'''Define SearchEngine for search dialogs.'''

import re

from tkinter import StringVar, BooleanVar, TclError

from tkinter import messagebox

def get(root):

'''Return the singleton SearchEngine instance for the process.

The single SearchEngine saves settings between dialog instances.

If there is not a SearchEngine already, make one.

'''

if not hasattr(root, "_searchengine"):

root._searchengine = SearchEngine(root)

# This creates a cycle that persists until root is deleted.

return root._searchengine

class SearchEngine:

"""Handles searching a text widget for Find, Replace, and Grep."""

def __init__(self, root):

'''Initialize Variables that save search state.

The dialogs bind these to the UI elements present in the dialogs.

'''

self.root = root # need for report_error()

self.patvar = StringVar(root, '') # search pattern

self.revar = BooleanVar(root, False) # regular expression?

self.casevar = BooleanVar(root, False) # match case?

self.wordvar = BooleanVar(root, False) # match whole word?

self.wrapvar = BooleanVar(root, True) # wrap around buffer?

self.backvar = BooleanVar(root, False) # search backwards?

# Access methods

def getpat(self):

return self.patvar.get()

def setpat(self, pat):

self.patvar.set(pat)

def isre(self):

return self.revar.get()

def iscase(self):

return self.casevar.get()

def isword(self):

return self.wordvar.get()

def iswrap(self):

return self.wrapvar.get()

def isback(self):

return self.backvar.get()

# Higher level access methods

def setcookedpat(self, pat):

"Set pattern after escaping if re."

# called only in search.py: 66

if self.isre():

pat = re.escape(pat)

self.setpat(pat)

def getcookedpat(self):

pat = self.getpat()

if not self.isre(): # if True, see setcookedpat

pat = re.escape(pat)

if self.isword():

pat = r"\b%s\b" % pat

return pat

def getprog(self):

"Return compiled cooked search pattern."

pat = self.getpat()

if not pat:

self.report_error(pat, "Empty regular expression")

return None

pat = self.getcookedpat()

flags = 0

if not self.iscase():

flags = flags | re.IGNORECASE

try:

prog = re.compile(pat, flags)

except re.PatternError as e:

self.report_error(pat, e.msg, e.pos)

return None

return prog

def report_error(self, pat, msg, col=None):

# Derived class could override this with something fancier

msg = "Error: " + str(msg)

if pat:

msg = msg + "\nPattern: " + str(pat)

if col is not None:

msg = msg + "\nOffset: " + str(col)

messagebox.showerror("Regular expression error",

msg, master=self.root)

def search_text(self, text, prog=None, ok=0):

'''Return (lineno, matchobj) or None for forward/backward search.

This function calls the right function with the right arguments.

It directly return the result of that call.

Text is a text widget. Prog is a precompiled pattern.

The ok parameter is a bit complicated as it has two effects.

If there is a selection, the search begin at either end,

depending on the direction setting and ok, with ok meaning that

the search starts with the selection. Otherwise, search begins

at the insert mark.

To aid progress, the search functions do not return an empty

match at the starting position unless ok is True.

'''

if not prog:

prog = self.getprog()

if not prog:

return None # Compilation failed -- stop

wrap = self.wrapvar.get()

first, last = get_selection(text)

if self.isback():

if ok:

start = last

else:

start = first

line, col = get_line_col(start)

res = self.search_backward(text, prog, line, col, wrap, ok)

else:

if ok:

start = first

else:

start = last

line, col = get_line_col(start)

res = self.search_forward(text, prog, line, col, wrap, ok)

return res

def search_forward(self, text, prog, line, col, wrap, ok=0):

wrapped = 0

startline = line

chars = text.get("%d.0" % line, "%d.0" % (line+1))

while chars:

m = prog.search(chars[:-1], col)

if m:

if ok or m.end() > col:

return line, m

line = line + 1

if wrapped and line > startline:

break

col = 0

ok = 1

chars = text.get("%d.0" % line, "%d.0" % (line+1))

if not chars and wrap:

wrapped = 1

wrap = 0

line = 1

chars = text.get("1.0", "2.0")

return None

def search_backward(self, text, prog, line, col, wrap, ok=0):

wrapped = 0

startline = line

chars = text.get("%d.0" % line, "%d.0" % (line+1))

while True:

m = search_reverse(prog, chars[:-1], col)

if m:

if ok or m.start() < col:

return line, m

line = line - 1

if wrapped and line < startline:

break

ok = 1

if line <= 0:

if not wrap:

break

wrapped = 1

wrap = 0

pos = text.index("end-1c")

line, col = map(int, pos.split("."))

chars = text.get("%d.0" % line, "%d.0" % (line+1))

col = len(chars) - 1

return None

def search_reverse(prog, chars, col):

'''Search backwards and return an re match object or None.

This is done by searching forwards until there is no match.

Prog: compiled re object with a search method returning a match.

Chars: line of text, without \\n.

Col: stop index for the search; the limit for match.end().

'''

m = prog.search(chars)

if not m:

return None

found = None

i, j = m.span() # m.start(), m.end() == match slice indexes

while i < col and j <= col:

found = m

if i == j:

j = j+1

m = prog.search(chars, j)

if not m:

break

i, j = m.span()

return found

def get_selection(text):

'''Return tuple of 'line.col' indexes from selection or insert mark.

'''

try:

first = text.index("sel.first")

last = text.index("sel.last")

except TclError:

first = last = None

if not first:

first = text.index("insert")

if not last:

last = first

return first, last

def get_line_col(index):

'''Return (line, col) tuple of ints from 'line.col' string.'''

line, col = map(int, index.split(".")) # Fails on invalid index

return line, col

if __name__ == "__main__":

from unittest import main

main('idlelib.idle_test.test_searchengine', verbosity=2)