"""Basic regular expression demostration 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',

                     'LOCALE',

                     '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)

            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, 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()