public final void scanTrue() {
        if (ch != 't') {
            throw new JSONException("error parse true");
        }
        next();

        if (ch != 'r') {
            throw new JSONException("error parse true");
        }
        next();

        if (ch != 'u') {
            throw new JSONException("error parse true");
        }
        next();

        if (ch != 'e') {
            throw new JSONException("error parse true");
        }
        next();

        if (ch == ' '  ||
            ch == ','  ||
            ch == '}'  ||
            ch == ']'  ||
            ch == '\n' ||
            ch == '\r' ||
            ch == '\t' ||
            ch == EOI  ||
            ch == '\f' ||
            ch == '\b' ||
            ch == ':'  ||
            ch == '/') {
            token = JSONToken.TRUE;
        } else {
            throw new JSONException("scan true error");
        }
    }
internal method, don't invoke
@param token
src/main/java/com/alibaba/fastjson/parser/JSONLexerBase.java