84 lines
2.8 KiB
Rust
84 lines
2.8 KiB
Rust
// 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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/// Correctness for protocols
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/*
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This section of code makes sure the protocol is likely to generate
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correct code. The correctness criteria include:
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* No protocols transition to states that don't exist.
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* Messages step to states with the right number of type parameters.
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In addition, this serves as a lint pass. Lint warns for the following
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things.
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* States with no messages, it's better to step to !.
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It would also be nice to warn about unreachable states, but the
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visitor infrastructure for protocols doesn't currently work well for
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that.
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*/
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use ast;
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use codemap::span;
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use ext::base::ext_ctxt;
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use ext::pipes::proto::{state, protocol, next_state};
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use ext::pipes::proto;
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impl proto::visitor<(), (), ()> for @ext_ctxt {
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fn visit_proto(&self, _proto: protocol, _states: &[()]) { }
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fn visit_state(&self, state: state, _m: &[()]) {
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let messages = &*state.messages;
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if messages.len() == 0 {
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self.span_warn(
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state.span, // use a real span!
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fmt!("state %s contains no messages, \
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consider stepping to a terminal state instead",
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state.name))
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}
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}
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fn visit_message(&self, name: ~str, _span: span, _tys: &[@ast::Ty],
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this: state, next: Option<next_state>) {
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match next {
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Some(ref next_state) => {
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let proto = this.proto;
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if !proto.has_state(next_state.state) {
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// This should be a span fatal, but then we need to
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// track span information.
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self.span_err(
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proto.get_state(next_state.state).span,
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fmt!("message %s steps to undefined state, %s",
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name, next_state.state));
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}
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else {
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let next = proto.get_state(next_state.state);
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if next.generics.ty_params.len() != next_state.tys.len() {
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self.span_err(
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next.span, // use a real span
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fmt!("message %s target (%s) \
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needs %u type parameters, but got %u",
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name, next.name,
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next.generics.ty_params.len(),
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next_state.tys.len()));
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}
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}
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}
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None => ()
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}
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}
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}
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