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🔨 realized callback parser wirh SAX interface #971

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This commit is contained in:
Niels Lohmann
2018-03-28 23:39:39 +02:00
parent 4f6b2b6429
commit 5f723bbec6
4 changed files with 273 additions and 698 deletions
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318
include/nlohmann/detail/input/parser.hpp
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@@ -83,7 +83,6 @@ class parser
{
if (callback)
{
/*
json_sax_dom_callback_parser<BasicJsonType> sdp(result, callback, allow_exceptions);
sax_parse_internal(&sdp);
result.assert_invariant();
@@ -102,24 +101,6 @@ class parser
result = value_t::discarded;
return;
}
*/
parse_internal(true, result);
result.assert_invariant();
// in strict mode, input must be completely read
if (strict)
{
get_token();
expect(token_type::end_of_input);
}
// in case of an error, return discarded value
if (errored)
{
result = value_t::discarded;
return;
}
// set top-level value to null if it was discarded by the callback
// function
@@ -179,280 +160,6 @@ class parser
}
private:
/*!
@brief the actual parser
@throw parse_error.101 in case of an unexpected token
@throw parse_error.102 if to_unicode fails or surrogate error
@throw parse_error.103 if to_unicode fails
*/
void parse_internal(bool keep, BasicJsonType& result)
{
// never parse after a parse error was detected
assert(not errored);
// this function is only called when a callback is given
assert(callback);
// start with a discarded value
if (not result.is_discarded())
{
result.m_value.destroy(result.m_type);
result.m_type = value_t::discarded;
}
switch (last_token)
{
case token_type::begin_object:
{
if (keep)
{
keep = callback(depth++, parse_event_t::object_start, result);
if (keep)
{
// explicitly set result to object to cope with {}
result.m_type = value_t::object;
result.m_value = value_t::object;
}
}
// read next token
get_token();
// closing } -> we are done
if (last_token == token_type::end_object)
{
if (keep and not callback(--depth, parse_event_t::object_end, result))
{
result.m_value.destroy(result.m_type);
result.m_type = value_t::discarded;
}
break;
}
// parse values
string_t key;
BasicJsonType value;
while (true)
{
// store key
if (not expect(token_type::value_string))
{
return;
}
key = m_lexer.get_string();
bool keep_tag = false;
if (keep)
{
BasicJsonType k(key);
keep_tag = callback(depth, parse_event_t::key, k);
}
// parse separator (:)
get_token();
if (not expect(token_type::name_separator))
{
return;
}
// parse and add value
get_token();
value.m_value.destroy(value.m_type);
value.m_type = value_t::discarded;
parse_internal(keep, value);
if (JSON_UNLIKELY(errored))
{
return;
}
if (keep and keep_tag and not value.is_discarded())
{
result.m_value.object->emplace(std::move(key), std::move(value));
}
// comma -> next value
get_token();
if (last_token == token_type::value_separator)
{
get_token();
continue;
}
// closing }
if (not expect(token_type::end_object))
{
return;
}
break;
}
if (keep and not callback(--depth, parse_event_t::object_end, result))
{
result.m_value.destroy(result.m_type);
result.m_type = value_t::discarded;
}
break;
}
case token_type::begin_array:
{
if (keep)
{
keep = callback(depth++, parse_event_t::array_start, result);
if (keep)
{
// explicitly set result to array to cope with []
result.m_type = value_t::array;
result.m_value = value_t::array;
}
}
// read next token
get_token();
// closing ] -> we are done
if (last_token == token_type::end_array)
{
if (not callback(--depth, parse_event_t::array_end, result))
{
result.m_value.destroy(result.m_type);
result.m_type = value_t::discarded;
}
break;
}
// parse values
BasicJsonType value;
while (true)
{
// parse value
value.m_value.destroy(value.m_type);
value.m_type = value_t::discarded;
parse_internal(keep, value);
if (JSON_UNLIKELY(errored))
{
return;
}
if (keep and not value.is_discarded())
{
result.m_value.array->push_back(std::move(value));
}
// comma -> next value
get_token();
if (last_token == token_type::value_separator)
{
get_token();
continue;
}
// closing ]
if (not expect(token_type::end_array))
{
return;
}
break;
}
if (keep and not callback(--depth, parse_event_t::array_end, result))
{
result.m_value.destroy(result.m_type);
result.m_type = value_t::discarded;
}
break;
}
case token_type::literal_null:
{
result.m_type = value_t::null;
break;
}
case token_type::value_string:
{
result.m_type = value_t::string;
result.m_value = m_lexer.get_string();
break;
}
case token_type::literal_true:
{
result.m_type = value_t::boolean;
result.m_value = true;
break;
}
case token_type::literal_false:
{
result.m_type = value_t::boolean;
result.m_value = false;
break;
}
case token_type::value_unsigned:
{
result.m_type = value_t::number_unsigned;
result.m_value = m_lexer.get_number_unsigned();
break;
}
case token_type::value_integer:
{
result.m_type = value_t::number_integer;
result.m_value = m_lexer.get_number_integer();
break;
}
case token_type::value_float:
{
result.m_type = value_t::number_float;
result.m_value = m_lexer.get_number_float();
// throw in case of infinity or NAN
if (JSON_UNLIKELY(not std::isfinite(result.m_value.number_float)))
{
if (allow_exceptions)
{
JSON_THROW(out_of_range::create(406, "number overflow parsing '" +
m_lexer.get_token_string() + "'"));
}
expect(token_type::uninitialized);
}
break;
}
case token_type::parse_error:
{
// using "uninitialized" to avoid "expected" message
if (not expect(token_type::uninitialized))
{
return;
}
break; // LCOV_EXCL_LINE
}
default:
{
// the last token was unexpected; we expected a value
if (not expect(token_type::literal_or_value))
{
return;
}
break; // LCOV_EXCL_LINE
}
}
if (keep and not callback(depth, parse_event_t::value, result))
{
result.m_value.destroy(result.m_type);
result.m_type = value_t::discarded;
}
}
bool sax_parse_internal(json_sax_t* sax)
{
// two values for the structured values
@@ -762,27 +469,6 @@ class parser
return (last_token = m_lexer.scan());
}
/*!
@throw parse_error.101 if expected token did not occur
*/
bool expect(token_type t)
{
if (JSON_UNLIKELY(t != last_token))
{
errored = true;
if (allow_exceptions)
{
JSON_THROW(parse_error::create(101, m_lexer.get_position(), exception_message(t)));
}
else
{
return false;
}
}
return true;
}
std::string exception_message(const token_type expected)
{
std::string error_msg = "syntax error - ";
@@ -805,16 +491,12 @@ class parser
}
private:
/// current level of recursion
int depth = 0;
/// callback function
const parser_callback_t callback = nullptr;
/// the type of the last read token
token_type last_token = token_type::uninitialized;
/// the lexer
lexer_t m_lexer;
/// whether a syntax error occurred
bool errored = false;
/// whether to throw exceptions in case of errors
const bool allow_exceptions = true;
};