Use stacked context for nested bindings.

Binding context may be stacked when a new binding group is introduced
within a const expression.

gcc/rust/ChangeLog:

	* resolve/rust-name-resolution-context.h: Use BindingLayer instead.
	* resolve/rust-name-resolution-context.cc (BindingLayer::BindingLayer):
	Add new constructor for binding layer.
	(BindingLayer::bind_test): Add a function to test a binding constraint.
	(BindingLayer::push): Push a new binding group.
	(BindingLayer::and_binded): Add function to test and-binding
	constraint.
	(BindingLayer::or_binded): Add function to test or-binding constraints.
	(BindingLayer::insert_ident): Insert a new identifier in the current
	binding group.
	(BindingLayer::merge): Merge current binding group with it's parent.
	(BindingLayer::get_source): Get the source of the current binding
	group.
	* resolve/rust-late-name-resolver-2.0.cc: Use stacked context for
	binding group.
	* util/rust-stacked-contexts.h: Add mutable peek function.

Signed-off-by: Pierre-Emmanuel Patry <pierre-emmanuel.patry@embecosm.com>

1 files changed, 59 insertions, 0 deletions

diff --git a/gcc/rust/resolve/rust-name-resolution-context.cc b/gcc/rust/resolve/rust-name-resolution-context.cc
index 35befc1..7f47e85 100644
--- a/gcc/rust/resolve/rust-name-resolution-context.cc
+++ b/gcc/rust/resolve/rust-name-resolution-context.cc
@@ -23,6 +23,65 @@
 namespace Rust {
 namespace Resolver2_0 {
 
+BindingLayer::BindingLayer (BindingSource source) : source (source)
+{
+  push (Binding::Kind::Product);
+}
+
+bool
+BindingLayer::bind_test (Identifier ident, Binding::Kind kind)
+{
+  for (auto &bind : bindings)
+    {
+      if (bind.set.find (ident) != bind.set.cend () && bind.kind == kind)
+	{
+	  return true;
+	}
+    }
+  return false;
+}
+
+void
+BindingLayer::push (Binding::Kind kind)
+{
+  bindings.push_back (Binding (kind));
+}
+
+bool
+BindingLayer::is_and_bound (Identifier ident)
+{
+  return bind_test (ident, Binding::Kind::Product);
+}
+
+bool
+BindingLayer::is_or_bound (Identifier ident)
+{
+  return bind_test (ident, Binding::Kind::Or);
+}
+
+void
+BindingLayer::insert_ident (Identifier ident)
+{
+  bindings.back ().set.insert (ident);
+}
+
+void
+BindingLayer::merge ()
+{
+  auto last_binding = bindings.back ();
+  bindings.pop_back ();
+  for (auto &value : last_binding.set)
+    {
+      bindings.back ().set.insert (value);
+    }
+}
+
+BindingSource
+BindingLayer::get_source () const
+{
+  return source;
+}
+
 NameResolutionContext::NameResolutionContext ()
   : mappings (Analysis::Mappings::get ())
 {}