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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 std::collections::HashSet;
use syntax::ast;
use syntax::attr;
use syntax::parse::token;
use syntax::visit;
use syntax::visit::Visitor;
use syntax::attr::AttrMetaMethods;
/// 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) {
// We're only interested in `extern crate`.
match vi.node {
ast::ViewItemExternCrate(..) => (),
_ => return,
}
// Parse the attributes relating to macro / plugin loading.
let mut load_registrar = false;
let mut macro_selection = Some(HashSet::new()); // None => load all
let mut reexport = HashSet::new();
for attr in vi.attrs.iter() {
let mut used = true;
match attr.name().get() {
"phase" => {
self.sess.span_err(attr.span, "#[phase] is deprecated; use \
#[macro_use], #[plugin], and/or #[no_link]");
}
"plugin" => load_registrar = true,
"macro_use" => {
let names = attr.meta_item_list();
if names.is_none() {
// no names => load all
macro_selection = None;
}
if let (Some(sel), Some(names)) = (macro_selection.as_mut(), names) {
for name in names.iter() {
if let ast::MetaWord(ref name) = name.node {
sel.insert(name.clone());
} else {
self.sess.span_err(name.span, "bad macro import");
}
}
}
}
"macro_reexport" => {
let names = match attr.meta_item_list() {
Some(names) => names,
None => {
self.sess.span_err(attr.span, "bad macro reexport");
continue;
}
};
for name in names.iter() {
if let ast::MetaWord(ref name) = name.node {
reexport.insert(name.clone());
} else {
self.sess.span_err(name.span, "bad macro reexport");
}
}
}
_ => used = false,
}
if used {
attr::mark_used(attr);
}
}
let mut macros = vec![];
let mut registrar = None;
let load_macros = match macro_selection.as_ref() {
Some(sel) => sel.len() != 0 || reexport.len() != 0,
None => true,
};
if load_macros || load_registrar {
let pmd = self.reader.read_plugin_metadata(vi);
if load_macros {
macros = pmd.exported_macros();
}
if load_registrar {
registrar = pmd.plugin_registrar();
}
}
for mut def in macros.into_iter() {
let name = token::get_ident(def.ident);
def.use_locally = match macro_selection.as_ref() {
None => true,
Some(sel) => sel.contains(&name),
};
def.export = reexport.contains(&name);
self.plugins.macros.push(def);
}
if let Some((lib, symbol)) = registrar {
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);
}
}
}