diff options
| -rw-r--r-- | doc/custom-writers.md | 16 | ||||
| -rw-r--r-- | src/Text/Pandoc/Writers/Custom.hs | 30 |
2 files changed, 37 insertions, 9 deletions
diff --git a/doc/custom-writers.md b/doc/custom-writers.md index 6df603288..fb08cd120 100644 --- a/doc/custom-writers.md +++ b/doc/custom-writers.md @@ -50,3 +50,19 @@ the functions in `sample.lua` according to your needs. ``` {.lua include="sample.lua"} ``` + +# Template variables + +New template variables can be added, or existing ones +modified, by returning a second value from function `Doc`. + +For example, the following will add the current date in +variable `date`, unless `date` is already defined as either a +metadata value or a variable: + +``` lua +function Doc (body, meta, vars) + vars.date = vars.date or meta.data or os.date '%B %e, %Y' + return body, vars +end +``` diff --git a/src/Text/Pandoc/Writers/Custom.hs b/src/Text/Pandoc/Writers/Custom.hs index d13fbfb24..95e7355ae 100644 --- a/src/Text/Pandoc/Writers/Custom.hs +++ b/src/Text/Pandoc/Writers/Custom.hs @@ -16,20 +16,23 @@ Conversion of 'Pandoc' documents to custom markup using a Lua writer. -} module Text.Pandoc.Writers.Custom ( writeCustom ) where +import Control.Applicative (optional) import Control.Arrow ((***)) import Control.Exception import Control.Monad (when) import Data.List (intersperse) import qualified Data.Map as M +import Data.Maybe (fromMaybe) import qualified Data.Text as T import Data.Text (Text, pack) import HsLua as Lua hiding (Operation (Div), render) import HsLua.Class.Peekable (PeekError) import Text.DocLayout (render, literal) +import Text.DocTemplates (Context) import Control.Monad.IO.Class (MonadIO) import Text.Pandoc.Definition import Text.Pandoc.Lua (Global (..), runLua, setGlobals) -import Text.Pandoc.Lua.Util (addField, dofileWithTraceback) +import Text.Pandoc.Lua.Util (addField, dofileWithTraceback, peekViaJSON) import Text.Pandoc.Options import Text.Pandoc.Class (PandocMonad) import Text.Pandoc.Templates (renderTemplate) @@ -98,12 +101,12 @@ writeCustom luaFile opts doc@(Pandoc meta _) = do -- to handle this more gracefully): when (stat /= Lua.OK) Lua.throwErrorAsException - rendered <- docToCustom opts doc - context <- metaToContext opts - (fmap (literal . pack) . blockListToCustom) - (fmap (literal . pack) . inlineListToCustom) - meta - return (pack rendered, context) + (rendered, context) <- docToCustom opts doc + metaContext <- metaToContext opts + (fmap (literal . pack) . blockListToCustom) + (fmap (literal . pack) . inlineListToCustom) + meta + return (pack rendered, context <> metaContext) case res of Left msg -> throw msg Right (body, context) -> return $ @@ -113,10 +116,19 @@ writeCustom luaFile opts doc@(Pandoc meta _) = do renderTemplate tpl $ setField "body" body context docToCustom :: forall e. PeekError e - => WriterOptions -> Pandoc -> LuaE e String + => WriterOptions -> Pandoc -> LuaE e (String, Context Text) docToCustom opts (Pandoc (Meta metamap) blocks) = do body <- blockListToCustom blocks - invoke @e "Doc" body (fmap (Stringify @e) metamap) (writerVariables opts) + -- invoke doesn't work with multiple return values, so we have to call + -- `Doc` manually. + Lua.getglobal "Doc" -- function + push body -- argument 1 + push (fmap (Stringify @e) metamap) -- argument 2 + push (writerVariables opts) -- argument 3 + call 3 2 + rendered <- peek (nth 2) -- first return value + context <- forcePeek . optional $ peekViaJSON top -- snd return value + return (rendered, fromMaybe mempty context) -- | Convert Pandoc block element to Custom. blockToCustom :: forall e. PeekError e |