Add utils.isdir(fs,path,info) and utils.isfile(fs,path.info).

These helper functions can often tell the type of a path by inspecting the
info dict (e.g. checking flags in st_mode) and can thus avoid an additional
query to the filesystem.  They fall back to calling fs.isdir() or fs.isfile()
if the info dict doesn't give any clues.

ChangeLog

@@ -56,4 +56,7 @@
     * MountFS: added support for mounting at the root directory, and for
       mounting over an existing mount.
     * Added 'getpathurl' and 'haspathurl' methods
+    * Added utils.isdir(fs,path,info) and utils.isfile(fs,path,info); these
+      can often determine whether a path is a file or directory by inspecting
+      the info dict and avoid an additional query to the filesystem.
 

fs/utils.py

@@ -15,6 +15,7 @@ __all__ = ['copyfile',
 import shutil
 import os
 import sys
+import stat
 from fs.mountfs import MountFS
 from fs.path import pathjoin, pathsplit
 from fs.errors import DestinationExistsError
@@ -180,6 +181,38 @@ def countbytes(fs):
     return total
 
 
+def isdir(fs,path,info=None):
+    """Check whether a path within a filesystem is a directory.
+
+    If you're able to provide the info dict for the path, this may be possible
+    without querying the filesystem (e.g. by checking st_mode).
+    """
+    if info is not None:
+        st_mode = info.get("st_mode")
+        if st_mode:
+            if stat.S_ISDIR(st_mode):
+                return True
+            if stat.S_ISREG(st_mode):
+                return False
+    return fs.isdir(path)
+
+
+def isfile(fs,path,info=None):
+    """Check whether a path within a filesystem is a file.
+
+    If you're able to provide the info dict for the path, this may be possible
+    without querying the filesystem (e.g. by checking st_mode).
+    """
+    if info is not None:
+        st_mode = info.get("st_mode")
+        if st_mode:
+            if stat.S_ISREG(st_mode):
+                return True
+            if stat.S_ISDIR(st_mode):
+                return False
+    return fs.isfile(path)
+
+
 def find_duplicates(fs,
                     compare_paths=None,
                     quick=False,