Reviewed-by: thiago

the "namespace" created by the prefix is supposed to be cleared before
new values are added.

we are so fast now, we can burn a few cycles again ... :}

variable names are mapped as soon as they become known (and not when
using them). that sprinkles map() calls everywhere, but it's faster.

Task-number: QTCREATORBUG-229

- match just the spec name without a possible path
- resolve the default spec

unfortunately, the efforts to use only absolute paths internally became
externally visible ...

previously, the entire value hash was simply pushed on a stack upon
entering a custom function. the problem with that was that setting the
function's argument already detached (i.e., copied) the entire hash.
so instead store only actually modified values in nested scopes and let
lookups cascade to parent scopes.

improvement: 2% for qt, 15% for creator ...

it is extremely unlikely that a function would change one of the
interesting variables (all types of source file lists) but not re-export
them subsequently. thus the scoping only complicates matters and burns
cpu cycles.

we ignore the tiny possibility that this could illegitimately reset a
list while doing exact parsing - the subsequent cumulative parsing would
most likely catch these files again anyway.

these values do not require evaluating magic variables. the semantics
would be totally unclear anyway.

the last step was moving the statics to a common class which is
initialized at startup.

Only revert stuff that is linked to fast string concat.

This reverts commit e70530c5. It
did break builds on older gcc versions (gcc 4.1.2 64 bit Linux,
gcc 4.0.1 on Mac OS X):

parser/qmljsgrammar_p.h: In static member function ???static int
QmlJSGrammar::nt_action(int, int)???:
parser/qmljsgrammar_p.h:188: error: ???QmlJSGrammar::<anonymous enum>???
is/uses anonymous type
parser/qmljsgrammar_p.h:188: error:   trying to instantiate
???template<class T> struct QConcatenable???
...

Reviewed-by: Oswald Buddenhagen

this makes the i/o part of the evaluator thread-safe.
for safety, assert absolute paths in IoUtils::exists().

on the way, i "stole" some code i wrote for KDE. there have been no
copyright-worthy contributions from others to it, so this is legal.

somewhat faster again

now items have no vtable any more

it's overengineered for our purpose and would just get in the way of
planned optimizations.

use a hash of magic variable names to ints, which allows fast lookup
followed by a jump table dispatch

doing it in 1.3 as well to avoid possible later conflicts

potentially reduces the number of file::exists() calls

partly by removing unnecessary calls, partly by providing minimalistic
reimplementations.
this gives a quite incredible performance boost ...

this gives a rather impressive speed boost.
if qmake wasn't trying to be so clever, we could get even more
out of this.

that way we save the creation of a temporary stringlist

now that we know the size of the entire file, we can use a single fixed
buffer instead of growing one on-demand - in the case where we just read
the file, we can even re-use the file buffer itself.
this should improve performance for files with very many line
continuations, but the practical impact drowns in the noise.
anyway, the code is nicer, as we don't abuse qstring that obviously any
more.