rustc: Rename rustc_macro to proc_macro

This commit blanket renames the `rustc_macro` infrastructure to `proc_macro`,
which reflects the general consensus of #35900. A follow up PR to Cargo will be
required to purge the `rustc-macro` name as well.

1 files changed, 137 insertions, 0 deletions

diff --git a/src/libproc_macro_plugin/lib.rs b/src/libproc_macro_plugin/lib.rs
new file mode 100644
index 00000000000..e82e97b5134
--- /dev/null
+++ b/src/libproc_macro_plugin/lib.rs
@@ -0,0 +1,137 @@
+// 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 package provides the `qquote!` macro for syntax creation, and the prelude
+//! (at libproc_macro::prelude) provides a number of operations:
+//! - `concat`, for concatenating two TokenStreams.
+//! - `ident_eq`, for checking if two identifiers are equal regardless of syntax context.
+//! - `str_to_token_ident`, for converting an `&str` into a Token.
+//! - `keyword_to_token_delim`, for converting a `parse::token::keywords::Keyword` into a
+//!    Token.
+//! - `build_delimited`, for creating a new TokenStream from an existing one and a delimiter
+//!    by wrapping the TokenStream in the delimiter.
+//! - `build_bracket_delimited`, `build_brace_delimited`, and `build_paren_delimited`, for
+//!    easing the above.
+//! - `build_empty_args`, which returns a TokenStream containing `()`.
+//! - `lex`, which takes an `&str` and returns the TokenStream it represents.
+//!
+//! The `qquote!` macro also imports `syntax::ext::proc_macro_shim::prelude::*`, so you
+//! will need to `extern crate syntax` for usage. (This is a temporary solution until more
+//! of the external API in libproc_macro is stabilized to support the token construction
+//! operations that the qausiquoter relies on.) The shim file also provides additional
+//! operations, such as `build_block_emitter` (as used in the `cond` example below).
+//!
+//! ## TokenStreams
+//!
+//! TokenStreams serve as the basis of the macro system. They are, in essence, vectors of
+//! TokenTrees, where indexing treats delimited values as a single term. That is, the term
+//! `even(a+c) && even(b)` will be indexibly encoded as `even | (a+c) | even | (b)` where,
+//! in reality, `(a+c)` is actually a decorated pointer to `a | + | c`.
+//!
+//! If a user has a TokenStream that is a single, delimited value, they can use
+//! `maybe_delimited` to destruct it and receive the internal vector as a new TokenStream
+//! as:
+//! ```
+//! `(a+c)`.maybe_delimited() ~> Some(a | + | c)`
+//! ```
+//!
+//! Check the TokenStream documentation for more information; the structure also provides
+//! cheap concatenation and slicing.
+//!
+//! ## 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/")]
+#![cfg_attr(not(stage0), deny(warnings))]
+
+#![feature(staged_api)]
+#![feature(rustc_diagnostic_macros)]
+#![feature(rustc_private)]
+
+extern crate rustc_plugin;
+extern crate syntax;
+extern crate syntax_pos;
+#[macro_use] extern crate log;
+
+mod qquote;
+pub mod build;
+pub mod parse;
+pub mod prelude;
+use qquote::qquote;
+
+use rustc_plugin::Registry;
+
+// ____________________________________________________________________________________________
+// Main macro definition
+
+#[plugin_registrar]
+pub fn plugin_registrar(reg: &mut Registry) {
+    reg.register_macro("qquote", qquote);
+}