Fix throw exception by \,

[rstm-sf]

Fix throw exception by \, (#139 )
Add test for \,

• Closes \thinspace exception #139.

[rstm-sf]

Or, there seems to be another solution -- make non-static

[ForNeVeR]

Honestly I fail to understand how is this supposed to fix any errors. Could you please explain? What was the initial issue?

[rstm-sf]

Initial issue was that a value is added on an existing key
https://github.com/ForNeVeR/wpf-math/blob/351e010a3e76a82001dc337e822d82ef8012321f/src/WpfMath/TexPredefinedFormulaParser.cs#L177

But these are just the consequences of another issue -- argValueParsers and actionParsers is static
https://github.com/ForNeVeR/wpf-math/blob/351e010a3e76a82001dc337e822d82ef8012321f/src/WpfMath/TexPredefinedFormulaParser.cs#L18-L19

In case of parsing \,, we get into the next loop
https://github.com/ForNeVeR/wpf-math/blob/351e010a3e76a82001dc337e822d82ef8012321f/src/WpfMath/TexPredefinedFormulaParser.cs#L111-L122

where calling parse \thinspace
https://github.com/ForNeVeR/wpf-math/blob/351e010a3e76a82001dc337e822d82ef8012321f/src/WpfMath/Data/PredefinedTexFormulas.xml#L48-L50

in CreateTeXFormulaParser.Parse(SourceSpan, XElement)
https://github.com/ForNeVeR/wpf-math/blob/351e010a3e76a82001dc337e822d82ef8012321f/src/WpfMath/TexPredefinedFormulaParser.cs#L169-L170

and CreateTeXFormulaParser.TempFormulas (for \,) assigned the reference to the another dictionary. And, after returning the result of parsing \thinspace, the reference to another dictionary is returned back, and the worker is over
https://github.com/ForNeVeR/wpf-math/blob/351e010a3e76a82001dc337e822d82ef8012321f/src/WpfMath/TexPredefinedFormulaParser.cs#L118

[rstm-sf]

@ForNeVeR, hello!

Do you think there is a better way to solve the problem, or did I explain it poorly?

[ForNeVeR]

@rstm-sf I am sorry for delay, I was rather occupied (happens to me triple a year these days), so I haven't properly reviewed these changes yet. Consider the ball on my side now.

[rstm-sf]

@ForNeVeR ok, np ;)

[rstm-sf]

Hmm, it was able to pending, but I still want it to be \,

[ForNeVeR]

I still very much dislike the whole PredefinedFormulas business. This PR doesn't solve the root cause of the issue (it is a bit deeper), but I think it makes the resulting behavior more correct.

I tend to approve that and leave everything else for #180.

[ForNeVeR]

Thanks for your contribution!