Rendering Wiki markup as HTML

Here is the core logic to turn text files into HTML, adhering to the conventions used in wiki's like this one.

  -- Wippler's wicked wiki renderer
  -- 12/02/2001 jcw@equi4.com

  if not linesplit then dofile('util.lua') end --XXX

  wiki={}

  function wiki.linetype(l)
    local l=gsub(l,'%s*$','')
    local l=gsub(l,'(\t)','    ')
    local x={cat='-',txt=l}
    local f=function (t,m)
              local a,b,c,d,e
              a,b,c,d,e=strfind(%l,m)
              if a and imod(strlen(c),3)==0 then
                %x.cat,%x.depth,%x.aux,%x.txt=t,strlen(c)/3,d,e
                return %x
              end
            end
    if f('U','^(   +)(%*) (.+)$') then return x end
    if f('O','^(   +)([1-9#])%. (.+)$') then return x end
    if f('D','^(   +)([^:]+):   (.+)$') then return x end
    if strsub(l,1,1)==' ' then
      x.cat,x.depth='Q',1
    elseif strfind(l,'^%-%-%-%-+$') then
      x.cat='H'
    end
    return x
  end

  function wiki.brackets(l)
    l=gsub(l,'%[%[','[')
    l=gsub(l,'%]%]',']')
    return l
  end

  function wiki.hilites(l)
    l=gsub(l,"'''([^'].-)'''","<B>%1</B>")
    l=gsub(l,"''([^'].-)''","<I>%1</I>")
    return l
  end

  function wiki.refs(l,t,r)
    if t then
      l=gsub(l,'%[%[','&lbra;')
      local f=function (u)
                local s=strsub(u,2,-2)
                local n=%t[strlower(s)]
                if n then
                  tinsert(%r,n)
                  u='<A HREF="'..n..'">'..s..'</A>'
                end
                return u
              end
      l=gsub(l,'(%b[])',f)
      l=gsub(l,'&lbra;','[[')
    end
    return l
  end

  function wiki.links(l,u)
    local types={http=1,https=1,ftp=1,news=1,mailto=1}
    local f=function (t,p)
              local a=t..':'..p
              if %types[t] then
                tinsert(%u,a)
                a='<A HREF="'..a..'">'..a..'</A>'
              end
              return a
            end
    l=gsub(l,'(%w+):([^%s]+[^%]%)%s%.,!%?;:\'>])',f)
    return l
  end

  function wiki.urls(l,u)
    l=gsub(l,'%[%[','&lbra;')
    local f=function (r)
              if not %u[r] then
                tinsert(%u,r)
                %u[r]=getn(%u)
              end
              return '[<A HREF="'..r..'">'..%u[r]..'</A>]'
            end
    l=gsub(l,'%[<A HREF="(.-)">%1</A>%]',f)
    l=gsub(l,'&lbra;','[[')
    return l
  end

  function wiki.genhtml(v,t)
    local last,reset,depth,o,r,u='','',0,{},{},{}
    tinsert(v,{cat='-',txt=''})
    for i=1,getn(v) do
      local x,d=v[i],0
      local l=htmlize(x.txt)
      if x.cat==last and x.depth then d=x.depth end
      while d<depth do
        o[getn(o)]=o[getn(o)]..reset
        depth=depth-1
      end
      if x.depth then d=x.depth end
      while d>depth do
        if x.cat=='Q' then
          l='<PRE>'..l
          reset='</PRE>'
        else
          l='<'..x.cat..'L>'..l
        end
        depth=depth+1
      end
      if x.cat=='H' then
        l='<HR SIZE='..(strlen(l)-3)..'>'
      elseif x.cat=='U' or x.cat=='O' then
        l='<LI>'..l
        reset='</'..x.cat..'L>'
      elseif x.cat=='D' then
        l='<DT>'..x.aux..'<DD>'..l
        reset='</DL>'
      elseif x.cat=='-' and l=='' then
        if last=='-' then l='<P>' else l='<BR>' end
      end
      if x.cat=='Q' then
        l=wiki.links(l,u)
      else
        l=wiki.refs(l,t,r)
        l=wiki.links(l,u)
        l=wiki.urls(l,u)
        l=wiki.brackets(l)
        l=wiki.hilites(l)
      end
      tinsert(o,l)
      last=x.cat
    end
    return o,r,u
  end

  -- call this to enable lookup of titles and page numbers
  function wiki.LoadTitles(f)
    local t={}
    for i,v in linesplit(f) do
      local n=strfind(v,'\t')
      if n then
        local a,b=tonumber(strsub(v,1,n-1)),strsub(v,n+1)
        t[a],t[strlower(b)]=b,a
      end
    end
    return t
  end

  -- convert string with wiki markup into a html representation
  function wiki.Render(text,titles)
    return wiki.genhtml(map(linesplit(text),wiki.linetype),titles)
  end

An example of its output can be found at http://mini.net/cgi-bin/tcl/0 - this is a CGI script based on this code, rendering a snapshot of a wiki about Tcl, with many hundreds of pages of content. This is just proof of concept for now...