C++ BTreeNode::type方法代码示例

QString Expression::processConstant( const QString & expr, bool * isConstant )
{
	bool temp;
	if (!isConstant)
		isConstant = &temp;
	
	QString code;
	
	// Make a tree to put the expression in.
	BTreeBase *tree = new BTreeBase();
	BTreeNode *root = new BTreeNode();

	// parse the expression into the tree
	buildTree(expr,tree,root,0);
	// compile the tree into assembly code
	tree->setRoot(root);
	tree->pruneTree(tree->root());
	//code = traverseTree(tree->root());
	// Look to see if it is a number
	if( root->type() == number )
	{
		code = root->value();
		*isConstant = true;
	}
	else
	{
		code = "";
		*isConstant = false;
	}
	
	// Note deleting the tree deletes all nodes, so the root
	// doesn't need deleting separately.
	delete tree;
	return code;
}

void BTreeBase::pruneTree(BTreeNode *root, bool /*conditionalRoot*/)
{
	Traverser t(root);
	
	t.descendLeftwardToTerminal();
	bool done = false;
	while(!done)
	{
	//t.descendLeftwardToTerminal();
	if( t.current()->parent() )
	{
		if( t.oppositeNode()->hasChildren() ) pruneTree(t.oppositeNode());
	}
	
	t.moveToParent();
	if( !t.current()->hasChildren() )
	{
		//if(t.current() == t.root()) done = true;
		if(!t.current()->parent()) done = true;
		continue;
	}

	BTreeNode *l = t.current()->left();
	BTreeNode *r = t.current()->right();
	BTreeNode *n = 0;
	BTreeNode *z = 0;
	

	// Deal with situations where there are two constants so we want
	// to evaluate at compile time
	if( (l->type() == number && r->type() == number) ) // && !(t.current()==root&&conditionalRoot) )
	{
		if(t.current()->childOp() == Expression::division && r->value() == "0" ) 
		{
			t.current()->setChildOp(Expression::divbyzero);
			return;
		}
		QString value = QString::number(Parser::doArithmetic(l->value().toInt(),r->value().toInt(),t.current()->childOp()));
		t.current()->deleteChildren();
		t.current()->setChildOp(Expression::noop);
		t.current()->setType(number);
		t.current()->setValue(value);
	}
	
	// Addition and subtraction
	else if(t.current()->childOp() == Expression::addition || t.current()->childOp() == Expression::subtraction)
	{
	// See if one of the nodes is 0, and set n to the node that actually has data,
	// z to the one containing zero.
	bool zero = false;
	if( l->value() == "0" )
	{
		zero = true;
		n = r;
		z = l;
	}
	else if( r->value() == "0" )
	{
		zero = true;
		n = l;
		z = r;
	}
	// Now get rid of the useless nodes
	if(zero)
	{
		BTreeNode *p = t.current(); // save in order to delete after

		replaceNode(p,n);
		t.setCurrent(n);
		// Delete the old nodes
		delete p;
		delete z;
	}
	}
	
	// Multiplication and division
	else if(t.current()->childOp() == Expression::multiplication || t.current()->childOp() == Expression::division)
	{
	// See if one of the nodes is 0, and set n to the node that actually has data,
	// z to the one containing zero.
	bool zero = false;
	bool one = false;
	if( l->value() == "1" )
	{
		one = true;
		n = r;
		z = l;
	}
	else if( r->value() == "1" )
	{
		one = true;
		n = l;
		z = r;
	}
	if( l->value() == "0" )
	{
		zero = true;
		n = r;
		z = l;
	}
//.........这里部分代码省略.........