More Constraints
Just before and
just after are another
useful pair of constraints.
Just before selects a
region matching the first pattern only if it appears immediately
before a region matching the second pattern. The regions can be
separated by spaces and linebreaks, but not by letters or
punctuation. For example:
State just before ZipCode
Try this pattern now. You should see it select "PA" and "MA", but not
"Massachusetts" because it doesn't appear immediately before a region
matching ZipCode.
Jared L. Cohon
Carnegie Mellon University
5000 Forbes Ave
Pittsburgh PA 15213
Charles M. Vest
Massachusetts Institute of Technology
77 Massachusetts Ave
Cambridge MA 02139
Just after is opposite in sense to
just before,
so
ZipCode just after State would select the ZIP codes instead.
Starting and
ending are also useful
constraints.
Starting selects a region only if it
starts at the same place as a region matching the second pattern.
For
ending, the regions must end at the same place.
For example:
Word starting "c"
Try this pattern now. You should see it select every word in the page
that starts with the letter
c.
Other constraints are also available, including
anywhere before,
anywhere
after, and
equal to. You'll find a complete
list of constraints in the pattern language reference at the end of
this tutorial.
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