This PR came about as I pondered how feasible it was to change the default escape character from backslash to null string, since the latter emulates Excel's own actions. Also, surveying issues relating to CSV, it seems that people are often in a situation where the current defaults aren't optimal for them (e.g. they are in a region where semicolon rather than comma is a better default delimiter). My case and that case can both be handled by methods after a reader is constructed. However, the issues also show that many use `IOFactory::load` rather than `new Csv()`, and the methods to affect the defaults are not available in that case.
Adding a static callback that can be invoked by the constructor addresses all these problems. This can be set as part of the user application's normal initialization, and no special attention needs to be paid to CSV loads thereafter, no matter how they are invoked.
This also makes it feasible to use 'guess' as inputEncoding, by providing a new setFallbackEncoding (default CP1252) method to use if none of the heuristic tests pass. There was already the ability to guess the encoding before `$reader->load()`, but not before `IOFactory::load`.
Almost all typehints in Reader/Csv and Reader/Csv/Delimiter are now part of the function signature rather than in the DocBlock. The exceptions are one method in Delimiter which uses a `resource` parameter, and the `canRead` and `load` methods, which must match the signature in IOFactory. I will look into changing those later.
The Csv Reader tests are moved into their own directory. All Phpstan baseline entries involving Csv Reader are eliminated.
Fix for #2082. Xlsx Writer was writing a cell which is a formula which evaluates to boolean false as an empty XML tag. This is okay for Excel 365, but not for Excel 2016-. Change to write the tag as a value of 0 instead, which works for all Excel releases. Add test.
19_NamedRange.php was not changed to use absolute addressing when that was introduced to Named Ranges. Consequently, the output from this sample has been wrong ever since, for both Xls and Xlsx.
There was an additional problem with Xls. It appears that the Xls Writer Parser does not parse multiple concatenations using the ampersand operator correctly. So, `=B1+" "+B2` was parsed as `=B1+" "`. I believe that this is due to ampersand being treated as a condition rather than an operator; `A1>A2>A3` isn't valid, but `A1&A2&A3` is. My original PR (#1992, which I will now close) only partially resolved this, but I think moving ampersand handling from `condition` to `expression` is fully successful.
There are already more than ample tests for Named Ranges, so I did not add a new one for that purpose. However, I did add a new test for the Xls parser problem.
oleibman
Adrien Crivelli
MarkBaker
Tanguy De Taxis
xandros15