/// <summary>
/// Parses a token stream creating the largest statement possible
/// </summary>
/// <param name="stream">Stream of tokens to parse</param>
/// <returns>Statement</returns>
private StatementList ParseStatement(Stream stream)
{
var previousToken = stream.Peek();
if (previousToken == null)
{
Errors.Add(new EndOfStreamException());
return(new StatementList());
}
var tokenType = previousToken.Type;
Token identifier = null;
switch (tokenType)
{
case TokenType.Identifier:
//standard identifier
identifier = stream.Next();
break;
case TokenType.OpenBracket:
case TokenType.OpenParenthesis:
//ignore these
break;
case TokenType.StringLiteral:
case TokenType.StringLiteralPipe:
case TokenType.QuotedStringLiteral:
//string statement
identifier = stream.Next();
break;
case TokenType.At:
stream.GetNextNoReturn();
identifier = stream.Next();
break;
case TokenType.Equal:
stream.GetNextNoReturn();
identifier = stream.Next();
break;
default:
Errors.Add(new UnexpectedToken(previousToken));
return(new StatementList());
//throw new ParserException(stream.Peek());
}
Statement statement;
StatementTail tail = null;
while (stream.Peek() != null)
{
var token = stream.Peek();
if (token == null)
{
break;
}
switch (token.Type)
{
case TokenType.OpenParenthesis:
case TokenType.OpenBracket:
case TokenType.OpenBrace:
tail = ParseStatementTail(stream);
break;
case TokenType.GreaterThan:
//consume greater than
stream.NextNoReturn();
//might be a single child or a statement list of siblings
tail = ParseSingleStatementTail(stream, tail);
break;
case TokenType.StringLiteralPipe:
if (previousToken is StringLiteralPipeToken)
{
//if the previous token was a string literal pipe then we don't continue processing
goto default;
}
//this overrides all previous tail elements
tail = ParseSingleStatementTail(stream, tail);
break;
default:
GetStatementFromToken(identifier, tail);
goto checkForSiblings;
}
}
checkForSiblings:
statement = GetStatementFromToken(identifier, tail, previousToken);
var list = new StatementList();
list.Add(statement);
while (stream.Peek() != null)
{
//Parrot.Debugger.Debug.WriteLine("Looking for siblings");
if (stream.Peek().Type == TokenType.Plus)
{
//it's now a statementlist not a statement
stream.NextNoReturn();
var siblings = ParseStatement(stream);
foreach (var sibling in siblings)
{
list.Add(sibling);
}
}
else
{
break;
}
}
return(list);
}
/// <summary>
/// Parses a token stream creating the largest statement possible
/// </summary>
/// <param name="stream">Stream of tokens to parse</param>
/// <returns>Statement</returns>
private StatementList ParseStatement(Stream stream)
{
var previousToken = stream.Peek();
if (previousToken == null)
{
Errors.Add(new EndOfStreamException());
return new StatementList();
}
var tokenType = previousToken.Type;
Token identifier = null;
switch (tokenType)
{
case TokenType.Identifier:
//standard identifier
identifier = stream.Next();
break;
case TokenType.OpenBracket:
case TokenType.OpenParenthesis:
//ignore these
break;
case TokenType.StringLiteral:
case TokenType.StringLiteralPipe:
case TokenType.QuotedStringLiteral:
//string statement
identifier = stream.Next();
break;
case TokenType.At:
stream.GetNextNoReturn();
identifier = stream.Next();
break;
case TokenType.Equal:
stream.GetNextNoReturn();
identifier = stream.Next();
break;
default:
Errors.Add(new UnexpectedToken(previousToken));
return new StatementList();
//throw new ParserException(stream.Peek());
}
Statement statement;
StatementTail tail = null;
while (stream.Peek() != null)
{
var token = stream.Peek();
if (token == null)
{
break;
}
switch (token.Type)
{
case TokenType.OpenParenthesis:
case TokenType.OpenBracket:
case TokenType.OpenBrace:
tail = ParseStatementTail(stream);
break;
case TokenType.GreaterThan:
//consume greater than
stream.NextNoReturn();
//might be a single child or a statement list of siblings
tail = ParseSingleStatementTail(stream, tail);
break;
case TokenType.StringLiteralPipe:
if (previousToken is StringLiteralPipeToken)
{
//if the previous token was a string literal pipe then we don't continue processing
goto default;
}
//this overrides all previous tail elements
tail = ParseSingleStatementTail(stream, tail);
break;
default:
GetStatementFromToken(identifier, tail);
goto checkForSiblings;
}
}
checkForSiblings:
statement = GetStatementFromToken(identifier, tail, previousToken);
var list = new StatementList();
list.Add(statement);
while (stream.Peek() != null)
{
//Parrot.Debugger.Debug.WriteLine("Looking for siblings");
if (stream.Peek().Type == TokenType.Plus)
{
//it's now a statementlist not a statement
stream.NextNoReturn();
var siblings = ParseStatement(stream);
foreach (var sibling in siblings)
{
list.Add(sibling);
}
}
else
{
break;
}
}
return list;
}
