package chroma

// Coalesce is a Lexer interceptor that collapses runs of common types into a single token.
func Coalesce(lexer Lexer) Lexer {
	return &coalescer{lexer}
}

type coalescer struct {
	Lexer
}

func (d *coalescer) Tokenise(options *TokeniseOptions, text string, out func(*Token)) error {
	var last *Token
	defer func() { out(last) }()
	return d.Lexer.Tokenise(options, text, func(token *Token) {
		if last == nil {
			last = token
		} else {
			if last.Type == token.Type && len(last.Value) < 8192 {
				last.Value += token.Value
			} else {
				out(last)
				last = token
			}
		}
	})
}