-- $Id: html.lua,v 1.2 2007-05-12 04:37:20 tclua Exp $

module(..., package.seeall)

entity = {

nbsp = " ",

lt = "<",

gt = ">",

quot = "\"",

amp = "&",

}

-- keep unknown entity as is

setmetatable(entity, {

__index = function (t, key)

return "&" .. key .. ";"

end

})

block = {

"address",

"blockquote",

"center",

"dir", "div", "dl",

"fieldset", "form",

"h1", "h2", "h3", "h4", "h5", "h6", "hr",

"isindex",

"menu",

"noframes",

"ol",

"p",

"pre",

"table",

"ul",

}

inline = {

"a", "abbr", "acronym", "applet",

"b", "basefont", "bdo", "big", "br", "button",

"cite", "code",

"dfn",

"em",

"font",

"i", "iframe", "img", "input",

"kbd",

"label",

"map",

"object",

"q",

"s", "samp", "select", "small", "span", "strike", "strong", "sub", "sup",

"textarea", "tt",

"u",

"var",

}

tags = {

a = { empty = false },

abbr = {empty = false} ,

acronym = {empty = false} ,

address = {empty = false} ,

applet = {empty = false} ,

area = {empty = true} ,

b = {empty = false} ,

base = {empty = true} ,

basefont = {empty = true} ,

bdo = {empty = false} ,

big = {empty = false} ,

blockquote = {empty = false} ,

body = { empty = false, },

br = {empty = true} ,

button = {empty = false} ,

caption = {empty = false} ,

center = {empty = false} ,

cite = {empty = false} ,

code = {empty = false} ,

col = {empty = true} ,

colgroup = {

empty = false,

optional_end = true,

child = {"col",},

},

dd = {empty = false} ,

del = {empty = false} ,

dfn = {empty = false} ,

dir = {empty = false} ,

div = {empty = false} ,

dl = {empty = false} ,

dt = {

empty = false,

optional_end = true,

child = {

inline,

"del",

"ins",

"noscript",

"script",

},

},

em = {empty = false} ,

fieldset = {empty = false} ,

font = {empty = false} ,

form = {empty = false} ,

frame = {empty = true} ,

frameset = {empty = false} ,

h1 = {empty = false} ,

h2 = {empty = false} ,

h3 = {empty = false} ,

h4 = {empty = false} ,

h5 = {empty = false} ,

h6 = {empty = false} ,

head = {empty = false} ,

hr = {empty = true} ,

html = {empty = false} ,

i = {empty = false} ,

iframe = {empty = false} ,

img = {empty = true} ,

input = {empty = true} ,

ins = {empty = false} ,

isindex = {empty = true} ,

kbd = {empty = false} ,

label = {empty = false} ,

legend = {empty = false} ,

li = {

empty = false,

optional_end = true,

child = {

inline,

block,

"del",

"ins",

"noscript",

"script",

},

},

link = {empty = true} ,

map = {empty = false} ,

menu = {empty = false} ,

meta = {empty = true} ,

noframes = {empty = false} ,

noscript = {empty = false} ,

object = {empty = false} ,

ol = {empty = false} ,

optgroup = {empty = false} ,

option = {

empty = false,

optional_end = true,

child = {},

},

p = {

empty = false,

optional_end = true,

child = {

inline,

"del",

"ins",

"noscript",

"script",

},

} ,

param = {empty = true} ,

pre = {empty = false} ,

q = {empty = false} ,

s = {empty = false} ,

samp = {empty = false} ,

script = {empty = false} ,

select = {empty = false} ,

small = {empty = false} ,

span = {empty = false} ,

strike = {empty = false} ,

strong = {empty = false} ,

style = {empty = false} ,

sub = {empty = false} ,

sup = {empty = false} ,

table = {empty = false} ,

tbody = {empty = false} ,

td = {

empty = false,

optional_end = true,

child = {

inline,

block,

"del",

"ins",

"noscript",

"script",

},

},

textarea = {empty = false} ,

tfoot = {

empty = false,

optional_end = true,

child = {"tr",},

},

th = {

empty = false,

optional_end = true,

child = {

inline,

block,

"del",

"ins",

"noscript",

"script",

},

},

thead = {

empty = false,

optional_end = true,

child = {"tr",},

},

title = {empty = false} ,

tr = {

empty = false,

optional_end = true,

child = {

"td", "th",

},

},

tt = {empty = false} ,

u = {empty = false} ,

ul = {empty = false} ,

var = {empty = false} ,

}

setmetatable(tags, {

__index = function (t, key)

return {empty = false}

end

})

-- string buffer implementation

function newbuf ()

local buf = {

_buf = {},

clear = function (self) self._buf = {}; return self end,

content = function (self) return table.concat(self._buf) end,

append = function (self, s)

self._buf[#(self._buf) + 1] = s

return self

end,

set = function (self, s) self._buf = {s}; return self end,

}

return buf

end

-- unescape character entities

function unescape (s)

function entity2string (e)

return entity[e]

end

return s.gsub(s, "&(#?%w+);", entity2string)

end

-- iterator factory

function makeiter (f)

local co = coroutine.create(f)

return function ()

local code, res = coroutine.resume(co)

return res

end

end

-- constructors for token

function Tag (s)

return string.find(s, "^</") and

{type = "End", value = s} or

{type = "Start", value = s}

end

function Text (s)

local unescaped = unescape(s)

return {type = "Text", value = unescaped}

end

-- lexer: text mode

function text (f, buf)

local c = f:read(1)

if c == "<" then

if buf:content() ~= "" then coroutine.yield(Text(buf:content())) end

buf:set(c)

return tag(f, buf)

elseif c then

buf:append(c)

return text(f, buf)

else

if buf:content() ~= "" then coroutine.yield(Text(buf:content())) end

end

end

-- lexer: tag mode

function tag (f, buf)

local c = f:read(1)

if c == ">" then

coroutine.yield(Tag(buf:append(c):content()))

buf:clear()

return text(f, buf)

elseif c then

buf:append(c)

return tag(f, buf)

else

if buf:content() ~= "" then coroutine.yield(Tag(buf:content())) end

end

end

function parse_starttag(tag)

local tagname = string.match(tag, "<%s*(%w+)")

local elem = {_attr = {}}

elem._tag = tagname

for key, _, val in string.gmatch(tag, "(%w+)%s*=%s*([\"'])(.-)%2", i) do

local unescaped = unescape(val)

elem._attr[key] = unescaped

end

return elem

end

function parse_endtag(tag)

local tagname = string.match(tag, "<%s*/%s*(%w+)")

return tagname

end

-- find last element that satisfies given predicate

function rfind(t, pred)

local length = #t

for i=length,1,-1 do

if pred(t[i]) then

return i, t[i]

end

end

end

function flatten(t, acc)

acc = acc or {}

for i,v in ipairs(t) do

if type(v) == "table" then

flatten(v, acc)

else

acc[#acc + 1] = v

end

end

return acc

end

function optional_end_p(elem)

if tags[elem._tag].optional_end then

return true

else

return false

end

end

function valid_child_p(child, parent)

local schema = tags[parent._tag].child

if not schema then return true end

for i,v in ipairs(flatten(schema)) do

if v == child._tag then

return true

end

end

return false

end

-- tree builder

function parse(f)

local root = {_tag = "#document", _attr = {}}

local stack = {root}

for i in makeiter(function () return text(f, newbuf()) end) do

if i.type == "Start" then

local new = parse_starttag(i.value)

local top = stack[#stack]

while

top._tag ~= "#document" and

optional_end_p(top) and

not valid_child_p(new, top)

do

stack[#stack] = nil

top = stack[#stack]

end

top[#top+1] = new -- appendchild

if not tags[new._tag].empty then

stack[#stack+1] = new -- push

end

elseif i.type == "End" then

local tag = parse_endtag(i.value)

local openingpos = rfind(stack, function(v)

if v._tag == tag then

return true

else

return false

end

end)

if openingpos then

local length = #stack

for j=length,openingpos,-1 do

table.remove(stack, j)

end

end

else -- Text

local top = stack[#stack]

top[#top+1] = i.value

end

end

return root

end

function parsestr(s)

local handle = {

_content = s,

_pos = 1,

read = function (self, length)

if self._pos > string.len(self._content) then return end

local ret = string.sub(self._content, self._pos, self._pos + length - 1)

self._pos = self._pos + length

return ret

end

}

return parse(handle)

end