code review 6454150: go/scanner: faster scanning

go/scanner: faster scanning

Optimize some common cases.

benchmark            old ns/op    new ns/op    delta
BenchmarkScanFile       718907       667960   -7.09%

benchmark             old MB/s     new MB/s  speedup
BenchmarkScanFile        23.03        25.51    1.11x

[gri, 2012-08-14 16:39:28]

Hello r@golang.org (cc: golang-dev@googlegroups.com),

I'd like you to review this change to
https://code.google.com/p/go

[gri, 2012-08-14 16:40:16]

Hello r@golang.org (cc: golang-dev@googlegroups.com),

Please take another look.

[r, 2012-08-14 18:00:14]

LGTM

[gri, 2012-08-14 18:27:00]

*** Submitted as http://code.google.com/p/go/source/detail?r=a14ef77ab98c ***

go/scanner: faster scanning

Optimize some common cases.

benchmark            old ns/op    new ns/op    delta
BenchmarkScanFile       718907       667960   -7.09%

benchmark             old MB/s     new MB/s  speedup
BenchmarkScanFile        23.03        25.51    1.11x

R=r
CC=golang-dev
http://codereview.appspot.com/6454150

[dsymonds, 2012-09-05 07:13:06]

This CL introduced a regression. This program:
  package x
  import "time"
  const μs = time.Microsecond
no longer parses; the "μs" is not present in the AST.

[dsymonds, 2012-09-05 07:17:25]

I filed http://code.google.com/p/go/issues/detail?id=4043. I'm going
to take a quick stab at it now.

[dsymonds, 2012-09-05 07:21:26]

Sorry for the noise. Apparently I was using a client that was synced between
this bug-introducing CL and the CL that fixed it.