Introduce ConstraintExpression

[Dreamescaper]

Created classes ConstraintExpression and ConstraintPartExpression, and moved methods from AssertExpressionHelper there.

ConstraintExpression represents the whole constraint expression (e.g. Is.Not.Null & Is.EqualTo("1").Or.EqualTo("A").IgnoreCase), and has property ConstraintPartExpression[] ConstraintParts.

ConstraintPartExpression represents single part of constraint expression, which are combined using binary operators (| or &) or constraint expression operator properties (.And or .Or).
(e.g. Is.Not.Null, Is.EqualTo("1"), EqualTo("A").IgnoreCase)
ConstraintPartExpression has three main properties:

• PrefixExpressions - expressions which go before actual constraint method/property expression (Not, None, Count, Property(...) etc).
• RootExpression - actual constraint method/property expression (Null, EqualTo("1") etc.)
• SuffixExpressions - expressions which go after actual constraint expression (IgnoreCase, Within(...), Using(...) etc)

Created draft PR to show idea and for discussion. If suggested approach makes sense, I will add tests, add docs, etc.

[mikkelbu]

Thanks for supplying this @Dreamescaper. I'm been busy due to the holidays, but hopefully I can give this a proper look tomorrow.

[mikkelbu]

At first when I read the above description I thought that ConstraintPartExpression should be named ConstraintExpressionPart, but looking through the code I think that ConstraintPartExpression is the right choice.

I like that we are removing some of the technical details from the analyzers and into classes that represents concepts, and I think that this is a step in the right direction, so I very much think that the approach makes sense (and hopefully we can simplify more in later PRs).

I've left some minor comments - mostly nitpick.

[Dreamescaper]

Updated PR with tests, added docs, minor changes.

Happy New Year :)

[mikkelbu]

Also Happy new year from my end. I'll take a look at this PR next year :)

[mikkelbu]

I just corrected one typo. Otherwise, I think it looks great. Thanks