To concisely answer your question, everything beneath the LeftHandSideExpression production is a valid LeftHandSideExpression. I think the question you are really asking is: What is a valid LeftHandSideExpression and also assignable? The answer to that is anything that resolves to a Reference which is a well defined concept in the specification. In your example new … Read more
The URL bits of all three of your examples are valid CSS, according to the CSS specification. Note that the spec identifies some characters in a URL which will need to be escaped with a backslash if present in an unquoted URI, such as parentheses, commas, white space characters, single quotes (‘) and double quotes … Read more
You can see one for Perl regexp (displayed a little more in detail here, as posted by edg)
To check if a grammar is LL(1), one option is to construct the LL(1) parsing table and check for any conflicts. These conflicts can be FIRST/FIRST conflicts, where two different productions would have to be predicted for a nonterminal/terminal pair. FIRST/FOLLOW conflicts, where two different productions are predicted, one representing that some production should be … Read more
This is an anonymous function that will run as soon as it is declared. Its parameter is myFunkyAlert and inside the function it will be referenced as the fun variable. The reason we usually write a function like that is to avoid conflicts, due to scoping. Example: var myFunkyAlert = “The funky alert”; (function(fun) { … Read more
My first ugly approach was: allTerms :: Omega T allTerms = do which <- each [ 1,2,3 ] if which == 1 then return A else if which == 2 then do x <- allTerms return $ B x else do x <- allTerms y <- allTerms return $ C x y But then, after … Read more
I needed this for a C# project so here’s the C# port of the Python code mentioned above. Make sure to include using System.Text.RegularExpressions; in your source file. private string GetIndefiniteArticle(string noun_phrase) { string word = null; var m = Regex.Match(noun_phrase, @”\w+”); if (m.Success) word = m.Groups[0].Value; else return “an”; var wordi = word.ToLower(); foreach … Read more
A context free grammar is a grammar which satisfies certain properties. In computer science, grammars describe languages; specifically, they describe formal languages. A formal language is just a set (mathematical term for a collection of objects) of strings (sequences of symbols… very similar to the programming usage of the word “string”). A simple example of … Read more
A symbol table is just a versioned map of id’s to values. This is one solution, using a push and pop of scopes as the versioning mechanism — push a scope on entry of a scope defining rule and pop on exit. package net.certiv.metal.symbol; import java.util.ArrayList; import java.util.LinkedHashMap; import java.util.Map; import net.certiv.metal.types.ScopeType; import net.certiv.metal.util.Strings; public … Read more
Similar thread: Get repeated matches with preg_match_all() Check the chosen answer plus mine might be useful I will duplicate there: From http://www.php.net/manual/en/regexp.reference.repetition.php : When a capturing subpattern is repeated, the value captured is the substring that matched the final iteration. I personally give up and going to do this in 2 steps. EDIT: I see … Read more