Add handle recursive expressions

[borodichAlex]

• tests and linter show no problems (npm t)
• tests are added/updated for bug fixes and new features
• code is properly formatted (npm run fmt)
• description of changes is added in CHANGELOG.md

Сloses #5

[tshemsedinov]

We can't throw on a first recursion iteration, because expressions can contain conditions and we can exit recursion. Here is another test case to show exit from recursion. But this implementation throws.

Instead of call chain we can just use try/catch to intercept RangeError: Maximum call stack size exceeded or can use array to hold call stack and count cell name in this array to add limitation for throwing an error after 1000 recursion steps or so. @borodichAlex

[borodichAlex]

We can't throw on a first recursion iteration, because expressions can contain conditions and we can exit recursion. Here is another test case to show exit from recursion. But this implementation throws.

Instead of call chain we can just use try/catch to intercept RangeError: Maximum call stack size exceeded or can use array to hold call stack and count cell name in this array to add limitation for throwing an error after 1000 recursion steps or so. @borodichAlex

I implemented the second option. Only I used Map instead of Array.
Limit in 1000 steps is very much. 'RangeError: Maximum call stack size exceeded' is throw before than it. Can we will set limit in 100 steps?

[borodichAlex]

How does assignment work in this case? A1 = 1
When I run this code, I don't see to change value in A1.

When I run this code, I don't see to change value in A1. But I see new A1 property in end of object.

<ref *1> Sheet {
  data: Map(2) { 'A1' => 100, 'B1' => 2 },
  expressions: Map(3) {
    'C1' => [Function (anonymous)],
    'D1' => [Function (anonymous)],
    'E1' => [Function (anonymous)]
  },
  values: [Circular *1],
  context: [Circular *1],
  cells: [Circular *1],
  callChain: Map(3) { 'E1' => 1, 'D1' => 1, 'C1' => 1 },
  A1: 1
}

@tshemsedinov

[borodichAlex]

I'm not sure. But case above is don't work correctly.
So, I added test case which exit from recursive expression but I use Math.random instead of Assigment (A1 = 1) 51f9230

@tshemsedinov

[blackakula]

Math.random is not stable for use in unit tests. Of course, it is a low probability, that you will get 100 "one"s results in a row, but still, one of 2^100 test runs may fail with message:

Exit from recursive expression use Math.random ........ 0/1
  not ok fail
    --- wanted                                                                                     
    +++ found                                                                                      
    -[null]                                                                                        
    +{                                                                                             
    +  "message": "Recursive expression error"                                                     
    +  "name": "Error"                                                                             
    +  "stack": "Error: Recursive expression error                                                 

[borodichAlex]

Oh, ok, thanks
I used this test to show 'exit from recursive expression' (only math.random came to mind)
when somebody will say how assignment in expression is work to I fix previous test

[tshemsedinov]

We can use F1 as a counter, increment it each C1 cell calculation triggered and exit recursion after certain limit

[borodichAlex]

We can use F1 as a counter, increment it each C1 cell calculation triggered and exit recursion after certain limit

How we can change cell's value? @tshemsedinov
I written about it above

[tshemsedinov]

Suggested change

	sheet.cells['C1'] = '= A1 *E1';
	sheet.cells['D1'] = '=C1+8';
	sheet.cells['E1'] = '=D1/2';
	sheet.cells['C1'] = '= A1 * E1';
	sheet.cells['D1'] = '= C1 + 8';
	sheet.cells['E1'] = '= D1 / 2';