I have XML file:
<expressions>
<addition id="1">
<item>2</item>
<item>3</item>
<item>4</item>
</addition>
<subtraction id="2">
<minuend>3</minuend>
<subtrahend>2</subtrahend>
</subtraction>
<multiplication id="3">
<factor>5</factor>
<factor>6</factor>
<factor>8</factor>
</multiplication>
<division id="4">
<dividend>54</dividend>
<divisor>9</divisor>
</division>
</expressions>
Need to parse it and provide the result like another XML:
<expressions>
<result id="1">9</result>
<result id="2">1</result>
<result id="3">240</result>
<result id="4">6</result>
</expressions>
Currently I'm investigating the BOOST in area of ptree and read_xml Please advise where additional information could be found? Thanks in advance
My current investigation results are:
I have the class which defines Expression with virtual function which evaluates expression, lower on inheritance tree this function should be overridden and implemented in context of expression type.
class AbstractExpression
{
public:
AbstractExpression(ExpressionType aType){}
virtual ~AbstractExpression() {}
// Evaluates expression (must be overrided by child)
virtual int evalExpr() const = 0;
};
Inherited classes are additionExpression, substractionExpression, multiplicationExpression, divisionExpression.
Besides this I have implemented methods of data manipulation in every inherited class.
At the end I've wrote some code, which counts this XML:
using boost::property_tree::ptree;
ptree pt;
read_xml("/PATH_TO/valuator.xml", pt);
const ptree & expressions = pt.get_child("expressions");
BOOST_FOREACH(const ptree::value_type & currExpr, expressions){
std::string readExprType = currExpr.first;
std::cout << "currExpr = " << readExprType << std::endl;
if (readExprType == "addition") {
AbstractExpression *addExpr = new additionExpression();
BOOST_FOREACH(const ptree::value_type & additionNodeEl, currExpr.second){
std::string val = additionNodeEl.second.data();
((additionExpression*)addExpr)->addVal( atoi(val.c_str()) );
}
std::cout << "addition result = " << addExpr->evalExpr() << std::endl;
delete addExpr;
} else if (readExprType == "multiplication") {
AbstractExpression *multExpr = new multiplicationExpression();
BOOST_FOREACH(const ptree::value_type &multNodeEl, currExpr.second) {
std::string val = multNodeEl.second.data();
if (!val.empty())
((multiplicationExpression*)multExpr)->addVal( atoi(val.c_str()) );
}
std::cout << "multiplication node result = " << multExpr->evalExpr() << std::endl;
delete multExpr;
} else if (readExprType == "subtraction") {
AbstractExpression *substrExpr = new substractionExpression();
BOOST_FOREACH(const ptree::value_type &substNodeEl, currExpr.second) {
std::string elTypeName = substNodeEl.first;
std::string val = substNodeEl.second.data();
if (elTypeName == "minuend") {
((substractionExpression*)substrExpr)->setMinuend( atoi(val.c_str()) );
} else if (elTypeName == "subtrahend") {
((substractionExpression*)substrExpr)->setSubtrahend( atoi(val.c_str()) );
}
}
std::cout << "subtraction node result = " << substrExpr->evalExpr() << std::endl;
delete substrExpr;
} else if (readExprType == "division") {
AbstractExpression *divExpr = new divisionExpression();
BOOST_FOREACH(const ptree::value_type &divNodeEl, currExpr.second) {
std::string elTypeName = divNodeEl.first;
std::string val = divNodeEl.second.data();
if ( elTypeName == "dividend" ) {
((divisionExpression*)divExpr)->setDividend( atoi(val.c_str()) );
} else if ( elTypeName == "divisor" ) {
((divisionExpression*)divExpr)->setDivisor( atoi(val.c_str()) );
}
}
std::cout << "dividend node result = " << divExpr->evalExpr() << std::endl;
delete divExpr;
}
}
Now I need to write all these results to XML.
