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snaki 2022-08-28 21:39:25 +02:00
commit b97fd3c64f
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111
calc.lua Executable file
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#!/usr/bin/env lua
function splitTokens(s)
local tokens = {}
for i in string.gmatch(s, '%w+') do
table.insert(tokens, i)
end
return tokens
end
PLUS = 'a'
MINUS = 's'
TIMES = 'm'
DIVIDE = 'd'
function isDash(token)
return token == PLUS or token == MINUS
end
function isDot(token)
return token == TIMES or token == DIVIDE
end
function parseNum(tokens)
local val = table.remove(tokens, 1)
val = tonumber(val)
return {
['type'] = 'num',
['num'] = val
}
end
function parseFactor(tokens)
local lhs = parseNum(tokens)
while isDot(tokens[1]) do
local op = table.remove(tokens, 1)
local rhs = parseNum(tokens)
lhs = {
['type'] = 'op',
['op'] = op,
['lhs'] = lhs,
['rhs'] = rhs
}
end
return lhs
end
function parseTerm(tokens)
local lhs = parseFactor(tokens)
while isDash(tokens[1]) do
local op = table.remove(tokens, 1)
local rhs = parseFactor(tokens)
lhs = {
['type'] = 'op',
['op'] = op,
['lhs'] = lhs,
['rhs'] = rhs,
}
end
return lhs
end
function parseExpr(tokens)
return parseTerm(tokens)
end
function eval(expr)
if expr['type'] == 'num' then
return expr['num']
elseif expr['type'] == 'op' then
local lval = eval(expr['lhs'])
local rval = eval(expr['rhs'])
if expr['op'] == PLUS then
return lval + rval
elseif expr['op'] == MINUS then
return lval - rval
elseif expr['op'] == TIMES then
return lval * rval
elseif expr['op'] == DIVIDE then
return lval / rval
else
print('invalid operator!')
end
else
print('invalid expr type!')
end
end
return eval(parseExpr(splitTokens(expr:toStringNoDot())))
function printTree(expr, depth)
local indent = string.rep(' ', depth)
print(indent .. 'type: ' .. expr['type'])
if expr['type'] == 'num' then
print(indent .. 'num: ' .. expr['num'])
elseif expr['type'] == 'op' then
print(indent .. 'op: ' .. expr['op'])
print(indent .. 'lhs:')
printTree(expr['lhs'], depth + 1)
print(indent .. 'rhs:')
printTree(expr['rhs'], depth + 1)
else
print('invalid expr type!')
end
end
program = '1.a.2.m.3.s.4'
tree = parseExpr(splitTokens(program))
printTree(tree, 0)
print('result: ', eval(tree))

79
pdns.lua Normal file
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; expr = qname:makeRelative(newDN('calc.cyfn.de.'))
function splitTokens(s)
local tokens = {}
for i in string.gmatch(s, '%w+') do
table.insert(tokens, i)
end
return tokens
end
PLUS = 'a'
MINUS = 's'
TIMES = 'm'
DIVIDE = 'd'
function isDash(token)
return token == PLUS or token == MINUS
end
function isDot(token)
return token == TIMES or token == DIVIDE
end
function parseNum(tokens)
local val = table.remove(tokens, 1)
val = tonumber(val)
return {
['type'] = 'num',
['num'] = val
}
end
function parseFactor(tokens)
local lhs = parseNum(tokens)
while isDot(tokens[1]) do
local op = table.remove(tokens, 1)
local rhs = parseNum(tokens)
lhs = {
['type'] = 'op',
['op'] = op,
['lhs'] = lhs,
['rhs'] = rhs
}
end
return lhs
end
function parseTerm(tokens)
local lhs = parseFactor(tokens)
while isDash(tokens[1]) do
local op = table.remove(tokens, 1)
local rhs = parseFactor(tokens)
lhs = {
['type'] = 'op',
['op'] = op,
['lhs'] = lhs,
['rhs'] = rhs,
}
end
return lhs
end
function parseExpr(tokens)
return parseTerm(tokens)
end
function eval(expr)
if expr['type'] == 'num' then
return expr['num']
elseif expr['type'] == 'op' then
local lval = eval(expr['lhs'])
local rval = eval(expr['rhs'])
if expr['op'] == PLUS then
return lval + rval
elseif expr['op'] == MINUS then
return lval - rval
elseif expr['op'] == TIMES then
return lval * rval
elseif expr['op'] == DIVIDE then
return lval / rval
else
print('invalid operator!')
end
else
print('invalid expr type!')
end
end
return eval(parseExpr(splitTokens(expr:toStringNoDot())))