excelize: support nested calc for if formula

[bailantaotao]

PR Details

Support nested calc for if formula

Description

if formula can be placed with formula, e.q. ROUND

Related Issue

#987

Motivation and Context

it solves the problem for nested formula doesn't calculation

How Has This Been Tested

MAC os 11.5
golang 1.16.6

Types of changes

• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.

[codecov-commenter]

Codecov Report

Merging #988 (f44fc43) into master (43a057b) will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@           Coverage Diff           @@
##           master     #988   +/-   ##
=======================================
  Coverage   97.48%   97.48%           
=======================================
  Files          31       31           
  Lines       11085    11096   +11     
=======================================
+ Hits        10806    10817   +11     
  Misses        155      155           
  Partials      124      124           

Flag	Coverage Δ
unittests	97.48% <100.00%> (+<0.01%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
calc.go	97.93% <100.00%> (+<0.01%)	⬆️

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[xuri]

LGTM, thanks for your PR.