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What is a 'semantic predicate' in ANTLR?
... instead of a parser rule) that will match numbers in the range of 0..999. Now in the parser, you'd like to make a distinction between low- and hight numbers (low: 0..500, high: 501..999). This could be done using a disambiguating semantic predicate where you inspect the token next in the stream (in...
SVN: Ignore some directories recursively
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As of subversion 1.8, there is now the svn:global-ignores property which works like svn:ignore but recursively (so set this on your top-level directory)
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Detect backspace in empty UITextField
...essed in the iPhone keyboard on a UITextField that is empty? I want to know when Backspace is pressed only if the UITextField is empty.
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The input is not a valid Base-64 string as it contains a non-base 64 character
...w. Logic is to remove everything after , if data: is present. Bam. Working now.
– Maxime Rouiller
Jun 14 '16 at 13:14
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Drop unused factor levels in a subsetted data frame
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It is a known issue, and one possible remedy is provided by drop.levels() in the gdata package where your example becomes
> drop.levels(subdf)
letters numbers
1 a 1
2 b 2
3 c 3
> levels(dro...
Converting .NET DateTime to JSON [duplicate]
...r, that's fine too, but if that means you're doing substring + validation, now you're into multiple lines of code (hopefully in a separate function) which means more things that can go wrong and more programmer time spent (programmers being more expensive than CPUs).
– gregmac
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How to install plugins to Sublime Text 2 editor?
...me, type in install and press enter, then search for emmet.
EDIT: You can now also press Ctrl + Shift + P right away and use the command 'Install Package Control' instead of following the install instructions. (Tested on Build 3126)
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Can PostgreSQL index array columns?
...tage from the original Berkeley design of Postgres and very hard to change now. And it's generally working just fine. Here is a thread on pgsql-bugs with Tom Lane commenting on this.
Some PostGis functions (like ST_DWithin()) seem to violate this principal, but that is not so. Those functions are r...
How to get C# Enum description from value? [duplicate]
...urn Enumerations.GetEnumDescription((Enum)(object)((TEnum)EnumValue));
}
now I can write:
MyEnum my = MyEnum.HereIsAnother;
string description = my.ToDescription();
System.Diagnostics.Debug.Print(description);
Note: replace "Enumerations" above with your class name
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Create an array with same element repeated multiple times
...always better to avoid growing arrays by appending when possible. If you know the final size, use it.
– Tom Karzes
Aug 8 '16 at 20:01
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