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# Base 64 encoding and decoding
use patterns
enum JSONDecodeResult(
Success(json:JSON)
Failure(reason:Text)
)
func invalid(text:Text -> JSONDecodeResult)
return Failure("Unrecognized JSON: $(text.quoted())")
extend Text
func json_quoted(text:Text -> Text)
return '"' ++ text.translate({
"\\"="\\\\",
'"'='\\"',
"\f"="\\f",
"\r"="\\r",
"\n"="\\n",
"\b"="\\b",
"\t"="\\t",
}) ++ '"'
enum JSON(
Object(items:{Text=JSON})
Array(items:[JSON])
Boolean(value:Bool)
String(text:Text)
Number(n:Num)
Null
)
func encode(j:JSON -> Text)
when j is Object(items)
return "{" ++ ", ".join([
'$(k.json_quoted()): $(v.encode())'
for k,v in items
]) ++ "}"
is Array(items)
return "[" ++ ", ".join([item.encode() for item in items]) ++ "]"
is Boolean(value)
return (if value then "true" else "false")
is String(text)
return text.json_quoted()
is Number(n)
return "$n"
is Null
return "null"
func pretty_print(j:JSON, max_line:Int=80, indent:Text=" ", current_indent:Text="" -> Text)
inline := j.encode()
if inline.length > max_line
next_indent := current_indent ++ indent
when j is Object(items)
return "{\n$next_indent" ++ ",\n$next_indent".join([
'$(k.json_quoted()): $(v.pretty_print(max_line, indent, next_indent))'
for k,v in items
]) ++ "\n$current_indent}"
is Array(items)
return "[\n$next_indent" ++ ",\n$next_indent".join([item.pretty_print(max_line, indent, next_indent) for item in items]) ++ "\n$current_indent]"
else pass
return inline
func parse_text(text:Text, remainder:&Text? = none -> JSONDecodeResult)
if text.starts_with('"')
string := ""
pos := 2
escapes := {"n"="\n", "t"="\t", "r"="\r", '"'='"', "\\"="\\", "/"="/", "b"="\b", "f"="\f"}
while pos <= text.length
c := text[pos]
if c == '"'
if remainder
remainder[] = text.from(pos + 1)
return Success(JSON.String(string))
if c == "\\"
stop if pos + 1 > text.length
if esc := escapes[text[pos+1]]
string ++= esc
pos += 2
else if m := text.matching_pattern($Pat/u{4 digit}/)
string ++= Text.from_codepoints([Int32.parse(m.captures[1])!])
pos += 1 + m.text.length
else
if remainder
remainder[] = text
return JSONDecodeResult.invalid(text)
else
string ++= c
pos += 1
if remainder
remainder[] = text
return JSONDecodeResult.invalid(text)
func parse(text:Text, remainder:&Text? = none, trailing_commas:Bool=no -> JSONDecodeResult)
if text.starts_with("true", remainder)
return Success(JSON.Boolean(yes))
else if text.starts_with("false", remainder)
return Success(JSON.Boolean(no))
else if text.starts_with("null", remainder)
return Success(JSON.Null)
else if n := Num.parse(text, remainder)
return Success(JSON.Number(n))
else if text.starts_with('"')
return JSON.parse_text(text, remainder)
else if text.starts_with("[")
elements : &[JSON]
text = text.from(2).trim_pattern($Pat"{whitespace}", right=no)
repeat
when JSON.parse(text, &text) is Success(elem)
elements.insert(elem)
else stop
if delim := text.matching_pattern($Pat'{0+ ws},{0+ ws}')
text = text.from(delim.text.length + 1)
else stop
if trailing_commas
if delim := text.matching_pattern($Pat'{0+ ws},{0+ ws}')
text = text.from(delim.text.length + 1)
if terminator := text.matching_pattern($Pat'{0+ ws}]')
if remainder
remainder[] = text.from(terminator.text.length + 1)
return Success(JSON.Array(elements))
else if text.starts_with("{")
object : &{Text=JSON}
text = text.from(2).trim_pattern($Pat"{whitespace}", right=no)
repeat
key_text := text
when JSON.parse_text(text, &text) is Success(key)
if separator := text.matching_pattern($Pat'{0+ ws}:{0+ ws}')
text = text.from(separator.text.length + 1)
else
return JSONDecodeResult.invalid(text)
when JSON.parse(text, &text) is Success(value)
when key is String(str)
object[str] = value
else
return JSONDecodeResult.invalid(key_text)
else
return JSONDecodeResult.invalid(text)
else stop
if delim := text.matching_pattern($Pat'{0+ ws},{0+ ws}')
text = text.from(delim.text.length + 1)
else stop
if trailing_commas
if delim := text.matching_pattern($Pat'{0+ ws},{0+ ws}')
text = text.from(delim.text.length + 1)
if terminator := text.matching_pattern($Pat'{0+ ws}{}}')
if remainder
remainder[] = text.from(terminator.text.length + 1)
return Success(JSON.Object(object))
return JSONDecodeResult.invalid(text)
func main(input=(/dev/stdin), pretty_print:Bool = no, trailing_commas:Bool = yes)
text := (input.read() or exit("Invalid file: $input")).trim_pattern($Pat"{whitespace}")
while text.length > 0
when JSON.parse(text, remainder=&text, trailing_commas=trailing_commas) is Success(json)
if pretty_print
say(json.pretty_print())
else
say(json.encode())
is Failure(msg)
exit("\033[31;1m$msg\033[m", code=1)
text = text.trim_pattern($Pat"{whitespace}")
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