#!/usr/bin/env python3

"""Basic regular expression demonstration facility (Perl style syntax)."""

from tkinter import *
import re

class ReDemo:

 def __init__(self, master):
 self.master = master

 self.promptdisplay = Label(self.master, anchor=W,
 text="Enter a Perl-style regular expression:")
 self.promptdisplay.pack(side=TOP, fill=X)

 self.regexdisplay = Entry(self.master)
 self.regexdisplay.pack(fill=X)
 self.regexdisplay.focus_set()

 self.addoptions()

 self.statusdisplay = Label(self.master, text="", anchor=W)
 self.statusdisplay.pack(side=TOP, fill=X)

 self.labeldisplay = Label(self.master, anchor=W,
 text="Enter a string to search:")
 self.labeldisplay.pack(fill=X)
 self.labeldisplay.pack(fill=X)

 self.showframe = Frame(master)
 self.showframe.pack(fill=X, anchor=W)

 self.showvar = StringVar(master)
 self.showvar.set("first")

 self.showfirstradio = Radiobutton(self.showframe,
 text="Highlight first match",
 variable=self.showvar,
 value="first",
 command=self.recompile)
 self.showfirstradio.pack(side=LEFT)

 self.showallradio = Radiobutton(self.showframe,
 text="Highlight all matches",
 variable=self.showvar,
 value="all",
 command=self.recompile)
 self.showallradio.pack(side=LEFT)

 self.stringdisplay = Text(self.master, width=60, height=4)
 self.stringdisplay.pack(fill=BOTH, expand=1)
 self.stringdisplay.tag_configure("hit", background="yellow")

 self.grouplabel = Label(self.master, text="Groups:", anchor=W)
 self.grouplabel.pack(fill=X)

 self.grouplist = Listbox(self.master)
 self.grouplist.pack(expand=1, fill=BOTH)

 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 ('IGNORECASE',
 'MULTILINE',
 'DOTALL',
 'VERBOSE'):
 if len(self.boxes) % 3 == 0:
 frame = Frame(self.master)
 frame.pack(fill=X)
 self.frames.append(frame)
 val = getattr(re, name).value
 var = IntVar()
 box = Checkbutton(frame,
 variable=var, text=name,
 offvalue=0, onvalue=val,
 command=self.recompile)
 box.pack(side=LEFT)
 self.boxes.append(box)
 self.vars.append(var)

 def getflags(self):
 flags = 0
 for var in self.vars:
 flags = flags | var.get()
 flags = flags
 return flags

 def recompile(self, event=None):
 try:
 self.compiled = re.compile(self.regexdisplay.get(),
 self.getflags())
 bg = self.promptdisplay['background']
 self.statusdisplay.config(text="", background=bg)
 except re.error as msg:
 self.compiled = None
 self.statusdisplay.config(
 text="re.error: %s" % str(msg),
 background="red")
 self.reevaluate()

 def reevaluate(self, event=None):
 try:
 self.stringdisplay.tag_remove("hit", "1.0", END)
 except TclError:
 pass
 try:
 self.stringdisplay.tag_remove("hit0", "1.0", END)
 except TclError:
 pass
 self.grouplist.delete(0, END)
 if not self.compiled:
 return
 self.stringdisplay.tag_configure("hit", background="yellow")
 self.stringdisplay.tag_configure("hit0", background="orange")
 text = self.stringdisplay.get("1.0", END)
 last = 0
 nmatches = 0
 while last <= len(text):
 m = self.compiled.search(text, last)
 if m is None:
 break
 first, last = m.span()
 if last == first:
 last = first+1
 tag = "hit0"
 else:
 tag = "hit"
 pfirst = "1.0 + %d chars" % first
 plast = "1.0 + %d chars" % last
 self.stringdisplay.tag_add(tag, pfirst, plast)
 if nmatches == 0:
 self.stringdisplay.yview_pickplace(pfirst)
 groups = list(m.groups())
 groups.insert(0, m.group())
 for i in range(len(groups)):
 g = "%2d: %r" % (i, groups[i])
 self.grouplist.insert(END, g)
 nmatches = nmatches + 1
 if self.showvar.get() == "first":
 break

 if nmatches == 0:
 self.statusdisplay.config(text="(no match)",
 background="yellow")
 else:
 self.statusdisplay.config(text="")


# Main function, run when invoked as a stand-alone Python program.

def main():
 root = Tk()
 demo = ReDemo(root)
 root.protocol('WM_DELETE_WINDOW', root.quit)
 root.mainloop()

if __name__ == '__main__':
 main()