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v/vlib/strconv/atoi.v

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module strconv
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// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
// TODO: use optionals, or some way to return default with error.
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const (
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// int_size is the size in bits of an int or uint value.
// int_size = 32 << (~u32(0) >> 63)
// max_u64 = u64(u64(1 << 63) - 1)
int_size = 32
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max_u64 = u64(18446744073709551615) // as u64 // use this until we add support
)
pub fn byte_to_lower(c byte) byte {
return c | (`x` - `X`)
}
// common_parse_uint is called by parse_uint and allows the parsing
// to stop on non or invalid digit characters and return with an error
pub fn common_parse_uint(s string, _base int, _bit_size int, error_on_non_digit bool, error_on_high_digit bool) ?u64 {
result, err := common_parse_uint2(s, _base, _bit_size)
// TODO: error_on_non_digit and error_on_high_digit have no difference
if err != 0 && (error_on_non_digit || error_on_high_digit) {
match err {
-1 { return error('common_parse_uint: wrong base $_base for $s') }
-2 { return error('common_parse_uint: wrong bit size $_bit_size for $s') }
-3 { return error('common_parse_uint: integer overflow $s') }
else { return error('common_parse_uint: syntax error $s') }
}
}
return result
}
// the first returned value contains the parsed value,
// the second returned value contains the error code (0 = OK, >1 = index of first non-parseable character + 1, -1 = wrong base, -2 = wrong bit size, -3 = overflow)
pub fn common_parse_uint2(s string, _base int, _bit_size int) (u64, int) {
mut bit_size := _bit_size
mut base := _base
if s.len < 1 || !underscore_ok(s) {
// return error('parse_uint: syntax error $s')
return u64(0), 1
}
base0 := base == 0
mut start_index := 0
if 2 <= base && base <= 36 {
// valid base; nothing to do
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} else if base == 0 {
// Look for octal, hex prefix.
base = 10
if s[0] == `0` {
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if s.len >= 3 && byte_to_lower(s[1]) == `b` {
base = 2
start_index += 2
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} else if s.len >= 3 && byte_to_lower(s[1]) == `o` {
base = 8
start_index += 2
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} else if s.len >= 3 && byte_to_lower(s[1]) == `x` {
base = 16
start_index += 2
}
// manage leading zeros in decimal base's numbers
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else if s.len >= 2 && (s[1] >= `0` && s[1] <= `9`) {
base = 10
start_index++
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} else {
base = 8
start_index++
}
}
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} else {
// return error('parse_uint: base error $s - $base')
return u64(0), -1
}
if bit_size == 0 {
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bit_size = strconv.int_size
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} else if bit_size < 0 || bit_size > 64 {
// return error('parse_uint: bitsize error $s - $bit_size')
return u64(0), -2
}
// Cutoff is the smallest number such that cutoff*base > maxUint64.
// Use compile-time constants for common cases.
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cutoff := strconv.max_u64 / u64(base) + u64(1)
max_val := if bit_size == 64 { strconv.max_u64 } else { (u64(1) << u64(bit_size)) - u64(1) }
mut n := u64(0)
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for i in start_index .. s.len {
c := s[i]
cl := byte_to_lower(c)
mut d := byte(0)
if c == `_` && base0 {
// underscore_ok already called
continue
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} else if `0` <= c && c <= `9` {
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d = c - `0`
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} else if `a` <= cl && cl <= `z` {
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d = cl - `a` + 10
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} else {
return n, i + 1
}
if d >= byte(base) {
return n, i + 1
}
if n >= cutoff {
// n*base overflows
// return error('parse_uint: range error $s')
return max_val, -3
}
n *= u64(base)
n1 := n + u64(d)
if n1 < n || n1 > max_val {
// n+v overflows
// return error('parse_uint: range error $s')
return max_val, -3
}
n = n1
}
return n, 0
}
// parse_uint is like parse_int but for unsigned numbers.
pub fn parse_uint(s string, _base int, _bit_size int) ?u64 {
return common_parse_uint(s, _base, _bit_size, true, true)
}
// common_parse_int is called by parse int and allows the parsing
// to stop on non or invalid digit characters and return with an error
pub fn common_parse_int(_s string, base int, _bit_size int, error_on_non_digit bool, error_on_high_digit bool) ?i64 {
mut s := _s
mut bit_size := _bit_size
if s.len < 1 {
// return error('parse_int: syntax error $s')
return i64(0)
}
// Pick off leading sign.
mut neg := false
if s[0] == `+` {
s = s[1..]
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} else if s[0] == `-` {
neg = true
s = s[1..]
}
// Convert unsigned and check range.
// un := parse_uint(s, base, bit_size) or {
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// return i64(0)
// }
un := common_parse_uint(s, base, bit_size, error_on_non_digit, error_on_high_digit) ?
if un == 0 {
return i64(0)
}
if bit_size == 0 {
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bit_size = strconv.int_size
}
// TODO: check should u64(bit_size-1) be size of int (32)?
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cutoff := u64(1) << u64(bit_size - 1)
if !neg && un >= cutoff {
// return error('parse_int: range error $s0')
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return i64(cutoff - u64(1))
}
if neg && un > cutoff {
// return error('parse_int: range error $s0')
return -i64(cutoff)
}
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return if neg { -i64(un) } else { i64(un) }
}
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// parse_int interprets a string s in the given base (0, 2 to 36) and
// bit size (0 to 64) and returns the corresponding value i.
//
// If the base argument is 0, the true base is implied by the string's
// prefix: 2 for "0b", 8 for "0" or "0o", 16 for "0x", and 10 otherwise.
// Also, for argument base 0 only, underscore characters are permitted
// as defined by the Go syntax for integer literals.
//
// The bitSize argument specifies the integer type
// that the result must fit into. Bit sizes 0, 8, 16, 32, and 64
// correspond to int, int8, int16, int32, and int64.
// If bitSize is below 0 or above 64, an error is returned.
pub fn parse_int(_s string, base int, _bit_size int) ?i64 {
return common_parse_int(_s, base, _bit_size, true, true)
}
// atoi is equivalent to parse_int(s, 10, 0), converted to type int.
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pub fn atoi(s string) ?int {
if s == '' {
return error('strconv.atoi: parsing "$s": invalid syntax ')
}
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if (strconv.int_size == 32 && (0 < s.len && s.len < 10))
|| (strconv.int_size == 64 && (0 < s.len && s.len < 19)) {
// Fast path for small integers that fit int type.
mut start_idx := 0
if s[0] == `-` || s[0] == `+` {
start_idx++
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if s.len - start_idx < 1 {
// return 0, &NumError{fnAtoi, s0, ErrSyntax}
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return error('strconv.atoi: parsing "$s": invalid syntax ')
}
}
mut n := 0
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for i in start_idx .. s.len {
ch := s[i] - `0`
if ch > 9 {
// return 0, &NumError{fnAtoi, s0, ErrSyntax}
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return error('strconv.atoi: parsing "$s": invalid syntax ')
}
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n = n * 10 + int(ch)
}
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return if s[0] == `-` { -n } else { n }
}
// Slow path for invalid, big, or underscored integers.
int64 := parse_int(s, 10, 0) ?
return int(int64)
}
// underscore_ok reports whether the underscores in s are allowed.
// Checking them in this one function lets all the parsers skip over them simply.
// Underscore must appear only between digits or between a base prefix and a digit.
fn underscore_ok(s string) bool {
// saw tracks the last character (class) we saw:
// ^ for beginning of number,
// 0 for a digit or base prefix,
// _ for an underscore,
// ! for none of the above.
mut saw := `^`
mut i := 0
// Optional sign.
if s.len >= 1 && (s[0] == `-` || s[0] == `+`) {
i++
}
// Optional base prefix.
mut hex := false
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if s.len - i >= 2 && s[i] == `0` && (byte_to_lower(s[i + 1]) == `b`
|| byte_to_lower(s[i + 1]) == `o` || byte_to_lower(s[i + 1]) == `x`) {
saw = `0` // base prefix counts as a digit for "underscore as digit separator"
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hex = byte_to_lower(s[i + 1]) == `x`
i += 2
}
// Number proper.
for ; i < s.len; i++ {
// Digits are always okay.
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if (`0` <= s[i] && s[i] <= `9`) || (hex && `a` <= byte_to_lower(s[i])
&& byte_to_lower(s[i]) <= `f`) {
saw = `0`
continue
}
// Underscore must follow digit.
if s[i] == `_` {
if saw != `0` {
return false
}
saw = `_`
continue
}
// Underscore must also be followed by digit.
if saw == `_` {
return false
}
// Saw non-digit, non-underscore.
saw = `!`
}
return saw != `_`
}