import org.jetbrains.kotlin.lexer.KtTokens.SAFE_ACCESS
import org.jetbrains.kotlin.lexer.KtTokens.SEMICOLON


internal
val kotlinGrammar: KotlinGrammar by lazy(LazyThreadSafetyMode.PUBLICATION) {
    KotlinGrammar()
}


@Suppress("MemberVisibilityCanBePrivate")
internal
class KotlinGrammar : Combinator(true, true) {

    // basic building blocks
    val annotationMarker = token(AT) * notWhiteSpace()

    fun `will not parse empty annotation`() {
        kotlinGrammar.annotation.failToConsumeFrom("""@""")
        kotlinGrammar.annotation.failToConsumeFrom("""@ \n """)
    }

    @Test
    fun `will not parse @ followed by whitespace`() {
        kotlinGrammar.annotation.failToConsumeFrom("@ something")
        kotlinGrammar.annotation.failToConsumeFrom("@\nsomething")
        kotlinGrammar.annotation.failToConsumeFrom("@/*comment*/something")

    }

    fun KotlinLexer.parseAnnotation(): IntRange? {
        val startIndex = currentPosition

        if (let(kotlinGrammar.fileAnnotation) is ParserResult.Success<*>) {
            return null; // ignoring file annotation
        }

        restore(startIndex)
        if (let(kotlinGrammar.annotation) is ParserResult.Success<*>) {
            return startIndex.offset until currentPosition.offset
        }