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// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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use driver::session;
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use driver::session::Session;
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use syntax::parse::token::special_idents;
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use syntax::ast::{crate, node_id, item, item_fn};
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use syntax::codemap::span;
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use syntax::visit::{default_visitor, mk_vt, vt, Visitor, visit_crate, visit_item};
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use syntax::attr::{attrs_contains_name};
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use syntax::ast_map;
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use core::util;
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struct EntryContext {
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session: Session,
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ast_map: ast_map::map,
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// The top-level function called 'main'
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main_fn: Option<(node_id, span)>,
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// The function that has attribute named 'main'
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attr_main_fn: Option<(node_id, span)>,
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// The function that has the attribute 'start' on it
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start_fn: Option<(node_id, span)>,
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// The functions that one might think are 'main' but aren't, e.g.
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// main functions not defined at the top level. For diagnostics.
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non_main_fns: ~[(node_id, span)],
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}
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type EntryVisitor = vt<@mut EntryContext>;
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pub fn find_entry_point(session: Session, crate: @crate, ast_map: ast_map::map) {
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// FIXME #4404 android JNI hacks
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if *session.building_library ||
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session.targ_cfg.os == session::os_android {
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// No need to find a main function
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return;
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}
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let ctxt = @mut EntryContext {
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session: session,
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ast_map: ast_map,
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main_fn: None,
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attr_main_fn: None,
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start_fn: None,
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non_main_fns: ~[],
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};
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visit_crate(crate, ctxt, mk_vt(@Visitor {
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visit_item: |item, ctxt, visitor| find_item(item, ctxt, visitor),
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.. *default_visitor()
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}));
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configure_main(ctxt);
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}
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fn find_item(item: @item, ctxt: @mut EntryContext, visitor: EntryVisitor) {
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match item.node {
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item_fn(*) => {
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if item.ident == special_idents::main {
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match ctxt.ast_map.find(&item.id) {
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Some(&ast_map::node_item(_, path)) => {
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if path.len() == 0 {
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// This is a top-level function so can be 'main'
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if ctxt.main_fn.is_none() {
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ctxt.main_fn = Some((item.id, item.span));
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} else {
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ctxt.session.span_err(
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item.span,
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~"multiple 'main' functions");
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}
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} else {
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// This isn't main
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ctxt.non_main_fns.push((item.id, item.span));
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}
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}
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_ => util::unreachable()
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}
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}
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if attrs_contains_name(item.attrs, ~"main") {
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if ctxt.attr_main_fn.is_none() {
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ctxt.attr_main_fn = Some((item.id, item.span));
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} else {
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ctxt.session.span_err(
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item.span,
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~"multiple 'main' functions");
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}
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}
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if attrs_contains_name(item.attrs, ~"start") {
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if ctxt.start_fn.is_none() {
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ctxt.start_fn = Some((item.id, item.span));
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} else {
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ctxt.session.span_err(
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item.span,
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~"multiple 'start' functions");
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}
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}
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}
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_ => ()
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}
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visit_item(item, ctxt, visitor);
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}
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fn configure_main(ctxt: @mut EntryContext) {
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let this = &mut *ctxt;
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if this.start_fn.is_some() {
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*this.session.entry_fn = this.start_fn;
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*this.session.entry_type = Some(session::EntryStart);
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} else if this.attr_main_fn.is_some() {
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*this.session.entry_fn = this.attr_main_fn;
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*this.session.entry_type = Some(session::EntryMain);
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} else if this.main_fn.is_some() {
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*this.session.entry_fn = this.main_fn;
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*this.session.entry_type = Some(session::EntryMain);
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} else {
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// No main function
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this.session.err(~"main function not found");
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if !this.non_main_fns.is_empty() {
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// There were some functions named 'main' though. Try to give the user a hint.
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this.session.note(~"the main function must be defined at the crate level \
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but you have one or more functions named 'main' that are not \
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defined at the crate level. Either move the definition or attach \
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the `#[main]` attribute to override this behavior.");
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for this.non_main_fns.each |&(_, span)| {
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this.session.span_note(span, ~"here is a function named 'main'");
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}
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}
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this.session.abort_if_errors();
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}
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}
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