jsonw.gno

  1// Package jsonw builds JSON text for realm query endpoints.
  2//
  3// Values are plain strings holding encoded JSON, composed with Obj and Arr:
  4//
  5//	jsonw.Obj(
  6//		"id", jsonw.Uint(b.ID),
  7//		"title", jsonw.String(b.Title),
  8//		"tags", jsonw.Strings(b.Tags),
  9//	)
 10//
 11// String escapes everything JSON requires and replaces invalid UTF-8, so
 12// user-supplied text can never break the document.
 13package jsonw
 14
 15import (
 16	"strconv"
 17	"strings"
 18	"time"
 19	"unicode/utf8"
 20)
 21
 22const Null = "null"
 23
 24// String encodes s as a JSON string.
 25func String(s string) string {
 26	var b strings.Builder
 27	b.WriteByte('"')
 28	for i := 0; i < len(s); {
 29		r, size := utf8.DecodeRuneInString(s[i:])
 30		if r == utf8.RuneError && size == 1 {
 31			b.WriteString(`\ufffd`)
 32			i++
 33			continue
 34		}
 35		switch {
 36		case r == '"':
 37			b.WriteString(`\"`)
 38		case r == '\\':
 39			b.WriteString(`\\`)
 40		case r == '\n':
 41			b.WriteString(`\n`)
 42		case r == '\r':
 43			b.WriteString(`\r`)
 44		case r == '\t':
 45			b.WriteString(`\t`)
 46		case r < 0x20 || r == 0x7f || r == 0x2028 || r == 0x2029:
 47			b.WriteString(`\u`)
 48			h := strconv.FormatInt(int64(r), 16)
 49			for j := len(h); j < 4; j++ {
 50				b.WriteByte('0')
 51			}
 52			b.WriteString(h)
 53		default:
 54			b.WriteString(s[i : i+size])
 55		}
 56		i += size
 57	}
 58	b.WriteByte('"')
 59	return b.String()
 60}
 61
 62// Int encodes n. Values beyond JavaScript's safe integer range are encoded
 63// as strings so clients never lose precision.
 64func Int(n int64) string {
 65	if n > 9007199254740991 || n < -9007199254740991 {
 66		return `"` + strconv.FormatInt(n, 10) + `"`
 67	}
 68	return strconv.FormatInt(n, 10)
 69}
 70
 71// Uint encodes n, as a string beyond JavaScript's safe integer range.
 72func Uint(n uint64) string {
 73	if n > 9007199254740991 {
 74		return `"` + strconv.FormatUint(n, 10) + `"`
 75	}
 76	return strconv.FormatUint(n, 10)
 77}
 78
 79// Bool encodes v.
 80func Bool(v bool) string {
 81	if v {
 82		return "true"
 83	}
 84	return "false"
 85}
 86
 87// Time encodes t as RFC 3339 in UTC, or null when zero.
 88func Time(t time.Time) string {
 89	if t.IsZero() {
 90		return Null
 91	}
 92	return String(t.UTC().Format(time.RFC3339))
 93}
 94
 95// Obj builds an object from alternating keys and encoded values.
 96func Obj(kv ...string) string {
 97	if len(kv)%2 != 0 {
 98		panic("jsonw: Obj needs key/value pairs")
 99	}
100	var b strings.Builder
101	b.WriteByte('{')
102	for i := 0; i < len(kv); i += 2 {
103		if i > 0 {
104			b.WriteByte(',')
105		}
106		b.WriteString(String(kv[i]))
107		b.WriteByte(':')
108		b.WriteString(kv[i+1])
109	}
110	b.WriteByte('}')
111	return b.String()
112}
113
114// Arr builds an array from encoded values.
115func Arr(items []string) string {
116	return "[" + strings.Join(items, ",") + "]"
117}
118
119// Strings encodes a list of strings.
120func Strings(ss []string) string {
121	out := make([]string, len(ss))
122	for i, s := range ss {
123		out[i] = String(s)
124	}
125	return Arr(out)
126}
127
128// Addresses encodes a list of addresses as strings.
129func Addresses(as []address) string {
130	out := make([]string, len(as))
131	for i, a := range as {
132		out[i] = String(a.String())
133	}
134	return Arr(out)
135}