Bug 18604 – Backslash escape (\) for splitting CSS rules into a couple of lines fails in WebKit

• Component: CSS
• Status: RESOLVED INVALID

[jasneet]

I Steps:
Go to 
http://www.hixie.ch/tests/evil/css/css21/contributions/incoming/00003.xht

II Issue:
The text appears red instead of green as backslash parsing fails.

III Conclusion:
issue with backslash parsing

IV Other browsers:
IE7: not ok; link does not open
FF3: ok
Opera9.24: ok

V Nightly tested: 32005

Another link with same issue: 
http://www.hixie.ch/tests/evil/css/css21/contributions/incoming/00006.xht 
(this test passes in Opera)

[Robert Blaut]

I can confirm the bug. It violates the definition of CSS 2.1 CR:
"It is possible to break strings over several lines, for esthetic or other reasons, but in such a case the newline itself has to be escaped with a backslash (\). For instance, the following two selectors are exactly the same:

a[title="a not s\
o very long title"] {/*...*/}
a[title="a not so very long title"] {/*...*/}" [http://www.w3.org/TR/CSS21/syndata.html#strings]

[Robert Blaut]

Created attachment 21458 [details]
minimal test case

[Alexey Proskuryakov]

See also: bug 28885.

[Glenn Adams]

the analysis of this bug is incorrect; in particular, the attached test case and the test from hixie cited below [1] contain a backslash that is OUTSIDE of a string, and NOT in a string;

[1] http://www.hixie.ch/tests/evil/css/css21/contributions/incoming/00003.xht

the text cited below in comment #1 refers to backslash appearing IN a string; the more complete, relevant text from CSS 2.1 is found in Section 4.1.3 [2] which states:

"First, inside a string, a backslash followed by a newline is ignored (i.e., the string is deemed not to contain either the backslash or the newline). Outside a string, a backslash followed by a newline stands for itself (i.e., a DELIM followed by a newline)."

[2] http://www.w3.org/TR/CSS2/syndata.html

so, in fact, the backslash followed by newline that appears in these tests should be treated as the token sequence <DELIM NL>

according to the general grammar in [3], DELIM matches the 'any' non-terminal, so the attached test should parse as two consecutive rulesets:

ruleset <= 'h1 {background: white; color: red}'
ruleset <= '\ zzz, h1 {color: green}'

where in the second ruleset the selector non-terminal matches DELIM IDENT DELIM IDENT

[3] http://www.w3.org/TR/CSS2/syndata.html#tokenization

now, however, the more restrictive grammar in Appendix G [4] does not admit backslash or DELIM as a token in a selector, so consequently, the second ruleset fails to match the selector non-terminal, and thus the entire second statement is treated as a malformed statement and ignored [5]

[4] http://www.w3.org/TR/CSS2/grammar.html
[5] http://www.w3.org/TR/CSS2/syndata.html#parsing-errors

i checked both Opera and FF and both behave the same as WK