrar] pub fn plugin_registrar(reg: &mut Registry) { reg.register_syntax_extension(Symbol::intern("qquote"), SyntaxExtension::ProcMacro(Box::new(qquote))); }