[webkit-reviews] review denied: [Bug 37698] Line not wrapped at certain punctuations : [Attachment 62400] Updated patch
bugzilla-daemon at webkit.org
bugzilla-daemon at webkit.org
Sun Jul 25 19:00:03 PDT 2010
mitz at webkit.org has denied Xianzhu Wang <phnixwxz at gmail.com>'s request for
review:
Bug 37698: Line not wrapped at certain punctuations
https://bugs.webkit.org/show_bug.cgi?id=37698
Attachment 62400: Updated patch
https://bugs.webkit.org/attachment.cgi?id=62400&action=review
------- Additional Comments from mitz at webkit.org
> +static const int asciiLineBreakTableFirstChar = '!';
> +static const int asciiLineBreakTableLastChar = 127;
Perhaps UChar is a more appropriate type for these. Can we define the latter in
terms of the size of asciiLineBreakTable, or compile-time assert that the size
matches the constants?
> +// Pack 8 bits into one byte
> +#define B(a, b, c, d, e, f, g, h) \
> + ((a) | ((b) << 1) | ((c) << 2) | ((d) << 3) | ((e) << 4) | ((f) << 5) |
((g) << 6) | ((h) << 7))
I wonder if the memory savings are worth the extra work at runtime for shifting
bits. I guess if there’s no measurable performance regression then it doesn’t
matter.
> +// Line breaking table row for each digit (0-9)
> +#define DI { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
> +
> +// Line breaking table row for ascii letters (a-z A-Z)
> +#define AL { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 }
> +
> +#define F 0xFF
> +
> +// Line breaking table for printable ASCII characters. Most part of the
table is compatibile with Firefox 3.6,
> +// except that the rows '-' and '?' still remain the behaviors before this
change.
People reading this comment in the future will not know what “this change” is.
I think it’s useful, when describing the behavior, to refer to the Unicode
standard and to other browser engines, and call out the differences.
>
This is a trade-off between
> +// compatibility with other browsers and backward-compatibility. Additional
line break opportunities are added
> +// at least as possible.
I am not sure what the last sentence means. The least possible additional line
breaking opportunities would be zero.
> +static const unsigned char asciiLineBreakTable[][12] = {
> + // ! " # $ % & ' ( ) * + , - . / 0 1-8 9 : ; <
= > ? @ A-X Y Z [ \ ] ^ _ ` a-x y z { | } ~
DEL
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // !
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // "
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // #
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // $
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // %
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // &
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // '
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // (
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // )
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // *
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // +
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // ,
> + { B(1, 1, 1, 1, 1, 1, 1, 1), B(1, 1, 1, 1, 1, 1, 1, 1), F, B(1, 1, 1, 1,
1, 1, 1, 1), F, F, F, B(1, 1, 1, 1, 1, 1, 1, 1), F, F, F, B(1, 1, 1, 1, 1, 1,
1, 1) }, // -
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // .
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // /
> + DI, DI, DI, DI, DI, DI, DI, DI, DI, DI, // 0-9
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // :
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // ;
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // <
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // =
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // >
> + { B(0, 0, 1, 1, 1, 1, 0, 1), B(0, 1, 1, 0, 1, 0, 0, 1), F, B(1, 0, 0, 1,
1, 1, 0, 1), F, F, F, B(1, 1, 1, 1, 0, 1, 1, 1), F, F, F, B(1, 1, 1, 1, 0, 1,
1, 0) }, // ?
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // @
> + AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL,
AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, // A-Z
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // [
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // '\'
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // ]
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // ^
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // _
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // `
> + AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL,
AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, AL, // a-z
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // {
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // |
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // }
> + { B(0, 0, 0, 0, 0, 0, 0, 1), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 1,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 1, 0, 0, 0,
0, 0) }, // ~
> + { B(0, 0, 0, 0, 0, 0, 0, 0), B(0, 0, 0, 0, 0, 0, 0, 0), 0, B(0, 0, 0, 0,
0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0, 0, 0), 0, 0, 0, B(0, 0, 0, 0, 0, 0,
0, 0) }, // DEL
> +};
Please #undef the macros (B, AL, DI, F) here.
> + default:
> + // If both ch and nextCh are ASCII characters, use a lookup table
for enhanced speed and for compatibility
> + // with Internet Explorer 8 compatible mode.
Is there such a thing as “Internet Explorer 8 compatible mode”? What is it
compatible with? Can we just say that this is done for compatibility with that
thing? It’s slightly confusing to read about IE8 here and about Firefox above.
I suggest putting all the specifics of the table in one place. Here it’s enough
to say that we use the lookup table because it’s faster and it has different
rules from the Unicode specification.
> + if (ch >= asciiLineBreakTableFirstChar && ch <=
asciiLineBreakTableLastChar
> + && nextCh >= asciiLineBreakTableFirstChar && nextCh <=
asciiLineBreakTableLastChar) {
> + const unsigned char* tableRow = asciiLineBreakTable[ch -
asciiLineBreakTableFirstChar];
> + int nextChIndex = nextCh - asciiLineBreakTableFirstChar;
> + unsigned char b = tableRow[nextChIndex / 8];
> + return (b >> (nextChIndex % 8)) & 1;
To me, the expression
b & (1 << (nextChIndex % 8))
(with a corresponding change to the B macro) is clearer than the one you wrote,
but I guess that’s just a matter of personal preference.
Have you tested this patch for performance impact?
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