count_as_transcoded

ztd::text::count_as_transcoded is a function that takes an input sequence of code_units and attempts to count them, according to the error handler that is given. Because the error handler is included as part of the function call (and is provided by default is one is not passed in), the count operation will also continue to count if the error handler sets the error_code member of the result to ztd::text::encoding_error::ok but still performs some action. This is, for example, the case with ztd::text::replacement_handler_t - output replacement code units or code points will be counted as part of the final count and returned with result.error_code == ztd::text::encoding_error::ok. You can differentiate error-less text from non-error text by checking result.errors_were_handled(), which will be true if the error handler is called regardless of whether or not the error handler “smooths” the problem over by inserting replacement characters, doing nothing, or otherwise.

The overloads of this function increase the level of control you have with each passed argument. At the last overload with four arguments, the function attempts to work call some extension points or falls back to the base function call in this order:

  • The text_count_as_transcoded(input, from_encoding, to_encoding, from_handler, to_handler, from_state, to_state) extension point, if possible.

  • An internal, implementation-defined customization point.

  • The basic_count_as_transcoded base function.

The base function call, basic_count_as_transcoded, simply performs the core counting loop using the Lucky 7 design.

During the basic_count_as_transcoded loop, if it detects that there is a preferable text_count_as_transcoded_one, it will call that method as text_count_as_transcoded_one(input, encoding, handler, state) inside of the loop rather than doing the core design.

Note

👉 This means that if you implement none of the extension points whatsoever, implementing the basic decode_one and encode_one functions on your Encoding Object type will guarantee a proper, working implementation.

Note

👉 If you need to call the “basic” form of this function that takes no secret implementation shortcuts or user-defined extension points, then call basic_count_as_transcoded directly. This can be useful to stop infinity loops when your extension points cannot handle certain inputs and thereby needs to “delegate” to the basic case.


Functions

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