Refactoring assignment

Refactoring assignment

The idea is to have more _emitXXX methods, so that different paths for
the same semantic action (e.g. implicit vs explicit 'this') call the
same _emitXXX method.

This is the first (simplest) step: assignments.

R=jmesserly@google.com

Committed: https://github.com/dart-lang/dev_compiler/commit/ed8eaf2ea96a5d0acf28e9f686cf0391abbee5d8

[sra1, 2016-06-07 22:33:52]

Description was changed from

==========
Semantic dispatch for assignment

The idea is to have more _emitXXX methods, so that different paths for
the same semantic action (e.g. implicit vs explicit 'this') call the
same _emitXXX method.

This is the first (simplest) step: assignments.
==========

to

==========
Refactoring assignment

The idea is to have more _emitXXX methods, so that different paths for
the same semantic action (e.g. implicit vs explicit 'this') call the
same _emitXXX method.

This is the first (simplest) step: assignments.
==========

[sra1, 2016-06-07 22:33:53]

sra@google.com changed reviewers:
+ jmesserly@google.com

[sra1, 2016-06-07 22:41:48]

WDYT?

There are a few small changes in some tests due to the fact that
Class.staticField is no longer following the same path for lval and rvals.

e.g. previously the code in one test was 

      let o$ = assign_op_test.AssignOpTest;
      o$.f = dart.dsend(o$.f, '+', 1);

now:

    assign_op_test.AssignOpTest.f = dart.dsend(assign_op_test.AssignOpTest.f,
'+', 1);

I think it is OK for the time-being for static accesses to be indivisible. We
can add it back later once other paths are refactored.

[Jennifer Messerly, 2016-06-07 23:04:21]

A couple of questions, otherwise LGTM!

https://codereview.chromium.org/2039173005/diff/20001/lib/src/compiler/code_g...
File lib/src/compiler/code_generator.dart (right):

https://codereview.chromium.org/2039173005/diff/20001/lib/src/compiler/code_g...
lib/src/compiler/code_generator.dart:2781: JS.Expression _badAssignment(String
problem, Expression lhs, Expression rhs) {
do we know what can hit this? Is it a compiler bug or a bug in the user code?

If compiler bug -- should be fine to throw from the compiler. Our error message
has instructions on how to report these.

If it's a bug in user code -- throwing seems good, although it'd be good to
throw an Error and not a string (JS tools do better with Errors, e.g. Karma is
not happy if you throw String, it won't give you a stack trace).

https://codereview.chromium.org/2039173005/diff/20001/lib/src/compiler/code_g...
lib/src/compiler/code_generator.dart:2887: // TODO(sra): Fix.
Fix what? :)

[sra1, 2016-06-07 23:56:07]

https://codereview.chromium.org/2039173005/diff/20001/lib/src/compiler/code_g...
File lib/src/compiler/code_generator.dart (right):

https://codereview.chromium.org/2039173005/diff/20001/lib/src/compiler/code_g...
lib/src/compiler/code_generator.dart:2781: JS.Expression _badAssignment(String
problem, Expression lhs, Expression rhs) {
On 2016/06/07 23:04:20, John Messerly wrote:
> do we know what can hit this? Is it a compiler bug or a bug in the user code?
> 
> If compiler bug -- should be fine to throw from the compiler. Our error
message
> has instructions on how to report these.
> 
> If it's a bug in user code -- throwing seems good, although it'd be good to
> throw an Error and not a string (JS tools do better with Errors, e.g. Karma is
> not happy if you throw String, it won't give you a stack trace).

It should be a compiler bug (e.g. List = null;).
I'm not clear on what error cases end up passed through to codegen.
I'll add a todo and fix the exception type.

https://codereview.chromium.org/2039173005/diff/20001/lib/src/compiler/code_g...
lib/src/compiler/code_generator.dart:2887: // TODO(sra): Fix.
On 2016/06/07 23:04:20, John Messerly wrote:
> Fix what? :)

Done.

[sra1, 2016-06-08 00:09:57]

Description was changed from

==========
Refactoring assignment

The idea is to have more _emitXXX methods, so that different paths for
the same semantic action (e.g. implicit vs explicit 'this') call the
same _emitXXX method.

This is the first (simplest) step: assignments.
==========

to

==========
Refactoring assignment

The idea is to have more _emitXXX methods, so that different paths for
the same semantic action (e.g. implicit vs explicit 'this') call the
same _emitXXX method.

This is the first (simplest) step: assignments.

R=jmesserly@google.com

Committed:
https://github.com/dart-lang/dev_compiler/commit/ed8eaf2ea96a5d0acf28e9f686cf...
==========

[sra1, 2016-06-08 00:10:00]

Committed patchset #2 (id:20001) manually as
ed8eaf2ea96a5d0acf28e9f686cf0391abbee5d8 (presubmit successful).