I'm moving redemo.py here from Demo/tkinter/guido, since it is

somewhat useful to learn regular expressions, and this way it'll be
installed on Windows.

This closes bug report 115609.

Tools/scripts/redemo.py

+"""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: %s" % (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()