From: "'William Lupton' via pandoc-discuss" <pandoc-discuss-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
To: pandoc-discuss-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org
Subject: Re: Lua Filter: Detect Type of Inlines
Date: Sat, 13 May 2023 11:56:12 +0100 [thread overview]
Message-ID: <CAEe_xxj+mWtBs2=PF31Dh24VEApmG8ZAY+_GpWfBFEwCVPpMuw@mail.gmail.com> (raw)
In-Reply-To: <f31b8b9b-f30e-45c6-91d5-caddb494f5b0n-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
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A couple of things:
1. This seems a good moment to mention that my
https://github.com/wlupton/pandoc-lua-logging has moved to
https://github.com/pandoc-ext/logging (it's redirected automatically)
2. Its logging.lua module contains this wrapper around
pandoc.utils.type() (sorry for the rather non-obvious ({Inline=1,
Block=1})[typ] idiom ... I no longer think that this is a particularly
good idea!)
logging.type = function(value)
-- this can return 'Inlines', 'Blocks', 'Inline', 'Block' etc., or
-- anything that built-in type() can return, namely 'nil', 'number',
-- 'string', 'boolean', 'table', 'function', 'thread', or 'userdata'
local typ = pandoc.utils.type(value)
-- it seems that it can also return strings like 'pandoc Row'; replace
-- spaces with periods
-- XXX I'm not sure that this is done consistently, e.g. I don't think
-- it's done for pandoc.Attr or pandoc.List?
typ = typ:gsub(' ', '.')
-- map Inline and Block to the tag name
-- XXX I guess it's intentional that it doesn't already do this?
return ({Inline=1, Block=1})[typ] and value.tag or typ
end
On Sat, 13 May 2023 at 10:00, ThomasH <therch-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> wrote:
> Great, thanks.
>
> On Friday, May 12, 2023 at 7:41:50 PM UTC+2 Albert Krewinkel wrote:
>
>>
>> ThomasH <the...-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> writes:
>>
>> > I want to detect the types of the inline elements of a paragraph. I
>> > understand there is pandoc.utils.type() that basically does that, but
>> > when I run
>> >
>> > function Para(para)
>> > for i = 1,#para.content,1 do
>> > print(tostring(pandoc.utils.type(para.content[i])))
>> > end
>> > end
>> >
>> > all that is printed is "Inline" for all elements, not specific types
>> > like Str, Span, Link or Image. How can I get at the specific types?
>>
>> The trick here is that we are using Haskell terminology: Inline is a
>> *type*, and Str, Span, Link, etc. are *constructors* for this type. In
>> Lua (and JSON) contexts, the property that identifies the name of the
>> constructor of a value is called a "tag". Try this:
>>
>> ``` lua
>> function Para(para)
>> for i = 1,#para.content do
>> print(para.content[i].tag))
>> end
>> end
>> ```
>>
>> The `.t` property is an alias for `.tag` and can be used as well.
>>
>> I have plans to change the behavior of `pandoc.utils.type` and to make
>> the function return two results. The first result would stay as-is, with
>> the second result containing the constructor name. But I need to run
>> more tests to ensure that this won't lead to performance degradation.
>>
>>
>> --
>> Albert Krewinkel
>> GPG: 8eed e3e2 e8c5 6f18 81fe e836 388d c0b2 1f63 1124
>>
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prev parent reply other threads:[~2023-05-13 10:56 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-05-12 17:13 ThomasH
[not found] ` <4d901ab9-179d-4274-8ce9-fdf36056905fn-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
2023-05-12 17:32 ` Albert Krewinkel
[not found] ` <87o7mpqwfd.fsf-9EawChwDxG8hFhg+JK9F0w@public.gmane.org>
2023-05-13 9:00 ` ThomasH
[not found] ` <f31b8b9b-f30e-45c6-91d5-caddb494f5b0n-/JYPxA39Uh5TLH3MbocFFw@public.gmane.org>
2023-05-13 10:56 ` 'William Lupton' via pandoc-discuss [this message]
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