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"""Basic regular expression demostration facility.
This displays a window with two type-in boxes. In the top box, you enter a
regular expression. In the bottom box, you enter a string. The first
match in the string of the regular expression is highlighted with a yellow
background (or red if the match is empty -- then the character at the match
is highlighted). The highlighting is continuously updated. At the bottom
are a number of checkboxes which control the regular expression syntax used
(see the regex_syntax module for descriptions). When there's no match, or
when the regular expression is syntactically incorrect, an error message is
displayed.
"""
from Tkinter import *
import regex
import regex_syntax
class RegexDemo:
def __init__(self, master):
self.master = master
self.topframe = Frame(self.master)
self.topframe.pack(fill=X)
self.promptdisplay = Label(self.topframe, text="Enter a string:")
self.promptdisplay.pack(side=LEFT)
self.statusdisplay = Label(self.topframe, text="", anchor=W)
self.statusdisplay.pack(side=LEFT, fill=X)
self.regexdisplay = Entry(self.master)
self.regexdisplay.pack(fill=X)
self.regexdisplay.focus_set()
self.labeldisplay = Label(self.master, anchor=W,
text="Enter a string:")
self.labeldisplay.pack(fill=X)
self.labeldisplay.pack(fill=X)
self.stringdisplay = Text(self.master, width=60, height=4)
self.stringdisplay.pack(fill=BOTH, expand=1)
self.stringdisplay.tag_configure("hit", background="yellow")
self.addoptions()
self.regexdisplay.bind('<Key>', self.recompile)
self.stringdisplay.bind('<Key>', self.reevaluate)
self.compiled = None
self.recompile()
btags = self.regexdisplay.bindtags()
self.regexdisplay.bindtags(btags[1:] + btags[:1])
btags = self.stringdisplay.bindtags()
self.stringdisplay.bindtags(btags[1:] + btags[:1])
def addoptions(self):
self.frames = []
self.boxes = []
self.vars = []
for name in ( 'RE_NO_BK_PARENS',
'RE_NO_BK_VBAR',
'RE_BK_PLUS_QM',
'RE_TIGHT_VBAR',
'RE_NEWLINE_OR',
'RE_CONTEXT_INDEP_OPS'):
if len(self.boxes) % 3 == 0:
frame = Frame(self.master)
frame.pack(fill=X)
self.frames.append(frame)
val = getattr(regex_syntax, name)
var = IntVar()
box = Checkbutton(frame,
variable=var, text=name,
offvalue=0, onvalue=val,
command=self.newsyntax)
box.pack(side=LEFT)
self.boxes.append(box)
self.vars.append(var)
def newsyntax(self):
syntax = 0
for var in self.vars:
syntax = syntax | var.get()
regex.set_syntax(syntax)
self.recompile()
def recompile(self, event=None):
try:
self.compiled = regex.compile(self.regexdisplay.get())
self.statusdisplay.config(text="")
except regex.error, msg:
self.compiled = None
self.statusdisplay.config(text="regex.error: %s" % str(msg))
self.reevaluate()
def reevaluate(self, event=None):
try:
self.stringdisplay.tag_remove("hit", "1.0", END)
except TclError:
pass
if not self.compiled:
return
text = self.stringdisplay.get("1.0", END)
i = self.compiled.search(text)
if i < 0:
self.statusdisplay.config(text="(no match)")
else:
self.statusdisplay.config(text="")
regs = self.compiled.regs
first, last = regs[0]
if last == first:
last = first+1
self.stringdisplay.tag_configure("hit",
background="red")
else:
self.stringdisplay.tag_configure("hit",
background="yellow")
pfirst = "1.0 + %d chars" % first
plast = "1.0 + %d chars" % last
self.stringdisplay.tag_add("hit", pfirst, plast)
self.stringdisplay.yview_pickplace(pfirst)
# Main function, run when invoked as a stand-alone Python program.
def main():
root = Tk()
demo = RegexDemo(root)
root.protocol('WM_DELETE_WINDOW', root.quit)
root.mainloop()
if __name__ == '__main__':
main()
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