public void PeekBeforeRead()
{
var enumerator = "1234".GetEnumerator();
PeekBuffer <char> buffer = new PeekBuffer <char>(enumerator);
Assert.IsTrue(buffer.TryPeek(out var item));
Assert.AreEqual('1', item);
Assert.IsTrue(buffer.TryPeek(1, out item));
Assert.AreEqual('2', item);
Assert.IsTrue(buffer.TryRead(out item));
Assert.AreEqual('1', item);
Assert.IsTrue(buffer.TryRead(out item));
Assert.AreEqual('2', item);
Assert.IsTrue(buffer.TryPeek(out item));
Assert.AreEqual('3', item);
Assert.IsTrue(buffer.TryPeek(1, out item));
Assert.AreEqual('4', item);
Assert.IsTrue(buffer.TryRead(out item));
Assert.AreEqual('3', item);
Assert.IsTrue(buffer.TryRead(out item));
Assert.AreEqual('4', item);
}
public void TryPeek_Sequential()
{
var enumerator = "123".GetEnumerator();
PeekBuffer <char> buffer = new PeekBuffer <char>(enumerator);
Assert.IsTrue(buffer.TryPeek(0, out var peeked));
Assert.AreEqual('1', peeked);
Assert.IsTrue(buffer.TryPeek(1, out peeked));
Assert.AreEqual('2', peeked);
Assert.IsTrue(buffer.TryPeek(2, out peeked));
Assert.AreEqual('3', peeked);
}
public void TryPeek_OutOfOrder()
{
var enumerator = "ABC".GetEnumerator();
PeekBuffer <char> buffer = new PeekBuffer <char>(enumerator);
Assert.IsTrue(buffer.TryPeek(0, out var peeked));
Assert.AreEqual('A', peeked);
Assert.IsTrue(buffer.TryPeek(2, out peeked));
Assert.AreEqual('C', peeked);
Assert.IsTrue(buffer.TryPeek(1, out peeked));
Assert.AreEqual('B', peeked);
}
public bool CheckToken(PeekBuffer <char> buffer)
{
return(buffer.TryPeek(out var first) &&
buffer.TryPeek(1, out var second) &&
first == second &&
first == '/');
}
public void TryPeek_NegativeIndex()
{
var enumerator = "1".GetEnumerator();
PeekBuffer <char> buffer = new PeekBuffer <char>(enumerator);
buffer.TryPeek(-1, out char _);
}
public ProductionInfo ReadProduction(PeekBuffer <TokenInfo> tokenStream)
{
StringBuilder data = new StringBuilder();
tokenStream.TryRead(out var nameToken);
tokenStream.TryRead(out _);
data.Append(nameToken.Data.ToString());
data.Append("(");
while (tokenStream.TryPeek(out var next))
{
if (next.Type == TokenType.RightParen)
{
tokenStream.TryRead(out _);
data.Append(")");
return(new ProductionInfo(data.ToString()));
}
// Read next token
if (!ExpressionReader.FirstToken(next))
{
return(null);
}
if (!ExpressionReader.IsProduction(tokenStream))
{
return(null);
}
var expression = ExpressionReader.ReadProduction(tokenStream);
if (expression == null)
{
return(null);
}
data.Append(expression.Data);
// The token after an expression should be comma or right-paren
if (!tokenStream.TryPeek(out next))
{
return(null);
}
if (next.Type == TokenType.RightParen)
{
continue;
}
if (next.Type == TokenType.Comma)
{
tokenStream.TryRead(out _);
}
}
return(null);
}
public bool IsProduction(PeekBuffer <TokenInfo> tokenStream, int index = 0)
{
return(tokenStream.TryPeek(index++, out var first) && first.Type == TokenType.Name &&
tokenStream.TryPeek(index, out var second) && second.Type == TokenType.LeftParen);
}
