c++使用json教程

#include <iostream> //#include "json/value.h" #include "json/value.h" #include "json/writer.h" #include <utility> #include <stdexcept> #include <cstring> #include <cassert> #ifdef JSON_USE_CPPTL # include <cpptl/conststring.h> #endif #include <cstddef> // size_t #ifndef JSON_USE_SIMPLE_INTERNAL_ALLOCATOR # include "json_batchallocator.h" #endif // #ifndef JSON_USE_SIMPLE_INTERNAL_ALLOCATOR #define JSON_ASSERT_UNREACHABLE assert( false ) #define JSON_ASSERT( condition ) assert( condition ); // @todo <= change this into an exception throw #define JSON_ASSERT_MESSAGE( condition, message ) if (!( condition )) throw std::runtime_error( message ); namespace Json { const Value Value::null; const Int Value::minInt = Int( ~(UInt(-1)/2) ); const Int Value::maxInt = Int( UInt(-1)/2 ); const UInt Value::maxUInt = UInt(-1); // A "safe" implementation of strdup. Allow null pointer to be passed. // Also avoid warning on msvc80. // //inline char *safeStringDup( const char *czstring ) //{ // if ( czstring ) // { // const size_t length = (unsigned int)( strlen(czstring) + 1 ); // char *newString = static_cast<char *>( malloc( length ) ); // memcpy( newString, czstring, length ); // return newString; // } // return 0; //} // //inline char *safeStringDup( const std::string &str ) //{ // if ( !str.empty() ) // { // const size_t length = str.length(); // char *newString = static_cast<char *>( malloc( length + 1 ) ); // memcpy( newString, str.c_str(), length ); // newString[length] = 0; // return newString; // } // return 0; //} ValueAllocator::~ValueAllocator() { } class DefaultValueAllocator : public ValueAllocator { public: virtual ~DefaultValueAllocator() { } virtual char *makeMemberName( const char *memberName ) { return duplicateStringValue( memberName ); } virtual void releaseMemberName( char *memberName ) { releaseStringValue( memberName ); } virtual char *duplicateStringValue( const char *value, unsigned int length = unknown ) { //@todo invesgate this old optimization //if ( !value || value[0] == 0 ) // return 0; if ( length == unknown ) length = (unsigned int)strlen(value); char *newString = static_cast<char *>( malloc( length + 1 ) ); memcpy( newString, value, length ); newString[length] = 0; return newString; } virtual void releaseStringValue( char *value ) { if ( value ) free( value ); } }; static ValueAllocator *&valueAllocator() { static DefaultValueAllocator defaultAllocator; static ValueAllocator *valueAllocator = &defaultAllocator; return valueAllocator; } static struct DummyValueAllocatorInitializer { DummyValueAllocatorInitializer() { valueAllocator(); // ensure valueAllocator() statics are initialized before main(). } } dummyValueAllocatorInitializer; // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // ValueInternals... // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// #ifdef JSON_VALUE_USE_INTERNAL_MAP # include "json_internalarray.inl" # include "json_internalmap.inl" #endif // JSON_VALUE_USE_INTERNAL_MAP # include "json_valueiterator.inl" // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // class Value::CommentInfo // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// Value::CommentInfo::CommentInfo() : comment_( 0 ) { } Value::CommentInfo::~CommentInfo() { if ( comment_ ) valueAllocator()->releaseStringValue( comment_ ); } void Value::CommentInfo::setComment( const char *text ) { if ( comment_ ) valueAllocator()->releaseStringValue( comment_ ); JSON_ASSERT( text ); JSON_ASSERT_MESSAGE( text[0]=='\0' || text[0]=='/', "Comments must start with /"); // It seems that /**/ style comments are acceptable as well. comment_ = valueAllocator()->duplicateStringValue( text ); } // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // class Value::CZString // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// # ifndef JSON_VALUE_USE_INTERNAL_MAP // Notes: index_ indicates if the string was allocated when // a string is stored. Value::CZString::CZString( int index ) : cstr_( 0 ) , index_( index ) { } Value::CZString::CZString( const char *cstr, DuplicationPolicy allocate ) : cstr_( allocate == duplicate ? valueAllocator()->makeMemberName(cstr) : cstr ) , index_( allocate ) { } Value::CZString::CZString( const CZString &other ) : cstr_( other.index_ != noDuplication && other.cstr_ != 0 ? valueAllocator()->makeMemberName( other.cstr_ ) : other.cstr_ ) , index_( other.cstr_ ? (other.index_ == noDuplication ? noDuplication : duplicate) : other.index_ ) { } Value::CZString::~CZString() { if ( cstr_ && index_ == duplicate ) valueAllocator()->releaseMemberName( const_cast<char *>( cstr_ ) ); } void Value::CZString::swap( CZString &other ) { std::swap( cstr_, other.cstr_ ); std::swap( index_, other.index_ ); } Value::CZString & Value::CZString::operator =( const CZString &other ) { CZString temp( other ); swap( temp ); return *this; } bool Value::CZString::operator<( const CZString &other ) const { if ( cstr_ ) return strcmp( cstr_, other.cstr_ ) < 0; return index_ < other.index_; } bool Value::CZString::operator==( const CZString &other ) const { if ( cstr_ ) return strcmp( cstr_, other.cstr_ ) == 0; return index_ == other.index_; } int Value::CZString::index() const { return index_; } const char * Value::CZString::c_str() const { return cstr_; } bool Value::CZString::isStaticString() const { return index_ == noDuplication; } #endif // ifndef JSON_VALUE_USE_INTERNAL_MAP // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // class Value::Value // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// // ////////////////////////////////////////////////////////////////// /*! \internal Default constructor initialization must be equivalent to: * memset( this, 0, sizeof(Value) ) * This optimization is used in ValueInternalMap fast allocator. */ Value::Value( ValueType type ) : type_( type ) , allocated_( 0 ) , comments_( 0 ) # ifdef JSON_VALUE_USE_INTERNAL_MAP , itemIsUsed_( 0 ) #endif { switch ( type ) { case nullValue: break; case intValue: case uintValue: value_.int_ = 0; break; case realValue: value_.real_ = 0.0; break; case stringValue: value_.string_ = 0; break; #ifndef JSON_VALUE_USE_INTERNAL_MAP case arrayValue: case objectValue: value_.map_ = new ObjectValues(); break; #else case arrayValu