2025-02-05 10:52:15 +01:00

47 lines
1.9 KiB
Nim

import std/parseutils
import pkg/chronos
when not declared(parseDuration): # Odd code formatting to minimize diff v. mainLine
const Whitespace = {' ', '\t', '\v', '\r', '\l', '\f'}
func toLowerAscii(c: char): char =
if c in {'A' .. 'Z'}:
char(uint8(c) xor 0b0010_0000'u8)
else:
c
func parseDuration*(s: string, size: var Duration): int =
## Parse a size qualified by simple time into `Duration`.
##
runnableExamples:
var res: Duration # caller must still know if 'b' refers to bytes|bits
doAssert parseDuration("10H", res) == 3
doAssert res == initDuration(hours = 10)
doAssert parseDuration("64m", res) == 6
doAssert res == initDuration(minutes = 64)
doAssert parseDuration("7m/block", res) == 2 # '/' stops parse
doAssert res == initDuration(minutes = 7) # 1 shl 30, forced binary metric
doAssert parseDuration("3d", res) == 2 # '/' stops parse
doAssert res == initDuration(days = 3) # 1 shl 30, forced binary metric
const prefix = "s" & "mhdw" # byte|bit & lowCase metric-ish prefixes
const timeScale = [1.0, 60.0, 3600.0, 86_400.0, 604_800.0]
var number: float
var scale = 1.0
result = parseFloat(s, number)
if number < 0: # While parseFloat accepts negatives ..
result = 0 #.. we do not since sizes cannot be < 0
else:
let start = result # Save spot to maybe unwind white to EOS
while result < s.len and s[result] in Whitespace:
inc result
if result < s.len: # Illegal starting char => unity
if (let si = prefix.find(s[result].toLowerAscii); si >= 0):
inc result # Now parse the scale
scale = timeScale[si]
else: # Unwind result advancement when there..
result = start #..is no unit to the end of `s`.
var sizeF = number * scale + 0.5 # Saturate to int64.high when too big
size = seconds(int(sizeF))