css-inherit-fn/_less-inherit.less

Sass and Less mixins to enable CSS --var: calc(inherit(--var) + 1);

// * css-inherit-fn/_less-inherit.less
// * BSD 2-Clause License
// * Copyright (c) Jane Ori, PropJockey, 2022

.buildDepthSelector(
  @evenOdd, @sel, @maxDepth, @i: 1,
  @full: ~"", @selX: @sel, @comma: ~""
) when (@i <= @maxDepth) {
  .buildDepthSelector(
    ~"", @sel, @maxDepth, (@i + 2),
    "@{full}@{comma}@{selX}:not(@{selX} @{sel})",
    "@{selX} @{sel} @{sel}", ", "
  );
}
.buildDepthSelector(
  @evenOdd, @sel, @maxDepth, @i: 1,
  @full: ~"", @selX: ~"", @comma: ~""
) when (@evenOdd = "even") {
  @selX: "@{sel} @{sel}";
  @i: 2;
  .buildDepthSelector(
    ~"", @sel, @maxDepth, (@i + 2),
    "@{full}@{comma}@{selX}:not(@{selX} @{sel})",
    "@{selX} @{sel} @{sel}", ", "
  );
}
.buildDepthSelector(
  @evenOdd, @sel, @maxDepth, @i: 1,
  @full: ~"", @selX: ~"", @comma: ~""
) when (@i > @maxDepth) {
  @escaped: e(@full);
  @result: :where(@escaped);
}

.__inheritchainswap(@ioA, @ioB, @assignments) {
  @argLen: length(@assignments);
  each(range(1, @argLen, 1), {
    @assignment: extract(@assignments, @value);
    @var: e(replace(@assignment, "([^:]+):.*", "$1"));
    @val: replace(@assignment, "[^:]+:\s*(.*)", "$1");
    @inheritVal: replace(@val, "inherit\(--", "var(--@{ioA}", "g");
    @{var}: e(@inheritVal);
    @outVar: replace(@var, "--", "--@{ioB}", "");
    @{outVar}: var(e(@var));
  });
}

.buildInherit(@sel, @maxDepth, @assignments...) {
  @odd: .buildDepthSelector("odd", @sel, @maxDepth)[@result];
  @evn: .buildDepthSelector("even", @sel, @maxDepth)[@result];
  @{odd} {
    .__inheritchainswap("io1_", "io2_", @assignments);
  }
  @{evn} {
    .__inheritchainswap("io2_", "io1_", @assignments);
  }
}