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local patok = require 'patok'
local inspect = require 'inspect'
local pm = require 'piecemeal'
local lexer = patok {
op = '[+*]',
digit = '%d+',
space = '%s+',
}()
local lex = {
-- plus = pm.lexeme 'plus',
plus = pm.value '+',
times = pm.value '*',
digit = pm.postp(pm.lexeme 'digit', function(d) return tonumber(d.value) end),
space = pm.opt(pm.lexeme 'space')
}
local function findnums(d, acc)
local out = acc or {}
for _, v in ipairs(d) do -- only ipairs to avoid triggering on tokens
if type(v) == 'number' then
table.insert(out, v)
elseif type(v) == 'table' then
findnums(v, out)
end
end
return out
end
local mult = pm.postp(
pm.all(lex.digit, pm.star(pm.all(lex.space, lex.times, lex.space, lex.digit))),
function (d)
local acc = 1
for _, v in ipairs(findnums(d)) do
acc = acc * v
end
return acc
end)
local add = pm.postp(
pm.all(mult, pm.star(pm.all(lex.space, lex.plus, lex.space, mult))),
function (d)
local acc = 0
for _, v in ipairs(findnums(d)) do
acc = acc + v
end
return acc
end)
local expr = add
local test
if arg[1] then
local f = io.open(arg[1], 'r')
test = f:read '*a'
f:close()
else
test = [[10 + 5 * 2 + 10]]
end
local eind, out = pm.parse(test, lexer, expr)
print(eind, out)
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