platformMatch

lib.meta.platformMatch

Docs pulled from | This Revision | about 1 hour ago

Check to see if a platform is matched by the given meta.platforms element.

A meta.platform pattern is either

(legacy) a system string.
(modern) a pattern for the entire platform structure (see lib.systems.inspect.platformPatterns).
(modern) a pattern for the platform parsed field (see lib.systems.inspect.patterns).

We can inject these into a pattern for the whole of a structured platform, and then match that.

Inputs

platform: 1. Function argument
elem: 2. Function argument

Examples

`lib.meta.platformMatch` usage example

lib.meta.platformMatch { system = "aarch64-darwin"; } "aarch64-darwin"
=> true

Noogle detected

Implementation

The following is the current implementation of this function.

platformMatch = platform: elem: (
    # Check with simple string comparison if elem was a string.
    #
    # The majority of comparisons done with this function will be against meta.platforms
    # which contains a simple platform string.
    #
    # Avoiding an attrset allocation results in significant  performance gains (~2-30) across the board in OfBorg
    # because this is a hot path for nixpkgs.
    if isString elem then platform ? system && elem == platform.system
    else matchAttrs (
      # Normalize platform attrset.
      if elem ? parsed then elem
      else { parsed = elem; }
    ) platform
  );