52 lines
1.0 KiB
Lua
52 lines
1.0 KiB
Lua
local _tl_compat; if (tonumber((_VERSION or ''):match('[%d.]*$')) or 0) < 5.3 then local p, m = pcall(require, 'compat53.module'); if p then _tl_compat = m end end; local table = _tl_compat and _tl_compat.table or table; local ForthStack = {}
|
|
|
|
|
|
|
|
Stack = {}
|
|
|
|
|
|
|
|
|
|
|
|
|
|
function Stack:push(val)
|
|
self.top = self.top + 1
|
|
table.insert(self.contents, val)
|
|
end
|
|
function Stack:pop()
|
|
self.top = self.top - 1
|
|
if self.top < 0 then
|
|
error("Stack underflow")
|
|
end
|
|
return table.remove(self.contents)
|
|
end
|
|
local stack_mt = { __index = Stack }
|
|
function Stack:new()
|
|
return setmetatable({ contents = {}, top = 0 }, stack_mt)
|
|
end
|
|
|
|
|
|
|
|
function ForthStack.add(stack)
|
|
local a = stack:pop()
|
|
local b = stack:pop()
|
|
if type(a) == "number" and type(b) == "number" then
|
|
local c = a + b
|
|
stack:push(c)
|
|
else
|
|
error("invalid operands for add operation!")
|
|
end
|
|
end
|
|
function ForthStack.dot(s)
|
|
print(s:pop())
|
|
end
|
|
local s = Stack:new()
|
|
s:push(1)
|
|
s:push(4)
|
|
ForthStack.add(s)
|
|
print(ForthStack.dot(s))
|
|
|
|
|
|
|
|
return ForthStack
|