--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/share/lua/5.2/luarocks/loader.lua	Fri Dec 14 22:24:27 2012 +0000
@@ -0,0 +1,212 @@
+
+--- A module which installs a Lua package loader that is LuaRocks-aware.
+-- This loader uses dependency information from the LuaRocks tree to load
+-- correct versions of modules. It does this by constructing a "context"
+-- table in the environment, which records which versions of packages were
+-- used to load previous modules, so that the loader chooses versions
+-- that are declared to be compatible with the ones loaded earlier.
+local global_env = _G
+local package, require, ipairs, pairs, table, type, next, unpack =
+      package, require, ipairs, pairs, table, type, next, unpack
+
+module("luarocks.loader")
+
+local path = require("luarocks.path")
+local manif_core = require("luarocks.manif_core")
+local deps = require("luarocks.deps")
+local cfg = require("luarocks.cfg")
+
+context = {}
+
+-- Contains a table when rocks trees are loaded,
+-- or 'false' to indicate rocks trees failed to load.
+-- 'nil' indicates rocks trees were not attempted to be loaded yet.
+rocks_trees = nil
+
+local function load_rocks_trees() 
+   local any_ok = false
+   local trees = {}
+   for _, tree in ipairs(cfg.rocks_trees) do
+      local manifest, err = manif_core.load_local_manifest(path.rocks_dir(tree))
+      if manifest then
+         any_ok = true
+         table.insert(trees, {tree=tree, manifest=manifest})
+      end
+   end
+   if not any_ok then
+      rocks_trees = false
+      return false
+   end
+   rocks_trees = trees
+   return true
+end
+
+--- Process the dependencies of a package to determine its dependency
+-- chain for loading modules.
+-- @param name string: The name of an installed rock.
+-- @param version string: The version of the rock, in string format
+function add_context(name, version)
+   -- assert(type(name) == "string")
+   -- assert(type(version) == "string")
+
+   if context[name] then
+      return
+   end
+   context[name] = version
+
+   if not rocks_trees and not load_rocks_trees() then
+      return nil
+   end
+
+   local providers = {}
+   for _, tree in ipairs(rocks_trees) do
+      local manifest = tree.manifest
+
+      local pkgdeps
+      if manifest.dependencies and manifest.dependencies[name] then
+         pkgdeps = manifest.dependencies[name][version]
+      end
+      if not pkgdeps then
+         return nil
+      end
+      for _, dep in ipairs(pkgdeps) do
+         local pkg, constraints = dep.name, dep.constraints
+   
+         for _, tree in ipairs(rocks_trees) do
+            local entries = tree.manifest.repository[pkg]
+            if entries then
+               for version, pkgs in pairs(entries) do
+                  if (not constraints) or deps.match_constraints(deps.parse_version(version), constraints) then
+                     add_context(pkg, version)
+                  end
+               end
+            end
+         end
+      end
+   end
+end
+
+--- Internal sorting function.
+-- @param a table: A provider table.
+-- @param b table: Another provider table.
+-- @return boolean: True if the version of a is greater than that of b.
+local function sort_versions(a,b)
+   return a.version > b.version
+end
+
+--- Request module to be loaded through other loaders,
+-- once the proper name of the module has been determined.
+-- For example, in case the module "socket.core" has been requested
+-- to the LuaRocks loader and it determined based on context that
+-- the version 2.0.2 needs to be loaded and it is not the current
+-- version, the module requested for the other loaders will be
+-- "socket.core_2_0_2".
+-- @param module The module name requested by the user, such as "socket.core"
+-- @param name The rock name, such as "luasocket"
+-- @param version The rock version, such as "2.0.2-1"
+-- @param module_name The actual module name, such as "socket.core" or "socket.core_2_0_2".
+-- @return table or (nil, string): The module table as returned by some other loader,
+-- or nil followed by an error message if no other loader managed to load the module.
+local function call_other_loaders(module, name, version, module_name)
+   for i, loader in pairs(package.loaders) do
+      if loader ~= luarocks_loader then
+         local results = { loader(module_name) }
+         if type(results[1]) == "function" then
+            return unpack(results)
+         end
+      end
+   end
+   return "Failed loading module "..module.." in LuaRocks rock "..name.." "..version
+end
+
+--- Search for a module in the rocks trees
+-- @param module string: module name (eg. "socket.core")
+-- @param filter_module_name function(string, string, string, string, number):
+-- a function that takes the module name (eg "socket.core"), the rock name
+-- (eg "luasocket"), the version (eg "2.0.2-1"), the path of the rocks tree
+-- (eg "/usr/local"), and the numeric index of the matching entry, so the
+-- filter function can know if the matching module was the first entry or not.
+-- @return string, string, string: name of the rock containing the module
+-- (eg. "luasocket"), version of the rock (eg. "2.0.2-1"),
+-- name of the module (eg. "socket.core", or "socket.core_2_0_2" if file is
+-- stored versioned).
+local function select_module(module, filter_module_name)
+   --assert(type(module) == "string")
+   --assert(type(filter_module_name) == "function")
+
+   if not rocks_trees and not load_rocks_trees() then
+      return nil
+   end
+
+   local providers = {}
+   for _, tree in ipairs(rocks_trees) do
+      local entries = tree.manifest.modules[module]
+      if entries then
+         for i, entry in ipairs(entries) do
+            local name, version = entry:match("^([^/]*)/(.*)$")
+            local module_name = tree.manifest.repository[name][version][1].modules[module]
+            if type(module_name) ~= "string" then
+               error("Invalid format in manifest file (invalid data for "..tostring(name).." "..tostring(version)..")")
+            end
+            module_name = filter_module_name(module_name, name, version, tree.tree, i)
+            if context[name] == version then
+               return name, version, module_name
+            end
+            version = deps.parse_version(version)
+            table.insert(providers, {name = name, version = version, module_name = module_name})
+         end
+      end
+   end
+
+   if next(providers) then
+      table.sort(providers, sort_versions)
+      local first = providers[1]
+      return first.name, first.version.string, first.module_name
+   end
+end
+
+--- Search for a module
+-- @param module string: module name (eg. "socket.core")
+-- @return string, string, string: name of the rock containing the module
+-- (eg. "luasocket"), version of the rock (eg. "2.0.2-1"),
+-- name of the module (eg. "socket.core", or "socket.core_2_0_2" if file is
+-- stored versioned).
+local function pick_module(module)
+   return
+      select_module(module, function(module_name, name, version, tree, i)
+         if i > 1 then
+            module_name = path.versioned_name(module_name, "", name, version)
+         end
+         module_name = path.path_to_module(module_name)
+         return module_name
+      end)
+end
+
+--- Return the pathname of the file that would be loaded for a module.
+-- @param module string: module name (eg. "socket.core")
+-- @return string: filename of the module (eg. "/usr/local/lib/lua/5.1/socket/core.so")
+function which(module)
+   local name, version, module_name = select_module(module, path.which_i)
+   return module_name
+end
+
+--- Package loader for LuaRocks support.
+-- A module is searched in installed rocks that match the
+-- current LuaRocks context. If module is not part of the
+-- context, or if a context has not yet been set, the module
+-- in the package with the highest version is used.
+-- @param module string: The module name, like in plain require().
+-- @return table: The module table (typically), like in plain
+-- require(). See <a href="http://www.lua.org/manual/5.1/manual.html#pdf-require">require()</a>
+-- in the Lua reference manual for details.
+function luarocks_loader(module)
+   local name, version, module_name = pick_module(module)
+   if not name then
+      return "No LuaRocks module found for "..module
+   else
+      add_context(name, version)
+      return call_other_loaders(module, name, version, module_name)
+   end
+end
+
+table.insert(global_env.package.loaders, 1, luarocks_loader)