in Text.Pandoc.Lua. Also to pushPandocModule.
This change allows users to override pandoc.lua with a file
in their local data directory, adding custom functions, etc.
@tarleb, if you think this is a bad idea, you can revert this.
But in general our data files are all overridable.
Now these functions return a pair of a reader/writer and an
Extensions, instead of building the extensions into the
reader/writer. The calling code must explicitly set
readerExtensions or writerExtensions using the Extensions
returned.
The point of the change is to make it possible for the
calling code to determine what extensions are being used.
See #3659.
Attributes was written to behave much like a normal table, in order to
simplify working with it. However, all Attr containing elements were
changed to provide panflute-like accessors to Attr components, rendering
the previous approach unnecessary.
A single `read` function parsing pandoc-supported formats is added to
the module. This is simpler and more convenient than the previous method
of exposing all reader functions individually.
Meta elements that are treated as lua tables (i.e. MetaList,
MetaInlines, MetaBlocks, and MetaMap), are no longer wrapped in an
additional table but simply marked via a metatable. This allows
treating those meta values just like normal tables, while still making
empty elements of those values distinguishable.
Element attributes are pushed to the stack via the `Attributes`
function. `Attributes` creates an Attr like triple, but the triple also
allows table-like access to key-value pairs.
Lua string are used to represent nullary data constructors. The previous
table-based representation was based on the JSON serialization, but can
be simplified. This also matches the way those arguments are passed to
custom writers.
The lua filters and custom lua writer system defined very similar
StackValue instances for strings and tuples. These instance definitions
are extracted to a separate module to enable sharing.
Native lua booleans and strings are used to represent MetaBool and
MetaString values. This is more natural than the previous table-based
representation. The old lua representation can still be read back to
haskell, ensuring compatibility with the `pandoc.MetaBool` and
`pandoc.MetaString` lua constructors.
Reading of simple block values from the lua stack is handled manually,
but most block constructors are still handled via instances of aeson's
Value type.
Getting inline instances from the lua stack is handled manually for some
simple inline constructors, including the `Str` constructor. This avoids
the indirect route through aeson's Value type and improves performance
considerably (approx. 30% speedup for some filters).
Plain text readers are exposed to lua scripts via the `pandoc.reader`
submodule, which is further subdivided by format. Converting e.g. a
markdown string into a pandoc document is possible from within lua:
doc = pandoc.reader.markdown.read_doc("Hello, World!")
A `read_block` convenience function is provided for all formats,
although it will still parse the whole string but return only the first
block as the result.
Custom reader options are not supported yet, default options are used
for all parsing operations.
The 0.5.0 release of hslua fixes problems with lua C modules on linux.
The signature of the `loadstring` function changed, so a compatibility
wrapper is introduced to allow both 0.4.* and 0.5.* versions to be used.
* Add `--lua-filter` option. This works like `--filter` but takes pathnames of special lua filters and uses the lua interpreter baked into pandoc, so that no external interpreter is needed. Note that lua filters are all applied after regular filters, regardless of their position on the command line.
* Add Text.Pandoc.Lua, exporting `runLuaFilter`. Add `pandoc.lua` to data files.
* Add private module Text.Pandoc.Lua.PandocModule to supply the default lua module.
* Add Tests.Lua to tests.
* Add data/pandoc.lua, the lua module pandoc imports when processing its lua filters.
* Document in MANUAL.txt.
