/// <summary>Extract a token from the front of a lexical input queue.</summary>
/// <param name="input">The input from which to extract a token. The extracted lexical bits will be removed from the queue.</param>
/// <param name="impliedBraces">Whether we're parsing a token context (so the outer '{{' and '}}' are implied); else parse as a tokenizable string which main contain a mix of literal and {{token}} values.</param>
/// <returns>Returns the token.</returns>
public LexTokenToken ExtractToken(Queue <LexBit> input, bool impliedBraces)
{
LexBit GetNextAndAssert(string expectedPhrase)
{
if (!input.Any())
{
throw new LexFormatException($"Reached end of input, expected {expectedPhrase}.");
}
return(input.Dequeue());
}
// start token
if (!impliedBraces)
{
LexBit startToken = GetNextAndAssert("start of token ('{{')");
if (startToken.Type != LexBitType.StartToken)
{
throw new LexFormatException($"Unexpected {startToken.Type} at start of token.");
}
}
// extract token name
LexBit name = GetNextAndAssert("token name");
if (name.Type != LexBitType.Literal)
{
throw new LexFormatException($"Unexpected {name.Type} where token name should be.");
}
// extract input argument if present
LexTokenInputArg inputArg = null;
if (input.Any() && input.Peek().Type == LexBitType.InputArgSeparator)
{
input.Dequeue();
inputArg = this.ExtractInputArgument(input);
}
// end token
if (!impliedBraces)
{
LexBit endToken = GetNextAndAssert("end of token ('}}')");
if (endToken.Type != LexBitType.EndToken)
{
throw new LexFormatException($"Unexpected {endToken.Type} before end of token.");
}
}
return(new LexTokenToken(name.Text.Trim(), inputArg, impliedBraces));
}
/// <summary>Construct an instance.</summary>
/// <param name="raw">The raw token input argument.</param>
/// <param name="context">The available token context.</param>
public TokenString(LexTokenInputArg raw, IContext context)
: this(lexTokens : raw?.Parts, context : context)
{
}
