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v/vlib/strconv/utilities.c.v

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module strconv
// import math
/*
f32/f64 to string utilities
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Copyright (c) 2019-2022 Dario Deledda. All rights reserved.
Use of this source code is governed by an MIT license
that can be found in the LICENSE file.
This file contains the f32/f64 to string utilities functions
These functions are based on the work of:
Publication:PLDI 2018: Proceedings of the 39th ACM SIGPLAN
Conference on Programming Language Design and ImplementationJune 2018
Pages 270282 https://doi.org/10.1145/3192366.3192369
inspired by the Go version here:
https://github.com/cespare/ryu/tree/ba56a33f39e3bbbfa409095d0f9ae168a595feea
*/
/*
f64 to string with string format
*/
// TODO: Investigate precision issues
// f32_to_str_l returns `f` as a `string` in decimal notation with a maximum of 6 digits after the dot.
//
// Example: assert strconv.f32_to_str_l(34.1234567) == '34.12346'
[manualfree]
pub fn f32_to_str_l(f f32) string {
s := f32_to_str(f, 6)
res := fxx_to_str_l_parse(s)
unsafe { s.free() }
return res
}
// f32_to_str_l_with_dot returns `f` as a `string` in decimal notation with a maximum of 6 digits after the dot.
// If the decimal digits after the dot are zero, a '.0' is appended for clarity.
//
// Example: assert strconv.f32_to_str_l_with_dot(34.) == '34.0'
[manualfree]
pub fn f32_to_str_l_with_dot(f f32) string {
s := f32_to_str(f, 6)
res := fxx_to_str_l_parse_with_dot(s)
unsafe { s.free() }
return res
}
// f64_to_str_l returns `f` as a `string` in decimal notation with a maximum of 18 digits after the dot.
//
// Example: assert strconv.f64_to_str_l(123.1234567891011121) == '123.12345678910111'
[manualfree]
pub fn f64_to_str_l(f f64) string {
s := f64_to_str(f, 18)
res := fxx_to_str_l_parse(s)
unsafe { s.free() }
return res
}
// f64_to_str_l_with_dot returns `f` as a `string` in decimal notation with a maximum of 18 digits after the dot.
// If the decimal digits after the dot are zero, a '.0' is appended for clarity.
//
// Example: assert strconv.f64_to_str_l_with_dot (34.) == '34.0'
[manualfree]
pub fn f64_to_str_l_with_dot(f f64) string {
s := f64_to_str(f, 18)
res := fxx_to_str_l_parse_with_dot(s)
unsafe { s.free() }
return res
}
// fxx_to_str_l_parse returns a `string` in decimal notation converted from a
// floating-point `string` in scientific notation.
//
// Example: assert strconv.fxx_to_str_l_parse('34.22e+00') == '34.22'
[direct_array_access; manualfree]
pub fn fxx_to_str_l_parse(s string) string {
// check for +inf -inf Nan
if s.len > 2 && (s[0] == `n` || s[1] == `i`) {
return s.clone()
}
m_sgn_flag := false
mut sgn := 1
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mut b := [26]u8{}
mut d_pos := 1
mut i := 0
mut i1 := 0
mut exp := 0
mut exp_sgn := 1
// get sign and decimal parts
for c in s {
if c == `-` {
sgn = -1
i++
} else if c == `+` {
sgn = 1
i++
} else if c >= `0` && c <= `9` {
b[i1] = c
i1++
i++
} else if c == `.` {
if sgn > 0 {
d_pos = i
} else {
d_pos = i - 1
}
i++
} else if c == `e` {
i++
break
} else {
return 'Float conversion error!!'
}
}
b[i1] = 0
// get exponent
if s[i] == `-` {
exp_sgn = -1
i++
} else if s[i] == `+` {
exp_sgn = 1
i++
}
mut c := i
for c < s.len {
exp = exp * 10 + int(s[c] - `0`)
c++
}
// allocate exp+32 chars for the return string
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mut res := []u8{len: exp + 32, init: 0}
mut r_i := 0 // result string buffer index
// println("s:${sgn} b:${b[0]} es:${exp_sgn} exp:${exp}")
if sgn == 1 {
if m_sgn_flag {
res[r_i] = `+`
r_i++
}
} else {
res[r_i] = `-`
r_i++
}
i = 0
if exp_sgn >= 0 {
for b[i] != 0 {
res[r_i] = b[i]
r_i++
i++
if i >= d_pos && exp >= 0 {
if exp == 0 {
res[r_i] = `.`
r_i++
}
exp--
}
}
for exp >= 0 {
res[r_i] = `0`
r_i++
exp--
}
} else {
mut dot_p := true
for exp > 0 {
res[r_i] = `0`
r_i++
exp--
if dot_p {
res[r_i] = `.`
r_i++
dot_p = false
}
}
for b[i] != 0 {
res[r_i] = b[i]
r_i++
i++
}
}
// Add a zero after the dot from the numbers like 2.
if r_i > 1 && res[r_i - 1] == `.` {
res[r_i] = `0`
r_i++
} else if `.` !in res {
// If there is no dot, add it with a zero
res[r_i] = `.`
r_i++
res[r_i] = `0`
r_i++
}
res[r_i] = 0
return unsafe { tos(res.data, r_i) }
}
// fxx_to_str_l_parse_with_dot returns a `string` in decimal notation converted from a
// floating-point `string` in scientific notation.
// If the decimal digits after the dot are zero, a '.0' is appended for clarity.
//
// Example: assert strconv.fxx_to_str_l_parse_with_dot ('34.e+01') == '340.0'
[direct_array_access; manualfree]
pub fn fxx_to_str_l_parse_with_dot(s string) string {
// check for +inf -inf Nan
if s.len > 2 && (s[0] == `n` || s[1] == `i`) {
return s.clone()
}
m_sgn_flag := false
mut sgn := 1
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mut b := [26]u8{}
mut d_pos := 1
mut i := 0
mut i1 := 0
mut exp := 0
mut exp_sgn := 1
// get sign and decimal parts
for c in s {
if c == `-` {
sgn = -1
i++
} else if c == `+` {
sgn = 1
i++
} else if c >= `0` && c <= `9` {
b[i1] = c
i1++
i++
} else if c == `.` {
if sgn > 0 {
d_pos = i
} else {
d_pos = i - 1
}
i++
} else if c == `e` {
i++
break
} else {
return 'Float conversion error!!'
}
}
b[i1] = 0
// get exponent
if s[i] == `-` {
exp_sgn = -1
i++
} else if s[i] == `+` {
exp_sgn = 1
i++
}
mut c := i
for c < s.len {
exp = exp * 10 + int(s[c] - `0`)
c++
}
// allocate exp+32 chars for the return string
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mut res := []u8{len: exp + 32, init: 0}
mut r_i := 0 // result string buffer index
// println("s:${sgn} b:${b[0]} es:${exp_sgn} exp:${exp}")
if sgn == 1 {
if m_sgn_flag {
res[r_i] = `+`
r_i++
}
} else {
res[r_i] = `-`
r_i++
}
i = 0
if exp_sgn >= 0 {
for b[i] != 0 {
res[r_i] = b[i]
r_i++
i++
if i >= d_pos && exp >= 0 {
if exp == 0 {
res[r_i] = `.`
r_i++
}
exp--
}
}
for exp >= 0 {
res[r_i] = `0`
r_i++
exp--
}
} else {
mut dot_p := true
for exp > 0 {
res[r_i] = `0`
r_i++
exp--
if dot_p {
res[r_i] = `.`
r_i++
dot_p = false
}
}
for b[i] != 0 {
res[r_i] = b[i]
r_i++
i++
}
}
// Add a zero after the dot from the numbers like 2.
if r_i > 1 && res[r_i - 1] == `.` {
res[r_i] = `0`
r_i++
} else if `.` !in res {
// If there is no dot, add it with a zero
res[r_i] = `.`
r_i++
res[r_i] = `0`
r_i++
}
res[r_i] = 0
return unsafe { tos(res.data, r_i) }
}