kratos/x/json_number.go

67 lines
1.2 KiB
Go

// Copyright © 2023 Ory Corp
// SPDX-License-Identifier: Apache-2.0
package x
// IsValidNumber reports whether s is a valid JSON number literal.
//
// Taken from encoding/json
func IsValidNumber(s string) bool {
// This function implements the JSON numbers grammar.
// See https://tools.ietf.org/html/rfc7159#section-6
// and https://json.org/number.gif
if s == "" {
return false
}
// Optional -
if s[0] == '-' {
s = s[1:]
if s == "" {
return false
}
}
// Digits
switch {
default:
return false
case s[0] == '0':
s = s[1:]
case '1' <= s[0] && s[0] <= '9':
s = s[1:]
for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
s = s[1:]
}
}
// . followed by 1 or more digits.
if len(s) >= 2 && s[0] == '.' && '0' <= s[1] && s[1] <= '9' {
s = s[2:]
for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
s = s[1:]
}
}
// e or E followed by an optional - or + and
// 1 or more digits.
if len(s) >= 2 && (s[0] == 'e' || s[0] == 'E') {
s = s[1:]
if s[0] == '+' || s[0] == '-' {
s = s[1:]
if s == "" {
return false
}
}
for len(s) > 0 && '0' <= s[0] && s[0] <= '9' {
s = s[1:]
}
}
// Make sure we are at the end.
return s == ""
}