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/*
* Modification History
*
* 2001-February-11 Jason Rohrer
* Created.
*
* 2001-March-7 Jason Rohrer
* Removed and extra if statement from the deserialization function.
*
* 2001-August-31 Jason Rohrer
* Added support for MultiConstantArgumentExpressions.
*
* 2001-September-4 Jason Rohrer
* Added support for FixedConstantExpressions.
*
* 2001-October-9 Jason Rohrer
* Fixed a bug in deserializing MultiConstantArgumentExpressions.
*/
#ifndef EXPRESSION_SERIALIZER_INCLUDED
#define EXPRESSION_SERIALIZER_INCLUDED
#include "Expression.h"
#include "UnaryOperationExpression.h"
#include "BinaryOperationExpression.h"
#include "ConstantExpression.h"
#include "InvertExpression.h"
#include "ProductExpression.h"
#include "PowerExpression.h"
#include "SumExpression.h"
#include "NegateExpression.h"
#include "SinExpression.h"
#include "FixedConstantExpression.h"
#include "MultiConstantArgumentExpression.h"
#include "minorGems/io/OutputStream.h"
#include "minorGems/io/InputStream.h"
#include "minorGems/io/TypeIO.h"
/**
* Utility class for serializing expressions
*
* @author Jason Rohrer
*/
class ExpressionSerializer {
public:
/**
* Serializes an expression onto a stream.
*
* @param inExpression the expression to serialize.
* @param inOutputStream the stream to write to.
*
* @return the number of bytes written.
*/
static long serializeExpression( Expression *inExpression,
OutputStream *inOutputStream );
/**
* Deserializes an expression from a stream.
*
* @param outExpression a pointer to where the expression
* pointer will be returned. A new expression is created,
* and it must be destroyed by the caller.
* @param inInputStream the stream to read from.
*
* @return the number of bytes read.
*/
static long deserializeExpression( Expression **outExpression,
InputStream *inInputStream );
};
// these can both be implemented recursively... exciting!
inline long ExpressionSerializer::serializeExpression(
Expression *inExpression, OutputStream *inOutputStream ) {
int numBytes = 0;
long expressionID = inExpression->getID();
// write the expression ID
numBytes += inOutputStream->writeLong( expressionID );
// first, deal with constant case
if( expressionID == ConstantExpression::staticGetID() ) {
// write the constant
ConstantExpression *c = (ConstantExpression *)inExpression;
numBytes += inOutputStream->writeDouble( c->getValue() );
}
else if( expressionID == FixedConstantExpression::staticGetID() ) {
// write the constant
FixedConstantExpression *c = (FixedConstantExpression *)inExpression;
numBytes += inOutputStream->writeDouble( c->getValue() );
}
// next deal with the multi-argument case
else if( expressionID == MultiConstantArgumentExpression::staticGetID() ) {
MultiConstantArgumentExpression *m =
(MultiConstantArgumentExpression*)inExpression;
Expression *wrappedExpression =
m->getWrappedExpression();
numBytes += serializeExpression(
wrappedExpression,
inOutputStream );
}
// finally, deal with the general case
else {
// write each of the expression's arguments in succession
for( int i=0; i<inExpression->getNumArguments(); i++ ) {
// call serialize recursively
numBytes += serializeExpression(
inExpression->getArgument( i ),
inOutputStream );
}
}
return numBytes;
}
inline long ExpressionSerializer::deserializeExpression(
Expression **outExpression, InputStream *inInputStream ) {
int numBytes = 0;
long expressionID;
// read the expression ID
numBytes += inInputStream->readLong( &expressionID );
// first, deal with constant case
if( expressionID == ConstantExpression::staticGetID() ) {
double constantValue;
numBytes += inInputStream->readDouble( &constantValue );
*outExpression = new ConstantExpression( constantValue );
}
else if( expressionID == FixedConstantExpression::staticGetID() ) {
double constantValue;
numBytes += inInputStream->readDouble( &constantValue );
*outExpression = new FixedConstantExpression( constantValue );
}
// next deal with the multi-argument case
else if( expressionID == MultiConstantArgumentExpression::staticGetID() ) {
// call deserialize recursively
Expression *wrappedExpression;
numBytes += deserializeExpression(
&wrappedExpression,
inInputStream );
MultiConstantArgumentExpression *m =
new MultiConstantArgumentExpression( wrappedExpression );
*outExpression = (Expression *)m;
}
// finally, deal with the general case
else {
// switch based on expression type
// note that we can't use switch/case here because
// staticGetID doesn't return a constant
if( expressionID == InvertExpression::staticGetID() ) {
*outExpression = new InvertExpression( NULL );
}
else if( expressionID == NegateExpression::staticGetID() ) {
*outExpression = new NegateExpression( NULL );
}
else if( expressionID == PowerExpression::staticGetID() ) {
*outExpression = new PowerExpression( NULL, NULL );
}
else if( expressionID == ProductExpression::staticGetID() ) {
*outExpression = new ProductExpression( NULL, NULL );
}
else if( expressionID == SinExpression::staticGetID() ) {
*outExpression = new SinExpression( NULL );
}
else if( expressionID == SumExpression::staticGetID() ) {
*outExpression = new SumExpression( NULL, NULL );
}
else {
printf( "Unknown expression type %d read from stream\n",
expressionID );
// default to a constant expression of 0
*outExpression = new ConstantExpression( 0 );
}
// now deserialize the arguments
// read each of the expression's arguments in succession
for( int i=0; i<(*outExpression)->getNumArguments(); i++ ) {
// call deserialize recursively
Expression *argument;
numBytes += deserializeExpression(
&argument,
inInputStream );
// set the argument into our expression
(*outExpression)->setArgument( i, argument );
}
} // end non-constant case
return numBytes;
}
#endif
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