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User interface
++++++++++++++
.. class:: nodoc
> module Main (main) where
> import System.Environment (getArgs)
> import Data.List (intercalate)
>
> import Codec.Pesto.Parse (parse, Instruction (Ingredient), Quantity (..))
> import Codec.Pesto.Graph (extract, toGraph, firstNodeId, resolveReferences)
> import Codec.Pesto.Lint (lint, extractMetadata, Metadata(..), LintResult (LintResult))
> import Codec.Pesto.Serialize (serialize)
The user-interface reads a single recipe from the standard input.
> main = do
> (op:_) <- getArgs
> s <- getContents
> either malformedRecipe (run op) (parse s)
It has three modes of operation, described in the next sections.
> run "dot" = runDot
> run "metadata" = runMeta
> run "ingredients" = runIngredients
> run _ = const (putStrLn "unknown operation")
dot
^^^
Since each recipe is just a directed graph (digraph), GraphViz’ dot language
can represent recipes as well. Example:
.. code:: bash
cabal run --verbose=0 pesto dot < spaghetti.pesto | dot -Tpng > spaghetti.png
> runDot stream = putStrLn $ toDot dotNodes dotEdges
> where
> (nodes, edges) = streamToGraph stream
> maxId = (maximum $ map fst nodes) + 1
> (lintNodes, lintEdges) = unzip $ map (uncurry lintToNodesEdges)
> $ zip [maxId..] (lint nodes edges)
> dotNodes = concat [
> [("node", [("fontname", "Roboto Semi-Light")])]
> , map (\(a, label) -> (show a, [("label", serialize label)])) nodes
> , lintNodes
> ]
> dotEdges = concat [
> map (both show) edges
> , concat lintEdges
> ]
> lintToNodesEdges nodeid (LintResult t nodes) = let
> n = (show nodeid, [("label", show t), ("color", "red")])
> e = map (\i -> both show (nodeid, i)) nodes
> in (n, e)
> both f (a, b) = (f a, f b)
> toDot nodes edges = "digraph a {"
> <> mconcat (map nodeToDot nodes)
> <> mconcat (map edgeToDot edges)
> <> "}"
> where
> edgeToDot (a, b) = a <> " -> " <> b <> ";"
> nodeToDot (a, b) = a <> " [" <> mconcat (mapToDot b) <> "];"
> mapToDot = map kvToDot
> kvToDot (k, v) = k <> "=\"" <> quoteString v <> "\""
> quoteString s = mconcat $ map quoteChar s
> quoteChar '\n' = "\\n"
> quoteChar '"' = "\\\""
> quoteChar x = [x]
metadata
^^^^^^^^
Print metadata as key-value pairs, separated by ``=``.
> runMeta stream = maybe (return ()) (mapM_ printMeta) $ uncurry extractMetadata $ streamToGraph stream
ingredients
^^^^^^^^^^^
Extract ingredients and print them in CSV format. This does not take
alternatives into account yet.
> runIngredients stream = mapM_ (putStrLn . csvQty) $ reverse $ foldl getIngredient [] stream
> where
> getIngredient xs (_, Ingredient q) = q:xs
> getIngredient xs _ = xs
> printMeta (_, (key, MetaStr value)) = putStrLn $ key ++ "=" ++ value
> printMeta (_, (key, MetaQty q)) = putStrLn $ key ++ "=" ++ csvQty q
> csvQty (Quantity a b c) = intercalate "," [serialize a, b, c]
Appendix
^^^^^^^^
> malformedRecipe = print
> streamToGraph stream = (nodes, edges)
> where
> doc = (head . extract . snd . unzip) stream
> nodes = zip [firstNodeId..] doc
> edges = toGraph nodes ++ resolveReferences nodes
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