savetable.lua

-- $Id: savetable.lua 3171 2008-11-06 09:06:29Z det $
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------
--
--  file:    savetable.lua
--  brief:   a human friendly table writer
--  author:  Dave Rodgers
--
--  Copyright (C) 2007.
--  Licensed under the terms of the GNU GPL, v2 or later.
--
--  2 Sept 2008, quantum: added table.show and table.print
--
--------------------------------------------------------------------------------
--------------------------------------------------------------------------------

if (table.echo) then
  return
end

local indentString = '  '

local savedTables = {}

-- setup a lua keyword map
local keyWords = {
 "and", "break", "do", "else", "elseif", "end", "false", "for", "function",
 "if", "in", "local", "nil", "not", "or", "repeat", "return", "then", "true",
 "until", "while"
}
local keyWordSet = {}
for _,w in ipairs(keyWords) do
  keyWordSet[w] = true
end
keyWords = nil  -- don't need the array anymore


--------------------------------------------------------------------------------

local function encloseStr(s)
  return string.format('%q', s)
end


local function encloseKey(s)
  local wrap = not (string.find(s, '^%a[_%a%d]*$'))
  if (not wrap) then
    if (string.len(s) <= 0) then wrap = true end
  end
  if (not wrap) then
    if (keyWordSet[s]) then wrap = true end
  end
    
  if (wrap) then
    return string.format('[%q]', s)
  else
    return s
  end
end


local keyTypes = {
  ['string']  = true,
  ['number']  = true,
  ['boolean'] = true,
}

local valueTypes = {
  ['string']  = true,
  ['number']  = true,
  ['boolean'] = true,
  ['table']   = true,
}


local function CompareKeys(kv1, kv2)
  local k1, v1 = kv1[1], kv1[2]
  local k2, v2 = kv2[1], kv2[2]

  local ktype1 = type(k1)
  local ktype2 = type(k2)
  if (ktype1 ~= ktype2) then
    return (ktype1 > ktype2)
  end

  local vtype1 = type(v1)
  local vtype2 = type(v2)
  if ((vtype1 == 'table') and (vtype2 ~= 'table')) then
    return false
  end
  if ((vtype1 ~= 'table') and (vtype2 == 'table')) then
    return true
  end

  return (k1 < k2)
end


local function MakeSortedTable(t)
  local st = {}
  for k,v in pairs(t) do
    if (keyTypes[type(k)] and valueTypes[type(v)]) then
      table.insert(st, { k, v })
    end
  end
  table.sort(st, CompareKeys)
  return st
end


local function SaveTable(t, file, indent)
  file:write('{\n')
  local indent = indent .. indentString
  
  local st = MakeSortedTable(t)
  
  for _,kv in ipairs(st) do
    local k, v = kv[1], kv[2]
    local ktype = type(k)
    local vtype = type(v)
    -- output the key
    if (ktype == 'string') then
      file:write(indent..encloseKey(k)..' = ')
    else
      file:write(indent..'['..tostring(k)..'] = ')
    end
    -- output the value
    if (vtype == 'string') then
      file:write(encloseStr(v)..',\n')
    elseif (vtype == 'number') then
      file:write(tostring(v)..',\n')
    elseif (vtype == 'boolean') then
      file:write(tostring(v)..',\n')
    elseif (vtype == 'table') then
      if (savedTables[v]) then
        error("table.save() does not support recursive tables")
      end
      if (next(v)) then
        savedTables[t] = true
        SaveTable(v, file, indent)
        file:write(indent..'},\n')
        savedTables[t] = nil
      else
        file:write('{},\n') -- empty table
      end
    end
  end
end


function ShowTable(t, indent)
  local strings = {}
  strings[#strings+1] = '{\n'
  local indent = indent .. indentString
  
  local st = MakeSortedTable(t)
  
  for _,kv in ipairs(st) do
    local k, v = kv[1], kv[2]
    local ktype = type(k)
    local vtype = type(v)
    -- output the key
    if (ktype == 'string') then
      strings[#strings+1] = (indent..encloseKey(k)..' = ')
    else
      strings[#strings+1] = (indent..'['..tostring(k)..'] = ')
    end
    -- output the value
    if (vtype == 'string') then
      strings[#strings+1] = (encloseStr(v)..',\n')
    elseif (vtype == 'number') then
      strings[#strings+1] = (tostring(v)..',\n')
    elseif (vtype == 'boolean') then
      strings[#strings+1] = (tostring(v)..',\n')
    elseif (vtype == 'table') then
      if (savedTables[v]) then
        error("table.save() does not support recursive tables")
      end
      if (next(v)) then
        savedTables[t] = true
        strings[#strings+1] = ShowTable(v, indent)
        strings[#strings+1] = (indent..'},\n')
        savedTables[t] = nil
      else
        strings[#strings+1] = ('{},\n') -- empty table
      end
    end
  end
  return table.concat(strings)
end


function table.show(t, header)
  local strings = {}
  
  if (header) then
    strings[#strings+1] = (header..'\n')
  end
  
  strings[#strings+1] = 'return '
  strings[#strings+1] = ShowTable(t, '')
  strings[#strings+1] = '}\n'
  for k,v in pairs(savedTables) do
    savedTables[k] = nil
  end
  return table.concat(strings)
end


function table.print(t, header)
  print(table.show(t, header))
end


function table.echo(t, header)
  Spring.Echo(table.show(t, header))
end


function table.save(t, filename, header)
  if (not filename) then
    error("Error while saving.")
    return
  end
  local file = io.open(filename, 'w')
  if (not file) then
    error("Error writing to "..filename..".\nFile not saved.")
    return
  end
  if (header) then
    file:write(header..'\n')
  end
  file:write('return ')
  SaveTable(t, file, '')
  file:write('}\n')
  file:close()
  for k,v in pairs(savedTables) do
    savedTables[k] = nil
  end
end