public Expr Parse(TokenStream stream)
{
// If this is a binary operation, find it's precedence.
while (true)
{
var firstPrecedence = Precedence.Get(stream.Get());
/*
* If this is a binary operation that binds at least as tightly
* as the current binary operation, consume it. Otherwise, the process
* is complete.
*/
if (firstPrecedence < minimalPrecedence)
{
return(leftSide);
}
// At this point, it's a binary operation.
TokenType binaryOperator = stream.Get().Type;
// TODO: Should check if it's a BINARY operator, not just an operator.
// Ensure the captured operator is validated.
if (!TokenIdentifier.IsOperator(binaryOperator))
{
throw new Exception(
$"Expected token to be a binary operator but got token type '{binaryOperator}'");
}
// Skip operator.
stream.Skip();
// Parse the right-side.
Expr rightSide = new PrimaryExprParser().Parse(stream);
// Ensure that the right-side was successfully parsed.
if (rightSide == null)
{
throw new Exception("Unable to parse the right-side of the binary expression");
}
// Determine the token precedence of the current token.
var secondPrecedence = Precedence.Get(stream.Get());
/*
* If binary operator binds less tightly with the right-side than
* the operator after right-side, let the pending operator take the
* right-side as its left-side.
*/
if (firstPrecedence < secondPrecedence)
{
// Invoke the right-side parser.
rightSide = new BinaryOpRightSideParser(rightSide, firstPrecedence + 1).Parse(stream);
// Ensure the right-side was successfully parsed.
if (rightSide == null)
{
throw new Exception("Unable to parse the right-side of the binary expression");
}
}
// Create the binary expression entity.
var binaryExpr = new BinaryExpr(leftSide, rightSide, firstPrecedence);
// Merge left-side/right-side.
leftSide = binaryExpr;
}
}
public Expr Parse(ParserContext context)
{
// If this is a binary operation, find it's precedence.
while (true)
{
// Capture the current token.
Token token = context.Stream.Current;
// Calculate precedence for the current token.
int firstPrecedence = Precedence.Get(token);
/*
* If this is a binary operation that binds at least as tightly
* as the current binary operation, consume it. Otherwise, the process
* is complete.
*/
if (firstPrecedence < this.minimalPrecedence)
{
// TODO: This should throw error? Research.
return(this.leftSide);
}
// At this point, it's a binary operation.
TokenType binaryOperator = token.Type;
// TODO: Should check if it's a BINARY operator, not just an operator.
// Ensure the captured operator is validated.
if (!TokenIdentifier.IsOperator(binaryOperator))
{
throw context.NoticeRepository.CreateException($"Expected token to be a binary operator but got token type '{binaryOperator}'");
}
// Skip operator.
context.Stream.Skip();
// Parse the right-side.
Expr rightSide = new PrimaryExprParser().Parse(context);
// Ensure that the right-side was successfully parsed.
if (rightSide == null)
{
throw new Exception("Unable to parse the right-side of the binary expression");
}
// Determine the token precedence of the current token.
int secondPrecedence = Precedence.Get(token);
/*
* If binary operator binds less tightly with the right-side than
* the operator after right-side, let the pending operator take the
* right-side as its left-side.
*/
if (firstPrecedence < secondPrecedence)
{
// Invoke the right-side parser.
rightSide = new BinaryOpRightSideParser(rightSide, firstPrecedence + 1).Parse(context);
// Ensure the right-side was successfully parsed.
if (rightSide == null)
{
throw new Exception("Unable to parse the right-side of the binary expression");
}
}
// Create the binary expression entity.
BinaryExpr binaryExpr = new BinaryExpr(binaryOperator, this.leftSide, rightSide, firstPrecedence);
// TODO: Name is temporary?
// Set the name of the binary expression's output.
binaryExpr.SetName("tmp");
// Merge left-side/right-side.
this.leftSide = binaryExpr;
}
}
/// <summary>
/// Retrieve the precedence of the current
/// token.
/// </summary>
public int GetCurrentPrecedence()
{
return(Precedence.Get(this.Stream.Get().Type));
}
