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|
package hjson
import (
"encoding/json"
"errors"
"math"
"strconv"
)
type parseNumber struct {
data []byte
at int // The index of the current character
ch byte // The current character
}
func (p *parseNumber) next() bool {
// get the next character.
len := len(p.data)
if p.at < len {
p.ch = p.data[p.at]
p.at++
return true
}
if p.at == len {
p.at++
p.ch = 0
}
return false
}
func (p *parseNumber) peek(offs int) byte {
pos := p.at + offs
if pos >= 0 && pos < len(p.data) {
return p.data[pos]
}
return 0
}
func startsWithNumber(text []byte) bool {
if _, err := tryParseNumber(text, true, false); err == nil {
return true
}
return false
}
func tryParseNumber(text []byte, stopAtNext, useJSONNumber bool) (interface{}, error) {
// Parse a number value.
p := parseNumber{
data: text,
at: 0,
ch: ' ',
}
leadingZeros := 0
testLeading := true
p.next()
if p.ch == '-' {
p.next()
}
for p.ch >= '0' && p.ch <= '9' {
if testLeading {
if p.ch == '0' {
leadingZeros++
} else {
testLeading = false
}
}
p.next()
}
if testLeading {
leadingZeros--
} // single 0 is allowed
if p.ch == '.' {
for p.next() && p.ch >= '0' && p.ch <= '9' {
}
}
if p.ch == 'e' || p.ch == 'E' {
p.next()
if p.ch == '-' || p.ch == '+' {
p.next()
}
for p.ch >= '0' && p.ch <= '9' {
p.next()
}
}
end := p.at
// skip white/to (newline)
for p.ch > 0 && p.ch <= ' ' {
p.next()
}
if stopAtNext {
// end scan if we find a punctuator character like ,}] or a comment
if p.ch == ',' || p.ch == '}' || p.ch == ']' ||
p.ch == '#' || p.ch == '/' && (p.peek(0) == '/' || p.peek(0) == '*') {
p.ch = 0
}
}
if p.ch > 0 || leadingZeros != 0 {
return 0, errors.New("Invalid number")
}
if useJSONNumber {
return json.Number(string(p.data[0 : end-1])), nil
}
number, err := strconv.ParseFloat(string(p.data[0:end-1]), 64)
if err != nil {
return 0, err
}
if math.IsInf(number, 0) || math.IsNaN(number) {
return 0, errors.New("Invalid number")
}
return number, nil
}
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