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/*******************************************************************************
copyright: Copyright (c) 2004 Kris Bell. All rights reserved
license: BSD style: $(LICENSE)
version: Mar 2004: Initial release
Dec 2006: Outback release
authors: Kris
*******************************************************************************/
module tango.io.device.Array;
private import tango.core.Exception;
private import tango.io.device.Conduit;
/******************************************************************************
******************************************************************************/
extern (C)
{
protected void * memcpy (void *dst, void *src, size_t);
}
/*******************************************************************************
Array manipulation typically involves appending, as in the
following example:
---
// create a small buffer
auto buf = new Array (256);
auto foo = "to write some D";
// append some text directly to it
buf.append ("now is the time for all good men ").append(foo);
---
Alternatively, one might use a formatter to append content:
---
auto output = new TextOutput (new Array(256));
output.format ("now is the time for {} good men {}", 3, foo);
---
A slice() method returns all valid content within the array.
*******************************************************************************/
class Array : Conduit, InputBuffer, OutputBuffer, Conduit.Seek
{
private void[] data; // the raw data buffer
private size_t index; // current read position
private size_t extent; // limit of valid content
private size_t dimension; // maximum extent of content
private size_t expansion; // for growing instances
private static char[] overflow = "output buffer is full";
private static char[] underflow = "input buffer is empty";
private static char[] eofRead = "end-of-flow while reading";
private static char[] eofWrite = "end-of-flow while writing";
/***********************************************************************
Ensure the buffer remains valid between method calls
***********************************************************************/
invariant
{
assert (index <= extent);
assert (extent <= dimension);
}
/***********************************************************************
Construct a buffer
Params:
capacity = the number of bytes to make available
growing = chunk size of a growable instance, or zero
to prohibit expansion
Remarks:
Construct a Buffer with the specified number of bytes
and expansion policy.
***********************************************************************/
this (size_t capacity, size_t growing = 0)
{
assign (new ubyte[capacity], 0);
expansion = growing;
}
/***********************************************************************
Construct a buffer
Params:
data = the backing array to buffer within
Remarks:
Prime a buffer with an application-supplied array. All content
is considered valid for reading, and thus there is no writable
space initially available.
***********************************************************************/
this (void[] data)
{
assign (data, data.length);
}
/***********************************************************************
Construct a buffer
Params:
data = the backing array to buffer within
readable = the number of bytes initially made
readable
Remarks:
Prime buffer with an application-supplied array, and
indicate how much readable data is already there. A
write operation will begin writing immediately after
the existing readable content.
This is commonly used to attach a Buffer instance to
a local array.
***********************************************************************/
this (void[] data, size_t readable)
{
assign (data, readable);
}
/***********************************************************************
Return the name of this conduit
***********************************************************************/
final override char[] toString ()
{
return "<array>";
}
/***********************************************************************
Transfer content into the provided dst
Params:
dst = destination of the content
Returns:
return the number of bytes read, which may be less than
dst.length. Eof is returned when no further content is
available.
Remarks:
Populates the provided array with content. We try to
satisfy the request from the buffer content, and read
directly from an attached conduit when the buffer is
empty.
***********************************************************************/
final override size_t read (void[] dst)
{
auto content = readable;
if (content)
{
if (content >= dst.length)
content = dst.length;
// transfer buffer content
dst [0 .. content] = data [index .. index + content];
index += content;
}
else
content = IConduit.Eof;
return content;
}
/***********************************************************************
Emulate OutputStream.write()
Params:
src = the content to write
Returns:
return the number of bytes written, which may be less than
provided (conceptually). Returns Eof when the buffer becomes
full.
Remarks:
Appends src content to the buffer, expanding as required if
configured to do so (via the ctor).
***********************************************************************/
final override size_t write (void[] src)
{
auto len = src.length;
if (len)
{
if (len > writable)
if (expand(len) < len)
return Eof;
// content may overlap ...
memcpy (&data[extent], src.ptr, len);
extent += len;
}
return len;
}
/***********************************************************************
Return a preferred size for buffering conduit I/O
***********************************************************************/
final override size_t bufferSize ()
{
return data.length;
}
/***********************************************************************
Release external resources
***********************************************************************/
override void detach ()
{
}
/***********************************************************************
Seek within the constraints of assigned content
***********************************************************************/
override long seek (long offset, Anchor anchor = Anchor.Begin)
{
if (offset > cast(long) limit)
offset = limit;
switch (anchor)
{
case Anchor.End:
index = cast(size_t) (limit - offset);
break;
case Anchor.Begin:
index = cast(size_t) offset;
break;
case Anchor.Current:
long o = cast(size_t) (index + offset);
if (o < 0)
o = 0;
if (o > cast(long) limit)
o = limit;
index = cast(size_t) o;
default:
break;
}
return index;
}
/***********************************************************************
Reset the buffer content
Params:
data = the backing array to buffer within. All content
is considered valid
Returns:
the buffer instance
Remarks:
Set the backing array with all content readable.
***********************************************************************/
Array assign (void[] data)
{
return assign (data, data.length);
}
/***********************************************************************
Reset the buffer content
Params:
data = the backing array to buffer within
readable = the number of bytes within data considered
valid
Returns:
the buffer instance
Remarks:
Set the backing array with some content readable. Use clear()
to reset the content (make it all writable).
***********************************************************************/
Array assign (void[] data, size_t readable)
{
this.data = data;
this.extent = readable;
this.dimension = data.length;
// reset to start of input
this.expansion = 0;
this.index = 0;
return this;
}
/***********************************************************************
Access buffer content
Remarks:
Return the entire backing array.
***********************************************************************/
final void[] assign ()
{
return data;
}
/***********************************************************************
Return a void[] read of the buffer from start to end, where
end is exclusive
***********************************************************************/
final void[] opSlice (size_t start, size_t end)
{
assert (start <= extent && end <= extent && start <= end);
return data [start .. end];
}
/***********************************************************************
Retrieve all readable content
Returns:
a void[] read of the buffer
Remarks:
Return a void[] read of the buffer, from the current position
up to the limit of valid content. The content remains in the
buffer for future extraction.
***********************************************************************/
final void[] slice ()
{
return data [index .. extent];
}
/***********************************************************************
Access buffer content
Params:
size = number of bytes to access
eat = whether to consume the content or not
Returns:
the corresponding buffer slice when successful, or
null if there's not enough data available (Eof; Eob).
Remarks:
Slices readable data. The specified number of bytes is
readd from the buffer, and marked as having been read
when the 'eat' parameter is set true. When 'eat' is set
false, the read position is not adjusted.
Note that the slice cannot be larger than the size of
the buffer ~ use method read(void[]) instead where you
simply want the content copied.
Note also that the slice should be .dup'd if you wish to
retain it.
Examples:
---
// create a buffer with some content
auto buffer = new Buffer ("hello world");
// consume everything unread
auto slice = buffer.slice (buffer.readable);
---
***********************************************************************/
final void[] slice (size_t size, bool eat = true)
{
if (size > readable)
error (underflow);
auto i = index;
if (eat)
index += size;
return data [i .. i + size];
}
/***********************************************************************
Append content
Params:
src = the content to _append
length = the number of bytes in src
Returns a chaining reference if all content was written.
Throws an IOException indicating eof or eob if not.
Remarks:
Append an array to this buffer
***********************************************************************/
final Array append (void[] src)
{
if (write(src) is Eof)
error (overflow);
return this;
}
/***********************************************************************
Iterator support
Params:
scan = the delagate to invoke with the current content
Returns:
Returns true if a token was isolated, false otherwise.
Remarks:
Upon success, the delegate should return the byte-based
index of the consumed pattern (tail end of it). Failure
to match a pattern should be indicated by returning an
IConduit.Eof
Note that additional iterator and/or reader instances
will operate in lockstep when bound to a common buffer.
***********************************************************************/
final bool next (size_t delegate (void[]) scan)
{
return reader (scan) != IConduit.Eof;
}
/***********************************************************************
Available content
Remarks:
Return count of _readable bytes remaining in buffer. This is
calculated simply as limit() - position()
***********************************************************************/
final size_t readable ()
{
return extent - index;
}
/***********************************************************************
Available space
Remarks:
Return count of _writable bytes available in buffer. This is
calculated simply as capacity() - limit()
***********************************************************************/
final size_t writable ()
{
return dimension - extent;
}
/***********************************************************************
Access buffer limit
Returns:
Returns the limit of readable content within this buffer.
Remarks:
Each buffer has a capacity, a limit, and a position. The
capacity is the maximum content a buffer can contain, limit
represents the extent of valid content, and position marks
the current read location.
***********************************************************************/
final size_t limit ()
{
return extent;
}
/***********************************************************************
Access buffer capacity
Returns:
Returns the maximum capacity of this buffer
Remarks:
Each buffer has a capacity, a limit, and a position. The
capacity is the maximum content a buffer can contain, limit
represents the extent of valid content, and position marks
the current read location.
***********************************************************************/
final size_t capacity ()
{
return dimension;
}
/***********************************************************************
Access buffer read position
Returns:
Returns the current read-position within this buffer
Remarks:
Each buffer has a capacity, a limit, and a position. The
capacity is the maximum content a buffer can contain, limit
represents the extent of valid content, and position marks
the current read location.
***********************************************************************/
final size_t position ()
{
return index;
}
/***********************************************************************
Clear array content
Remarks:
Reset 'position' and 'limit' to zero. This effectively
clears all content from the array.
***********************************************************************/
final Array clear ()
{
index = extent = 0;
return this;
}
/***********************************************************************
Emit/purge buffered content
***********************************************************************/
final override Array flush ()
{
return this;
}
/***********************************************************************
Write into this buffer
Params:
dg = the callback to provide buffer access to
Returns:
Returns whatever the delegate returns.
Remarks:
Exposes the raw data buffer at the current _write position,
The delegate is provided with a void[] representing space
available within the buffer at the current _write position.
The delegate should return the appropriate number of bytes
if it writes valid content, or IConduit.Eof on error.
***********************************************************************/
final size_t writer (size_t delegate (void[]) dg)
{
auto count = dg (data [extent..dimension]);
if (count != IConduit.Eof)
{
extent += count;
assert (extent <= dimension);
}
return count;
}
/***********************************************************************
Read directly from this buffer
Params:
dg = callback to provide buffer access to
Returns:
Returns whatever the delegate returns.
Remarks:
Exposes the raw data buffer at the current _read position. The
delegate is provided with a void[] representing the available
data, and should return zero to leave the current _read position
intact.
If the delegate consumes data, it should return the number of
bytes consumed; or IConduit.Eof to indicate an error.
***********************************************************************/
final size_t reader (size_t delegate (void[]) dg)
{
auto count = dg (data [index..extent]);
if (count != IConduit.Eof)
{
index += count;
assert (index <= extent);
}
return count;
}
/***********************************************************************
Expand existing buffer space
Returns:
Available space, without any expansion
Remarks:
Make some additional room in the buffer, of at least the
given size. Should not be public in order to avoid issues
with non-growable subclasses
***********************************************************************/
private final size_t expand (size_t size)
{
if (expansion)
{
if (size < expansion)
size = expansion;
dimension += size;
data.length = dimension;
}
return writable;
}
/***********************************************************************
Cast to a target type without invoking the wrath of the
runtime checks for misalignment. Instead, we truncate the
array length
***********************************************************************/
private static T[] convert(T)(void[] x)
{
return (cast(T*) x.ptr) [0 .. (x.length / T.sizeof)];
}
}
/******************************************************************************
******************************************************************************/
debug (Array)
{
import tango.io.Stdout;
void main()
{
auto b = new Array(6, 10);
b.seek (0);
b.write ("fubar");
Stdout.formatln ("extent {}, pos {}, read {}, bufsize {}",
b.limit, b.position, cast(char[]) b.slice, b.bufferSize);
b.write ("fubar");
Stdout.formatln ("extent {}, pos {}, read {}, bufsize {}",
b.limit, b.position, cast(char[]) b.slice, b.bufferSize);
}
}
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