Lua: add function `pandoc.template.get`.

The function allows to specify a template with the same argument value
that would be used with the `--template` command line parameter.

Closes: #9854

Co-authored-by: Carsten Gips <[email protected]>

1 files changed, 16 insertions, 3 deletions

diff --git a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Template.hs b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Template.hs
index 69dc75955..9cca6fda4 100644
--- a/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Template.hs
+++ b/pandoc-lua-engine/src/Text/Pandoc/Lua/Module/Template.hs
@@ -21,7 +21,7 @@ import Text.Pandoc.Lua.Marshal.Template (typeTemplate, peekTemplate, pushTemplat
 import Text.Pandoc.Lua.PandocLua (PandocLua (unPandocLua), liftPandocLua)
 import Text.Pandoc.Writers.Shared (metaToContext')
 import Text.Pandoc.Templates
-  ( compileTemplate, getDefaultTemplate, renderTemplate
+  ( compileTemplate, getDefaultTemplate, getTemplate, renderTemplate
   , runWithPartials, runWithDefaultPartials )
 
 import qualified Data.Text as T
@@ -91,14 +91,27 @@ functions =
      <#> opt (textParam "writer"
               ("name of the writer for which the template should be " <>
                "retrieved; defaults to the global `FORMAT`."))
-     =#> functionResult pushText "string"
-           "raw template"
+     =#> functionResult pushText "string" "raw template"
     #? T.unlines
     [ "Returns the default template for a given writer as a string. An"
     , "error is thrown if no such template can be found."
     ]
     `since` makeVersion [2,17]
 
+  , defun "get"
+     ### (unPandocLua . getTemplate)
+     <#> stringParam "filename" "name of the template"
+     =#> textResult "content of template file"
+     #? T.unlines
+     [ "Retrieve text for a template."
+     , ""
+     , "This function first checks the resource paths for a file of this"
+     , "name; if none is found, the `templates` directory in the user data"
+     , "directory is checked.  Returns the content of the file, or throws"
+     , "an error if no file is found."
+     ]
+    `since` makeVersion [3,2,1]
+
   , defun "meta_to_context"
      ### (\meta blockWriterIdx inlineWriterIdx -> unPandocLua $ do
              let blockWriter blks = liftPandocLua $ do