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#! /usr/bin/env lua
-- vim:sw=4:sts=4
--
-- Simple calculator demo. Evaluates input as Lua expression.
-- by Wolfgang Oertl 2007. The buttons are quite useless as you'd type
-- the numbers anyway, but this should show off some features, so...
--
-- Possible improvements: allow assignments to variables.
--
require "gtk"
local CALC = {}
CALC.__index = CALC
--
-- Calculate the expression by evaluating it as Lua expression.
-- Returns the result (a value as string) or nil and an error message.
--
function calculate(s)
local chunk, msg = loadstring("return " .. s, s)
if not chunk then
return nil, string.match(msg, ":%d: (.*)")
end
-- The global environment of the user defined function is set to "math", so
-- all functions of the math library (e.g. abs, asin, ceil, deg, exp,
-- floor, log, max, min, pi, pow, random, sin, sqrt) are available, but
-- nothing else: sandboxing!
setfenv(chunk, math)
local rc, result = pcall(chunk)
if not rc then return nil, result end
result = tostring(result)
return string.gsub(result, ",", ".")
end
--
-- A button has been pressed
--
function CALC:btn_click(c, op)
local s2
local s, pos, msg = c.entry:get_text(), -100, ""
if op == '=' then
if s ~= "" then
s2, msg = calculate(s)
if s2 then
s = s2
msg = ""
end
end
pos = -1
elseif op == 'AC' then
s = ""
elseif op == 'EXP' then
s = s .. "^"
elseif op == 'Ans' then
s = s .. "$ans" -- not working
elseif op == 'DEL' then
s = s:sub(1, s:len() - 1)
else
s = s .. op
end
c.entry:set_text(s)
c.message:set_text(msg)
if pos ~= -100 then c.entry:set_position(pos) end
end
function my_insert_text(entry, txt, len, posptr, userdata)
print("insert text", entry, txt, len, posptr, userdata)
end
--
-- Create a CALC object with a stack and the window. Add buttons.
--
function CALC.new()
local tbl
local vbox, hbox, btn
local c = { stack={} }
setmetatable(c, CALC)
c.win = gtk.window_new(gtk.WINDOW_TOPLEVEL)
c.win:connect('delete-event', gtk.main_quit)
c.win:set_title('Calculator')
tbl = gtk.table_new(6, 5, true) -- rows, cols, homogenous
c.win:add(tbl)
-- entry field
c.entry = gtk.entry_new()
c.entry:set_alignment(0.9)
c.entry:set_activates_default(true)
-- c.entry:connect('insert-text', my_insert_text)
tbl:attach_defaults(c.entry, 0, 5, 0, 1)
-- error message field
c.message = gtk.entry_new()
c.message:set_editable(false)
tbl:attach_defaults(c.message, 0, 5, 1, 2)
-- buttons
local buttons = { '7', '8', '9', 'DEL', 'AC',
'4', '5', '6', '*', '/',
'1', '2', '3', '+', '-',
0, '.', 'EXP', 'Ans', '=' }
local row = 1
local col = 0
for nr, lbl in pairs(buttons) do
if math.mod(nr, 5) == 1 then
row = row + 1
col = 0
end
btn = gtk.button_new_with_label(lbl)
tbl:attach_defaults(btn, col, col + 1, row, row + 1)
btn:connect('clicked', CALC.btn_click, c, lbl)
if lbl == '=' then
btn.flags = btn.flags + gtk.CAN_DEFAULT
btn:grab_default()
end
col = col + 1
end
c.win:show_all()
return c
end
local calc = CALC.new()
gtk.main()
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