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encoding.hex: remove strconv dependency (#11196)

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Miccah 2021-08-15 20:59:21 -05:00 committed by GitHub
parent 022503a107
commit 60f21f065f
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2 changed files with 49 additions and 12 deletions
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48
vlib/encoding/hex/hex.v
View File

@ -1,25 +1,39 @@
module hex
import strconv
import strings
// decode converts a hex string into an array of bytes. The expected
// input format is 2 ASCII characters for each output byte. If the provided
// string length is not a multiple of 2, an implicit `0` is prepended to it.
pub fn decode(s string) ?[]byte {
if s.len == 0 {
return []byte{}
} else if s.len <= 2 {
return [byte(strconv.parse_uint(s, 16, 8) ?)]
mut hex_str := s
if hex_str.len >= 2 {
if s[0] == `0` && (s[1] == `x` || s[1] == `X`) {
hex_str = s[2..]
}
}
// calculate the first byte depending on if s.len is odd
val := byte(strconv.parse_uint(s[..2 - (s.len & 1)], 16, 8) ?)
// set cap to s.len/2 rounded up
mut bytes := []byte{len: 1, cap: (s.len + 1) >> 1, init: val}
if hex_str.len == 0 {
return []byte{}
} else if hex_str.len == 1 {
return [char2nibble(hex_str[0]) ?]
} else if hex_str.len == 2 {
n1 := char2nibble(hex_str[0]) ?
n0 := char2nibble(hex_str[1]) ?
return [(n1 << 4) | n0]
}
// calculate the first byte depending on if hex_str.len is odd
mut val := char2nibble(hex_str[0]) ?
if hex_str.len & 1 == 0 {
val = (val << 4) | char2nibble(hex_str[1]) ?
}
// set cap to hex_str.len/2 rounded up
mut bytes := []byte{len: 1, cap: (hex_str.len + 1) >> 1, init: val}
// iterate over every 2 bytes
// the start index depends on if s.len is odd
for i := 2 - (s.len & 1); i < s.len; i += 2 {
bytes << byte(strconv.parse_uint(s[i..i + 2], 16, 8) ?)
// the start index depends on if hex_str.len is odd
for i := 2 - (hex_str.len & 1); i < hex_str.len; i += 2 {
n1 := char2nibble(hex_str[i]) ?
n0 := char2nibble(hex_str[i + 1]) ?
bytes << (n1 << 4) | n0
}
return bytes
}
@ -36,3 +50,13 @@ pub fn encode(bytes []byte) string {
unsafe { sb.free() }
return res
}
// char2nibble converts an ASCII hex character to it's hex value
fn char2nibble(b byte) ?byte {
match b {
`0`...`9` { return b - byte(`0`) }
`A`...`F` { return b - byte(`A`) + 10 }
`a`...`f` { return b - byte(`a`) + 10 }
else { return error('invalid hex char $b.ascii_str()') }
}
}

13
vlib/encoding/hex/hex_test.v
View File

@ -9,6 +9,8 @@ fn test_decode() ? {
assert decode('123') ? == [byte(0x1), 0x23]
assert decode('1234') ? == [byte(0x12), 0x34]
assert decode('12345') ? == [byte(0x1), 0x23, 0x45]
assert decode('0123456789abcdef') ? == [byte(0x01), 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef]
assert decode('123456789ABCDEF') ? == [byte(0x01), 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef]
}
fn test_decode_fails() ? {
@ -38,4 +40,15 @@ fn test_encode() ? {
assert encode(decode('123') ?) == '0123'
assert encode(decode('1234') ?) == '1234'
assert encode(decode('12345') ?) == '012345'
assert encode(decode('abcdef') ?) == 'abcdef'
assert encode(decode('ABCDEF') ?) == 'abcdef'
}
fn test_decode_0x() ? {
assert decode('0x') ? == []
assert decode('0x0') ? == [byte(0x0)]
assert decode('0X1234') ? == [byte(0x12), 0x34]
assert decode('0x12345') ? == [byte(0x1), 0x23, 0x45]
assert decode('0x0123456789abcdef') ? == [byte(0x01), 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef]
assert decode('0X123456789ABCDEF') ? == [byte(0x01), 0x23, 0x45, 0x67, 0x89, 0xab, 0xcd, 0xef]
}