Add xmlLoadString function

[Lpsd]

Currently, if you want to read XML data that is compatible with the other xml* functions, you need to create a file with the XML data (using fileCreate), then read that file using xmlLoadFile

This will allow you to read XML data via string using xmlLoadString(xmlString)

Example (client):

function init()
	print("Loading XML String [client]")

	local rootNode = xmlLoadString("<animals test='x'><monkey name='crosroad'></monkey> <turtle name='luxy'></turtle></animals>")

	if rootNode then
		local rootAttributes = xmlNodeGetAttributes(rootNode)
		print("Root Node", "Name: "..xmlNodeGetName(rootNode),  "Attributes :"..toJSON(rootAttributes))
		
		local children = xmlNodeGetChildren(rootNode)
		
		for i, childNode in ipairs(children) do
			local attributes = xmlNodeGetAttributes(childNode)
			
			print("Child #"..i, "Name: "..xmlNodeGetName(childNode), "Attributes :"..toJSON(attributes))
		end
	end
end
addEventHandler("onClientResourceStart", resourceRoot, init)

My only concerns in this commit are the following (someone who actually knows what they are doing should verify this):

Shared/XML/CXMLNodeImpl.cpp:17
Shared/XML/CXMLNodeImpl.h:62

First time looking into MTA's code, and hardly worked with C++ too, so let me know of anything dumb in my commit!

Note: I have been made aware of a branch which is ready to test, pugixml, so more than anything I am hoping this PR will speed that process up ;)

[qaisjp]

What happens if someone calls xmlSaveFile on this node?

[Lpsd]

I'm going to look at this shortly - I'll ensure that file-related XML functions do not work with xml-nodes created via xmlLoadString

[Lpsd]

This should now be fixed.

function init()
	print("Loading XML String [client]")

	local rootNode = xmlLoadString("<animals test='x'><monkey name='crosroad'></monkey> <turtle name='luxy'></turtle></animals>")
	
	if rootNode then
		print("Trying to save non-file XML node")
		
		local saveXML = xmlSaveFile(rootNode)
		
		print("xmlSaveFile Result:", saveXML)
		
		print("Trying to unload non-file XML node")
		
		local unloadXML = xmlUnloadFile(rootNode)
		
		print("xmlUnloadFile Result:", unloadXML)
	end
end
addEventHandler("onClientResourceStart", resourceRoot, init)

Both will return false in the above example.

[Lpsd]

The iterator/index value of the loop within CLuaMain::DestroyXML is passed to m_XMLFiles.erase, is it worth the time simply for "readability"? (also, the loop was already like this, and I feel it falls outside the specification of my PR)

I have, however, cleaned up the loop in CLuaMain::SaveXML (one of them, at least)

Aside from this, everything seems to be working great.

[Lpsd]

Fixed some issues brought to my attention by @patrikjuvonen

XML strings are now properly parsed, to iterate through all children (instead of just the 1st)

Also added checks for broken XML strings, and error outputting

[patrikjuvonen]

Waits for #821 to solve.

[qaisjp]

@patrikjuvonen I don't think this should be assigned to 1.5.7

[patrikjuvonen]

@patrikjuvonen I don't think this should be assigned to 1.5.7

I've moved it to backlog now. We should probably check what else is left in 1.5.7 milestone and move them elsewhere if unlikely to get them completed in time.

[botder]

The decision in pull request #821 (Pin down return value on failure) is now settled.

[patrikjuvonen]

Cool, thank you!
Great job on this PR. All ready to go after 1.5.7 is released! 👍