proj/common/utils/xml2lua.lua

--- @module Module providing a non-validating XML stream parser in Lua.
--
--  Features:
--  =========
--
--      * Tokenises well-formed XML (relatively robustly)
--      * Flexible handler based event API (see below)
--      * Parses all XML Infoset elements - ie.
--          - Tags
--          - Text
--          - Comments
--          - CDATA
--          - XML Decl
--          - Processing Instructions
--          - DOCTYPE declarations
--      * Provides limited well-formedness checking
--        (checks for basic syntax & balanced tags only)
--      * Flexible whitespace handling (selectable)
--      * Entity Handling (selectable)
--
--  Limitations:
--  ============
--
--      * Non-validating
--      * No charset handling
--      * No namespace support
--      * Shallow well-formedness checking only (fails
--        to detect most semantic errors)
--
--  API:
--  ====
--
--  The parser provides a partially object-oriented API with
--  functionality split into tokeniser and handler 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.
--
--  XML data is passed to the parser instance through the 'parse'
--  method (Note: must be passed a single string currently)
--
--  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 xml2lua = {}
local XmlParser = require("XmlParser")

---Recursivelly prints a table in an easy-to-ready format
--@param tb The table to be printed
--@param level the indentation level to start with
local function printableInternal(tb, level)
    if tb == nil then
        return
    end

    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)
            printableInternal(v, level+1)
        else
            print(spaces .. k..'='..v)
        end
    end
end

---Instantiates a XmlParser object to parse a XML string
--@param handler Handler module to be used to convert the XML string
--to another formats. See the available handlers at the handler directory.
-- Usually you get an instance to a handler module using, for instance:
-- local handler = require("xmlhandler/tree").
--@return a XmlParser object used to parse the XML
--@see XmlParser
function xml2lua.parser(handler)
    if handler == xml2lua then
        error("You must call xml2lua.parse(handler) instead of xml2lua:parse(handler)")
    end

    local options = {
        --Indicates if whitespaces should be striped or not
        stripWS = 1,
        expandEntities = 1,
        errorHandler = function(errMsg, pos)
            error(string.format("%s [char=%d]\n", errMsg or "Parse Error", pos))
        end
    }

    return XmlParser.new(handler, options)
end

---Recursivelly prints a table in an easy-to-ready format
--@param tb The table to be printed
function xml2lua.printable(tb)
    printableInternal(tb)
end

---Handler to generate a string prepresentation of a table
--Convenience function for printHandler (Does not support recursive tables).
--@param t Table to be parsed
--@return a string representation of the table
function xml2lua.toString(t)
    local sep = ''
    local res = ''
    if type(t) ~= 'table' then
        return t
    end

    for k,v in pairs(t) do
        if type(v) == 'table' then
            v = xml2lua.toString(v)
        end
        res = res .. sep .. string.format("%s=%s", k, v)
        sep = ','
    end
    res = '{'..res..'}'

    return res
end

--- Loads an XML file from a specified path
-- @param xmlFilePath the path for the XML file to load
-- @return the XML loaded file content
function xml2lua.loadFile(xmlFilePath)
    local f, e = io.open(xmlFilePath, "r")
    if f then
        --Gets the entire file content and stores into a string
        return f:read("*a")
    end

    error(e)
end

function xml2lua.decode(xml)
    local handler = require "bw.xml.tree"
    local parser = xml2lua.parser(handler)
    parser:parse(xml)
    return handler.root
end

return xml2lua