[[TOC()]]

= Streams and !StreamIterators =

=== Buffered ===

!BufferedInput and !BufferedOutput buffer the flow of data from a upstream input/output. A downstream neighbour can locate and use this buffer instead of creating another instance of their own.

(note that upstream is closer to the source, and downstream is further away)

=== Data ===

!DataInput represents a simple way to read binary data from an arbitrary !InputStream, such as a file:
{{{
#!d
auto input = new DataInput (new File("path"));
auto x = input.int32;
auto y = input.float64;
char[22] tmp;
auto len = input.array (tmp);
input.close;
}}}

!DataOutput is is similar, bot for output to an arbitrary !OutputStream, such as a file:
{{{
#!d
auto output = new DataOutput (new File("path", File.WriteCreate));
output.int32 (1024);
output.float64 (3.14159);
output.array ("hello world");
output.flush.close;
}}}

=== !DataFile ===

!DataFileInput and !DataFileOutput compose a seekable File with a Data class. A seek causes the buffer to be cleared or flushed.

=== Digester ===

!DigestInput injects a digest filter into an input stream, updating the digest as information flows through it.

!DigestOutput inject a digest filter into an output stream, updating the digest as information flows through it. Here's an example where we calculate an MD5 digest as a side-effect of copying a file:
{{{
#!d
auto output = new DigestOutput(new File("output", File.WriteCreate), new Md5);
output.copy (new File("input"));

Stdout.formatln ("hex digest: {}", output.digest.hexDigest);
}}}

=== Endian ===

Streams for swapping endian-order. The stream is treated as a set of same-sized elements. Note that partial elements are not mutated. See !EndianInput and !EndianOutput

=== Format ===

Simple way to hook up a utf8 formatter to an arbitrary !OutputStream, such as a file, socket, or other:
{{{
#!d
auto output = new FormatOutput!(char) (new File("path", File.WriteCreate));
output.formatln ("{} green bottles", 10);
output.close;
}}}

This is a wrapper around the Layout class, and is typed for either char, wchar or dchar output. 

=== Greedy ===

!GreedyOutput is a conduit filter that ensures its output is written in full.

!GreedyInput is a conduit filter that ensures its input is read in full.

=== Lines ===

Simple way to hook up a line-tokenizer to an arbitrary !InputStream, such as a file conduit:
{{{
#!d
auto input = new LineInput!(char) (new File("path"));
foreach (line; input)
            ...
input.close;
}}}

=== Map ===

!MapInput!(T) provides load facilities for a properties stream. That is, a file or other medium containing lines of text with a name=value layout

!MapOutput!(T) provides write facilities on a properties stream. That is, a file or other medium which will contain lines of text with a name=value layout

=== Snoop ===

!SnoopInput, !SnoopOutput represent streams for exposing call behaviour. By default, activity trace is sent to Cerr. This can be useful for logging/debugging the stream calls.

=== !TextFile ===

!TextFileInput and !TextFileOutput combines a File with Text IO.

=== Typed ===

!TypedInput!(T) and !TypedOutput!(T) are streams to expose simple native types as discrete elements. I/O is buffered and should yield fair performance.

=== Utf ===
!UtfInput!(T,S) and !UtfOutput!(S,T) represent UTF conversion streams, supporting cross-translation of char, wchar and dchar variants. For supporting endian variations, configure an appropriate Endian upstream of this one (closer to the source)

== Iterators ==

Tango has a set of classes to split streaming text into elements matching a specific pattern. These classes operate upon an !InputStream, and are templated for char, wchar, and dchar data types. For example, there’s an iterator for producing lines of text based upon finding embedded end-of-line markers. See Delimiters, Lines, Patterns and Quotes.

Iterator results are usually aliased directly from the containing buffer, thus avoiding heap activity where an application doesn’t need it. Where the resultant element is to be retained by the application, it should be copied before continuing.

=== Iterator Exceptions ===

An overflow exception is thrown where the size of a single element is larger than the containing buffer. Either the containing buffer is too small, or the element is overly large (a typical IO buffer is eight or sixteen kilobytes in size). Increase the buffer size to accommodate huge elements.