> This is a good point, and it suggests that we should simply add an Items
> (and TrueItems) extension method to FolderItem and have done with it.
> This is trivial to do; no need to wait for RS to add it for us.
I think it's somewhere between trivial and satisfying. :) Using
built-in RB functions is easy but slow on Windows if there are
hundreds of children. Constructing FolderItems was the bottleneck in
my tests.
I adapted some of Aaron's code (along with advice from this list) to
greatly speed this up on Windows by returning only the child names,
which can be further filtered so as to create only the FolderItems
that you need. What follows is the resulting ItemNames function, with
a bonus IsHidden function that reflects what I have learned about
hidden files on Mac and Windows. Comments on both are welcome.
==============
Function ItemNames(extends f as folderItem, ReturnFileNames as boolean
= true, ReturnFolderNames as boolean = true) As String()
// Returns an array containing the names of child items
// within the given folder item. Returns files and/or
// folders, as directed by the input booleans.
//
// Returns an empty array if f doesn't exist, or if f
// isn't a directory, or if both input booleans are false.
//
// The iteration is not recursive. On Windows, the special
// directories "." and ".." are ignored.
dim result() as string
if f.Directory then
#if TargetWin32
// On Windows, RB's f.Item(i) is slow for folders with large
// child item counts, so we use Declares on Windows instead.
// Adapted from Aaron Ballman - see http://tinyurl.com/5susum
Soft Declare Function FindFirstFileA Lib "Kernel32" (path as
CString, data as Ptr) as Integer
Soft Declare Function FindFirstFileW Lib "Kernel32" (path as
WString, data as Ptr) as Integer
Soft Declare Function FindNextFileA Lib "Kernel32" (handle as
Integer, data as Ptr) as Boolean
Soft Declare Function FindNextFileW Lib "Kernel32" (handle as
Integer, data as Ptr) as Boolean
Declare Sub FindClose Lib "Kernel32" (handle as Integer)
dim UnicodeIsAvailable as boolean =
System.IsFunctionAvailable("FindFirstFileW", "Kernel32")
dim ChildData as MemoryBlock // WIN32_FIND_DATA struct
dim ChildHandle as integer
if UnicodeIsAvailable then
ChildData = new MemoryBlock(592)
ChildHandle = FindFirstFileW(f.AbsolutePath + "*.*", ChildData)
else
ChildData = new MemoryBlock(318)
ChildHandle = FindFirstFileA(f.AbsolutePath + "*.*", ChildData)
end if
if ChildHandle <> -1 then
dim ChildAttrs as UInt32 // first 4 bytes of WIN32_FIND_DATA
dim ChildName as string
// Loop through remaining items in the folder.
dim FoundNextChild as Boolean
do // loop through remaining children
ChildAttrs = ChildData.UInt32Value(0)
const NameOffset = 44
if UnicodeIsAvailable then
ChildName = ChildData.WString(NameOffset)
FoundNextChild = FindNextFileW(ChildHandle, ChildData)
else
ChildName = ChildData.CString(NameOffset)
FoundNextChild = FindNextFileA(ChildHandle, ChildData)
end if
// Now that we have its name and attributes, we can decide
// whether this child should be added to our return array.
dim ChildIsFolder as boolean = (ChildAttrs and UInt32(16)) <> 0
if (ReturnFileNames and not ChildIsFolder) or _
(ReturnFolderNames and ChildIsFolder) then
if childName <> "." and childName <> ".." then
result.Append(ChildName)
end if
end if
loop until not FoundNextChild // should really test
GetLastError for ERROR_NO_MORE_FILES
FindClose ChildHandle
end if
#else
// On non-Windows systems, pure RB code seems pretty fast.
dim child as FolderItem
for i as integer = 1 to f.Count
child = f.TrueItem(i)
if (ReturnFileNames and not Child.Directory) or _
(ReturnFolderNames and Child.Directory) then
result.Append child.Name
end if
next i
#endif
end if
return result
End Function
==============
Function IsHidden(extends f as FolderItem, PerformMacOSXCheck as
boolean = true) As Boolean
// Returns true if the indicated item is hidden
// in the Finder on Mac OS X, or in the Explorer
// on Windows.
//
// On Windows or Mac Classic, you could test f.Visible,
// but on Mac OS X, that test isn't sufficient. There
// are two other ways to keep an item from appearing
// in the OS X Finder:
//
// 1) Start the item's name with a '.' character.
// For example, Mac OS X maintains an invisible
// file called ".DS_Store" in each folder.
//
// 2) List the item in a file named ".hidden" (which
// will itself be invisible, according to #1), in
// the same directory as the item to be hidden.
//
// There is a ".hidden" file in the root folder of
// every Mac OS X volume. Any other folder can have
// one too, but they're rare outside the root.
//
// By default, we do the more extensive check, on the
// theory that if you just want the Visible-level check,
// you can just call that. Or you can pass in False
// for PerformMacOSXCheck.
dim Visible as boolean = f.Visible
dim fHidden as folderItem
dim stream as TextInputStream
dim hiddenFiles as string
dim sep as string
// If it's invisible according to the .Visible flag,
// that's good enough on any platform. But if we're
// checking for OS X style visibility, we have to
// dig a little deeper.
if Visible then
if PerformMacOSXCheck then
if f.Name.Left(1) = "." then
Visible = false // starts with "." -> invisible
else
if f.Parent <> nil then // the root is always visible
fHidden = f.Parent.Child(".hidden")
if fHidden <> nil and fHidden.Exists and _
not fHidden.Directory then
stream = fHidden.OpenAsTextFile
if stream <> nil then
sep = chr(10)
hiddenFiles = sep + stream.ReadAll + sep
if hiddenFiles.InStr(sep + f.Name + sep) > 0 then
Visible = false // it's in our ".hidden" list
end if
end if
end if
end if
end if
end if
end if
return not Visible
End Function
==============
lj
_______________________________________________
Unsubscribe or switch delivery mode:
<http://www.realsoftware.com/support/listmanager/>
Search the archives:
<http://support.realsoftware.com/listarchives/lists.html>
|