3097ee1 · typeable/pandoc

git.iko.soy/typeable/pandoc

pandoc.mediabag module: add items function iterating over mediabag

A new function `pandoc.mediabag.items` was added to Lua module pandoc.mediabag. This allows users to lazily iterate over all media bag items, loading items into Lua one-by-one. Example: for filename, mime_type, content in pandoc.mediabag.items() do -- use media bag item. end This is a convenient alternative to using `mediabag.list` in combination with `mediabag.lookup`.

commit3097ee100ed260a5c2cea7df5bf80c989687df44 authorAlbert Krewinkel <albert@zeitkraut.de> dateFri 15 Feb 2019, 17:13 (8 years ago) parent8507d98

5 files changed+116−1

compare with master

unifiedsplit

doc/lua-filters.md+27 pandoc.cabal+1 src/Text/Pandoc/Lua/Marshaling/MediaBag.hs+75 src/Text/Pandoc/Lua/Module/MediaBag.hs+7−1 src/Text/Pandoc/MediaBag.hs+6

doc/lua-filters.md+27

@@ -2475,6 +2475,33 @@ Usage:

24752475 local contents = "Hello, World!"

24762476 pandoc.mediabag(fp, mt, contents)

24772477

2478+### iter {#mediabag-iter}

2479+

2480+`items ()`

2481+

2482+Returns an iterator triple to be used with Lua's generic `for`

2483+statement. The iterator returns the filepath, MIME type, and

2484+content of a media bag item on each invocation. Items are

2485+processed one-by-one to avoid excessive memory use.

2486+

2487+This function should be used only when full access to all items,

2488+including their contents, is required. For all other cases,

2489+[`list`](#mediabag-list) should be preferred.

2490+

2491+Returns:

2492+

2493+ - The iterator function; must be called with the iterator state

2494+ and the current iterator value.

2495+ - Iterator state – an opaque value to be passed to the iterator

2496+ function.

2497+ - Initial iterator value.

2498+

2499+Usage:

2500+

2501+ for fp, mt, contents in pandoc.mediabag.items() do

2502+ -- print(fp, mt, contents)

2503+ end

2504+

24782505### list {#mediabag-list}

24792506

24802507`list ()`

pandoc.cabal+1

@@ -591,6 +591,7 @@ library

591591 Text.Pandoc.Lua.Marshaling.AST,

592592 Text.Pandoc.Lua.Marshaling.AnyValue,

593593 Text.Pandoc.Lua.Marshaling.CommonState,

594+ Text.Pandoc.Lua.Marshaling.MediaBag,

594595 Text.Pandoc.Lua.Marshaling.ReaderOptions,

595596 Text.Pandoc.Lua.Marshaling.Version,

596597 Text.Pandoc.Lua.Module.MediaBag,

src/Text/Pandoc/Lua/Marshaling/MediaBag.hsnew file+75

@@ -0,0 +1,75 @@

1+{-# LANGUAGE NoImplicitPrelude #-}

2+{- |

3+ Module : Text.Pandoc.Lua.Marshaling.MediaBag

6+ License : GNU GPL, version 2 or above

7+ Maintainer : Albert Krewinkel <tarleb+pandoc@moltkeplatz.de>

8+ Stability : alpha

10+Instances to marshal (push) and unmarshal (peek) media data.

11+-}

12+module Text.Pandoc.Lua.Marshaling.MediaBag (pushIterator) where

13+

14+import Prelude

15+import Foreign.Ptr (Ptr)

16+import Foreign.StablePtr (StablePtr, deRefStablePtr, newStablePtr)

17+import Foreign.Lua (Lua, NumResults, Peekable, Pushable, StackIndex)

18+import Foreign.Lua.Types.Peekable (reportValueOnFailure)

19+import Foreign.Lua.Userdata (ensureUserdataMetatable, pushAnyWithMetatable,

20+ toAnyWithName)

21+import Text.Pandoc.MediaBag (MediaBag, mediaItems)

22+import Text.Pandoc.MIME (MimeType)

23+import Text.Pandoc.Lua.Marshaling.AnyValue (AnyValue (..))

24+

25+import qualified Data.ByteString.Lazy as BL

26+import qualified Foreign.Lua as Lua

27+import qualified Foreign.Storable as Storable

28+

29+-- | A list of 'MediaBag' items.

30+newtype MediaItems = MediaItems [(String, MimeType, BL.ByteString)]

31+

32+instance Pushable MediaItems where

33+ push = pushMediaItems

34+

35+instance Peekable MediaItems where

36+ peek = peekMediaItems

37+

38+-- | Push an iterator triple to be used with Lua's @for@ loop construct.

39+-- Each iterator invokation returns a tripple consisting of an item's

40+-- filename, MIME type, and content.

41+pushIterator :: MediaBag -> Lua NumResults

42+pushIterator mb = do

43+ Lua.pushHaskellFunction nextItem

44+ Lua.push (MediaItems $ mediaItems mb)

45+ Lua.pushnil

46+ return 3

47+

48+-- | Lua type name for @'MediaItems'@.

49+mediaItemsTypeName :: String

50+mediaItemsTypeName = "pandoc MediaItems"

51+

52+-- | Push a @MediaItems@ element to the stack.

53+pushMediaItems :: MediaItems -> Lua ()

54+pushMediaItems xs = pushAnyWithMetatable pushMT xs

55+ where

56+ pushMT = ensureUserdataMetatable mediaItemsTypeName (return ())

57+

58+-- | Retrieve a @MediaItems@ element from the stack.

59+peekMediaItems :: StackIndex -> Lua MediaItems

60+peekMediaItems = reportValueOnFailure mediaItemsTypeName

61+ (`toAnyWithName` mediaItemsTypeName)

62+

63+-- | Retrieve a list of items from an iterator state, return the first

64+-- item (if present), and advance the state.

65+nextItem :: Ptr (StablePtr MediaItems) -> AnyValue -> Lua NumResults

66+nextItem ptr _ = do

67+ (MediaItems items) <- Lua.liftIO $ deRefStablePtr =<< Storable.peek ptr

68+ case items of

69+ [] -> 2 <$ (Lua.pushnil *> Lua.pushnil)

70+ (key, mt, content):xs -> do

71+ Lua.liftIO $ Storable.poke ptr =<< newStablePtr (MediaItems xs)

72+ Lua.push key

73+ Lua.push mt

74+ Lua.push content

75+ return 3

src/Text/Pandoc/Lua/Module/MediaBag.hs+7−1

@@ -20,6 +20,7 @@ import Foreign.Lua (Lua, NumResults, Optional, liftIO)

2020import Text.Pandoc.Class (CommonState (..), fetchItem, putCommonState,

2121 runIOorExplode, setMediaBag)

2222import Text.Pandoc.Lua.Marshaling ()

23+import Text.Pandoc.Lua.Marshaling.MediaBag (pushIterator)

2324import Text.Pandoc.Lua.Util (addFunction)

2425import Text.Pandoc.MIME (MimeType)

2526

@@ -34,6 +35,7 @@ pushModule :: Lua NumResults

3435pushModule = do

3536 Lua.newtable

3637 addFunction "insert" insertMediaFn

38+ addFunction "items" items

3739 addFunction "lookup" lookupMediaFn

3840 addFunction "list" mediaDirectoryFn

3941 addFunction "fetch" fetch

@@ -66,9 +68,13 @@ insertMediaFn fp optionalMime contents = do

6668 modifyCommonState $ \st ->

6769 let mb = MB.insertMedia fp (Lua.fromOptional optionalMime) contents

6870 (stMediaBag st)

69− in st { stMediaBag = mb}

71+ in st { stMediaBag = mb }

7072 return 0

7173

74+-- | Returns iterator values to be used with a Lua @for@ loop.

75+items :: Lua NumResults

76+items = stMediaBag <$> getCommonState >>= pushIterator

77+

7278lookupMediaFn :: FilePath

7379 -> Lua NumResults

7480lookupMediaFn fp = do

src/Text/Pandoc/MediaBag.hs+6

@@ -19,6 +19,7 @@ module Text.Pandoc.MediaBag (

1919 lookupMedia,

2020 insertMedia,

2121 mediaDirectory,

22+ mediaItems

2223 ) where

2324import Prelude

2425import qualified Data.ByteString.Lazy as BL

@@ -66,3 +67,8 @@ mediaDirectory :: MediaBag -> [(String, MimeType, Int)]

6667mediaDirectory (MediaBag mediamap) =

6768 M.foldrWithKey (\fp (mime,contents) ->

6869 ((Posix.joinPath fp, mime, fromIntegral $ BL.length contents):)) [] mediamap

70+

71+mediaItems :: MediaBag -> [(String, MimeType, BL.ByteString)]

72+mediaItems (MediaBag mediamap) =

73+ M.foldrWithKey (\fp (mime,contents) ->

74+ ((Posix.joinPath fp, mime, contents):)) [] mediamap