/*
* intExpr = [ MINUS_SYMBOL ] term { addOp term }.
*/
SyntaxTreeNode IsIntExpr()
{
bool minusFlag;
SyntaxTreeNode leftTermNode = null;
SyntaxTreeNode rightTreeNode = null;
FilePosition position = GetInputFilePosition();
Symbol currentSymbol = this._scanner.PeekSymbol();
if (currentSymbol == Symbol.MINUS_SYMBOL)
{
this._scanner.NextSymbol();
minusFlag = true;
}
else
{
minusFlag = false;
}
if (null == (leftTermNode = IsIntTerm()))
{
if (!minusFlag)
return null;
else
{
return CreateErrorNode("intTerm expected after \'-\'");
}
}
if (minusFlag)
{
leftTermNode = new SyntaxTreeMonadicOpNode(position, Symbol.MINUS_SYMBOL, leftTermNode);
}
currentSymbol = this._scanner.PeekSymbol();
while (currentSymbol == Symbol.MINUS_SYMBOL || currentSymbol == Symbol.PLUS_SYMBOL)
{
position = GetInputFilePosition();
this._scanner.NextSymbol();
if (null == (rightTreeNode = IsIntTerm()))
{
return CreateErrorNode("intTerm expected after \'addOp\'");
}
else
{
leftTermNode = new SyntaxTreeDyadicOpNode(position, currentSymbol, leftTermNode, rightTreeNode);
currentSymbol = this._scanner.PeekSymbol();
}
}
return leftTermNode;
}
/*
* intTerm = isIntTerm { multOp intFactor }.
*/
SyntaxTreeNode IsIntTerm()
{
SyntaxTreeNode leftFactorNode = null;
SyntaxTreeNode rightFactorNode = null;
if (null == (leftFactorNode = IsIntFactor()))
return null;
Symbol currentSymbol = this._scanner.PeekSymbol();
while (currentSymbol == Symbol.TIMES_SYMBOL ||
currentSymbol == Symbol.DIVIDE_SYMBOL ||
currentSymbol == Symbol.MODULO_SYMBOL)
{
FilePosition position = GetInputFilePosition();
this._scanner.NextSymbol();
if (null == (rightFactorNode = IsIntFactor()))
{
return CreateErrorNode("intFactor expected after \'multOp\'");
}
else
{
leftFactorNode = new SyntaxTreeDyadicOpNode(position, currentSymbol, leftFactorNode, rightFactorNode);
currentSymbol = this._scanner.PeekSymbol();
}
}
return leftFactorNode;
}
/*
* boolExpr = intExpr relationOp intExpr { boolOp intExpr relationOp intExpr }.
*/
SyntaxTreeNode IsBoolExpr()
{
SyntaxTreeNode leftIntExprNode = null;
SyntaxTreeNode rightIntExprNode = null;
SyntaxTreeNode newBoolExprNode1 = null;
if (null == (leftIntExprNode = IsIntExpr()))
{
return null;
}
Symbol currentSymbol = this._scanner.PeekSymbol();
FilePosition position = GetInputFilePosition();
if (!IsRelationOpSymbol(currentSymbol))
{
return CreateErrorNode("\'relationOp\' expected after \'intExpr\'");
}
this._scanner.NextSymbol();
if (null == (rightIntExprNode = IsIntExpr()))
{
return CreateErrorNode("\'intExpr\' expected after \'relationOp\'");
}
newBoolExprNode1 = new SyntaxTreeDyadicOpNode(position, currentSymbol, leftIntExprNode, rightIntExprNode);
Symbol currentSymbolForBoolOp = this._scanner.PeekSymbol();
while (currentSymbolForBoolOp == Symbol.AND_SYMBOL || currentSymbolForBoolOp == Symbol.OR_SYMBOL)
{
position = GetInputFilePosition();
this._scanner.NextSymbol();
if (null == (leftIntExprNode = IsIntExpr()))
{
return CreateErrorNode("\'intExpr\' expected after \'boolOp\'");
}
currentSymbol = this._scanner.PeekSymbol();
if (!IsRelationOpSymbol(currentSymbol))
{
return CreateErrorNode("\'relationOp\' expected after \'intExpr\'");
}
this._scanner.NextSymbol();
if (null == (rightIntExprNode = IsIntExpr()))
{
return CreateErrorNode("\'intExpr\' expected after \'relationOp\'");
}
SyntaxTreeNode newBoolExprNode2 = new SyntaxTreeDyadicOpNode(position, currentSymbol, leftIntExprNode, rightIntExprNode);
newBoolExprNode1 = new SyntaxTreeDyadicOpNode(position, currentSymbolForBoolOp, newBoolExprNode1, newBoolExprNode2);
currentSymbolForBoolOp = this._scanner.PeekSymbol();
}
return newBoolExprNode1;
}