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v/vlib/x/json2/encoder.v

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// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module json2
import io
import strings
// Encoder encodes the an `Any` type into JSON representation.
// It provides parameters in order to change the end result.
pub struct Encoder {
newline u8
newline_spaces_count int
escape_unicode bool = true
}
pub const default_encoder = Encoder{}
// byte array versions of the most common tokens/chars to avoid reallocations
const null_in_bytes = 'null'.bytes()
const true_in_bytes = 'true'.bytes()
const false_in_bytes = 'false'.bytes()
const zero_in_bytes = [u8(`0`)]
const comma_bytes = [u8(`,`)]
const colon_bytes = [u8(`:`)]
const space_bytes = [u8(` `)]
const unicode_escape_chars = [u8(`\\`), `u`]
const quote_bytes = [u8(`"`)]
const escaped_chars = [(r'\b').bytes(), (r'\f').bytes(), (r'\n').bytes(),
(r'\r').bytes(), (r'\t').bytes()]
// encode_value encodes a value to the specific writer.
pub fn (e &Encoder) encode_value[T](val T, mut wr io.Writer) ! {
e.encode_value_with_level[T](val, 1, mut wr)!
}
fn (e &Encoder) encode_newline(level int, mut wr io.Writer) ! {
if e.newline != 0 {
wr.write([e.newline])!
for j := 0; j < level * e.newline_spaces_count; j++ {
wr.write(json2.space_bytes)!
}
}
}
fn (e &Encoder) encode_any(val Any, level int, mut wr io.Writer) ! {
match val {
string {
e.encode_string(val, mut wr)!
}
bool {
if val == true {
wr.write(json2.true_in_bytes)!
} else {
wr.write(json2.false_in_bytes)!
}
}
i8, i16, int, i64 {
wr.write(val.str().bytes())!
}
u8, u16, u32, u64 {
wr.write(val.str().bytes())!
}
f32, f64 {
$if !nofloat ? {
str_float := val.str().bytes()
wr.write(str_float)!
if str_float[str_float.len - 1] == `.` {
wr.write(json2.zero_in_bytes)!
}
return
}
wr.write(json2.zero_in_bytes)!
}
map[string]Any {
wr.write([u8(`{`)])!
mut i := 0
for k, v in val {
e.encode_newline(level, mut wr)!
e.encode_string(k, mut wr)!
wr.write(json2.colon_bytes)!
if e.newline != 0 {
wr.write(json2.space_bytes)!
}
e.encode_value_with_level(v, level + 1, mut wr)!
if i < val.len - 1 {
wr.write(json2.comma_bytes)!
}
i++
}
e.encode_newline(level - 1, mut wr)!
wr.write([u8(`}`)])!
}
[]Any {
wr.write([u8(`[`)])!
for i in 0 .. val.len {
e.encode_newline(level, mut wr)!
e.encode_value_with_level(val[i], level + 1, mut wr)!
if i < val.len - 1 {
wr.write(json2.comma_bytes)!
}
}
e.encode_newline(level - 1, mut wr)!
wr.write([u8(`]`)])!
}
[]int {
wr.write([u8(`[`)])!
for i in 0 .. val.len {
e.encode_newline(level, mut wr)!
e.encode_value_with_level(val[i], level + 1, mut wr)!
if i < val.len - 1 {
wr.write(json2.comma_bytes)!
}
}
e.encode_newline(level - 1, mut wr)!
wr.write([u8(`]`)])!
}
Null {
wr.write(json2.null_in_bytes)!
}
}
}
fn (e &Encoder) encode_value_with_level[T](val T, level int, mut wr io.Writer) ! {
$if T is string {
e.encode_string(val, mut wr)!
} $else $if T is Any {
e.encode_any(val, level, mut wr)!
} $else $if T is map[string]Any {
// weird quirk but val is destructured immediately to Any
e.encode_any(val, level, mut wr)!
} $else $if T is []Any {
e.encode_any(val, level, mut wr)!
} $else $if T is Null || T is bool || T is f32 || T is f64 || T is i8 || T is i16 || T is int
|| T is i64 || T is u8 || T is u16 || T is u32 || T is u64 {
e.encode_any(val, level, mut wr)!
} $else $if T is Encodable {
wr.write(val.json_str().bytes())!
} $else $if T is []int {
// wr.write(val.str)!
e.encode_any(val, level, mut wr)!
} $else $if T is $Struct {
e.encode_struct(val, level, mut wr)!
} $else $if T is $Enum {
e.encode_any(Any(int(val)), level, mut wr)!
} $else {
// dump(val.str())
return error('cannot encode value with ${typeof(val).name} type')
}
}
fn (e &Encoder) encode_struct[U](val U, level int, mut wr io.Writer) ! {
wr.write([u8(`{`)])!
mut i := 0
mut fields_len := 0
$for _ in U.fields {
fields_len++
}
$for field in U.fields {
mut json_name := ''
for attr in field.attrs {
if attr.contains('json: ') {
json_name = attr.replace('json: ', '')
break
}
}
e.encode_newline(level, mut wr)!
if json_name != '' {
e.encode_string(json_name, mut wr)!
} else {
e.encode_string(field.name, mut wr)!
}
wr.write(json2.colon_bytes)!
if e.newline != 0 {
wr.write(json2.space_bytes)!
}
if typeof(val.$(field.name)).name.contains('?') {
if field.typ == 20 {
if val.$(field.name).str() == 'Option(error: none)' {
// TODO?
} else {
e.encode_string(val.$(field.name).str().replace("Option('", '').trim_string_right("')"), mut
wr)!
}
}
} else {
match field.unaliased_typ {
string_type_idx {
e.encode_string(val.$(field.name).str(), mut wr)!
}
int_type_idx {
wr.write(val.$(field.name).str().bytes())!
}
byte_array_type_idx {
//! array
e.encode_array(val.$(field.name), level, mut wr)!
}
else {
field_value := val.$(field.name)
e.encode_value_with_level(field_value, level + 1, mut wr)!
}
}
}
if i < fields_len - 1 {
wr.write(json2.comma_bytes)!
}
i++
}
e.encode_newline(level - 1, mut wr)!
wr.write([u8(`}`)])!
}
fn (e &Encoder) encode_array[U](val U, level int, mut wr io.Writer) ! {
$if U is $Array {
wr.write([u8(`[`)])!
for i in 0 .. val.len {
e.encode_newline(level, mut wr)!
e.encode_value_with_level(val[i], level + 1, mut wr)!
if i < val.len - 1 {
wr.write(json2.comma_bytes)!
}
}
e.encode_newline(level - 1, mut wr)!
wr.write([u8(`]`)])!
} $else {
return error('encoded array value is not an array')
}
}
// str returns the JSON string representation of the `map[string]Any` type.
pub fn (f map[string]Any) str() string {
return Any(f).json_str()
}
// str returns the JSON string representation of the `[]Any` type.
pub fn (f []Any) str() string {
return Any(f).json_str()
}
// str returns the string representation of the `Any` type. Use the `json_str` method
// if you want to use the escaped str() version of the `Any` type.
pub fn (f Any) str() string {
if f is string {
return f
} else {
return f.json_str()
}
}
// json_str returns the JSON string representation of the `Any` type.
[manualfree]
pub fn (f Any) json_str() string {
return encode(f)
}
// prettify_json_str returns the pretty-formatted JSON string representation of the `Any` type.
[manualfree]
pub fn (f Any) prettify_json_str() string {
mut sb := strings.new_builder(4096)
defer {
unsafe { sb.free() }
}
mut enc := Encoder{
newline: `\n`
newline_spaces_count: 4
}
enc.encode_value(f, mut sb) or {}
return sb.str()
}
// CharLengthIterator is an iterator that generates a char
// length value of every iteration based on the given text.
// (e.g.: "t✔" => [t => 1, ✔ => 2])
struct CharLengthIterator {
text string
mut:
idx int
}
fn (mut iter CharLengthIterator) next() ?int {
if iter.idx >= iter.text.len {
return none
}
defer {
iter.idx++
}
mut len := 1
c := iter.text[iter.idx]
if (c & (1 << 7)) != 0 {
for t := u8(1 << 6); (c & t) != 0; t >>= 1 {
len++
iter.idx++
}
}
return len
}
// encode_string returns the JSON spec-compliant version of the string.
[manualfree]
fn (e &Encoder) encode_string(s string, mut wr io.Writer) ! {
mut char_lens := CharLengthIterator{
text: s
}
mut i := 0
wr.write(json2.quote_bytes)!
for char_len in char_lens {
if char_len == 1 {
chr := s[i]
if chr in important_escapable_chars {
for j := 0; j < important_escapable_chars.len; j++ {
if chr == important_escapable_chars[j] {
wr.write(json2.escaped_chars[j])!
break
}
}
} else if chr == `"` || chr == `/` || chr == `\\` {
wr.write([u8(`\\`), chr])!
} else if int(chr) < 0x20 {
hex_code := chr.hex().bytes()
wr.write(json2.unicode_escape_chars)! // \u
wr.write(json2.zero_in_bytes)! // \u0
wr.write(json2.zero_in_bytes)! // \u00
wr.write(hex_code)! // \u00xxxx
} else {
wr.write([u8(chr)])!
}
} else {
slice := s[i..i + char_len]
hex_code := slice.utf32_code().hex().bytes()
if !e.escape_unicode || hex_code.len < 4 {
// unescaped non-ASCII char
wr.write(slice.bytes())!
} else if hex_code.len == 4 {
// a unicode endpoint
wr.write(json2.unicode_escape_chars)!
wr.write(hex_code)!
} else {
// TODO: still figuring out what
// to do with more than 4 chars
wr.write(json2.space_bytes)!
}
unsafe {
slice.free()
hex_code.free()
}
}
i += char_len
}
wr.write(json2.quote_bytes)!
}