Versioning and compatibility policy

lexy uses calender versioning according to the following schema:

  • YYYY.MM the year and month of the release for N = 0.

  • N the minor/patch number of the release.

  • -beta suffix indicating a beta release.

Major releases

A major release is released when enough features have accumulated, but at least once for each new Unicode version. We promise:

  • No change in semantics of existing functionality. In particular, all DSL rules will continue to accept the same input as they have in the previous version, and produce the same values. This does not apply to the behavior on invalid input, see below.

  • No removal of functionality unless it has been deprecated in a previous major release.

  • Few build breaking changes: whenever possible, we will add an alternative with a different spelling and deprecate the previous version instead.

We reserve the right to:

  • Deprecate existing functionality and remove previously deprecated functionality.

  • Change anything that is not documented or explicitly marked as experimental (enabled by linking foonathan::lexy::experimental). In particular, writing custom rules, readers, or parse actions is not guaranteed to work across major releases.

  • Change everything about the extension headers.

  • Change the behavior of rules on invalid input. This includes generated error messages and error recovery. We reserve the right to add error recovery to rules that currently do not have error recovery, remove error recovery of existing rules, or change error recovery. What is considered invalid input does not change, however.

  • Change the ABI.

  • Add new functionality, change the signature of existing functions (in an API compatible way), change transitive includes and implementation details.

Minor releases

A minor (or patch) release is done to fix bugs or improve existing functionality. It increments N but leaves YYYY.MM unchanged, even if released in a different month. Minor releases are fully API and ABI compatible.

We will only add minor releases to the latest major release and do not support multiple major releases at the same time.

Beta release

We can do a beta release of any major or minor release first. We reserve the right to make any changes between the beta release and the final release for new functionality introduced in the beta release. Stability guarantees for existing functionality still applies.