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proc handleHexChar*(c: char, x: var int): bool {.inline.} =
## Converts `%xx` hexadecimal to the ordinal number and adds the result to `x`.
## Returns `true` if `c` is hexadecimal.
##
## When `c` is hexadecimal, the proc is equal to `x = x shl 4 + hex2Int(c)`.
runnableExamples:
var x = 0
assert handleHexChar('a', x)
assert x == 10
assert handleHexChar('B', x)
assert x == 171 # 10 shl 4 + 11
assert not handleHexChar('?', x)
assert x == 171 # unchanged
result = true
case c
of '0'..'9': x = (x shl 4) or (ord(c) - ord('0'))
of 'a'..'f': x = (x shl 4) or (ord(c) - ord('a') + 10)
of 'A'..'F': x = (x shl 4) or (ord(c) - ord('A') + 10)
else:
result = false
proc handleHexChar*(c: char): int {.inline.} =
case c
of '0'..'9': result = (ord(c) - ord('0'))
of 'a'..'f': result = (ord(c) - ord('a') + 10)
of 'A'..'F': result = (ord(c) - ord('A') + 10)
else: discard
proc decodePercent*(s: openArray[char], i: var int): char =
## Converts `%xx` hexadecimal to the character with ordinal number `xx`.
##
## If `xx` is not a valid hexadecimal value, it is left intact: only the
## leading `%` is returned as-is, and `xx` characters will be processed in the
## next step (e.g. in `uri.decodeUrl`) as regular characters.
result = '%'
if i+2 < s.len:
var x = 0
if handleHexChar(s[i+1], x) and handleHexChar(s[i+2], x):
result = chr(x)
inc(i, 2)
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