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num.go
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num.go
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// Copyright 2020 CUE Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package literal
import (
"cuelang.org/go/cue/errors"
"cuelang.org/go/cue/token"
"github.com/cockroachdb/apd/v2"
)
var baseContext apd.Context
func init() {
baseContext = apd.BaseContext
baseContext.Precision = 24
}
// NumInfo contains information about a parsed numbers.
//
// Reusing a NumInfo across parses may avoid memory allocations.
type NumInfo struct {
pos token.Pos
src string
p int
ch byte
buf []byte
mul Multiplier
base byte
neg bool
UseSep bool
isFloat bool
err error
}
// String returns a canonical string representation of the number so that
// it can be parsed with math.Float.Parse.
func (p *NumInfo) String() string {
if len(p.buf) > 0 && p.base == 10 && p.mul == 0 {
return string(p.buf)
}
var d apd.Decimal
_ = p.decimal(&d)
return d.String()
}
type decimal = apd.Decimal
// Decimal is for internal use.
func (p *NumInfo) Decimal(v *decimal) error {
return p.decimal(v)
}
func (p *NumInfo) decimal(v *apd.Decimal) error {
if p.base != 10 {
_, _, _ = v.SetString("0")
b := p.buf
if p.buf[0] == '-' {
v.Negative = p.neg
b = p.buf[1:]
}
v.Coeff.SetString(string(b), int(p.base))
return nil
}
_ = v.UnmarshalText(p.buf)
if p.mul != 0 {
_, _ = baseContext.Mul(v, v, mulToRat[p.mul])
cond, _ := baseContext.RoundToIntegralExact(v, v)
if cond.Inexact() {
return p.errorf("number cannot be represented as int")
}
}
return nil
}
// Multiplier reports which multiplier was used in an integral number.
func (p *NumInfo) Multiplier() Multiplier {
return p.mul
}
// IsInt reports whether the number is an integral number.
func (p *NumInfo) IsInt() bool {
return !p.isFloat
}
// ParseNum parses s and populates NumInfo with the result.
func ParseNum(s string, n *NumInfo) error {
*n = NumInfo{pos: n.pos, src: s, buf: n.buf[:0]}
if !n.next() {
return n.errorf("invalid number %q", s)
}
if n.ch == '-' {
n.neg = true
n.buf = append(n.buf, '-')
n.next()
}
seenDecimalPoint := false
if n.ch == '.' {
n.next()
seenDecimalPoint = true
}
err := n.scanNumber(seenDecimalPoint)
if err != nil {
return err
}
if n.err != nil {
return n.err
}
if n.p < len(n.src) {
return n.errorf("invalid number %q", s)
}
if len(n.buf) == 0 {
n.buf = append(n.buf, '0')
}
return nil
}
func (p *NumInfo) errorf(format string, args ...interface{}) error {
return errors.Newf(p.pos, format, args...)
}
// A Multiplier indicates a multiplier indicator used in the literal.
type Multiplier byte
const (
mul1 Multiplier = 1 + iota
mul2
mul3
mul4
mul5
mul6
mul7
mul8
mulBin = 0x10
mulDec = 0x20
K = mulDec | mul1
M = mulDec | mul2
G = mulDec | mul3
T = mulDec | mul4
P = mulDec | mul5
E = mulDec | mul6
Z = mulDec | mul7
Y = mulDec | mul8
Ki = mulBin | mul1
Mi = mulBin | mul2
Gi = mulBin | mul3
Ti = mulBin | mul4
Pi = mulBin | mul5
Ei = mulBin | mul6
Zi = mulBin | mul7
Yi = mulBin | mul8
)
func (p *NumInfo) next() bool {
if p.p >= len(p.src) {
p.ch = 0
return false
}
p.ch = p.src[p.p]
p.p++
if p.ch == '.' {
if len(p.buf) == 0 {
p.buf = append(p.buf, '0')
}
p.buf = append(p.buf, '.')
}
return true
}
func (p *NumInfo) digitVal(ch byte) (d int) {
switch {
case '0' <= ch && ch <= '9':
d = int(ch - '0')
case ch == '_':
p.UseSep = true
return 0
case 'a' <= ch && ch <= 'f':
d = int(ch - 'a' + 10)
case 'A' <= ch && ch <= 'F':
d = int(ch - 'A' + 10)
default:
return 16 // larger than any legal digit val
}
return d
}
func (p *NumInfo) scanMantissa(base int) bool {
hasDigit := false
var last byte
for p.digitVal(p.ch) < base {
if p.ch != '_' {
p.buf = append(p.buf, p.ch)
hasDigit = true
}
last = p.ch
p.next()
}
if last == '_' {
p.err = p.errorf("illegal '_' in number")
}
return hasDigit
}
func (p *NumInfo) scanNumber(seenDecimalPoint bool) error {
p.base = 10
if seenDecimalPoint {
p.isFloat = true
if !p.scanMantissa(10) {
return p.errorf("illegal fraction %q", p.src)
}
goto exponent
}
if p.ch == '0' {
// int or float
p.next()
switch p.ch {
case 'x', 'X':
p.base = 16
// hexadecimal int
p.next()
if !p.scanMantissa(16) {
// only scanned "0x" or "0X"
return p.errorf("illegal hexadecimal number %q", p.src)
}
case 'b':
p.base = 2
// binary int
p.next()
if !p.scanMantissa(2) {
// only scanned "0b"
return p.errorf("illegal binary number %q", p.src)
}
case 'o':
p.base = 8
// octal int
p.next()
if !p.scanMantissa(8) {
// only scanned "0o"
return p.errorf("illegal octal number %q", p.src)
}
default:
// int (base 8 or 10) or float
p.scanMantissa(8)
if p.ch == '8' || p.ch == '9' {
p.scanMantissa(10)
if p.ch != '.' && p.ch != 'e' && p.ch != 'E' {
return p.errorf("illegal integer number %q", p.src)
}
}
switch p.ch {
case 'e', 'E':
if len(p.buf) == 0 {
p.buf = append(p.buf, '0')
}
fallthrough
case '.':
goto fraction
}
if len(p.buf) > 0 {
p.base = 8
}
}
goto exit
}
// decimal int or float
if !p.scanMantissa(10) {
return p.errorf("illegal number start %q", p.src)
}
fraction:
if p.ch == '.' {
p.isFloat = true
p.next()
p.scanMantissa(10)
}
exponent:
switch p.ch {
case 'K', 'M', 'G', 'T', 'P':
p.mul = charToMul[p.ch]
p.next()
if p.ch == 'i' {
p.mul |= mulBin
p.next()
} else {
p.mul |= mulDec
}
var v apd.Decimal
p.isFloat = false
return p.decimal(&v)
case 'e', 'E':
p.isFloat = true
p.next()
p.buf = append(p.buf, 'e')
if p.ch == '-' || p.ch == '+' {
p.buf = append(p.buf, p.ch)
p.next()
}
if !p.scanMantissa(10) {
return p.errorf("illegal exponent %q", p.src)
}
}
exit:
return nil
}
var charToMul = map[byte]Multiplier{
'K': mul1,
'M': mul2,
'G': mul3,
'T': mul4,
'P': mul5,
'E': mul6,
'Z': mul7,
'Y': mul8,
}
var mulToRat = map[Multiplier]*apd.Decimal{}
func init() {
d := apd.New(1, 0)
b := apd.New(1, 0)
dm := apd.New(1000, 0)
bm := apd.New(1024, 0)
c := apd.BaseContext
for i := Multiplier(1); int(i) < len(charToMul); i++ {
// TODO: may we write to one of the sources?
var bn, dn apd.Decimal
_, _ = c.Mul(&dn, d, dm)
d = &dn
_, _ = c.Mul(&bn, b, bm)
b = &bn
mulToRat[mulDec|i] = d
mulToRat[mulBin|i] = b
}
}