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// Copyright 2016 Kyle Mayes // // Licensed under the Apache License, Version 2.0 (the "License"); // you may not use this file except in compliance with the License. // You may obtain a copy of the License at // // http://www.apache.org/licenses/LICENSE-2.0 // // Unless required by applicable law or agreed to in writing, software // distributed under the License is distributed on an "AS IS" BASIS, // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. // See the License for the specific language governing permissions and // limitations under the License. //! This crate provides a compiler plugin, `easy_plugin!`, which makes it easier to write compiler //! plugins. //! //! `easy_plugin!` generates a wrapper function around your plugin function which handles argument //! parsing and error reporting for you, significantly reducing the effort required to write a //! plugin. //! //! A usage of `easy_plugin!` consists of one or more `enum` or `struct` argument specifications //! followed by a plugin function. Here is a trivial example with only one argument specification //! which accepts an identifier. //! //! ```ignore //! easy_plugin! { //! struct Arguments { $a:ident } //! //! /// My trivial plugin. //! pub fn expand_trivial_plugin( //! _: &mut ExtCtxt, span: Span, arguments: Arguments //! ) -> PluginResult<Box<MacResult>> { //! println!("{:?}", arguments.a); //! Ok(DummyResult::any(span)) //! } //! } //! ``` //! //! Note that the third argument of the plugin function differs from the usual signature of a plugin //! function in that the type is `Arguments` instead of `&[TokenTree]`. This is because the //! generated wrapper function handles argument parsing and stores the parsed arguments into a //! generated struct named `Arguments`. //! //! The type you specify for the third argument of the plugin function will determine which of the //! argument specifications will be used to parse the plugin arguments. Here is an example with an //! `enum` argument specification that accepts either an attribute or a type. //! //! ```ignore //! easy_plugin! { //! enum Enum { //! Attribute { $attr:attr }, //! Type { $ty:ty }, //! } //! //! /// My `enum` plugin. //! pub fn expand_enum_plugin( //! _: &mut ExtCtxt, span: Span, arguments: Enum //! ) -> PluginResult<Box<MacResult>> { //! match arguments { //! Enum::Attribute { attr } => println!("{:?}", attr), //! Enum::Type { ty } => println!("{:?}", ty), //! } //! Ok(DummyResult::any(span)) //! } //! } //! ``` //! //! Every argument specification can use any previous argument specification as a part of itself. //! Here is an example with two argument specifications that accepts two comma-separated unary or //! binary expressions. //! //! ```ignore //! easy_plugin! { //! enum Expr { //! Binary { $left:expr $op:binop $right:expr }, //! Unary { $op:binop $expr:expr }, //! } //! //! struct Arguments { $a:$Expr, $b:$Expr } //! //! /// My expression plugin. //! pub fn expand_expression_plugin( //! _: &mut ExtCtxt, span: Span, arguments: Arguments //! ) -> PluginResult<Box<MacResult>> { //! match arguments.a { //! Expr::Binary { left, op, right } => println!("{:?}, {:?}, {:?}", left, op, right), //! Expr::Unary { op, expr } => println!("{:?}, {:?}", op, expr), //! } //! Ok(DummyResult::any(span)) //! } //! } //! ``` //! //! Finally, note that the `expand_expression_plugin` function is public and has a documentation //! comment. The visibility and attributes applied to your plugin function (including documentation //! comments) will be removed and applied to the generated wrapper function instead. In this //! example, the wrapper function will be public and have a documentation comment. //! //! # Specifications //! //! `easy_plugin!` argument specifications are very similar to the argument specifications you are //! used to writing for macros. There are three primary differences: inclusion of other argument //! specifications (as seen above), no restrictions on ordering, and additional types of named //! specifiers. //! //! | Name | Description | Storage Type | //! |:--------|:---------------------------------------|:----------------------| //! | `attr` | An attribute. | `Attribute` | //! | `binop` | A binary operator. | `Spanned<BinOpToken>` | //! | `block` | A brace-delimited statement sequence. | `P<Block>` | //! | `delim` | A delimited token tree sequence. | `Spanned<Delimited>` | //! | `expr` | An expression. | `P<Expr>` | //! | `ident` | An identifier. | `Spanned<Ident>` | //! | `item` | An item. | `P<Item>` | //! | `lftm` | A lifetime. | `Spanned<Name>` | //! | `lit` | A literal. | `Lit` | //! | `meta` | A "meta" item, as found in attributes. | `P<MetaItem>` | //! | `pat` | A pattern. | `P<Pat>` | //! | `path` | A qualified name. | `Path` | //! | `stmt` | A single statement. | `Stmt` | //! | `ty` | A type. | `P<Ty>` | //! | `tok` | A single token. | `Spanned<Token>` | //! | `tt` | A single token tree. | `TokenTree` | //! //! In addition to the specifiers above, there is also a specifier for each [`extractor`][extractor] //! function. For example, the specifier for the //! [`extractor::lit_to_str`](extractor/fn.lit_to_str.html) function is `lit_str`. The storage type //! for these specifiers is the return type of the corresponding [`extractor`][extractor] function. //! For example, the storage type of the `lit_str` specifier is `(String, StrStyle)`. //! //! [extractor]: extractor/index.html //! //! ## Sequences //! //! Argument specifications support sequences that are very similar to the sequences in macro //! argument specifications. For example, the following argument specification matches zero //! or more comma-separated parenthesized binary expressions. //! //! ```ignore //! $(($left:ident $op:binop $right:ident)), * //! ``` //! //! In addition to the `*` and `+` sequence operators, there is also a `?` operator which allows for //! sequences with either zero or one repetitions. This operator does not support separators. For //! example, the following argument specification can match either a binary expression or //! nothing at all. //! //! ```ignore //! $($left:ident $op:binop $right:ident)? //! ``` //! //! Named specifiers that occur in sequences cannot be stored directly as their storage type because //! there may be more than one or none at all. For this reason, named specifiers that occur in //! sequences have the storage type of either `Vec<$type>` or `Option<$type>` where `$type` is the //! base storage type. `Vec<$type>` is used for `*` and `+` sequences and `Option<$type>` is used //! for `?` sequences. //! //! An additional level of `Vec` or `Option` is added for each sequence level. For example, in the //! argument specification below, `$b:ident` occurs two sequence levels deep. The storage type for //! `b` in this case would be `Vec<Vec<Spanned<Ident>>>`. //! //! ```ignore //! $($a:ident $($b:ident)*)* //! ``` //! //! ## Named Sequences //! //! Argument specifications also support named sequences, which behave rather differently than //! regular sequences. Named sequences cannot contain named specifiers and instead consist of //! specific token trees that you wish to be counted. For example, the following argument //! specification will match either `pub struct { }` or just `struct { }`. //! //! ```ignore //! $public:(pub)? struct { } //! ``` //! //! These named sequences allow the usage of the same suffixes as regular sequences. The `*`, `+`, //! and `?` operators are supported and separators are supported for the `*` and `+` operators. For //! example, the following argument specification matches any number of comma-separated `A`s. //! //! ```ignore //! $a:(A), * //! ``` //! //! Because named sequences are counted, the storage types are simply `usize` for `*` and `+` named //! sequences and `bool` for `?`named sequences. #![cfg_attr(not(feature="syntex"), feature(plugin, plugin_registrar, rustc_private))] #![cfg_attr(not(feature="syntex"), plugin(synthax))] #![warn(missing_copy_implementations, missing_debug_implementations, missing_docs)] #![cfg_attr(feature="clippy", plugin(clippy))] #![cfg_attr(feature="clippy", warn(clippy))] #[cfg(feature="syntex")] extern crate syntex as rustc_plugin; #[cfg(feature="syntex")] extern crate syntex_syntax as syntax; #[cfg(feature="syntex")] extern crate syntex_errors as rustc_errors; #[cfg(not(feature="syntex"))] extern crate rustc_plugin; #[cfg(not(feature="syntex"))] extern crate syntax; #[cfg(not(feature="syntex"))] extern crate rustc_errors as rustc_errors; extern crate easy_plugin_parsers as parsers; extern crate synthax; pub use parsers::extractor; pub use parsers::{PluginResult}; pub use parsers::arguments::*; pub use parsers::specification::*; mod utility; pub use utility::{PluginResultExt, ToError}; mod expr; mod ast { include!(concat!(env!("OUT_DIR"), "/ast.rs")); } include!(concat!(env!("OUT_DIR"), "/lib.rs"));