From 699abc334895b5e737976d7aa6c1982a692d623b Mon Sep 17 00:00:00 2001
From: Peter Melnichenko <mpeterval@gmail.com>
Date: Mon, 16 May 2016 11:03:19 +0300
Subject: Refactor match_dep()

* Instead of applying blacklist and sorting versions
  in separate steps do a single pass over the list.
* On success return just the version instead of
  {name = name, version = version} since rock name is stored
  inside dependency table already.
---
 src/luarocks/deps.lua | 46 +++++++++++++++-------------------------------
 1 file changed, 15 insertions(+), 31 deletions(-)

diff --git a/src/luarocks/deps.lua b/src/luarocks/deps.lua
index 3c580623..536b6c51 100644
--- a/src/luarocks/deps.lua
+++ b/src/luarocks/deps.lua
@@ -322,48 +322,32 @@ end
 -- @param dep table: A dependency parsed in table format.
 -- @param blacklist table: Versions that can't be accepted. Table where keys
 -- are program versions and values are 'true'.
--- @return table or nil: A table containing fields 'name' and 'version'
--- representing an installed rock which matches the given dependency,
+-- @return string or nil: latest installed version of the rock matching the dependency
 -- or nil if it could not be matched.
 local function match_dep(dep, blacklist, deps_mode)
    assert(type(dep) == "table")
 
-   local versions = cfg.rocks_provided[dep.name]
+   local versions
    if cfg.rocks_provided[dep.name] then
       -- provided rocks have higher priority than manifest's rocks
       versions = { cfg.rocks_provided[dep.name] }
    else
       versions = manif_core.get_versions(dep.name, deps_mode)
    end
-   if not versions then
-      return nil
-   end
-   if blacklist then
-      local i = 1
-      while versions[i] do
-         if blacklist[versions[i]] then
-            table.remove(versions, i)
-         else
-            i = i + 1
-         end
-      end
-   end
-   local candidates = {}
+
+   local latest_version
    for _, vstring in ipairs(versions) do
-      local version = deps.parse_version(vstring)
-      if deps.match_constraints(version, dep.constraints) then
-         table.insert(candidates, version)
+      if not blacklist or not blacklist[vstring] then
+         local version = deps.parse_version(vstring)
+         if deps.match_constraints(version, dep.constraints) then
+            if not latest_version or version > latest_version then
+               latest_version = version
+            end
+         end
       end
    end
-   if #candidates == 0 then
-      return nil
-   else
-      table.sort(candidates)
-      return {
-         name = dep.name,
-         version = candidates[#candidates].string
-      }
-   end
+
+   return latest_version and latest_version.string
 end
 
 --- Attempt to match dependencies of a rockspec to installed rocks.
@@ -386,7 +370,7 @@ function deps.match_deps(rockspec, blacklist, deps_mode)
       local found = match_dep(dep, blacklist and blacklist[dep.name] or nil, deps_mode)
       if found then
          if not cfg.rocks_provided[dep.name] then
-            matched[dep] = found
+            matched[dep] = {name = dep.name, version = found}
          end
       else
          if dep.constraints[1] and dep.constraints[1].no_upgrade then
@@ -414,7 +398,7 @@ local function rock_status(name, deps_mode)
    local search = require("luarocks.search")
    local installed = match_dep(search.make_query(name), nil, deps_mode)
    local installation_type = cfg.rocks_provided[name] and "provided by VM" or "installed"
-   return installed and installed.version.." "..installation_type or "not installed"
+   return installed and installed.." "..installation_type or "not installed"
 end
 
 --- Check dependencies of a rock and attempt to install any missing ones.
-- 
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