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v/vlib/x/json2/decoder.v
Alexander Medvednikov 6756d28595 all: 2023 copyright
2023-03-28 22:55:57 +02:00

248 lines
4.9 KiB
V

// Copyright (c) 2019-2023 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
fn format_message(msg string, line int, column int) string {
return '[x.json2] ${msg} (${line}:${column})'
}
pub struct DecodeError {
line int
column int
message string
}
// code returns the error code of DecodeError
pub fn (err DecodeError) code() int {
return 3
}
// msg returns the message of the DecodeError
pub fn (err DecodeError) msg() string {
return format_message(err.message, err.line, err.column)
}
pub struct InvalidTokenError {
DecodeError
token Token
expected TokenKind
}
// code returns the error code of the InvalidTokenError
pub fn (err InvalidTokenError) code() int {
return 2
}
// msg returns the message of the InvalidTokenError
pub fn (err InvalidTokenError) msg() string {
footer_text := if err.expected != .none_ { ', expecting `${err.expected}`' } else { '' }
return format_message('invalid token `${err.token.kind}`${footer_text}', err.token.line,
err.token.full_col())
}
pub struct UnknownTokenError {
DecodeError
token Token
kind ValueKind = .unknown
}
// code returns the error code of the UnknownTokenError
pub fn (err UnknownTokenError) code() int {
return 1
}
// msg returns the error message of the UnknownTokenError
pub fn (err UnknownTokenError) msg() string {
return format_message("unknown token '${err.token.lit}' when decoding ${err.kind}.",
err.token.line, err.token.full_col())
}
struct Parser {
pub mut:
scanner &Scanner = unsafe { nil }
p_tok Token
tok Token
n_tok Token
n_level int
convert_type bool = true
}
fn (mut p Parser) next() {
p.p_tok = p.tok
p.tok = p.n_tok
p.n_tok = p.scanner.scan()
}
fn (mut p Parser) next_with_err() ! {
p.next()
if p.tok.kind == .error {
return DecodeError{
line: p.tok.line
column: p.tok.full_col()
message: p.tok.lit.bytestr()
}
}
}
// TODO: copied from v.util to avoid the entire module and its functions
// from being imported. remove later once -skip-unused is enabled by default.
fn skip_bom(file_content string) string {
mut raw_text := file_content
// BOM check
if raw_text.len >= 3 {
unsafe {
c_text := raw_text.str
if c_text[0] == 0xEF && c_text[1] == 0xBB && c_text[2] == 0xBF {
// skip three BOM bytes
offset_from_begin := 3
raw_text = tos(c_text[offset_from_begin], vstrlen(c_text) - offset_from_begin)
}
}
}
return raw_text
}
fn new_parser(srce string, convert_type bool) Parser {
src := skip_bom(srce)
return Parser{
scanner: &Scanner{
text: src.bytes()
}
convert_type: convert_type
}
}
// decode decodes provided JSON
pub fn (mut p Parser) decode() !Any {
p.next()
p.next_with_err()!
fi := p.decode_value()!
if p.tok.kind != .eof {
return InvalidTokenError{
token: p.tok
}
}
return fi
}
fn (mut p Parser) decode_value() !Any {
if p.n_level + 1 == 500 {
return DecodeError{
message: 'reached maximum nesting level of 500'
}
}
match p.tok.kind {
.lsbr {
return p.decode_array()
}
.lcbr {
return p.decode_object()
}
.int_, .float {
tl := p.tok.lit.bytestr()
kind := p.tok.kind
p.next_with_err()!
if p.convert_type {
$if !nofloat ? {
if kind == .float {
return Any(tl.f64())
}
}
return Any(tl.i64())
}
return Any(tl)
}
.bool_ {
lit := p.tok.lit.bytestr()
p.next_with_err()!
if p.convert_type {
return Any(lit.bool())
}
return Any(lit)
}
.null {
p.next_with_err()!
if p.convert_type {
return Any(null)
}
return Any('null')
}
.str_ {
str := p.tok.lit.bytestr()
p.next_with_err()!
return Any(str)
}
else {
return InvalidTokenError{
token: p.tok
}
}
}
return Any(null)
}
[manualfree]
fn (mut p Parser) decode_array() !Any {
mut items := []Any{}
p.next_with_err()!
p.n_level++
for p.tok.kind != .rsbr {
item := p.decode_value()!
items << item
if p.tok.kind == .comma {
p.next_with_err()!
if p.tok.kind == .rsbr {
return InvalidTokenError{
token: p.tok
}
}
} else if p.tok.kind != .rsbr {
return UnknownTokenError{
token: p.tok
kind: .array
}
}
}
p.next_with_err()!
p.n_level--
return Any(items)
}
fn (mut p Parser) decode_object() !Any {
mut fields := map[string]Any{}
p.next_with_err()!
p.n_level++
for p.tok.kind != .rcbr {
if p.tok.kind != .str_ {
return InvalidTokenError{
token: p.tok
expected: .str_
}
}
cur_key := p.tok.lit.bytestr()
p.next_with_err()!
if p.tok.kind != .colon {
return InvalidTokenError{
token: p.tok
expected: .colon
}
}
p.next_with_err()!
fields[cur_key] = p.decode_value()!
if p.tok.kind != .comma && p.tok.kind != .rcbr {
return UnknownTokenError{
token: p.tok
kind: .object
}
} else if p.tok.kind == .comma {
p.next_with_err()!
}
}
p.next_with_err()!
p.n_level--
return Any(fields)
}