v/vlib/x/json2/encoder.v

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// Copyright (c) 2019-2022 Alexander Medvednikov. All rights reserved.
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// Use of this source code is governed by an MIT license
// that can be found in the LICENSE file.
module json2
import io
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import strings
// Encoder encodes the an `Any` type into JSON representation.
// It provides parameters in order to change the end result.
pub struct Encoder {
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newline u8
newline_spaces_count int
escape_unicode bool = true
}
// 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()
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const zero_in_bytes = [u8(`0`)]
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const comma_bytes = [u8(`,`)]
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const colon_bytes = [u8(`:`)]
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const space_bytes = [u8(` `)]
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const unicode_escape_chars = [u8(`\\`), `u`]
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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 an `Any` value to the specific writer.
pub fn (e &Encoder) encode_value(f Any, mut wr io.Writer) ? {
e.encode_value_with_level(f, 1, mut wr)?
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}
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_value_with_level(f Any, level int, mut wr io.Writer) ? {
match f {
string {
e.encode_string(f, mut wr)?
}
bool {
if f == true {
wr.write(json2.true_in_bytes)?
} else {
wr.write(json2.false_in_bytes)?
}
}
int, u64, i64 {
wr.write(f.str().bytes())?
}
f32, f64 {
$if !nofloat ? {
str_float := f.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 f {
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 < f.len - 1 {
wr.write(json2.comma_bytes)?
}
i++
}
e.encode_newline(level - 1, mut wr)?
wr.write([u8(`}`)])?
}
[]Any {
wr.write([u8(`[`)])?
for i, v in f {
e.encode_newline(level, mut wr)?
e.encode_value_with_level(v, level + 1, mut wr)?
if i < f.len - 1 {
wr.write(json2.comma_bytes)?
}
}
e.encode_newline(level - 1, mut wr)?
wr.write([u8(`]`)])?
}
Null {
wr.write(json2.null_in_bytes)?
}
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}
}
// 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 {
mut sb := strings.new_builder(4096)
defer {
unsafe { sb.free() }
}
mut enc := Encoder{}
enc.encode_value(f, mut sb) or { return '' }
return sb.str()
}
// 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 '' }
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 {
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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)?
}