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decoder2: prepare for moving into json2 (#25039)

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Larsimusrex 2025-08-05 09:07:03 +02:00 • committed by GitHub
parent 13ba08fba2
commit c5b6d2a1c6
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8 changed files with 702 additions and 696 deletions
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506
vlib/x/json2/decoder2/decode.v
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@ -22,8 +22,7 @@ mut:
// ValueInfo represents the position and length of a value, such as string, number, array, object key, and object value in a JSON string.
struct ValueInfo {
position int // The position of the value in the JSON string.
pub:
position int // The position of the value in the JSON string.
value_kind ValueKind // The kind of the value.
mut:
length int // The length of the value in the JSON string.
@ -51,20 +50,6 @@ mut:
current_node &Node[ValueInfo] = unsafe { nil } // The current node in the linked list.
}
// new_decoder creates a new JSON decoder.
pub fn new_decoder[T](json string) !Decoder {
mut decoder := Decoder{
json: json
}
decoder.check_json_format(json)!
check_if_json_match[T](json)!
decoder.current_node = decoder.values_info.head
return decoder
}
// LinkedList represents a linked list to store ValueInfo.
struct LinkedList[T] {
mut:
@ -138,8 +123,7 @@ fn (list &LinkedList[T]) free() {
}
// ValueKind represents the kind of a JSON value.
pub enum ValueKind {
unknown
enum ValueKind {
array
object
string_
@ -148,8 +132,8 @@ pub enum ValueKind {
null
}
const max_context_lenght = 50
const max_extra_charaters = 5
const max_context_length = 50
const max_extra_characters = 5
const tab_width = 8
pub struct JsonDecodeError {
@ -189,13 +173,13 @@ fn (mut checker Decoder) checker_error(message string) ! {
}
}
cutoff := character_number > max_context_lenght
cutoff := character_number > max_context_length
// either start of string, last newline or a limited amount of characters
context_start := if cutoff { position - max_context_lenght } else { last_newline }
context_start := if cutoff { position - max_context_length } else { last_newline }
// print some extra characters
mut context_end := int_min(checker.json.len, position + max_extra_charaters)
mut context_end := int_min(checker.json.len, position + max_extra_characters)
context_end_newline := checker.json[position..context_end].index_u8(`\n`)
if context_end_newline != -1 {
@ -213,7 +197,7 @@ fn (mut checker Decoder) checker_error(message string) ! {
context += '\n'
if cutoff {
context += ' '.repeat(max_context_lenght + 3)
context += ' '.repeat(max_context_length + 3)
} else {
context += ' '.repeat(character_number)
}
@ -237,7 +221,7 @@ fn (mut decoder Decoder) decode_error(message string) ! {
}
start := error_info.position
end := start + int_min(error_info.length, max_context_lenght)
end := start + int_min(error_info.length, max_context_length)
mut line_number := 0
mut character_number := 0
@ -258,13 +242,13 @@ fn (mut decoder Decoder) decode_error(message string) ! {
}
}
cutoff := character_number > max_context_lenght
cutoff := character_number > max_context_length
// either start of string, last newline or a limited amount of characters
context_start := if cutoff { start - max_context_lenght } else { last_newline }
context_start := if cutoff { start - max_context_length } else { last_newline }
// print some extra characters
mut context_end := int_min(decoder.json.len, end + max_extra_charaters)
mut context_end := int_min(decoder.json.len, end + max_extra_characters)
context_end_newline := decoder.json[end..context_end].index_u8(`\n`)
if context_end_newline != -1 {
@ -282,7 +266,7 @@ fn (mut decoder Decoder) decode_error(message string) ! {
context += '\n'
if cutoff {
context += ' '.repeat(max_context_lenght + 3)
context += ' '.repeat(max_context_length + 3)
} else {
context += ' '.repeat(character_number)
}
@ -296,413 +280,6 @@ fn (mut decoder Decoder) decode_error(message string) ! {
}
}
// check_json_format checks if the JSON string is valid and updates the decoder state.
fn (mut checker Decoder) check_json_format(val string) ! {
checker_end := checker.json.len
// check if the JSON string is empty
if val == '' {
return checker.checker_error('empty string')
}
// skip whitespace
for val[checker.checker_idx] in whitespace_chars {
if checker.checker_idx == checker_end {
break
}
checker.checker_idx++
}
// check if generic type matches the JSON type
value_kind := get_value_kind(val[checker.checker_idx])
start_idx_position := checker.checker_idx
checker.values_info.push(ValueInfo{
position: start_idx_position
value_kind: value_kind
})
mut actual_value_info_pointer := checker.values_info.last()
match value_kind {
.unknown {
return checker.checker_error('unknown value kind')
}
.null {
// check if the JSON string is a null value
if checker_end - checker.checker_idx <= 3 {
return checker.checker_error('EOF error: expecting `null`')
}
is_not_ok := unsafe {
vmemcmp(checker.json.str + checker.checker_idx, null_in_string.str, null_in_string.len)
}
if is_not_ok != 0 {
return checker.checker_error('invalid null value. Got `${checker.json[checker.checker_idx..
checker.checker_idx + 4]}` instead of `null`')
}
checker.checker_idx += 3
}
.object {
if checker_end - checker.checker_idx < 2 {
return checker.checker_error('EOF error: expecting a complete object after `{`')
}
checker.checker_idx++
for val[checker.checker_idx] != `}` {
// skip whitespace
for val[checker.checker_idx] in whitespace_chars {
if checker.checker_idx == checker_end {
checker.checker_idx--
break
}
checker.checker_idx++
}
if val[checker.checker_idx] == `}` {
continue
}
if val[checker.checker_idx] != `"` {
return checker.checker_error('Expecting object key')
}
// Object key
checker.check_json_format(val)!
for val[checker.checker_idx] != `:` {
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('EOF error: key colon not found')
}
if val[checker.checker_idx] !in whitespace_chars {
return checker.checker_error('invalid value after object key')
}
checker.checker_idx++
}
if val[checker.checker_idx] != `:` {
return checker.checker_error('Expecting `:` after object key')
}
// skip `:`
checker.checker_idx++
// skip whitespace
for val[checker.checker_idx] in whitespace_chars {
checker.checker_idx++
}
match val[checker.checker_idx] {
`"`, `[`, `{`, `0`...`9`, `-`, `n`, `t`, `f` {
checker.check_json_format(val)!
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('EOF error: braces are not closed')
}
// whitespace
for val[checker.checker_idx] in whitespace_chars {
checker.checker_idx++
}
if val[checker.checker_idx] == `}` {
break
}
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('EOF error: braces are not closed')
}
if val[checker.checker_idx] == `,` {
checker.checker_idx++
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('EOF error: Expecting object key after `,`')
}
for val[checker.checker_idx] in whitespace_chars {
checker.checker_idx++
}
if val[checker.checker_idx] != `"` {
return checker.checker_error('Expecting object key after `,`')
}
} else {
if val[checker.checker_idx] == `}` {
break
} else {
return checker.checker_error('invalid object value')
}
}
}
else {
return checker.checker_error('invalid object value')
}
}
}
}
.array {
// check if the JSON string is an empty array
if checker_end >= checker.checker_idx + 2 {
checker.checker_idx++
} else {
return checker.checker_error('EOF error: There are not enough length for an array')
}
for val[checker.checker_idx] != `]` {
// skip whitespace
for val[checker.checker_idx] in whitespace_chars {
if checker.checker_idx == checker_end {
checker.checker_idx--
break
}
checker.checker_idx++
}
if val[checker.checker_idx] == `]` {
break
}
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('EOF error: array not closed')
}
checker.check_json_format(val)!
// whitespace
for val[checker.checker_idx] in whitespace_chars {
checker.checker_idx++
}
if val[checker.checker_idx] == `]` {
break
}
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('EOF error: braces are not closed')
}
if val[checker.checker_idx] == `,` {
checker.checker_idx++
for val[checker.checker_idx] in whitespace_chars {
checker.checker_idx++
}
if val[checker.checker_idx] == `]` {
return checker.checker_error('Cannot use `,`, before `]`')
}
continue
} else {
if val[checker.checker_idx] == `]` {
break
} else {
return checker.checker_error('`]` after value')
}
}
}
}
.string_ {
// check if the JSON string is a valid string
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('EOF error: string not closed')
}
checker.checker_idx++
// check if the JSON string is a valid escape sequence
for val[checker.checker_idx] != `"` {
if val[checker.checker_idx] == `\\` {
if checker.checker_idx + 1 >= checker_end - 1 {
return checker.checker_error('invalid escape sequence')
}
escaped_char := val[checker.checker_idx + 1]
match escaped_char {
`/`, `b`, `f`, `n`, `r`, `t`, `"`, `\\` {
checker.checker_idx++ // make sure escaped quotation marks are skipped
}
`u` {
// check if the JSON string is a valid unicode escape sequence
escaped_char_last_index := checker.checker_idx + 5
if escaped_char_last_index < checker_end {
// 2 bytes for the unicode escape sequence `\u`
checker.checker_idx += 2
for checker.checker_idx < escaped_char_last_index {
match val[checker.checker_idx] {
`0`...`9`, `a`...`f`, `A`...`F` {
checker.checker_idx++
}
else {
return checker.checker_error('invalid unicode escape sequence')
}
}
}
continue
} else {
return checker.checker_error('short unicode escape sequence ${checker.json[checker.checker_idx..escaped_char_last_index]}')
}
}
else {
return checker.checker_error('unknown escape sequence')
}
}
}
checker.checker_idx++
}
}
.number {
// check if the JSON string is a valid float or integer
if val[checker.checker_idx] == `-` {
checker.checker_idx++
}
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('expected digit got EOF')
}
// integer part
if val[checker.checker_idx] == `0` {
checker.checker_idx++
} else if val[checker.checker_idx] >= `1` && val[checker.checker_idx] <= `9` {
checker.checker_idx++
for checker.checker_idx < checker_end && val[checker.checker_idx] >= `0`
&& val[checker.checker_idx] <= `9` {
checker.checker_idx++
}
} else {
return checker.checker_error('expected digit got ${val[checker.checker_idx].ascii_str()}')
}
// fraction part
if checker.checker_idx != checker_end && val[checker.checker_idx] == `.` {
checker.checker_idx++
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('expected digit got EOF')
}
if val[checker.checker_idx] >= `0` && val[checker.checker_idx] <= `9` {
for checker.checker_idx < checker_end && val[checker.checker_idx] >= `0`
&& val[checker.checker_idx] <= `9` {
checker.checker_idx++
}
} else {
return checker.checker_error('expected digit got ${val[checker.checker_idx].ascii_str()}')
}
}
// exponent part
if checker.checker_idx != checker_end
&& (val[checker.checker_idx] == `e` || val[checker.checker_idx] == `E`) {
checker.checker_idx++
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('expected digit got EOF')
}
if val[checker.checker_idx] == `-` || val[checker.checker_idx] == `+` {
checker.checker_idx++
if checker.checker_idx == checker_end {
checker.checker_idx--
return checker.checker_error('expected digit got EOF')
}
}
if val[checker.checker_idx] >= `0` && val[checker.checker_idx] <= `9` {
for checker.checker_idx < checker_end && val[checker.checker_idx] >= `0`
&& val[checker.checker_idx] <= `9` {
checker.checker_idx++
}
} else {
return checker.checker_error('expected digit got ${val[checker.checker_idx].ascii_str()}')
}
}
checker.checker_idx--
}
.boolean {
// check if the JSON string is a valid boolean
match val[checker.checker_idx] {
`t` {
if checker_end - checker.checker_idx <= 3 {
return checker.checker_error('EOF error: expecting `true`')
}
is_not_ok := unsafe {
vmemcmp(checker.json.str + checker.checker_idx, true_in_string.str,
true_in_string.len)
}
if is_not_ok != 0 {
return checker.checker_error('invalid boolean value. Got `${checker.json[checker.checker_idx..
checker.checker_idx + 4]}` instead of `true`')
}
checker.checker_idx += 3
}
`f` {
if checker_end - checker.checker_idx <= 4 {
return checker.checker_error('EOF error: expecting `false`')
}
is_not_ok := unsafe {
vmemcmp(checker.json.str + checker.checker_idx, false_in_string.str,
false_in_string.len)
}
if is_not_ok != 0 {
return checker.checker_error('invalid boolean value. Got `${checker.json[checker.checker_idx..
checker.checker_idx + 5]}` instead of `false`')
}
checker.checker_idx += 4
}
else {
return checker.checker_error('invalid boolean')
}
}
}
}
actual_value_info_pointer.length = checker.checker_idx + 1 - start_idx_position
if checker.checker_idx < checker_end {
checker.checker_idx++
}
for checker.checker_idx < checker_end && val[checker.checker_idx] !in [`,`, `:`, `}`, `]`] {
// get trash characters after the value
if val[checker.checker_idx] !in whitespace_chars {
checker.checker_error('invalid value. Unexpected character after ${value_kind} end')!
} else {
// whitespace
}
checker.checker_idx++
}
}
// get_value_kind returns the kind of a JSON value.
fn get_value_kind(value u8) ValueKind {
if value == u8(`"`) {
return .string_
} else if value == u8(`t`) || value == u8(`f`) {
return .boolean
} else if value == u8(`{`) {
return .object
} else if value == u8(`[`) {
return .array
} else if (value >= u8(48) && value <= u8(57)) || value == u8(`-`) {
return .number
} else if value == u8(`n`) {
return .null
}
return .unknown
}
// decode decodes a JSON string into a specified type.
@[manualfree]
pub fn decode[T](val string) !T {
@ -717,7 +294,7 @@ pub fn decode[T](val string) !T {
json: val
}
decoder.check_json_format(val)!
decoder.check_json_format()!
mut result := T{}
decoder.current_node = decoder.values_info.head
@ -728,6 +305,10 @@ pub fn decode[T](val string) !T {
return result
}
fn get_dynamic_from_element[T](t T) []T {
return []T{}
}
// decode_value decodes a value from the JSON nodes.
@[manualfree]
fn (mut decoder Decoder) decode_value[T](mut val T) ! {
@ -862,16 +443,29 @@ fn (mut decoder Decoder) decode_value[T](mut val T) ! {
} $else $if T.unaliased_typ is $map {
decoder.decode_map(mut val)!
return
} $else $if T.unaliased_typ is $array {
unsafe {
val.len = 0
}
} $else $if T.unaliased_typ is $array_dynamic {
val.clear()
decoder.decode_array(mut val)!
// return to avoid the next increment of the current node
// this is because the current node is already incremented in the decode_array function
// remove this line will cause the current node to be incremented twice
// and bug recursive array decoding like `[][]int{}`
return
} $else $if T.unaliased_typ is $array_fixed {
mut dynamic_val := get_dynamic_from_element(val[0])
// avoid copying by pointing dynamic_val to val
unsafe {
dynamic_val.len = 0
dynamic_val.cap = val.len // ensures data wont reallocate
dynamic_val.data = &val
}
decoder.decode_array(mut dynamic_val)!
if dynamic_val.len != val.len {
decoder.decode_error('Fixed size array expected ${val.len} elements but got ${dynamic_val.len} elements')!
}
return
} $else $if T.unaliased_typ is $struct {
struct_info := decoder.current_node.value
@ -927,8 +521,6 @@ fn (mut decoder Decoder) decode_value[T](mut val T) ! {
current_field_info = struct_fields_info.head
mut field_used := false
// field loop
for {
if current_field_info == unsafe { nil } {
@ -939,7 +531,6 @@ fn (mut decoder Decoder) decode_value[T](mut val T) ! {
if current_field_info.value.is_skip {
if current_field_info.value.is_required == false {
field_used = true
current_field_info = current_field_info.next
continue
}
@ -948,13 +539,11 @@ fn (mut decoder Decoder) decode_value[T](mut val T) ! {
if current_field_info.value.is_omitempty {
match decoder.current_node.next.value.value_kind {
.null {
field_used = true
current_field_info = current_field_info.next
continue
}
.string_ {
if decoder.current_node.next.value.length == 2 {
field_used = true
current_field_info = current_field_info.next
continue
}
@ -962,7 +551,6 @@ fn (mut decoder Decoder) decode_value[T](mut val T) ! {
.number {
if decoder.json[decoder.current_node.next.value.position] == `0` {
if decoder.current_node.next.value.length == 1 {
field_used = true
current_field_info = current_field_info.next
continue
} else if decoder.current_node.next.value.length == 3 {
@ -971,7 +559,6 @@ fn (mut decoder Decoder) decode_value[T](mut val T) ! {
decoder.current_node.next.value.position,
float_zero_in_string.str, float_zero_in_string.len) == 0
} {
field_used = true
current_field_info = current_field_info.next
continue
}
@ -988,8 +575,6 @@ fn (mut decoder Decoder) decode_value[T](mut val T) ! {
vmemcmp(decoder.json.str + key_info.position + 1, current_field_info.value.json_name_ptr,
current_field_info.value.json_name_len) == 0
} {
field_used = true
$for field in T.fields {
if field.name.len == current_field_info.value.field_name_len {
if unsafe {
@ -1076,12 +661,6 @@ fn (mut decoder Decoder) decode_value[T](mut val T) ! {
}
current_field_info = current_field_info.next
}
if !field_used
&& decoder.json[key_info.position + 1..key_info.position + key_info.length - 1] != '_type' {
decoder.decode_error('unknown field `${decoder.json[key_info.position..
key_info.position + key_info.length]}`')!
}
}
// check if all required fields are present
@ -1125,6 +704,12 @@ fn (mut decoder Decoder) decode_value[T](mut val T) ! {
value_info := decoder.current_node.value
if value_info.value_kind == .number {
unsafe { decoder.decode_number(&val)! }
} else if value_info.value_kind == .string_ {
// recheck if string contains number
decoder.checker_idx = value_info.position + 1
decoder.check_number()!
unsafe { decoder.decode_number(&val)! }
} else {
return decoder.decode_error('Expected number, but got ${value_info.value_kind}')
@ -1277,7 +862,14 @@ fn get_number_digits[T](num T) int {
// use pointer instead of mut so enum cast works
@[unsafe]
fn (mut decoder Decoder) decode_number[T](val &T) ! {
number_info := decoder.current_node.value
mut number_info := decoder.current_node.value
if decoder.json[number_info.position] == `"` { // fake number
number_info = ValueInfo{
position: number_info.position + 1
length: number_info.length - 2
}
}
$if T.unaliased_typ is $float {
*val = T(strconv.atof_quick(decoder.json[number_info.position..number_info.position +