Contents

• Constants
• Functions
• Parser callbacks
• XMLParser object
• Code example

This class provides an interface to the XML parser, LuaExpat. It provides a SAX interface with an incremental XML parser.

With an event-based API like SAX the XML document can be fed to the parser in chunks, and the parsing begins as soon as the parser receives the first document chunk. LuaExpat reports parsing events (such as the start and end of elements) directly to the application through callbacks. The parsing of huge documents can benefit from this piecemeal operation.

See the online LuaExpat documentation for details on how to work with this parser. The code examples below should provide some basic help, too.

• close() - closes the parser, freeing all memory used by it.
• getCallbacks() - returns the callbacks table for this parser.
• parse(string) - parses more document data. the string contains the next part (or possibly all) of the document. Returns non-nil for success or nil, msg, line, col, pos for error.
• stop() - aborts parsing (can be called from within the parser callbacks).

local Depth = 0;

-- Define the callbacks:
local Callbacks = {
	CharacterData = function(a_Parser, a_String)
		LOG(string.rep(" ", Depth) .. "* " .. a_String);
	end

	EndElement = function(a_Parser, a_ElementName)
		Depth = Depth - 1;
		LOG(string.rep(" ", Depth) .. "- " .. a_ElementName);
	end

	StartElement = function(a_Parser, a_ElementName, a_Attribs)
		LOG(string.rep(" ", Depth) .. "+ " .. a_ElementName);
		Depth = Depth + 1;
	end
}

-- Create the parser:
local Parser = lxp.new(Callbacks);

-- Parse the XML file:
local f = io.open("file.xml", "rb");
while (true) do
	local block = f:read(128 * 1024);  -- Use a 128KiB buffer for reading
	if (block == nil) then
		-- End of file
		break;
	end
	Parser:parse(block);
end

-- Signalize to the parser that no more data is coming
Parser:parse();

-- Close the parser:
Parser:close();