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When formatting doubles as strings, use 17 digits of precision to ensure they are read back in without loss (up from 12 digits).

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Add a mode to the JSON parser to parse all real numbers into strings, so we can later parse them into doubles or another fixed/floating point format to preserve as much precision as needed
This commit is contained in:
Eric Frias 2015-03-31 09:47:54 -04:00
parent 09e645448d
commit 174e065bd5
4 changed files with 44 additions and 33 deletions
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3
include/fc/io/json.hpp
View file

@ -19,7 +19,8 @@ namespace fc
{
legacy_parser = 0,
strict_parser = 1,
relaxed_parser = 2
relaxed_parser = 2,
legacy_parser_with_string_doubles = 3
};
static ostream& to_stream( ostream& out, const fc::string& );

18
include/fc/io/json_relaxed.hpp
View file

@ -577,7 +577,7 @@ namespace fc { namespace json_relaxed
continue;
}
if( skip_white_space(in) ) continue;
string key = stringFromStream<T, strict>( in );
string key = json_relaxed::stringFromStream<T, strict>( in );
skip_white_space(in);
if( in.peek() != ':' )
{
@ -585,7 +585,7 @@ namespace fc { namespace json_relaxed
("key", key) );
}
in.get();
auto val = variant_from_stream<T, strict>( in );
auto val = json_relaxed::variant_from_stream<T, strict>( in );
obj(std::move(key),std::move(val));
skip_white_space(in);
@ -626,7 +626,7 @@ namespace fc { namespace json_relaxed
continue;
}
if( skip_white_space(in) ) continue;
ar.push_back( variant_from_stream<T, strict>(in) );
ar.push_back( json_relaxed::variant_from_stream<T, strict>(in) );
skip_white_space(in);
}
if( in.peek() != ']' )
@ -643,7 +643,7 @@ namespace fc { namespace json_relaxed
variant numberFromStream( T& in )
{
fc::string token = tokenFromStream(in);
variant result = parseNumberOrStr<strict>( token );
variant result = json_relaxed::parseNumberOrStr<strict>( token );
if( strict && !(result.is_int64() || result.is_uint64() || result.is_double()) )
FC_THROW_EXCEPTION( parse_error_exception, "expected: number" );
return result;
@ -696,11 +696,11 @@ namespace fc { namespace json_relaxed
in.get();
continue;
case '"':
return stringFromStream<T, strict>( in );
return json_relaxed::stringFromStream<T, strict>( in );
case '{':
return objectFromStream<T, strict>( in );
return json_relaxed::objectFromStream<T, strict>( in );
case '[':
return arrayFromStream<T, strict>( in );
return json_relaxed::arrayFromStream<T, strict>( in );
case '-':
case '+':
case '.':
@ -714,7 +714,7 @@ namespace fc { namespace json_relaxed
case '7':
case '8':
case '9':
return numberFromStream<T, strict>( in );
return json_relaxed::numberFromStream<T, strict>( in );
// null, true, false, or 'warning' / string
case 'a': case 'b': case 'c': case 'd': case 'e': case 'f': case 'g': case 'h':
case 'i': case 'j': case 'k': case 'l': case 'm': case 'n': case 'o': case 'p':
@ -725,7 +725,7 @@ namespace fc { namespace json_relaxed
case 'Q': case 'R': case 'S': case 'T': case 'U': case 'V': case 'W': case 'X':
case 'Y': case 'Z':
case '_': case '/':
return wordFromStream<T, strict>( in );
return json_relaxed::wordFromStream<T, strict>( in );
case 0x04: // ^D end of transmission
case EOF:
FC_THROW_EXCEPTION( eof_exception, "unexpected end of file" );

46
src/io/json.cpp
View file

@ -15,16 +15,15 @@
namespace fc
{
// forward declarations of provided functions
template<typename T> variant variant_from_stream( T& in );
template<typename T, json::parse_type parser_type> variant variant_from_stream( T& in );
template<typename T> char parseEscape( T& in );
template<typename T> fc::string stringFromStream( T& in );
template<typename T> bool skip_white_space( T& in );
template<typename T> fc::string stringFromToken( T& in );
template<typename T> variant_object objectFromStream( T& in );
template<typename T> variants arrayFromStream( T& in );
template<typename T> variant number_from_stream( T& in );
template<typename T, json::parse_type parser_type> variant_object objectFromStream( T& in );
template<typename T, json::parse_type parser_type> variants arrayFromStream( T& in );
template<typename T, json::parse_type parser_type> variant number_from_stream( T& in );
template<typename T> variant token_from_stream( T& in );
template<typename T> variant variant_from_stream( T& in );
void escape_string( const string& str, ostream& os );
template<typename T> void to_stream( T& os, const variants& a );
template<typename T> void to_stream( T& os, const variant_object& o );
@ -168,7 +167,7 @@ namespace fc
("token", token.str() ) );
}
template<typename T>
template<typename T, json::parse_type parser_type>
variant_object objectFromStream( T& in )
{
mutable_variant_object obj;
@ -197,7 +196,7 @@ namespace fc
("key", key) );
}
in.get();
auto val = variant_from_stream( in );
auto val = variant_from_stream<T, parser_type>( in );
obj(std::move(key),std::move(val));
skip_white_space(in);
@ -219,7 +218,7 @@ namespace fc
} FC_RETHROW_EXCEPTIONS( warn, "Error parsing object" );
}
template<typename T>
template<typename T, json::parse_type parser_type>
variants arrayFromStream( T& in )
{
variants ar;
@ -238,7 +237,7 @@ namespace fc
continue;
}
if( skip_white_space(in) ) continue;
ar.push_back( variant_from_stream(in) );
ar.push_back( variant_from_stream<T, parser_type>(in) );
skip_white_space(in);
}
if( in.peek() != ']' )
@ -251,7 +250,7 @@ namespace fc
return ar;
}
template<typename T>
template<typename T, json::parse_type parser_type>
variant number_from_stream( T& in )
{
fc::stringstream ss;
@ -309,7 +308,7 @@ namespace fc
if (str == "-." || str == ".") // check the obviously wrong things we could have encountered
FC_THROW_EXCEPTION(parse_error_exception, "Can't parse token \"${token}\" as a JSON numeric constant", ("token", str));
if( dot )
return to_double(str);
return parser_type == json::legacy_parser_with_string_doubles ? variant(str) : variant(to_double(str));
if( neg )
return to_int64(str);
return to_uint64(str);
@ -386,7 +385,7 @@ namespace fc
}
template<typename T>
template<typename T, json::parse_type parser_type>
variant variant_from_stream( T& in )
{
skip_white_space(in);
@ -404,9 +403,9 @@ namespace fc
case '"':
return stringFromStream( in );
case '{':
return objectFromStream( in );
return objectFromStream<T, parser_type>( in );
case '[':
return arrayFromStream( in );
return arrayFromStream<T, parser_type>( in );
case '-':
case '.':
case '0':
@ -419,7 +418,7 @@ namespace fc
case '7':
case '8':
case '9':
return number_from_stream( in );
return number_from_stream<T, parser_type>( in );
// null, true, false, or 'warning' / string
case 'n':
case 't':
@ -443,7 +442,9 @@ namespace fc
switch( ptype )
{
case legacy_parser:
return variant_from_stream( in );
return variant_from_stream<fc::stringstream, legacy_parser>( in );
case legacy_parser_with_string_doubles:
return variant_from_stream<fc::stringstream, legacy_parser_with_string_doubles>( in );
case strict_parser:
return json_relaxed::variant_from_stream<fc::stringstream, true>( in );
case relaxed_parser:
@ -709,7 +710,9 @@ namespace fc
switch( ptype )
{
case legacy_parser:
return variant_from_stream( bi );
return variant_from_stream<boost::filesystem::ifstream, legacy_parser>( bi );
case legacy_parser_with_string_doubles:
return variant_from_stream<boost::filesystem::ifstream, legacy_parser_with_string_doubles>( bi );
case strict_parser:
return json_relaxed::variant_from_stream<boost::filesystem::ifstream, true>( bi );
case relaxed_parser:
@ -723,7 +726,9 @@ namespace fc
switch( ptype )
{
case legacy_parser:
return variant_from_stream( in );
return variant_from_stream<fc::buffered_istream, legacy_parser>( in );
case legacy_parser_with_string_doubles:
return variant_from_stream<fc::buffered_istream, legacy_parser_with_string_doubles>( in );
case strict_parser:
return json_relaxed::variant_from_stream<buffered_istream, true>( in );
case relaxed_parser:
@ -756,7 +761,10 @@ namespace fc
switch( ptype )
{
case legacy_parser:
variant_from_stream( in );
variant_from_stream<fc::stringstream, legacy_parser>( in );
break;
case legacy_parser_with_string_doubles:
variant_from_stream<fc::stringstream, legacy_parser_with_string_doubles>( in );
break;
case strict_parser:
json_relaxed::variant_from_stream<fc::stringstream, true>( in );

10
src/string.cpp
View file

@ -9,6 +9,7 @@
#include <sstream>
#include <iomanip>
#include <locale>
#include <limits>
/**
* Implemented with std::string for now.
@ -127,11 +128,12 @@ namespace fc {
FC_RETHROW_EXCEPTIONS( warn, "${i} => double", ("i",i) )
}
fc::string to_string( double d)
fc::string to_string(double d)
{
std::stringstream ss;
ss << std::setprecision(12) << std::fixed << d;
return ss.str(); //boost::lexical_cast<std::string>(d);
// +2 is required to ensure that the double is rounded correctly when read back in. http://docs.oracle.com/cd/E19957-01/806-3568/ncg_goldberg.html
std::stringstream ss;
ss << std::setprecision(std::numeric_limits<double>::digits10 + 2) << std::fixed << d;
return ss.str();
}
fc::string to_string( uint64_t d)