While at it, let's get rid of the unescaping in TrivialPattern which was
buggy anyway: special operators such as \b were misinterpreted as trivial
patterns.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Originally, this developer wanted to (ab)use the PikeVM with a
hand-crafted program and an added "callback" opcode to parse the regular
expressions.
However, this turned out to be completely unnecessary: there are no
ambiguities in regular expression patterns, so there is no need to do
anything else than parse the pattern, one character at a time, into a
nested expression that then knows how to write itself into a program for
the PikeVM.
For the moment, we still hardcode the program for the regular expression
pattern demonstrating the challenge with the prioritized threads because
the compiler cannot yet parse reluctant operators.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Among other challenges, this regular expression is designed to demonstrate
that thread prioritization is finicky: Given the string 'aaaaaa' to match,
the first four threads will try to grab the second 'a', the third thread
(the one that matched the '(a??)' group) having scheduled the same
instruction pointer to the '(a+)' group that the second -- higher-priority
-- thread will try to advance to only after processing the '(a??)' group's
SPLIT. The second thread must override the third thread in that case,
essentially stopping the latter.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Instead of having an opcode 'CHAR', let's have the opcodes that fall
within the range of a char *be* the opcode 'match this character'.
While at it, break the ranges of the different types of opcodes apart
into ranges so that related operations are clustered.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Based on the just-implemented PikeVM, let's test it with a specific
regular expression. At this point, no parsing is implemented but instead
an explicit program executing a(bb)?a is hardcoded.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
This makes both the Pattern and the Matcher class abstract so that more
specialized patterns than the trivial patterns we support so far can be
implemented as convenient subclasses of the respective abstract base
classes.
To ease development, we work on copies in test/regex/ in the 'regex'
package. That way, it can be developed in Eclipse (because it does not
interfere with Oracle JRE's java.util.regex.* classes).
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
