Document where the parser uses peeking.

Document where the parser uses peeking.

R=danrubel@google.com

Committed: https://github.com/dart-lang/sdk/commit/2c53bcbf12dfca1bae95531ab60266e757c49604

[ahe, 2017-06-23 13:32:29]

ahe@google.com changed reviewers:
+ danrubel@google.com, johnniwinther@google.com

[ahe, 2017-06-23 13:32:29]

I'm trying to solve the type variable scope issue of generalized function types.
In addition, I'd like to reduce or eliminate peeking (in particular,
findMemberName).

I'm currently pursuing the idea that I can move all peeking into parseType and
pass in a continuation. For example, in parseTypedef:

    token = parseType(token, when: (Token next) => !optional("=", next));

Obviously, I'm worried about what the overhead of passing in a closure or
continuation is, so it is possible that it will just be:

    token = parseType(token, when: "=");

Anyway, to get an overview of what's needed, I surveyed all the places the
parser uses peeking and created this document.

[danrubel, 2017-06-24 21:41:11]

LGTM

[ahe, 2017-06-26 08:17:48]

Description was changed from

==========
Document where the parser uses peeking.
==========

to

==========
Document where the parser uses peeking.

R=danrubel@google.com

Committed:
https://github.com/dart-lang/sdk/commit/2c53bcbf12dfca1bae95531ab60266e757c49604
==========

[ahe, 2017-06-26 08:17:49]

Committed patchset #1 (id:1) manually as
2c53bcbf12dfca1bae95531ab60266e757c49604 (presubmit successful).