Implement import scope

Implement import scope

Implement the new scope rule for imports.

- Imported identifiers are in a scope that is shadowed
  by the importing library's top-level scope.
- Conflicting names imported from different libraries
  are not an error unless the name is referenced.
- Conflicting type names are only an error in checked mode.

In a follow-on change, I'll remove the "imported_into" pointers in libraries. They are no longer needed.


Issue 2945
Committed: https://code.google.com/p/dart/source/detail?r=10923

[regis, 2012-08-17 20:23:07]

LGTM

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc
File runtime/vm/parser.cc (right):

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:6237: String* Parser::ExpectTypeIdentifier(const char* msg)
{
This should be called ExpectClassIdentifier.

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:6243: ErrorMsg("illegal type name '%s'",
ident->ToCString());
"illegal class name"

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:7647: // Resolve an name by checking the global scope of
the current
s/an/a/

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:7671: "'%s' is defined in library '%s' and also in '%s'.",
We usually do not terminate error messages with a period.

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:7783: TRACE_PARSER("ResolveIdentInPrefixScope");
No TRACE_PARSER in other calls. On purpose?

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:8819: *qual_ident.ident);
indentation

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.h
File runtime/vm/parser.h (right):

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.h#newcode499
runtime/vm/parser.h:499: const String& ident);
Reorder these 6 methods and group them in pairs.
Explaining in a comment the difference between a Name and an Ident would be
helpful.

[hausner, 2012-08-17 21:05:52]

Thank you.

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc
File runtime/vm/parser.cc (right):

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:6237: String* Parser::ExpectTypeIdentifier(const char* msg)
{
On 2012/08/17 20:23:07, regis wrote:
> This should be called ExpectClassIdentifier.

Done.

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:6243: ErrorMsg("illegal type name '%s'",
ident->ToCString());
On 2012/08/17 20:23:07, regis wrote:
> "illegal class name"

Re-used the error message defined by the caller, since this check is used for
classes, interfaces, and typedefs.

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:7647: // Resolve an name by checking the global scope of
the current
On 2012/08/17 20:23:07, regis wrote:
> s/an/a/

Done.

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:7671: "'%s' is defined in library '%s' and also in '%s'.",
On 2012/08/17 20:23:07, regis wrote:
> We usually do not terminate error messages with a period.

Done.

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:7783: TRACE_PARSER("ResolveIdentInPrefixScope");
On 2012/08/17 20:23:07, regis wrote:
> No TRACE_PARSER in other calls. On purpose?

No on purpose. We have lots of functions that don't trace. I added a few where I
thought it makes sense.

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.cc#newcod...
runtime/vm/parser.cc:8819: *qual_ident.ident);
On 2012/08/17 20:23:07, regis wrote:
> indentation

Done.

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.h
File runtime/vm/parser.h (right):

http://codereview.chromium.org/10823396/diff/6002/runtime/vm/parser.h#newcode499
runtime/vm/parser.h:499: const String& ident);
On 2012/08/17 20:23:07, regis wrote:
> Reorder these 6 methods and group them in pairs.
> Explaining in a comment the difference between a Name and an Ident would be
> helpful.

Done.