(Lianja) Unzip One File to a Stream

Demonstrates how to unzip a particular file contained within a .zip archive to a Chilkat stream.

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// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

loZip = createobject("CkZip")

// First open a .zip.
llSuccess = loZip.OpenZip("qa_data/hamlet.zip")
if (llSuccess <> .T.) then
    ? loZip.LastErrorText
    release loZip
    return
endif

// Find the entry to be unzipped to a stream..
loEntry = loZip.FirstMatchingEntry("*hamlet.xml")
if (loZip.LastMethodSuccess <> .T.) then
    ? loZip.LastErrorText
    release loZip
    return
endif

// There are three ways we can unzip (inflate) to a stream.
// 
// 1) Set a sink file on the stream object and call UnzipToStream synchronously.
//    This unzips to the stream's sink (which is to simply unzip to a file in the filesystem).
// 
// 2) Create a stream object and call UnzipToStreamAsync.  This starts the unzip in a background
//    thread (after Task.Run is called).  Your application can then read the unzipped (inflated) file
//    directly from the stream.
// 
// 3) (not shown in this example) Unzip to a stream object that is the source of something else.
//    

// ----------------------------------------------------------------
// Case 1: Unzip to a file by setting the sink of streamA to a file.
loStreamA = createobject("CkStream")
loStreamA.SinkFile = "qa_output/hamletA.xml"

llSuccess = loEntry.UnzipToStream(loStreamA)
if (llSuccess <> .T.) then
    ? loEntry.LastErrorText
    release loEntry
    release loZip
    release loStreamA
    return
endif

// Close the stream to close the output file.
llSuccess = loStreamA.WriteClose()

// ----------------------------------------------------------------
// Case 2a: Uzip to a stream asynchronously. 
loStreamB = createobject("CkStream")

loUnzipTask = loEntry.UnzipToStreamAsync(loStreamB)
if (loEntry.LastMethodSuccess <> .T.) then
    ? loEntry.LastErrorText
    release loEntry
    release loZip
    release loStreamA
    release loStreamB
    return
endif

// Start the background unzip thread.
loUnzipTask.Run()

// Read the stream.  (this is reading the unzipped file data)
loSb = createobject("CkStringBuilder")
do while loStreamB.EndOfStream <> .T.
    // Each call to ReadSb appends to the contents of sb.
    loStreamB.ReadSb(loSb)
enddo
loSb.WriteFile("qa_output/hamletB.xml","utf-8",.F.)

release loUnzipTask
? "Success."

// ----------------------------------------------------------------
// Case 2b: Uzip to a stream asynchronously and emit output while reading. 
loStreamC = createobject("CkStream")

loUnzipTask = loEntry.UnzipToStreamAsync(loStreamC)
if (loEntry.LastMethodSuccess <> .T.) then
    ? loEntry.LastErrorText
    release loEntry
    release loZip
    release loStreamA
    release loStreamB
    release loSb
    release loStreamC
    return
endif

loUnzipTask.Run()

do while loStreamC.EndOfStream <> .T.
    s = loStreamC.ReadString()
    ? s
enddo

release loEntry
release loUnzipTask
? "Success."


release loZip
release loStreamA
release loStreamB
release loSb
release loStreamC