Penlight Documentation

## testxml.lua

    -- an example showing 'pl.lexer' doing some serious work.
    -- The resulting Lua table is in the same LOM format used by luaexpat.
    -- This is (clearly) not a professional XML parser, so don't use it
    -- on your homework!

    local lexer = require 'pl.lexer'
    local pretty = require 'pl.pretty'

    local append = table.insert
    local skipws,expecting = lexer.skipws,lexer.expecting

    local function parse_element (tok,tag)
    	local tbl,t,v,attrib
    	tbl = {}
    	tbl.tag = tag  -- LOM 'tag' is the element tag
    	t,v = skipws(tok)
    	while v ~= '/' and v ~= '>' do
    		if t ~= 'iden' then error('expecting attribute identifier') end
    		attrib = v
    		expecting(tok,'=')
    		v = expecting(tok,'string')
    		-- LOM: 'attr' subtable contains attrib/value pairs and an ordered list of attribs
    		if not tbl.attr then tbl.attr = {} end
    		tbl.attr[attrib] = v
    		append(tbl.attr,attrib)
    		t,v = skipws(tok)
    	end
    	if v == '/' then
    		expecting(tok,'>')
    		return tbl
    	end
    	-- pick up element data
    	t,v = tok()
    	while true do
    		if t == '<' then
    			t,v = skipws(tok)
    			if t == '/' then -- element end tag
    				t,v = tok()
    				if t == '>' then return tbl end
    				if t == 'iden' and v == tag then
    					if tok() == '>' then return tbl end
    				end
    				error('expecting end tag '..tag)
    			else
    				append(tbl,parse_element(tok,v)) -- LOM: child elements added to table
    				t,v = skipws(tok)
    			end
    		else
    			append(tbl,v) -- LOM: text added to table
    			t,v = skipws(tok)
    		end
    	end
    end

    local function parse_xml (tok)
    	local t = skipws(tok)
    	local v
    	while t == '<' do
    		t,v = tok()
    		if t == '?' or t == '!' then
    			-- skip meta stuff and commentary
    			repeat t = tok() until t == '>'
    			t = expecting(tok,'<')
    		else
    			return parse_element(tok,v)
    		end
    	end
    end

    local s = [[
    <?xml version="1.0" encoding="UTF-8"?>
    <sensor name="closure-meter-2" id="7D7D0600006F0D00" loc="100,100,0" device="closure-meter" init="true">
    <detector name="closure-meter" phenomenon="closure" units="mm" id="1"
        vmin="0" vmax="5000" device="closure-meter" calib="0,0;5000,5000"
        sampling_interval="25000" measurement_interval="600000"
    />
    </sensor>
    ]]

    local tok = lexer.scan(s,nil,{space=false},{string=true})
    local res = parse_xml(tok)
    print(pretty.write(res))

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