/// <summary>
/// Consumes a new <see cref="MediaCondition"/> or <see cref="MediaFeature"/>
/// </summary>
/// <param name="Stream"></param>
/// <returns></returns>
static IMediaCondition Consume_Media_Condition(DataConsumer <CssToken> Stream)
{/* Docs: https://www.w3.org/TR/mediaqueries-4/#media-condition */
if (Stream is null)
{
throw new CssParserException(CssErrors.STREAM_IS_NULL);
}
Consume_All_Whitespace(Stream);
if (ParserCommon.Starts_Media_Feature(Stream.AsSpan()))
{
/* Consume opening parentheses */
Stream.Consume();
var feature = Consume_Media_Feature(Stream);
/* Consume closing parentheses */
if (Stream.Next.Type == ECssTokenType.Parenth_Close)
{
Stream.Consume();
}
return(feature);
}
else if (ParserCommon.Starts_Media_Condition(Stream.AsSpan()))
{
EMediaCombinator Combinator = EMediaCombinator.None;
var conditionList = new LinkedList <IMediaCondition>();
if (Stream.Next.Type == ECssTokenType.Parenth_Close)
{
/* Empty media condition block */
Stream.Consume();
return(new MediaCondition(EMediaCombinator.None, Array.Empty <MediaFeature>()));
}
else if (Stream.Next.Type == ECssTokenType.Parenth_Open)
{
Stream.Consume();
}
Consume_All_Whitespace(Stream);
/* Repeatedly consume sub-media-conditions until we hit a closing parentheses */
do
{
Consume_All_Whitespace(Stream);
if (Stream.Next.Type == ECssTokenType.Parenth_Close)
{
/* End of this media condition block */
break;
}
/* Anything other than the first condition *MUST* specify a combinator */
if (conditionList.Count > 0)
{
if (!ParserCommon.Is_Combinator(Stream.Next))
{
throw new CssSyntaxErrorException(CssErrors.EXPECTING_COMBINATOR, Stream);
}
}
/* Otherwise we just COULD have a combinator */
if (ParserCommon.Is_Combinator(Stream.Next))
{
/* Consume combinator */
IdentToken combinatorToken = Stream.Consume() as IdentToken;
if (!Lookup.TryEnum(combinatorToken.Value, out EMediaCombinator combLookup))
{
throw new CssSyntaxErrorException(String.Format(CultureInfo.InvariantCulture, CssErrors.INVALID_COMBINATOR, combinatorToken.Value), Stream);
}
else if (Combinator == EMediaCombinator.None)
{/* This is the first combinator specified */
Combinator = combLookup;
}
else if (Combinator != EMediaCombinator.None && combLookup != Combinator)
{/* Ensure this new combinator matches the combinator for this method group */
throw new CssSyntaxErrorException(CssErrors.INVALID_MULTIPLE_COMBINATORS_ON_MEDIARULE, Stream);
}
}
Consume_All_Whitespace(Stream);
if (Stream.Next.Type != ECssTokenType.Parenth_Open)
{
throw new CssSyntaxErrorException(CssErrors.EXPECTING_OPENING_PARENTHESES, Stream);
}
/* Oh look a yummy little sub-condition for us to gobble up! */
var feature = Consume_Media_Condition(Stream);
conditionList.AddLast(feature);
}while (Stream.Next.Type != ECssTokenType.EOF);
/* Consume closing parentheses */
if (Stream.Next.Type == ECssTokenType.Parenth_Close)
{
Stream.Consume();
}
return(new MediaCondition(Combinator, conditionList));
}
throw new CssSyntaxErrorException(CssErrors.EXPECTING_MEDIA_CONDITION_START, Stream);
}
static MediaQuery Consume_MediaQuery(DataConsumer <CssToken> Stream = null)
{/* Docs: https://drafts.csswg.org/mediaqueries-4/#mq-syntax */
if (Stream is null)
{
throw new CssParserException(CssErrors.STREAM_IS_NULL);
}
if (Stream.Next.Type != ECssTokenType.Ident)
{
throw new CssSyntaxErrorException(CssErrors.EXPECTING_IDENT, Stream);
}
EMediaQueryModifier modifier = 0x0;
EMediaType mediaType = 0x0;
LinkedList <IMediaCondition> conditionList = new LinkedList <IMediaCondition>();
/* First check for media modifier */
if (Stream.Next.Type != ECssTokenType.Ident)
{
throw new CssSyntaxErrorException(CssErrors.EXPECTING_IDENT, Stream);
}
if (Lookup.TryEnum((Stream.Next as IdentToken).Value, out EMediaQueryModifier mod))
{
Stream.Consume();// consume this token
modifier = mod;
}
/* Skip 'and' keyword if present */
if (ParserCommon.Is_Combinator(Stream.Next))
{
Stream.Consume();
}
/* Set the media type */
if (Stream.Next.Type != ECssTokenType.Ident)
{
throw new CssSyntaxErrorException(CssErrors.EXPECTING_IDENT, Stream);
}
if (!Lookup.TryEnum((Stream.Next as IdentToken).Value, out EMediaType type))
{
throw new CssParserException(String.Format(CultureInfo.InvariantCulture, CssErrors.INVALID_MEDIA_TYPE, (Stream.Next as IdentToken).Value), Stream);
}
else
{
Stream.Consume();
}
/* Skip thew first combinator keyword if present */
Consume_All_Whitespace(Stream);
if (ParserCommon.Is_Combinator(Stream.Next))
{
Stream.Consume();
}
/* Now consume media conditions until we cant anymore */
do
{
Consume_All_Whitespace(Stream);
if (Stream.Next.Type != ECssTokenType.Parenth_Open)
{/* This isn't invalid, it just signals that we have no more features to consume */
break;
}
var condition = Consume_Media_Condition(Stream);
conditionList.AddLast(condition);
}while (Stream.Next.Type != ECssTokenType.EOF);
return(new MediaQuery(modifier, mediaType, conditionList));
}