'''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.error 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 1:
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)
