mirror of
https://github.com/SerenityOS/serenity
synced 2024-09-06 08:56:40 +00:00
AK: Implement a naive JSON parser.
This parser assumes that the JSON is well-formed and will choke horribly on invalid input. Since we're primarily interested in parsing our own output right now, this is less of a problem. Longer-term we're gonna need something better. :^)
This commit is contained in:
parent
bad8ab697b
commit
009b9bfd10
167
AK/JsonValue.cpp
167
AK/JsonValue.cpp
|
@ -1,3 +1,4 @@
|
|||
#include <AK/Function.h>
|
||||
#include <AK/JsonArray.h>
|
||||
#include <AK/JsonObject.h>
|
||||
#include <AK/JsonValue.h>
|
||||
|
@ -175,4 +176,170 @@ String JsonValue::serialized() const
|
|||
return builder.to_string();
|
||||
}
|
||||
|
||||
static bool is_whitespace(char ch)
|
||||
{
|
||||
return ch == ' ' || ch == '\n' || ch == '\t' || ch == '\v' || ch == '\r';
|
||||
}
|
||||
|
||||
JsonValue JsonValue::from_string(const StringView& input)
|
||||
{
|
||||
int index = 0;
|
||||
|
||||
auto peek = [&] {
|
||||
return input[index];
|
||||
};
|
||||
|
||||
auto consume = [&]() -> char {
|
||||
if (index < input.length())
|
||||
return input[index++];
|
||||
return '\0';
|
||||
};
|
||||
|
||||
auto consume_while = [&](auto condition) {
|
||||
while (condition(peek()))
|
||||
consume();
|
||||
};
|
||||
|
||||
auto extract_while = [&](auto condition) {
|
||||
StringBuilder builder;
|
||||
while (condition(peek()))
|
||||
builder.append(consume());
|
||||
return builder.to_string();
|
||||
};
|
||||
|
||||
auto consume_whitespace = [&] {
|
||||
consume_while([](char ch) { return is_whitespace(ch); });
|
||||
};
|
||||
|
||||
auto consume_specific = [&](char expected_ch) {
|
||||
char consumed_ch = consume();
|
||||
ASSERT(consumed_ch == expected_ch);
|
||||
};
|
||||
|
||||
Function<JsonValue()> parse;
|
||||
|
||||
auto parse_object_member = [&](JsonObject& object) {
|
||||
consume_whitespace();
|
||||
consume_specific('"');
|
||||
auto name = extract_while([](char ch) { return ch != '"'; });
|
||||
consume_specific('"');
|
||||
consume_whitespace();
|
||||
consume_specific(':');
|
||||
consume_whitespace();
|
||||
auto value = parse();
|
||||
object.set(name, value);
|
||||
};
|
||||
|
||||
auto parse_object = [&]() -> JsonValue {
|
||||
JsonObject object;
|
||||
consume_specific('{');
|
||||
for (;;) {
|
||||
consume_whitespace();
|
||||
if (peek() == '}')
|
||||
break;
|
||||
parse_object_member(object);
|
||||
consume_whitespace();
|
||||
if (peek() == '}')
|
||||
break;
|
||||
consume_specific(',');
|
||||
}
|
||||
consume_specific('}');
|
||||
return object;
|
||||
};
|
||||
|
||||
auto parse_array = [&]() -> JsonValue {
|
||||
JsonArray array;
|
||||
consume_specific('[');
|
||||
for (;;) {
|
||||
consume_whitespace();
|
||||
if (peek() == ']')
|
||||
break;
|
||||
array.append(parse());
|
||||
consume_whitespace();
|
||||
if (peek() == ']')
|
||||
break;
|
||||
consume_specific(',');
|
||||
}
|
||||
consume_whitespace();
|
||||
consume_specific(']');
|
||||
return array;
|
||||
};
|
||||
|
||||
auto parse_string = [&]() -> JsonValue {
|
||||
consume_specific('"');
|
||||
auto string = extract_while([](char ch) { return ch != '"'; });
|
||||
consume_specific('"');
|
||||
return JsonValue(string);
|
||||
};
|
||||
|
||||
auto parse_number = [&]() -> JsonValue {
|
||||
auto number_string = extract_while([](char ch) { return ch == '-' || (ch >= '0' && ch <= '9'); });
|
||||
bool ok;
|
||||
auto value = JsonValue(number_string.to_int(ok));
|
||||
ASSERT(ok);
|
||||
return value;
|
||||
};
|
||||
|
||||
auto consume_string = [&](const char* str) {
|
||||
for (size_t i = 0, length = strlen(str); i < length; ++i)
|
||||
consume_specific(str[i]);
|
||||
};
|
||||
|
||||
auto parse_true = [&]() -> JsonValue {
|
||||
consume_string("true");
|
||||
return JsonValue(true);
|
||||
};
|
||||
|
||||
auto parse_false = [&]() -> JsonValue {
|
||||
consume_string("false");
|
||||
return JsonValue(false);
|
||||
};
|
||||
|
||||
auto parse_null = [&]() -> JsonValue {
|
||||
consume_string("null");
|
||||
return JsonValue(JsonValue::Type::Null);
|
||||
};
|
||||
|
||||
auto parse_undefined = [&]() -> JsonValue {
|
||||
consume_string("undefined");
|
||||
return JsonValue(JsonValue::Type::Undefined);
|
||||
};
|
||||
|
||||
parse = [&]() -> JsonValue {
|
||||
consume_whitespace();
|
||||
auto type_hint = peek();
|
||||
switch (type_hint) {
|
||||
case '{':
|
||||
return parse_object();
|
||||
case '[':
|
||||
return parse_array();
|
||||
case '"':
|
||||
return parse_string();
|
||||
case '-':
|
||||
case '0':
|
||||
case '1':
|
||||
case '2':
|
||||
case '3':
|
||||
case '4':
|
||||
case '5':
|
||||
case '6':
|
||||
case '7':
|
||||
case '8':
|
||||
case '9':
|
||||
return parse_number();
|
||||
case 'f':
|
||||
return parse_false();
|
||||
case 't':
|
||||
return parse_true();
|
||||
case 'n':
|
||||
return parse_null();
|
||||
case 'u':
|
||||
return parse_undefined();
|
||||
}
|
||||
ASSERT_NOT_REACHED();
|
||||
};
|
||||
|
||||
return parse();
|
||||
}
|
||||
|
||||
}
|
||||
|
|
|
@ -21,6 +21,8 @@ public:
|
|||
Object,
|
||||
};
|
||||
|
||||
static JsonValue from_string(const StringView&);
|
||||
|
||||
explicit JsonValue(Type = Type::Null);
|
||||
~JsonValue() { clear(); }
|
||||
|
||||
|
|
Loading…
Reference in a new issue