feat(vim.version): add `vim.version.intersect()`

Problem: No way to compute intersection of two version ranges, which is
useful when computing version range that fits inside several reference
ranges.

Solution: Add `vim.version.intersect()`.

1 files changed, 18 insertions, 0 deletions

diff --git a/runtime/lua/vim/version.lua b/runtime/lua/vim/version.lua
index dee99a22cc..7c49e5d38f 100644
--- a/runtime/lua/vim/version.lua
+++ b/runtime/lua/vim/version.lua
@@ -361,6 +361,24 @@ function M.range(spec) -- Adapted from https://github.com/folke/lazy.nvim
   end
 end
 
+--- Computes the common range shared by the given ranges.
+---
+--- @since 14
+--- @param r1 vim.VersionRange First range to intersect.
+--- @param r2 vim.VersionRange Second range to intersect.
+--- @return vim.VersionRange? Maximal range that is present inside both `r1` and `r2`.
+---   `nil` if such range does not exist.
+function M.intersect(r1, r2)
+  assert(getmetatable(r1) == range_mt)
+  assert(getmetatable(r2) == range_mt)
+
+  local from = r1.from <= r2.from and r2.from or r1.from
+  local to = (r1.to == nil or (r2.to ~= nil and r2.to <= r1.to)) and r2.to or r1.to
+  if to == nil or from < to or (from == to and r1:has(from) and r2:has(from)) then
+    return setmetatable({ from = from, to = to }, VersionRange)
+  end
+end
+
 ---@param v string|vim.Version
 ---@return string
 local function create_err_msg(v)