utils.go

// Package jsongen
// Copyright 2024 Joshua J Baker. All rights reserved.
// Use of this source code is governed by an MIT-style
// license that can be found in the LICENSE file.
//
// https://github.com/tidwall/gjson
package jsongen

import (
	"unicode/utf8"

	"github.com/fufuok/utils"
	"github.com/fufuok/utils/pools/bytespool"
)

// DisableEscapeHTML will disable the automatic escaping of certain
// "problamatic" HTML characters when encoding to JSON.
// These character include '>', '<' and '&', which get escaped to \u003e,
// \u0026, and \u003c respectively.
//
// This is a global flag and will affect all further gjson operations.
// Ideally, if used, it should be set one time before other gjson functions
// are called.
var DisableEscapeHTML = false

var hexchars = [...]byte{
	'0', '1', '2', '3', '4', '5', '6', '7', '8', '9',
	'a', 'b', 'c', 'd', 'e', 'f',
}

// EscapeString 转义 JSON 字符串, 并在前后加上双引号
func EscapeString(s string) string {
	dst := bytespool.Make(len(s) + 2)
	return utils.B2S(AppendJSONString(dst, s))
}

// AppendJSONString is a convenience function that converts the provided string
// to a valid JSON string and appends it to dst.
//
//nolint:cyclop,nestif
func AppendJSONString(dst []byte, s string) []byte {
	dst = append(dst, make([]byte, len(s)+2)...)
	dst = append(dst[:len(dst)-len(s)-2], '"')
	for i := 0; i < len(s); i++ {
		if s[i] < ' ' {
			dst = append(dst, '\\')
			switch s[i] {
			case '\b':
				dst = append(dst, 'b')
			case '\f':
				dst = append(dst, 'f')
			case '\n':
				dst = append(dst, 'n')
			case '\r':
				dst = append(dst, 'r')
			case '\t':
				dst = append(dst, 't')
			default:
				dst = append(dst, 'u')
				dst = appendHex16(dst, uint16(s[i]))
			}
		} else if !DisableEscapeHTML &&
			(s[i] == '>' || s[i] == '<' || s[i] == '&') {
			dst = append(dst, '\\', 'u')
			dst = appendHex16(dst, uint16(s[i]))
		} else if s[i] == '\\' {
			dst = append(dst, '\\', '\\')
		} else if s[i] == '"' {
			dst = append(dst, '\\', '"')
		} else if s[i] > 127 {
			// read utf8 character
			r, n := utf8.DecodeRuneInString(s[i:])
			if n == 0 {
				break
			}
			if r == utf8.RuneError && n == 1 {
				dst = append(dst, `\ufffd`...)
			} else if r == '\u2028' || r == '\u2029' {
				dst = append(dst, `\u202`...)
				dst = append(dst, hexchars[r&0xF])
			} else {
				dst = append(dst, s[i:i+n]...)
			}
			i = i + n - 1
		} else {
			dst = append(dst, s[i])
		}
	}
	return append(dst, '"')
}

func appendHex16(dst []byte, x uint16) []byte {
	return append(dst,
		hexchars[x>>12&0xF], hexchars[x>>8&0xF],
		hexchars[x>>4&0xF], hexchars[x>>0&0xF],
	)
}