pretty.lua

--- Lua pretty printer from <a href="http://mini.net/cgi-bin/lua/44.html">http://mini.net/cgi-bin/lua/44.html</a><br/>
-- This was extracted from utility code in "util.lua".<br/>
-- 23/02/2001 jcw@equi4.com<br/>
-- Pretty displays a value, properly dealing with tables and cycles

local displayvalue=
  function (s)
    if not s or type(s)=='function' or type(s)=='userdata' then
      s=tostring(s)
    elseif type(s)~='number' then
      s=string.gsub(string.format('%q',s),'^"([^"\']*)"$',"'%1'")
    end
    return s
  end

local askeystr=
  function (u,s)
    if type(u)=='string' and string.find(u,'^[%w_]+$') then return s..u end
    return '['..displayvalue(u)..']'
  end

local horizvec=
  function (x,n)
    local o,e='',''
    for i=1,table.getn(x) do
      if type(x[i])=='table' then return end
      o=o..e..displayvalue(x[i])
      if string.len(o)>n then return end
      e=','
    end
    return '('..o..')'
  end

local horizmap=
  function (x,n)
    local o,e='',''
    for k,v in pairs(x) do
      if type(v)=='table' then return end
      o=o..e..askeystr(k,'')..'='..displayvalue(v)
      if string.len(o)>n then return end
      e=','
    end
    return '{'..o..'}'
  end

function pretty(p,x,h,q)
  if not p then p,x='globals',globals() end
  if type(x)=='table' then
    if not h then h={} end
    if h[x] then
      x=h[x]
    else
      if not q then q=p end
      h[x]=q
      local s={}
      for k,v in pairs(x) do table.insert(s,k) end
      if table.getn(s)>0 then
        local n=75-string.len(p)
        local f=table.getn(s)==table.getn(x) and horizvec(x,n)
        if not f then f=horizmap(x,n) end
        if not f then
          table.sort(s,function (a,b)
                   --if tag(a)~=tag(b) then a,b=tag(b),tag(a) end
                   if type(a)~=type(b) then a,b=type(b),type(a) end
                   return a<b
                 end)
          for i=1,table.getn(s) do
            if s[i] then
              local u=askeystr(s[i],'.')
              pretty(p..u,x[s[i]],h,q..u)
              p=string.rep(' ',string.len(p))
            end
          end
          return
        end
        x=f
      else
        x='{}'
      end
    end
  else
    x=displayvalue(x)
  end
  print(p..' = '..x)
end