Adds KaTeX math engine via the 'katex' ruby gem #489

glebm · 2018-01-25T00:59:37Z

This is a simpler all batteries included alternative to the sskatex engine.

ccorn · 2018-01-25T02:44:39Z

I have merged the proposed fix by @glebm to SsKaTeX and made a new release (no longer needs to overwrite EXECJS_RUNTIME to defer autodetection). Re-triggering the CI tests should now load the katex gem normally.

glebm · 2018-01-25T02:53:13Z

I've updated the PR to trigger a test re-run

glebm · 2018-01-25T03:39:52Z

The pre-2.3 targets are failing because the katex gem requires ruby 2.3+.

@gettalong Perhaps kramdown could drop official support for older rubies by removing them from .travis.yml? Ruby 2.2 EOL is scheduled for 2018-03-31.

ccorn · 2018-01-25T04:42:03Z

You may have to constrain the katex gem version in .travis.yml so that the availability of a version with a newer katex.js (and different HTML output) does not automatically trigger CI failures.

ccorn · 2018-01-25T05:42:19Z

For earlier rubies, the load failure would be reflected in the AVAILABLE member. You just need to exclude the installation attempts and the new test cases when the engine is not available.

You could replace the katex gem installation in .travis.yml with:

- ruby -e 'exit(RUBY_VERSION < "2.3" ? 0 : 1)' || gem install katex some_version_constraint_here

and augment test/test_files.rb with KATEX_AVAILABLE guards like SsKaTeX does.

glebm · 2018-01-25T20:28:46Z

Thanks @ccorn, I've done as you suggested and Travis is now green

gettalong · 2018-01-25T21:39:40Z

So @glebm, could you explain to me what this implementation offers over sskatex?

glebm · 2018-01-25T23:21:11Z

@gettalong The katex gem is much easier to set up, because it bundles all the KaTeX assets and registers them automatically with all the popular Ruby web frameworks (Rails, Sprockets without Rails, and Hanami).

See also the discussion at ccorn/sskatex#1

ccorn · 2018-01-26T06:28:24Z

From my point of view:

The katex engine is a locked-down fixed-configuration engine for untrusted users:
- No Javascript fragments configurable, thus suitable for applications which need to disable all means of code injection
- JS engine determined by ExecJS autodetection, not overridable
- Needs to cache only one execution context (within the gem) because there is only one configuration available
- KaTeX version determined by gem version; ~~no macros nor other options that SsKaTeX's katex_opts would allow to be passed to KaTeX~~ math_engine_opts passed directly to KaTeX; throwOnError turned off by default
- No logging
SsKaTeX is for trusted users who need more control or stability:
- KaTeX version is controlled by the user directly
- Passes KaTeX options via katex_opts, throws on errors by default
- Can change all JS engine and code aspects, supports logging/debug messages
- May be able to interface with MathJax by using different js_libs
- Makes sure to pass ASCII strings only
  - Useful for ancient engines like SpiderMonkey 1.8.5 which can run KaTeX just fine but may have been compiled without support for UTF-8 I/O
  - Note that such engines are deprecated in ExecJS and not autoselected.

Let me add that KaTeX version control is important; e.g. in recent releases the handling of \color has changed (which is intentional but backwards-incompatible by default).

ccorn · 2018-01-26T07:31:24Z

In Rakefile, the added line s.add_development_dependency 'katex' may need to be conditioned on RUBY_VERSION as well. Edit: Rather not. rake test works, and rake dev:gem shall not be affected.

Anyway, to avoid repeating that criterion too often, the KATEX_AVAILABLE test in test/test_files.rb could be made similar to the one for MATHJAX_NODE_AVAILABLE (that is, just test the AVAILABLE member). This would then work regardless of whether katex is a development dependency or not.

gettalong · 2018-01-26T16:46:53Z

@glebm If it is only that, then there is no real reason to add this to kramdown. If there were any big features that katex has but sskatex hasn't, than it would make sense. But from kramdown's point of view it doesn't make sense to provide two ways to do effectively the same.

ccorn · 2018-01-26T21:12:43Z

The workings and outputs are indeed almost the same (if the underlying KaTeX versions are the same), almost because SsKaTeX escapes non-ASCII characters passing to and from the engine.

But the target user sets are disjoint: untrusted users on a github-pages-like service vs trusted individuals with their own specific setups. It solves the security issue discussed in #471 by bundling all the ingredients and binding the associated maintenance costs to the katex gem. I imagine that the katex version could be advertised for general use, and if individuals run into problems with their personal setups, they can be asked to use SsKaTeX for better control.

(I fear that some cloud service provider with unsecured kramdown setup will come complaining that his platform spent most of its computing power in horribly inefficient bitcoin mining. In that case, it would be good to be able to say not only RTFM but that there is a secure KaTeX alternative.)

gettalong

@glebm I have thought about this PR and decided to accept it. Some needed changes can be seen in this review.

Thanks for your contributions! And @ccorn - thanks for your input!

gettalong · 2018-01-30T17:09:17Z

.travis.yml

@@ -22,6 +22,8 @@ before_install:
  - sudo apt-get install texlive-latex-base texlive-latex-recommended texlive-fonts-recommended texlive-latex-extra tidy
  - gem install rake
  - gem install minitest coderay stringex ritex execjs sskatex
+  - >
+    ruby -e 'exit RUBY_VERSION < "2.3" ? 0 : 1' || gem install katex -v 0.3.0


Please put this on one line, there is no need for splitting it across two.

It contains a :. Do you know how it should be escaped if it's on one line?

Figured it out, done.

Hm... always something new to learn 👍 You are correct, the colon poses a problem, sorry. So leave that as it is.

gettalong · 2018-01-30T17:14:12Z

doc/math_engine/katex.page

@@ -0,0 +1,29 @@
+---


Please reformat the documentation to 100 columns. And you also need to link to this page on the documentation.page.

gettalong · 2018-01-30T17:37:09Z

lib/kramdown/converter.rb

@@ -50,7 +50,7 @@ module Converter

    configurable(:math_engine)

-    ['Mathjax', "MathjaxNode", "SsKaTeX", "Ritex", "Itex2MML"].each do |klass_name|
+    %w(Mathjax MathjaxNode Katex SsKaTeX Ritex Itex2MML).each do |klass_name|


Please just add your mathe engine here. No need to change the styling.

It then does not fit on one line. How do you want it indented if it's split across multiple lines?

Nevermind, from looking at other code I see that the undocumented column limit is not 80.

Column limit is 100. When I have some more time I will add support for a linting tool...

gettalong · 2018-01-30T17:38:06Z

lib/kramdown/converter/math_engine/katex.rb

+
+    def self.call(converter, el, opts)
+      display_mode = el.options[:category] == :block
+      result = ::Katex.render el.value,


This method call is missing parentheses.

Parenthesis are optional here. Do you have a style guide / a lint command to make sure I haven't missed anything else?

No, not for kramdown. I would just use them here.

gettalong · 2018-01-30T19:04:26Z

test/test_files.rb

@@ -42,14 +42,16 @@ class TestFiles < Minitest::Test
                               warn("Skipping MathjaxNode tests as MathjaxNode is not available")
                           end

-  KATEX_AVAILABLE = begin
+  SSKATEX_AVAILABLE = begin


The following lines should be indented two additional spaces since SSKATEX_AVAILABLE is two characters longer than KATEX_AVAILABLE.

ccorn · 2018-01-31T09:36:11Z

Adding KaTeX to the Output list in doc/documentation.page makes no sense.
What requires updates are doc/converter/html.page (math section) and doc/documentation.template (math engines).
In test/test_files.rb, line 46 (below SSKATEX_AVAILABLE) still requires +2 indent.

ccorn · 2018-01-31T09:55:14Z

The sources doc/converter/html.page and/or the individual math engine's pages should probably include a discussion katex vs sskatex:

katex	sskatex
easy to use	more control
for untrusted users	for trusted users

I'd provide one in a follow-up PR if you do not want to touch SsKaTeX parts. In two rough sentences: Use katex unless you need more control and can be trusted to configure sskatex. Do not make the sskatex gem available to a service with untrusted users.

glebm · 2018-01-31T10:41:32Z

@ccorn I've addressed your comments.

I'd provide one in a follow-up PR if you do not want to touch SsKaTeX parts.

I'm going to take you up on this, thank you.

ccorn · 2018-01-31T10:44:04Z

In doc/math_engine/katex.page, it should IMHO be mentioned where the fonts and CSS are stored, at least with a link to the gem's manual registration section so that e.g. Jekyll users can configure their system appropriately.

glebm · 2018-01-31T10:53:05Z

@ccorn I've added a link to the Assets section in the gem's docs to avoid duplicating any specifics here, because they may get out of date. For example, as Jekyll is a common use case, I'd like to support Automatic Registration for Jekyll in the future as well, if possible.

Aside: if you use jekyll-assets, then automatic registration works (Sprockets without Rails case).

ccorn · 2018-01-31T11:30:45Z

Just mentioning that there are no Rdoc comments in lib/kramdwon/converter/math_engine/katex.rb. But there is really not much to say anyway, and the adjacent itex2mml.rb or ritex.rb (which have very similar structure) are about as sparse.

ccorn · 2018-01-31T11:53:32Z

IMHO, this PR (checked up to 4216c67) now has all required ingredients.
(I'd move the KaTeX in the documentation.template closer to SsKaTeX, leaving the default MathJax at the top of the list, but that's just my taste.)
I have also tried it on a small Jekyll tree with a couple hundred formulas, and it works (after setting the KaTeX assets to those of v0.8.3; I sometimes try other snapshots).

gettalong · 2018-02-03T09:07:28Z

@glebm Thanks for all the work - please squash the commits into one and rebase on current master, then I will merge.

Thanks for your contribution!

This is a simpler all batteries included alternative to the `sskatex` engine.

glebm · 2018-02-03T13:37:22Z

@gettalong Done!

gettalong · 2018-02-03T20:33:30Z

@glebm Thanks - I have merged the commit.

glebm mentioned this pull request Jan 25, 2018

Bug: This gem messes with ExecJS runtime selection ccorn/sskatex#2

Closed

glebm force-pushed the katex branch 3 times, most recently from 21104b4 to 9cae595 Compare January 25, 2018 02:25

glebm force-pushed the katex branch from 9cae595 to f4c8639 Compare January 25, 2018 02:52

glebm force-pushed the katex branch 2 times, most recently from 50dc1b4 to dbb46ba Compare January 25, 2018 03:23

glebm force-pushed the katex branch 2 times, most recently from b2c6794 to 3e73fb1 Compare January 25, 2018 19:41

gettalong self-assigned this Jan 27, 2018

gettalong requested changes Jan 30, 2018

View reviewed changes

glebm force-pushed the katex branch from 52d5b7a to 2f39f79 Compare January 30, 2018 19:33

Adds KaTeX math engine via the 'katex' ruby gem

7e53f8b

This is a simpler all batteries included alternative to the `sskatex` engine.

glebm force-pushed the katex branch from 4216c67 to 7e53f8b Compare February 3, 2018 13:37

gettalong merged commit 7e53f8b into gettalong:master Feb 3, 2018

glebm deleted the katex branch February 3, 2018 23:25

glebm mentioned this pull request Jun 23, 2018

Support parsing at text level KaTeX/KaTeX#604

Open

Adds KaTeX math engine via the 'katex' ruby gem #489

Adds KaTeX math engine via the 'katex' ruby gem #489

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glebm commented Jan 25, 2018

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