|
Server : Apache System : Linux cs317.bluehost.com 4.19.286-203.ELK.el7.x86_64 #1 SMP Wed Jun 14 04:33:55 CDT 2023 x86_64 User : andertr9 ( 1047) PHP Version : 8.2.18 Disable Function : NONE Directory : /usr/share/doc/lua-socket-3.1.0/ |
Upload File : |
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<meta name="description" content="LuaSocket: LTN12 support">
<meta name="keywords" content="Lua, LuaSocket, Filters, Source, Sink,
Pump, Support, Library">
<title>LuaSocket: LTN12 module</title>
<link rel="stylesheet" href="reference.css" type="text/css">
</head>
<body>
<!-- header +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<div class="header">
<hr>
<center>
<table summary="LuaSocket logo">
<tr><td align="center"><a href="http://www.lua.org">
<img width="128" height="128" border="0" alt="LuaSocket" src="luasocket.png">
</a></td></tr>
<tr><td align="center" valign="top">Network support for the Lua language
</td></tr>
</table>
<p class="bar">
<a href="index.html">home</a> ·
<a href="index.html#download">download</a> ·
<a href="installation.html">installation</a> ·
<a href="introduction.html">introduction</a> ·
<a href="reference.html">reference</a>
</p>
</center>
<hr>
</div>
<!-- ltn12 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<h2 id="ltn12">LTN12</h2>
<p> The <tt>ltn12</tt> namespace implements the ideas described in
<a href="http://lua-users.org/wiki/FiltersSourcesAndSinks">
LTN012, Filters sources and sinks</a>. This manual simply describes the
functions. Please refer to the LTN for a deeper explanation of the
functionality provided by this module.
</p>
<p>
To obtain the <tt>ltn12</tt> namespace, run:
</p>
<pre class="example">
-- loads the LTN21 module
local ltn12 = require("ltn12")
</pre>
<!-- filters ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<h3 id="filter">Filters</h3>
<!-- chain ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="filter.chain">
ltn12.filter.<b>chain(</b>filter<sub>1</sub>, filter<sub>2</sub>
[, ... filter<sub>N</sub>]<b>)</b>
</p>
<p class="description">
Returns a filter that passes all data it receives through each of a
series of given filters.
</p>
<p class="parameters">
<tt>Filter<sub>1</sub></tt> to <tt>filter<sub>N</sub></tt> are simple
filters.
</p>
<p class="return">
The function returns the chained filter.
</p>
<p class="note">
The nesting of filters can be arbitrary. For instance, the useless filter
below doesn't do anything but return the data that was passed to it,
unaltered.
</p>
<pre class="example">
-- load required modules
local ltn12 = require("ltn12")
local mime = require("mime")
-- create a silly identity filter
id = ltn12.filter.chain(
mime.encode("quoted-printable"),
mime.encode("base64"),
mime.decode("base64"),
mime.decode("quoted-printable")
)
</pre>
<!-- cycle ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="filter.cycle">
ltn12.filter.<b>cycle(</b>low [, ctx, extra]<b>)</b>
</p>
<p class="description">
Returns a high-level filter that cycles though a low-level filter by
passing it each chunk and updating a context between calls.
</p>
<p class="parameters">
<tt>Low</tt> is the low-level filter to be cycled,
<tt>ctx</tt> is the initial context and <tt>extra</tt> is any extra
argument the low-level filter might take.
</p>
<p class="return">
The function returns the high-level filter.
</p>
<pre class="example">
-- load the ltn12 module
local ltn12 = require("ltn12")
-- the base64 mime filter factory
encodet['base64'] = function()
return ltn12.filter.cycle(b64, "")
end
</pre>
<!-- pumps ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<h3 id="pump">Pumps</h3>
<!-- all ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="pump.all">
ltn12.pump.<b>all(</b>source, sink<b>)</b>
</p>
<p class="description">
Pumps <em>all</em> data from a <tt>source</tt> to a <tt>sink</tt>.
</p>
<p class="return">
If successful, the function returns a value that evaluates to
<b><tt>true</tt></b>. In case
of error, the function returns a <b><tt>false</tt></b> value, followed by an error message.
</p>
<!-- step +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="pump.step">
ltn12.pump.<b>step(</b>source, sink<b>)</b>
</p>
<p class="description">
Pumps <em>one</em> chunk of data from a <tt>source</tt> to a <tt>sink</tt>.
</p>
<p class="return">
If successful, the function returns a value that evaluates to
<b><tt>true</tt></b>. In case
of error, the function returns a <b><tt>false</tt></b> value, followed by an error message.
</p>
<!-- sinks ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<h3 id="sink">Sinks</h3>
<!-- chain ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="sink.chain">
ltn12.sink.<b>chain(</b>filter, sink<b>)</b>
</p>
<p class="description">
Creates and returns a new sink that passes data through a <tt>filter</tt> before sending it to a given <tt>sink</tt>.
</p>
<!-- error ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="sink.error">
ltn12.sink.<b>error(</b>message<b>)</b>
</p>
<p class="description">
Creates and returns a sink that aborts transmission with the error
<tt>message</tt>.
</p>
<!-- file +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="sink.file">
ltn12.sink.<b>file(</b>handle, message<b>)</b>
</p>
<p class="description">
Creates a sink that sends data to a file.
</p>
<p class="parameters">
<tt>Handle</tt> is a file handle. If <tt>handle</tt> is <tt><b>nil</b></tt>,
<tt>message</tt> should give the reason for failure.
</p>
<p class="return">
The function returns a sink that sends all data to the given <tt>handle</tt>
and closes the file when done, or a sink that aborts the transmission with
the error <tt>message</tt>
</p>
<p class="note">
In the following example, notice how the prototype is designed to
fit nicely with the <tt>io.open</tt> function.
</p>
<pre class="example">
-- load the ltn12 module
local ltn12 = require("ltn12")
-- copy a file
ltn12.pump.all(
ltn12.source.file(io.open("original.png", "rb")),
ltn12.sink.file(io.open("copy.png", "wb"))
)
</pre>
<!-- null +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="sink.null">
ltn12.sink.<b>null()</b>
</p>
<p class="description">
Returns a sink that ignores all data it receives.
</p>
<!-- simplify +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="sink.simplify">
ltn12.sink.<b>simplify(</b>sink<b>)</b>
</p>
<p class="description">
Creates and returns a simple sink given a fancy <tt>sink</tt>.
</p>
<!-- table ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="sink.table">
ltn12.sink.<b>table(</b>[table]<b>)</b>
</p>
<p class="description">
Creates a sink that stores all chunks in a table. The chunks can later be
efficiently concatenated into a single string.
</p>
<p class="parameters">
<tt>Table</tt> is used to hold the chunks. If
<tt><b>nil</b></tt>, the function creates its own table.
</p>
<p class="return">
The function returns the sink and the table used to store the chunks.
</p>
<pre class="example">
-- load needed modules
local http = require("socket.http")
local ltn12 = require("ltn12")
-- a simplified http.get function
function http.get(u)
local t = {}
local respt = request{
url = u,
sink = ltn12.sink.table(t)
}
return table.concat(t), respt.headers, respt.code
end
</pre>
<!-- sinks ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<h3 id="source">Sources</h3>
<!-- cat ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="source.cat">
ltn12.source.<b>cat(</b>source<sub>1</sub> [, source<sub>2</sub>, ...,
source<sub>N</sub>]<b>)</b>
</p>
<p class="description">
Creates a new source that produces the concatenation of the data produced
by a number of sources.
</p>
<p class="parameters">
<tt>Source<sub>1</sub></tt> to <tt>source<sub>N</sub></tt> are the original
sources.
</p>
<p class="return">
The function returns the new source.
</p>
<!-- chain ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="source.chain">
ltn12.source.<b>chain(</b>source, filter<b>)</b>
</p>
<p class="description">
Creates a new <tt>source</tt> that passes data through a <tt>filter</tt>
before returning it.
</p>
<p class="return">
The function returns the new source.
</p>
<!-- empty ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="source.empty">
ltn12.source.<b>empty()</b>
</p>
<p class="description">
Creates and returns an empty source.
</p>
<!-- error ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="source.error">
ltn12.source.<b>error(</b>message<b>)</b>
</p>
<p class="description">
Creates and returns a source that aborts transmission with the error
<tt>message</tt>.
</p>
<!-- file +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="source.file">
ltn12.source.<b>file(</b>handle, message<b>)</b>
</p>
<p class="description">
Creates a source that produces the contents of a file.
</p>
<p class="parameters">
<tt>Handle</tt> is a file handle. If <tt>handle</tt> is <tt><b>nil</b></tt>,
<tt>message</tt> should give the reason for failure.
</p>
<p class="return">
The function returns a source that reads chunks of data from
given <tt>handle</tt> and returns it to the user,
closing the file when done, or a source that aborts the transmission with
the error <tt>message</tt>
</p>
<p class="note">
In the following example, notice how the prototype is designed to
fit nicely with the <tt>io.open</tt> function.
</p>
<pre class="example">
-- load the ltn12 module
local ltn12 = require("ltn12")
-- copy a file
ltn12.pump.all(
ltn12.source.file(io.open("original.png", "rb")),
ltn12.sink.file(io.open("copy.png", "wb"))
)
</pre>
<!-- simplify +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="source.simplify">
ltn12.source.<b>simplify(</b>source<b>)</b>
</p>
<p class="description">
Creates and returns a simple source given a fancy <tt>source</tt>.
</p>
<!-- string +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="source.string">
ltn12.source.<b>string(</b>string<b>)</b>
</p>
<p class="description">
Creates and returns a source that produces the contents of a
<tt>string</tt>, chunk by chunk.
</p>
<!-- table +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<p class="name" id="source.table">
ltn12.source.<b>table(</b>table<b>)</b>
</p>
<p class="description">
Creates and returns a source that produces the numerically-indexed values of a <tt>table</tt> successively beginning at 1. The source returns nil (end-of-stream) whenever a nil value is produced by the current index, which proceeds forward regardless.
</p>
<!-- footer +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ -->
<div class="footer">
<hr>
<center>
<p class="bar">
<a href="index.html">home</a> ·
<a href="index.html#down">download</a> ·
<a href="installation.html">installation</a> ·
<a href="introduction.html">introduction</a> ·
<a href="reference.html">reference</a>
</p>
<p>
<small>
Last modified by Diego Nehab on <br>
Thu Apr 20 00:25:41 EDT 2006
</small>
</p>
</center>
</div>
</body>
</html>