Python directory recursion with conditional function - python-2.7

Question

I am working on a function that will recurse a directory tree from a given starting point over a given number of directory levels and return files and/or folders as a list. I want to have the option of passing a condition to this function to be evaluated for each file or folder before it is added to the list. For example, I may want my function to return only a list of files with the extension '.py', or I might want only filenames that match with some regex expression.
My code below works fine without passing any conditions to get_items(), but when using conditions I am unable to get any files and folders below the top directory, regardless of what recursion_level is set to.
If the condition and condition args are set to None, the code below prints a list of all '.py' files found in the top four directory levels. With the given arguments, though, only '.py' files in the top directory are captured.
It seems that the code under if depth != 0: in def get_items() is not being executed when a condition is given
#! /usr/bin/env python
import os
import os.path as path
import re
### --------------------------------------------------
### DEFINE DIRECTORY RECURSION METHODS:
# Get files and/or directories from input dir (defines a generator object)
# (Solution inspired by post & comments at stackoverflow.com/questions/35315873)
def get_items(input_dir,mode='f',depth=0,condition=None,arg=None,show_hidden=False):
dirs,files = {},{}
# Use dictionary to assign generator outputs from mode
modes = {'f':files,'d':dirs,'w':(input_dir,dirs,files)}
dir_list = os.listdir(input_dir)
# print '\nDIRECTORY "{}" CONTAINS {} FILES.'.format(path.basename(input_dir),len(dir_list))
for name in dir_list:
# Ignore hidden files (Mac OS)
if name.startswith('.') and not show_hidden:
continue
# print '\t',name
path_name = path.join(input_dir,name)
# Check if file satisfies the given conditional function
if condition and not condition(*((path_name,arg) if arg else (path_name,))):
continue
# Append item to appropriate dictionary with 'name' as key and 'path' as value
(dirs if path.isdir(path_name) else files)[name]=path_name
yield modes[mode]
# If depth not yet zero, call the function for the next level down
if depth != 0:
# print '\nFOUND {} SUBDIRECTORIES TO PROCESS:'.format(len(dirs))
for d in dirs:
for i in get_items(dirs[d],mode,depth-1,condition,arg,show_hidden):
yield i
# Parse output from get_items() to simple lists
def parse_trees(dir_trees):
all_dirs,all_files = [],[]
for tree in dir_trees:
obj_type = type(tree)
# If a tuple object is encountered (walk mode)
if obj_type is tuple:
# top = tree[0]
dirs,files = [branch.values() for branch in tree[1:]]
# If a dictionary is encountered (files or dirs mode)
elif obj_type is dict:
dirs,files = [],[]
for branch in tree:
# Access dictionary values to get path
branch_path = tree[branch]
# Append path to appropriate list
(dirs if path.isdir(branch_path) else files).append(branch_path)
# print branch
all_dirs += dirs
all_files += files
return all_files,all_dirs
### --------------------------------------------------
### DEFINE FILE CONDITION CHECKS:
# Check the basename of a given file for a regex pattern match
def pattern_check(file_path,pattern):
filename = path.split(file_path)[1]
# basename,ext = path.splitext(filename)
return (True if re.search(pattern,filename) else False)
# Check for the extension in a given list argument
def ext_check(file_path,extensions):
filename = path.split(file_path)[1]
basename,ext = path.splitext(filename)
return (True if ext in extensions else False)
### --------------------------------------------------
### EXECUTE:
mydir = os.getcwd()
recursion_depth = 3
condition_method,condition_arg = ext_check,['.py']
dir_trees = get_items(mydir,'f',recursion_depth,condition_method,condition_arg,False)
file_list,dir_list = parse_trees(dir_trees)
if dir_list:
print '\nDIRS:'
for d in dir_list:
print '\t',d
if file_list:
print '\nFILES:'
for f in file_list:
print '\t',f
print '\n'