PN Math Evaluator [37]

< > BotCompany Repo | #37 // PN Math Evaluator

Lua code

-- simple PN math evaluator
-- expects input in "input"

tokens = {}
for token in string.gmatch(input, "[^%s]+") do
  table.insert(tokens, token)
end

stack = {}

function push(x) table.insert(stack, x) end
function pop() local x = stack[#stack]; stack[#stack] = nil; return x end

for i = #tokens, 1, -1 do
  token = tokens[i]
  if token:match('^[0-9]+$') then
    push(tonumber(token))
  else
    arg1 = pop()
    arg2 = pop()
    if token == '+' then
      push(arg1+arg2)
    elseif token == '*' then
      push(arg1*arg2)
    else
      error("Unknown operation: "..token)
    end
  end
end

return pop()

Relations

solves #38 [pitcher]

Travelled to 12 computer(s): aoiabmzegqzx, bhatertpkbcr, cbybwowwnfue, gwrvuhgaqvyk, ishqpsrjomds, lpdgvwnxivlt, mqqgnosmbjvj, pyentgdyhuwx, pzhvpgtvlbxg, tslmcundralx, tvejysmllsmz, vouqrxazstgt

Image recognition results

Recognizer	Recognition Result	Visualize	Recalc
#308	639	[visualize]

Recognizer

Recognition Result

Visualize

Recalc

#308

639

[visualize]

Snippet ID:

#37

Snippet name:

PN Math Evaluator

Eternal ID of this version:

#37/1

Text MD5:

602ffbe90ec65a817ed361a9c1b49507

Author:

stefan

Category:

Type:

Lua code

Public (visible to everyone):

Yes

Archived (hidden from active list):

Created/modified:

2013-12-15 09:15:51

Source code size:

639 bytes / 31 lines

Pitched / IR pitched:

Yes / Yes

Views / Downloads:

1529 / 362

Referenced in:

[show references]

1	-- simple PN math evaluator
2	-- expects input in "input"
3
4	tokens = {}
5	for token in string.gmatch(input, "[^%s]+") do
6	table.insert(tokens, token)
7	end
8
9	stack = {}
10
11	function push(x) table.insert(stack, x) end
12	function pop() local x = stack[#stack]; stack[#stack] = nil; return x end
13
14	for i = #tokens, 1, -1 do
15	token = tokens[i]
16	if token:match('^[0-9]+$') then
17	push(tonumber(token))
18	else
19	arg1 = pop()
20	arg2 = pop()
21	if token == '+' then
22	push(arg1+arg2)
23	elseif token == '*' then
24	push(arg1*arg2)
25	else
26	error("Unknown operation: "..token)
27	end
28	end
29	end
30
31	return pop()