html: simplify and optimize escape/unescape
The html package uses some specific code to escape special characters.
Actually, the strings.Replacer can be used instead, and is much more
efficient. The converse operation is more complex but can still be
slightly optimized.
Credits to Ken Bloom (kabloom@google.com), who first submitted a
similar patch at https://codereview.appspot.com/
141930043
Added benchmarks and slightly optimized UnescapeString.
benchmark old ns/op new ns/op delta
BenchmarkEscape-4 118713 19825 -83.30%
BenchmarkEscapeNone-4 87653 3784 -95.68%
BenchmarkUnescape-4 24888 23417 -5.91%
BenchmarkUnescapeNone-4 14423 157 -98.91%
benchmark old allocs new allocs delta
BenchmarkEscape-4 9 2 -77.78%
BenchmarkEscapeNone-4 0 0 +0.00%
BenchmarkUnescape-4 2 2 +0.00%
BenchmarkUnescapeNone-4 0 0 +0.00%
benchmark old bytes new bytes delta
BenchmarkEscape-4 24800 12288 -50.45%
BenchmarkEscapeNone-4 0 0 +0.00%
BenchmarkUnescape-4 10240 10240 +0.00%
BenchmarkUnescapeNone-4 0 0 +0.00%
Fixes #8697
Change-Id: I208261ed7cbe9b3dee6317851f8c0cf15528bce4
Reviewed-on: https://go-review.googlesource.com/9808
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>