From 901b672107ef681830f7c9013bba444eb6c90d84 Mon Sep 17 00:00:00 2001
From: Jasper Van der Jeugt <jaspervdj@gmail.com>
Date: Wed, 6 Apr 2011 14:40:36 +0200
Subject: Play with dependency analyzer

---
 src/Hakyll/Core/DirectedGraph/DependencySolver.hs | 70 -----------------------
 1 file changed, 70 deletions(-)
 delete mode 100644 src/Hakyll/Core/DirectedGraph/DependencySolver.hs

(limited to 'src/Hakyll/Core/DirectedGraph/DependencySolver.hs')

diff --git a/src/Hakyll/Core/DirectedGraph/DependencySolver.hs b/src/Hakyll/Core/DirectedGraph/DependencySolver.hs
deleted file mode 100644
index 54826ff..0000000
--- a/src/Hakyll/Core/DirectedGraph/DependencySolver.hs
+++ /dev/null
@@ -1,70 +0,0 @@
--- | Given a dependency graph, this module provides a function that will
--- generate an order in which the graph can be visited, so that all the
--- dependencies of a given node have been visited before the node itself is
--- visited.
---
-module Hakyll.Core.DirectedGraph.DependencySolver
-    ( solveDependencies
-    ) where
-
-import Prelude
-import qualified Prelude as P
-import Data.Set (Set)
-import Data.Maybe (mapMaybe)
-import qualified Data.Map as M
-import qualified Data.Set as S
-
-import Hakyll.Core.DirectedGraph
-import Hakyll.Core.DirectedGraph.Internal
-
--- | Solve a dependency graph. This function returns an order to run the
--- different nodes
---
-solveDependencies :: Ord a
-                  => DirectedGraph a  -- ^ Graph
-                  -> [a]              -- ^ Resulting plan
-solveDependencies = P.reverse . order [] [] S.empty
-
--- | Produce a reversed order using a stack
---
-order :: Ord a
-      => [a]              -- ^ Temporary result
-      -> [Node a]         -- ^ Backtrace stack
-      -> Set a            -- ^ Items in the stack
-      -> DirectedGraph a  -- ^ Graph
-      -> [a]              -- ^ Ordered result
-order temp stack set graph@(DirectedGraph graph')
-    -- Empty graph - return our current result
-    | M.null graph' = temp
-    | otherwise = case stack of
-
-        -- Empty stack - pick a node, and add it to the stack
-        [] ->
-            let (tag, node) = M.findMin graph'
-            in order temp (node : stack) (S.insert tag set) graph
-
-        -- At least one item on the stack - continue using this item
-        (node : stackTail) ->
-            -- Check which dependencies are still in the graph
-            let tag = nodeTag node
-                deps = S.toList $ nodeNeighbours node
-                unsatisfied = mapMaybe (`M.lookup` graph') deps
-            in case unsatisfied of
-                
-                -- All dependencies for node are satisfied, we can return it and
-                -- remove it from the graph
-                [] -> order (tag : temp) stackTail (S.delete tag set)
-                            (DirectedGraph $ M.delete tag graph')
-
-                -- There is at least one dependency left. We need to solve that
-                -- one first...
-                (dep : _) -> if nodeTag dep `S.member` set
-                    -- The dependency is already in our stack - cycle detected!
-                    then cycleError
-                    -- Continue with the dependency
-                    else order temp (dep : node : stackTail)
-                                    (S.insert (nodeTag dep) set)
-                                    graph
-  where
-    cycleError = error $  "Hakyll.Core.DirectedGraph.DependencySolver.order: "
-                       ++ "Cycle detected!"  -- TODO: Dump cycle
-- 
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