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lua/xmlhandler/tree.lua

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+local function init()
+	local obj = {
+		root = {},
+		options = {noreduce = {}}
+	}
+
+	obj._stack = {obj.root, n=1}  
+	return obj  
+end
+
+--- @module XML Tree Handler.
+-- Generates a lua table from an XML content string.
+-- It 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
+-- 
+-- * Mixed-Content behaves unpredictably - the relationship
+--   between text elements and embedded tags is lost and
+--   multiple levels of mixed content does not work
+-- * 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)
+--
+-- In general however this format is relatively useful.
+--
+-- It is much easier to understand by running some test
+-- data through 'testxml.lua -simpletree' than to read this)
+--
+-- Options
+-- =======
+--	options.noreduce = { <tag> = bool,.. }
+--		- Nodes not to reduce children vector even if only
+--		  one child
+--
+--  License:
+--  ========
+--
+--  This code is freely distributable under the terms of the [MIT license](LICENSE).
+--
+--@author Paul Chakravarti (paulc@passtheaardvark.com)
+--@author Manoel Campos da Silva Filho
+local tree = init()
+
+---Instantiates a new handler object.
+--Each instance can handle a single XML.
+--By using such a constructor, you can parse
+--multiple XML files in the same application.
+--@return the handler instance
+function tree:new()
+	local obj = init()
+
+	obj.__index = self
+	setmetatable(obj, self)
+
+	return obj
+end
+
+--Gets the first key of a table
+--@param tb table to get its first key
+--@return the table's first key, nil if the table is empty
+--or the given parameter if it isn't a table
+local function getFirstKey(tb)
+   if type(tb) == "table" then
+	  for k, v in pairs(tb) do
+		  return k
+	  end
+
+	  return nil
+   end
+
+   return tb
+end
+
+--- Recursively removes redundant vectors for nodes
+-- with single child elements
+function tree:reduce(node, key, parent)
+	for k,v in pairs(node) do
+		if type(v) == 'table' then
+			self:reduce(v,k,node)
+		end
+	end
+	if #node == 1 and not self.options.noreduce[key] and 
+		node._attr == nil then
+		parent[key] = node[1]
+	else
+		node.n = nil
+	end
+end
+
+---Parses a start tag.
+-- @param tag a {name, attrs} table
+-- where name is the name of the tag and attrs
+-- is a table containing the atributtes of the tag
+function tree:starttag(tag)
+	local node = {}
+	if self.parseAttributes == true then
+		node._attr=tag.attrs
+	end
+
+	--Table in the stack representing the tag being processed
+	local current = self._stack[#self._stack]
+
+	if current[tag.name] then
+		table.insert(current[tag.name], node)
+	else
+		current[tag.name] = {node; n=1}
+	end
+
+	table.insert(self._stack, node)
+end
+
+---Parses an end tag.
+-- @param tag a {name, attrs} table
+-- where name is the name of the tag and attrs
+-- is a table containing the atributtes of the tag
+function tree:endtag(tag, s)
+	--Table in the stack representing the tag being processed
+	local current = self._stack[#self._stack]
+	--Table in the stack representing the containing tag of the current tag
+	local prev = self._stack[#self._stack-1]
+	if not prev[tag.name] then
+		error("XML Error - Unmatched Tag ["..s..":"..tag.name.."]\n")
+	end
+	if prev == self.root then
+		-- Once parsing complete, recursively reduce tree
+		self:reduce(prev, nil, nil)
+	end
+
+	local firstKey = getFirstKey(current)
+	table.remove(self._stack)
+end
+
+---Parses a tag content.
+-- @param t text to process
+function tree:text(text)
+	local current = self._stack[#self._stack]
+	table.insert(current, text)
+end
+
+---Parses CDATA tag content.
+tree.cdata = tree.text
+tree.__index = tree
+return tree