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load.rs
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load.rs
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// Copyright 2012-2013 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.
//! Used by `rustc` when loading a plugin, or a crate with exported macros.
use session::Session;
use metadata::creader::CrateReader;
use plugin::registry::Registry;
use std::mem;
use std::os;
use std::dynamic_lib::DynamicLibrary;
use syntax::ast;
use syntax::attr;
use syntax::visit;
use syntax::visit::Visitor;
use syntax::attr::AttrMetaMethods;
/// Metadata for a single plugin crate.
pub struct PluginMetadata {
/// Macros exported by the crate.
pub macros: Vec<ast::MacroDef>,
/// Path to the shared library file, and registrar function symbol.
pub registrar: Option<(Path, String)>,
}
/// Pointer to a registrar function.
pub type PluginRegistrarFun =
fn(&mut Registry);
/// Information about loaded plugins.
pub struct Plugins {
/// Imported macros.
pub macros: Vec<ast::MacroDef>,
/// Registrars, as function pointers.
pub registrars: Vec<PluginRegistrarFun>,
}
struct PluginLoader<'a> {
sess: &'a Session,
reader: CrateReader<'a>,
plugins: Plugins,
}
impl<'a> PluginLoader<'a> {
fn new(sess: &'a Session) -> PluginLoader<'a> {
PluginLoader {
sess: sess,
reader: CrateReader::new(sess),
plugins: Plugins {
macros: vec!(),
registrars: vec!(),
},
}
}
}
/// Read plugin metadata and dynamically load registrar functions.
pub fn load_plugins(sess: &Session, krate: &ast::Crate,
addl_plugins: Option<Plugins>) -> Plugins {
let mut loader = PluginLoader::new(sess);
visit::walk_crate(&mut loader, krate);
let mut plugins = loader.plugins;
match addl_plugins {
Some(addl_plugins) => {
// Add in the additional plugins requested by the frontend
let Plugins { macros: addl_macros, registrars: addl_registrars } = addl_plugins;
plugins.macros.extend(addl_macros.into_iter());
plugins.registrars.extend(addl_registrars.into_iter());
}
None => ()
}
return plugins;
}
// note that macros aren't expanded yet, and therefore macros can't add plugins.
impl<'a, 'v> Visitor<'v> for PluginLoader<'a> {
fn visit_view_item(&mut self, vi: &ast::ViewItem) {
match vi.node {
ast::ViewItemExternCrate(_, _, _) => {
let mut plugin_phase = false;
for attr in vi.attrs.iter().filter(|a| a.check_name("phase")) {
let phases = attr.meta_item_list().unwrap_or(&[]);
if attr::contains_name(phases, "plugin") {
plugin_phase = true;
}
if attr::contains_name(phases, "syntax") {
plugin_phase = true;
self.sess.span_warn(attr.span,
"phase(syntax) is a deprecated synonym for phase(plugin)");
}
}
if !plugin_phase { return; }
let PluginMetadata { macros, registrar } =
self.reader.read_plugin_metadata(vi);
self.plugins.macros.extend(macros.into_iter());
match registrar {
Some((lib, symbol)) => self.dylink_registrar(vi, lib, symbol),
_ => (),
}
}
_ => (),
}
}
fn visit_mac(&mut self, _: &ast::Mac) {
// bummer... can't see plugins inside macros.
// do nothing.
}
}
impl<'a> PluginLoader<'a> {
// Dynamically link a registrar function into the compiler process.
fn dylink_registrar(&mut self, vi: &ast::ViewItem, path: Path, symbol: String) {
// Make sure the path contains a / or the linker will search for it.
let path = os::make_absolute(&path).unwrap();
let lib = match DynamicLibrary::open(Some(&path)) {
Ok(lib) => lib,
// this is fatal: there are almost certainly macros we need
// inside this crate, so continue would spew "macro undefined"
// errors
Err(err) => self.sess.span_fatal(vi.span, err[])
};
unsafe {
let registrar =
match lib.symbol(symbol[]) {
Ok(registrar) => {
mem::transmute::<*mut u8,PluginRegistrarFun>(registrar)
}
// again fatal if we can't register macros
Err(err) => self.sess.span_fatal(vi.span, err[])
};
self.plugins.registrars.push(registrar);
// Intentionally leak the dynamic library. We can't ever unload it
// since the library can make things that will live arbitrarily long
// (e.g. an @-box cycle or a task).
mem::forget(lib);
}
}
}