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fix #7717 roundtrip float to string; fix parseFloat for js (#18248)

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* refs #7717 roundtrip float to string
* make parseFloat more correct
* improve float tests
* improve float tests
* cleanup
This commit is contained in:
Timothee Cour
2021-06-12 22:32:47 -07:00
committed by GitHub
parent 897e50d5fe
commit c871e22da2
3 changed files with 130 additions and 81 deletions
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99
lib/system/jssys.nim
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@@ -716,19 +716,23 @@ proc tenToThePowerOf(b: int): BiggestFloat =
const
IdentChars = {'a'..'z', 'A'..'Z', '0'..'9', '_'}
# XXX use JS's native way here
proc nimParseBiggestFloat(s: string, number: var BiggestFloat, start = 0): int {.
compilerproc.} =
var
esign = 1.0
sign = 1.0
i = start
exponent: int
flags: int
number = 0.0
proc parseFloatNative(a: string): float =
let a2 = a.cstring
asm """
`result` = Number(`a2`);
"""
#[
xxx how come code like this doesn't give IndexDefect ?
let z = s[10000] == 'a'
]#
proc nimParseBiggestFloat(s: string, number: var BiggestFloat, start: int): int {.compilerproc.} =
var sign: bool
var i = start
if s[i] == '+': inc(i)
elif s[i] == '-':
sign = -1.0
sign = true
inc(i)
if s[i] == 'N' or s[i] == 'n':
if s[i+1] == 'A' or s[i+1] == 'a':
@@ -741,51 +745,40 @@ proc nimParseBiggestFloat(s: string, number: var BiggestFloat, start = 0): int {
if s[i+1] == 'N' or s[i+1] == 'n':
if s[i+2] == 'F' or s[i+2] == 'f':
if s[i+3] notin IdentChars:
number = Inf*sign
number = if sign: -Inf else: Inf
return i+3 - start
return 0
while s[i] in {'0'..'9'}:
# Read integer part
flags = flags or 1
number = number * 10.0 + toFloat(ord(s[i]) - ord('0'))
inc(i)
while s[i] == '_': inc(i)
# Decimal?
if s[i] == '.':
var hd = 1.0
inc(i)
while s[i] in {'0'..'9'}:
# Read fractional part
flags = flags or 2
number = number * 10.0 + toFloat(ord(s[i]) - ord('0'))
hd = hd * 10.0
inc(i)
while s[i] == '_': inc(i)
number = number / hd # this complicated way preserves precision
# Again, read integer and fractional part
if flags == 0: return 0
# Exponent?
if s[i] in {'e', 'E'}:
inc(i)
if s[i] == '+':
inc(i)
elif s[i] == '-':
esign = -1.0
inc(i)
if s[i] notin {'0'..'9'}:
return 0
while s[i] in {'0'..'9'}:
exponent = exponent * 10 + ord(s[i]) - ord('0')
inc(i)
while s[i] == '_': inc(i)
# Calculate Exponent
let hd = tenToThePowerOf(exponent)
if esign > 0.0: number = number * hd
else: number = number / hd
# evaluate sign
number = number * sign
result = i - start
var buf: string
# we could also use an `array[char, N]` buffer to avoid reallocs, or
# use a 2-pass algorithm that first computes the length.
if sign: buf.add '-'
template addInc =
buf.add s[i]
inc(i)
template eatUnderscores =
while s[i] == '_': inc(i)
while s[i] in {'0'..'9'}: # Read integer part
buf.add s[i]
inc(i)
eatUnderscores()
if s[i] == '.': # Decimal?
addInc()
while s[i] in {'0'..'9'}: # Read fractional part
addInc()
eatUnderscores()
# Again, read integer and fractional part
if buf.len == ord(sign): return 0
if s[i] in {'e', 'E'}: # Exponent?
addInc()
if s[i] == '+': inc(i)
elif s[i] == '-': addInc()
if s[i] notin {'0'..'9'}: return 0
while s[i] in {'0'..'9'}:
addInc()
eatUnderscores()
number = parseFloatNative(buf)
result = i - start
# Workaround for IE, IE up to version 11 lacks 'Math.trunc'. We produce
# 'Math.trunc' for Nim's ``div`` and ``mod`` operators: