Fix interpolation edge cases with escapes

[mgreter]

Fixes #1115

[coveralls]

Coverage increased (+0.04%) to 80.32% when pulling 8e04865 on mgreter:bugfix/issue_1115 into f90a1b7 on sass:master.

[xzyfer]

👍

[xzyfer]

I've created the spec for this issue - sass/sass-spec#340

This PR is an improvement on the current behaviour, however it still fails this spec.

[xzyfer]

So I've spent all weekend getting my head around our string handling code, and feel it's already over complicated. I'm super reluctant to add another flag to our String AST nodes i.e. String::sass_fix_1291

I wonder if we can tackle this case entirely in the Eval phase instead?

[coveralls]

Coverage decreased (-0.03%) to 80.29% when pulling 08a00b5 on mgreter:bugfix/issue_1115 into daf9163 on sass:master.

[mgreter]

@xzyfer I fully agree, but the handling by ruby sass is pretty complex and AFAIR I was able to get rid of quite a few flags with my last refactoring. But I pretty much gave up to understand how ruby sass internally handles interpolations and escape sequences (We keep finding new edge cases all the time). So for the time beeing I really only see the way to implement specific code paths for these cases, until we have a good enough spec suite to tackle another refactoring. My last commit should solve the reported issues, but it is far away from beeing pretty. I'm having problems coming up with ideas how to name all those different escape/unescape functions, but I currently don't see a way to get rid of them.

[coveralls]

Coverage decreased (-0.02%) to 80.3% when pulling e771bc5 on mgreter:bugfix/issue_1115 into daf9163 on sass:master.

[mgreter]

Btw. I have used this extended test case:

foo {
    content: "x\79";
    content: "#{x}\79";
    content: "x\0\1\2\3\4\5\6\7\8\9\7a";
    content: "#{x}\0\1\2\3\4\5\6\7\8\9\7a";
    content: "x#{\0\1\2\3\4\5\6\7\8\9}\7a";
    content: "x\a\A\b\B\c\C\d\D\e\E\f\F\g\G\7a";
    content: "#{x}\a\A\b\B\c\C\d\D\e\E\f\F\g\G\7a";
    content: "x#{\a\A\b\B\c\C\d\D\e\E\f\F\g\G}\7a";
}

baz {
    // another regression
    content: "xy#{\7a}";
}

[coveralls]

Coverage decreased (-0.06%) to 80.26% when pulling d928f7d on mgreter:bugfix/issue_1115 into daf9163 on sass:master.

[coveralls]

Coverage decreased (-0.06%) to 80.26% when pulling 8265b6b on mgreter:bugfix/issue_1115 into daf9163 on sass:master.

[coveralls]

Coverage decreased (-0.05%) to 80.27% when pulling 7df70e6 on mgreter:bugfix/issue_1115 into daf9163 on sass:master.