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| -rw-r--r-- | doc/lua-filters.md | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/doc/lua-filters.md b/doc/lua-filters.md index 9e4d438ea..5e43afb26 100644 --- a/doc/lua-filters.md +++ b/doc/lua-filters.md @@ -105,11 +105,22 @@ element filtering function. In other words, filter entries will be called for each corresponding element in the document, getting the respective element as input. -The element function's output must be an element of the same -type as the input. This means a filter function acting on an -inline element must return an inline, and a block element must -remain a block element after filter application. Pandoc will -throw an error if this condition is violated. +The return of a filter function must one of the following: + +- nil: this means that the object should remain unchanged. +- a pandoc object: this must be of the same type as the input + and will replace the original object. +- a list of pandoc objects: these will replace the original + object; the list is merged with the neighbors of the orignal + objects (spliced into the list the original object belongs + to); returning an empty list deletes the object. + +The function's output must result in an element of the same type +as the input. This means a filter function acting on an inline +element must return either nil, an inline, or a list of inlines, +and a function filtering a block element must return one of nil, +a block, or a list of block elements. Pandoc will throw an error +if this condition is violated. If there is no function matching the element's node type, then the filtering system will look for a more general fallback |