")
local result = transformer:parse_xml("hello, world")
transform.print_tex(result)
\end{luacode*}
\end{framed}
\noindent\textbf{Select attributes}
\begin{verbatim}
local transformer = transform.new()
transformer:add_action("b", "\\textbf{@<.>}")
-- this will select only elements with "style" attribute
transformer:add_action("b[style]", "\\textcolor{@{style}}{\\textbf{@<.>}}")
local text = 'hello world'
local result = transformer:parse_xml(text)
transform.print_tex(result)
\end{verbatim}
\begin{framed}
\begin{luacode*}
local transform = require "luaxml-transform"
local transformer = transform.new()
transformer:add_action("b", "\\textbf{@<.>}")
-- this will select only elements with "style" attribute
transformer:add_action("b[style]", "\\textcolor{@{style}}{\\textbf{@<.>}}")
local text = 'hello world'
local result = transformer:parse_xml(text)
transform.print_tex("\\verb|" .. result .. "|")
\end{luacode*}
\end{framed}
\subsubsection{Transforming using Lua functions}
You can use Lua functions for more complex transformations where simple templates don't suffice.
\begin{verbatim}
transformer:add_custom_action("CSS selector", function)
\end{verbatim}
\noindent\textbf{Example}
\begin{verbatim}
local transformer = transform.new()
local xml_text = "worldhello, "
-- load helper functions
local get_child_element = transform.get_child_element
local process_children = transform.process_children
-- define custom action
transformer:add_custom_action("x", function(el)
-- it basically just swaps child elements,
-- like in the template @<2>@<1>
local first = process_children(get_child_element(el, 1))
local second = process_children(get_child_element(el, 2))
return second .. first
end)
local result = transformer:parse_xml(xml_text)
transform.print_tex(result)
\end{verbatim}
\begin{framed}
\begin{luacode*}
local transform = require "luaxml-transform"
local transformer = transform.new()
local xml_text = "worldhello, "
-- load helper functions
local get_child_element = transform.get_child_element
local process_children = transform.process_children
-- define custom action
transformer:add_custom_action("x", function(el)
-- it basically just swaps child elements,
-- like in the template @<2>@<1>
local first = process_children(get_child_element(el, 1))
local second = process_children(get_child_element(el, 2))
return second .. first
end)
local result = transformer:parse_xml(xml_text)
transform.print_tex(result)
\end{luacode*}
\end{framed}
\subsubsection{Character handling}
You may want to escape certain characters, or replace them with
\LaTeX\ commands. You can use the \texttt{unicodes} table contained
in the Transform object:
\begin{verbatim}
local transformer = transform.new()
-- you must use the Unicode character code
transformer.unicodes[124] = "\\textbar"
local text = '|'
local result = transformer:parse_xml(text)
transform.print_tex(result)
\end{verbatim}
\begin{framed}
\begin{luacode*}
local transform = require "luaxml-transform"
local transformer = transform.new()
-- you must use the Unicode character code
transformer.unicodes[124] = "\\textbar"
local text = '|'
local result = transformer:parse_xml(text)
transform.print_tex("\\verb|" .. result .. "|")
\end{luacode*}
\end{framed}
\section{The API documentation}
\input{doc/api.tex}
\section{Low-level functions usage}
% The processing is done with several handlers, their usage will be shown in the
% following section. Full description of handlers is given in the original
% documentation in section \ref{sec:handlers}.
% \subsection{Usage examples}
The original |LuaXML| library provides some low-level functions for |XML| handling.
First of all, we need to load the libraries:
\begin{verbatim}
xml = require('luaxml-mod-xml')
handler = require('luaxml-mod-handler')
\end{verbatim}
The |luaxml-mod-xml| file contains the xml parser and also the serializer. In
|luaxml-mod-handler|, various handlers for dealing with xml data are defined.
Handlers transforms the |xml| file to data structures which can be handled from
the Lua code. More information about handlers can be found in the original
documentation, section \ref{sec:handlers}.
\subsection{The simpleTreeHandler}
\begin{verbatim}
sample = [[
hello
world.
another
]]
treehandler = handler.simpleTreeHandler()
x = xml.xmlParser(treehandler)
x:parse(sample)
\end{verbatim}
You have to create handler object, using |handler.simpleTreeHandler()| and xml
parser object using |xml.xmlParser(handler object)|. |simpleTreehandler|
creates simple table hierarchy, with top root node in |treehandler.root|
\begin{verbatim}
-- pretty printing function
function printable(tb, level)
level = level or 1
local spaces = string.rep(' ', level*2)
for k,v in pairs(tb) do
if type(v) ~= "table" then
print(spaces .. k..'='..v)
else
print(spaces .. k)
level = level + 1
printable(v, level)
end
end
end
-- print table
printable(treehandler.root)
-- print xml serialization of table
print(xml.serialize(treehandler.root))
-- direct access to the element
print(treehandler.root["a"]["b"][1])
\end{verbatim}
This code produces the following output:
\begin{verbatim}
output:
a
d=hello
b
1=world.
2
1=another
_attr
at=Hi
hello
world.
another
world.
\end{verbatim}
First part is pretty-printed dump of Lua table structure contained in the handler, the second
part is |xml| serialized from that table and the last part demonstrates direct access to particular
elements.
Note that |simpleTreeHandler| creates tables that can be easily accessed using
standard lua functions, but if the xml document is of mixed-content type\footnote{%
This means that element may contain both children elements and text.}:
\begin{verbatim}
hello
world
\end{verbatim}
\noindent then it produces wrong results. It is useful mostly for data |xml| files, not for
text formats like |xhtml|.
\subsection{The domHandler}
% For complex xml documents with mixed content, |domHandler| is capable of representing any valid XML document:
For complex xml documents, it is best to use the |domHandler|, which creates object which contains all information
from the |xml| document.
\begin{verbatim}
-- file dom-sample.lua
-- next line enables scripts called with texlua to use luatex libraries
--kpse.set_program_name("luatex")
function traverseDom(current,level)
local level = level or 0
local spaces = string.rep(" ",level)
local root= current or current.root
local name = root._name or "unnamed"
local xtype = root._type or "untyped"
local attributes = root._attr or {}
if xtype == "TEXT" then
print(spaces .."TEXT : " .. root._text)
else
print(spaces .. xtype .. " : " .. name)
end
for k, v in pairs(attributes) do
print(spaces .. " ".. k.."="..v)
end
local children = root._children or {}
for _, child in ipairs(children) do
traverseDom(child, level + 1)
end
end
local xml = require('luaxml-mod-xml')
local handler = require('luaxml-mod-handler')
local x = 'hello world, how are you?
'
local domHandler = handler.domHandler()
local parser = xml.xmlParser(domHandler)
parser:parse(x)
traverseDom(domHandler.root)
\end{verbatim}
The ROOT element is stored in |domHandler.root| table, it's child nodes are stored in |_children|
tables. Node type is saved in |_type| field, if the node type is |ELEMENT|, then |_name| field contains
element name, |_attr| table contains element attributes. |TEXT| node contains text content in |_text|
field.
The previous code produces following output in the terminal: % after command
% |texlua dom-sample.lua| running:
\begin{verbatim}
ROOT : unnamed
ELEMENT : p
TEXT : hello
ELEMENT : a
href=http://world.com/
TEXT : world
TEXT : , how are you?
\end{verbatim}
% With \verb|domHandler|, you can process documents with mixed content, like
% \verb|xhtml|, so it is a most powerful handler.
\clearpage
\part{Original \texttt{LuaXML} documentation by Paul Chakravarti}
\medskip
\noindent This document was created automatically from the original source code comments using Pandoc\footnote{\url{http://johnmacfarlane.net/pandoc/}}
\section{Overview}
This module provides a non-validating XML stream parser in Lua.
\section{Features}
\begin{itemize}
\item
Tokenises well-formed XML (relatively robustly)
\item
Flexible handler based event api (see below)
\item
Parses all XML Infoset elements - ie.
\begin{itemize}
\item
Tags
\item
Text
\item
Comments
\item
CDATA
\item
XML Decl
\item
Processing Instructions
\item
DOCTYPE declarations
\end{itemize}
\item
Provides limited well-formedness checking (checks for basic syntax \&
balanced tags only)
\item
Flexible whitespace handling (selectable)
\item
Entity Handling (selectable)
\end{itemize}
\section{Limitations}
\begin{itemize}
\item
Non-validating
\item
No charset handling
\item
No namespace support
\item
Shallow well-formedness checking only (fails to detect most semantic
errors)
\end{itemize}
\section{API}
The parser provides a partially object-oriented API with functionality
split into tokeniser and hanlder components.
The handler instance is passed to the tokeniser and receives callbacks
for each XML element processed (if a suitable handler function is
defined). The API is conceptually similar to the SAX API but implemented
differently.
The following events are generated by the tokeniser
\begin{verbatim}
handler:starttag - Start Tag
handler:endtag - End Tag
handler:text - Text
handler:decl - XML Declaration
handler:pi - Processing Instruction
handler:comment - Comment
handler:dtd - DOCTYPE definition
handler:cdata - CDATA
\end{verbatim}
The function prototype for all the callback functions is
\begin{verbatim}
callback(val,attrs,start,end)
\end{verbatim}
where attrs is a table and val/attrs are overloaded for specific
callbacks - ie.
\begin{tabular}{llp{5cm}}
Callback & val & attrs (table)\\
\hline
starttag & name & |{ attributes (name=val).. }|\\
endtag & name & nil\\
text & || & nil\\
cdata & | | & nil\\
decl & "xml" & |{ attributes (name=val).. }|\\
pi & pi name & \begin{verbatim}{ attributes (if present)..
_text =
}\end{verbatim}\\
comment & || & nil\\
dtd & root element & \begin{verbatim}{ _root = ,
_type = SYSTEM|PUBLIC,
_name = ,
_uri = ,
_internal =
}\end{verbatim}\\
\end{tabular}
(starttag \& endtag provide the character positions of the start/end of the
element)
XML data is passed to the parser instance through the `parse' method
(Note: must be passed as single string currently)
\section{Options}
Parser options are controlled through the `self.options' table.
Available options are -
\begin{itemize}
\item
stripWS
Strip non-significant whitespace (leading/trailing) and do not
generate events for empty text elements
\item
expandEntities
Expand entities (standard entities + single char numeric entities only
currently - could be extended at runtime if suitable DTD parser added
elements to table (see obj.\_ENTITIES). May also be possible to expand
multibyre entities for UTF--8 only
\item
errorHandler
Custom error handler function
\end{itemize}
NOTE: Boolean options must be set to `nil' not `0'
\section{Usage}
Create a handler instance -
\begin{verbatim}
h = { starttag = function(t,a,s,e) .... end,
endtag = function(t,a,s,e) .... end,
text = function(t,a,s,e) .... end,
cdata = text }
\end{verbatim}
(or use predefined handler - see luaxml-mod-handler.lua)
Create parser instance -
\begin{verbatim}
p = xmlParser(h)
\end{verbatim}
Set options -
\begin{verbatim}
p.options.xxxx = nil
\end{verbatim}
Parse XML data -
\begin{verbatim}
xmlParser:parse(",
_type = ROOT|ELEMENT|TEXT|COMMENT|PI|DECL|DTD,
_attr = { Node attributes - see callback API },
_parent =
_children = { List of child nodes - ROOT/NODE only }
}
\end{verbatim}
\subsubsection{simpleTreeHandler}
simpleTreeHandler is a simplified handler which attempts to generate a
more `natural' table based structure which supports many common XML
formats.
The XML tree structure is mapped directly into a recursive table
structure with node names as keys and child elements as either a table
of values or directly as a string value for text. Where there is only a
single child element this is inserted as a named key - if there are
multiple elements these are inserted as a vector (in some cases it may
be preferable to always insert elements as a vector which can be
specified on a per element basis in the options). Attributes are
inserted as a child element with a key of `\_attr'.
Only Tag/Text \& CDATA elements are processed - all others are ignored.
This format has some limitations - primarily
\begin{itemize}
\item Mixed-Content behaves unpredictably - the relationship between text
elements and embedded tags is lost and multiple levels of mixed
content does not work
\item If a leaf element has both a text element and attributes then the text
must be accessed through a vector (to provide a container for the
attribute)
\end{itemize}
In general however this format is relatively useful.
\subsection{Options}
\begin{verbatim}
simpleTreeHandler.options.noReduce = { = bool,.. }
- Nodes not to reduce children vector even if only
one child
domHandler.options.(comment|pi|dtd|decl)Node = bool
- Include/exclude given node types
\end{verbatim}
\subsection{Usage}
Pased as delegate in xmlParser constructor and called as callback by
xmlParser:parse(xml) method.
\section{History}
This library is fork of LuaXML library originaly created by Paul
Chakravarti. Some files not needed for use with luatex were droped from the distribution.
Documentation was converted from original comments in the source code.
\section{License}
This code is freely distributable under the terms of the Lua license
(\url{http://www.lua.org/copyright.html})
\end{document}