According to Ilya Zakharevich:
Chip Salzenberg writes:
In contrast, working frame-based, I only need walk the attribute tree,
find the attributes that apply to the given characters, and copy them.
That's O(log N) or so -- certainly better than O(N). More
significantly, it requires *no* knowledge of metadata semantics.
Same for inline data. There is absolutely no difference between
semantic of having metadata inline or separate.
I disagree. Before you try to make this assertion again, please
explain how Perl would properly handle the 'll' case with code-based
metadata. Be sure to allow for the various kinds of metadata nesting
behavior: <b> doesn't nest, <li> nests, and <p> marks a spot instead
of a region. And Perl's RE and other character-processing engines
need to know this to handle them properly in the 'll' case.
Who cares how is it implemented? We discuss *semantic* here.
You've missed the point. Big time.
Here is the point, in large friendly letters for clarity:
* The Perl Runtime Should Not Have To Know *
* About Nesting Behaviors of Metadata *
Since <ul> (not <li>, thinko above, sorry) nests, whereas <b> doesn't,
and <p> marks a spot so nesting is not a relevant question.
Therefore, proper extraction of '<b>ll</b>' from '<b>hello</b>' would
require Perl to (1) be aware of the nesting behaviors of embedded
codes, and (2) keep track of the current state of all those attributes
at any point in a string.
I find both of these implications unacceptable.
(1) Knowledge of specific metadata encoding schemes does not belong in
the Perl source code. Period.
(2) Imposing metadata state tracking on every non-trivial regex is
also unacceptable. ("Non-trivial" in this context means "using memory
parens or metadata queries". Note also that using "$&" even once
imposes memory-paren-like behavior on _all_ regexes.)
btree approach is acceptable in the sense that *any* operation gets a
small-multiplier (say, x20) slow-down only.
You cannot be taken seriously if you say "times 20". That's impossible.
--
Chip Salzenberg - a.k.a. -
<chip(_at_)perlsupport(_dot_)com>
"... under cover of afternoon in the biggest car in the county?!" //MST3K
