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  • Are there any Parsing Expression Grammar (PEG) libraries for Javascript or PHP?

    - by Peter J. Wasilko
    I find myself drawn to the Parsing Expression Grammar formalism for describing domain specific languages, but so far the implementation code I've found has been written in languages like Java and Haskell that aren't web server friendly in the shared hosting environment that my organization has to live with. Does anyone know of any PEG libraries or PackRat Parser Generators for Javascript or PHP? Of course code generators in any languages that can produce Javascript or PHP source code would do the trick.

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  • How to Solve this Error "Cannot convert lambda expression to type 'string' because it is not a deleg

    - by peace
    . I get this error: "Cannot convert lambda expression to type 'string' because it is not a delegate type" - keyword select become underlined in blue Can you please advice. Employee emp = new Employee(); comHandledBySQt.DataSource = from x in emp.GetDataFromTable("1") select new { x.Id, Name = x.FirstName + " " + x.LastName }; comHandledBySQt.DisplayMember = "Name"; comHandledBySQt.ValueMember = "Id"; Above code should displays drop list of employees first name and last name in a combo box

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  • A more elegant way to parse a string with ruby regular expression using variable grouping?

    - by i0n
    At the moment I have a regular expression that looks like this: ^(cat|dog|bird){1}(cat|dog|bird)?(cat|dog|bird)?$ It matches at least 1, and at most 3 instances of a long list of words and makes the matching words for each group available via the corresponding variable. Is there a way to revise this so that I can return the result for each word in the string without specifying the number of groups beforehand? ^(cat|dog|bird)+$ works but only returns the last match separately , because there is only one group.

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  • how to write regular expression using proc in TCL to deal with following pattern ?

    - by Passion
    Hello Guys, I am new to TCL and seeking a help to deal with the following expression. I am getting the i/p string from the user to validate any of these strings below & no others in a line in CLI { GHI GII GJI GKI} and another tricky one is to write regexp to match only the characters which begin with alphabet A & end with B, It also have 1 or more of either YO or OY in between using procedure. Thank you

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  • How can I right a regular expression to check if the 2 properties in an asp.net control have the same name?

    - by xaisoft
    I have the following asp.net custom validator: <asp:CustomValidator runat="server" ClientValidationFunction="valUCRRequired" ID="valUCRRequired" ErrorMessage="Field 7-Date/Time Between is Required" ControlToValidate="DTE_FROM" /> Notice that the ID and ClientValidationFunction have the same value. I want to do a regular expression search where they are the same. Right now, I am just searching for all CustomValidators.

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  • Search tool that uses a grammar rather than regular expression?

    - by Tom Hubbard
    Are there any search tools that allow you to set up a simple token/grammar parsing system that work similar to regular expressions? What we want to do is search our ColdFusion code for queries that do not have cfqueryparams in them. A regular expression gets a bit tough in this situation because I can't keep track of the start tags while looking for something else before getting an end tag. It seems like a parsing system would work more accurately.

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  • Binding to element in WPF: can the Path expression do math?

    - by John
    Hi I'm trying to bind a control to the parent's Height/width property using ElementName and a Path. However, I don't want to bind to the actual height, but to exactly half the height. Can the Path expression do the math? e.g. Path={ActualHeight/2} I couldn't find a way to do that. IS there any other clever approach? Thanks!

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  • How to use Regular Expression to extract information from a HTML webpage?

    - by user569248
    How to use Regular Expression to extract the answer "Here is the answer" from a HTML webpage like this? <b>Last Question:</b> <b>Here is the answer</b> ..:: Update ::.. Thanks everybody! Here is my solution by using BeautifulSoup since I'm using Python framework: response = opener.open(url) the_page = response.read() soup = BeautifulSoup(''.join(the_page)) paraText1 = soup.body.find('div', 'div_id', text = u'Last Question:') if paraText1: answer = paraText1.next

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  • How To? Use an Expression Tree to call a Generic Method when the Type is only known at runtime.

    - by David Williams
    Please bear with me; I am very new to expression trees and lambda expressions, but trying to learn. This is something that I solved using reflection, but would like to see how to do it using expression trees. I have a generic function: private void DoSomeThing<T>( param object[] args ) { // Some work is done here. } that I need to call from else where in my class. Now, normally, this would be be simple: DoSomeThing<int>( blah ); but only if I know, at design time that I am working with an int. When I do not know the type until runtime is where I need the help. Like I said, I know how to do it via reflection, but I would like to do it via expression trees, as my (very limited) understanding is that I can do so. Any suggestions or points to sites where I can get this understanding, preferably with sample code?

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  • How to create a dynamic Linq Join extension method

    - by Royd Brayshay
    There was a library of dynamic Linq extensions methods released as a sample with VS2008. I'd like to extend it with a Join method. The code below fails with a parameter miss match exception at run time. Can anyone find the problem? public static IQueryable Join(this IQueryable outer, IEnumerable inner, string outerSelector, string innerSelector, string resultsSelector, params object[] values) { if (inner == null) throw new ArgumentNullException("inner"); if (outerSelector == null) throw new ArgumentNullException("outerSelector"); if (innerSelector == null) throw new ArgumentNullException("innerSelector"); if (resultsSelector == null) throw new ArgumentNullException("resultsSelctor"); LambdaExpression outerSelectorLambda = DynamicExpression.ParseLambda(outer.ElementType, null, outerSelector, values); LambdaExpression innerSelectorLambda = DynamicExpression.ParseLambda(inner.AsQueryable().ElementType, null, innerSelector, values); ParameterExpression[] parameters = new ParameterExpression[] { Expression.Parameter(outer.ElementType, "outer"), Expression.Parameter(inner.AsQueryable().ElementType, "inner") }; LambdaExpression resultsSelectorLambda = DynamicExpression.ParseLambda(parameters, null, resultsSelector, values); return outer.Provider.CreateQuery( Expression.Call( typeof(Queryable), "Join", new Type[] { outer.ElementType, inner.AsQueryable().ElementType, outerSelectorLambda.Body.Type, innerSelectorLambda.Body.Type, resultsSelectorLambda.Body.Type }, outer.Expression, inner.AsQueryable().Expression, Expression.Quote(outerSelectorLambda), Expression.Quote(innerSelectorLambda), Expression.Quote(resultsSelectorLambda))); } I've now fixed it myself, here's the answer. Please vote it up or add a better one.

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  • Compilation error while compiling an existing code base

    - by brijesh
    Hi, While building an existing code base on Mac OS using its native build setup I am getting some basic strange error while compilation phase. /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/bits/locale_facets.h: In constructor 'std::collate_byname<_CharT::collate_byname(const char*, size_t)': /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/bits/locale_facets.h:1072: error: '_M_c_locale_collate' was not declared in this scope /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/ppc-darwin/bits/messages_members.h: In constructor 'std::messages_byname<_CharT::messages_byname(const char*, size_t)': /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/ppc-darwin/bits/messages_members.h:79: error: '_M_c_locale_messages' was not declared in this scope /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits: At global scope: /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:897: error: 'float __builtin_huge_valf()' cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:897: error: a function call cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:897: error: 'float __builtin_huge_valf()' cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:897: error: a function call cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:899: error: 'float __builtin_nanf(const char*)' cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:899: error: a function call cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:899: error: 'float __builtin_nanf(const char*)' cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:899: error: a function call cannot appear in a constant-expression /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:900: error: field initializer is not constant /Developer/SDKs/MacOSX10.3.9.sdk/usr/include/gcc/darwin/3.3/c++/limits:915: error: field initializer is not constant

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  • Passing in a lambda to a Where statement

    - by sonicblis
    I noticed today that if I do this: var items = context.items.Where(i => i.Property < 2); items = items.Where(i => i.Property > 4); Once I access the items var, it executes only the first line as the data call and then does the second call in memory. However, if I do this: var items = context.items.Where(i => i.Property < 2).Where(i => i.Property > 4); I get only one expression executed against the context that includes both where statements. I have a host of variables that I want to use to build the expression for the linq lambda, but their presence or absence changes the expression such that I'd have to have a rediculous number of conditionals to satisfy all cases. I thought I could just add the Where() statements as in my first example above, but that doesn't end up in a single expression that contains all of the criteria. Therefore, I'm trying to create just the lambda itself as such: //bogus syntax if (var1 == "something") var expression = Expression<Func<item, bool>>(i => i.Property == "Something); if (var2 == "somethingElse") expression = expression.Where(i => i.Property2 == "SomethingElse"); And then pass that in to the where of my context.Items to evaluate. A) is this right, and B) if so, how do you do it?

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  • Creating a sort function for a generic list

    - by Andrey
    I have a method for sorting generic lists by the object fields: public static IQueryable<T> SortTable<T>(IQueryable<T> q, string sortfield, bool ascending) { var p = Expression.Parameter(typeof(T), "p"); if (typeof(T).GetProperty(sortfield).PropertyType == typeof(int?)) { var x = Expression.Lambda<Func<T, int?>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } else if (typeof(T).GetProperty(sortfield).PropertyType == typeof(int)) { var x = Expression.Lambda<Func<T, int>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } else if (typeof(T).GetProperty(sortfield).PropertyType == typeof(DateTime)) { var x = Expression.Lambda<Func<T, DateTime>>(Expression.Property(p, sortfield), p); if (ascending) q = q.OrderBy(x); else q = q.OrderByDescending(x); } // many more for every type return q; } Is there any way I can collapse those ifs to a single generic statement? The main problem is that for the part Expression.Lambda<Func<T, int>> I am not sure how to write it generically.

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  • Can I strictly evaluate a boolean expression stored as a string in Java?

    - by D Lawson
    I would like to be able to evaluate an boolean expression stored as a string, like the following: "hello" == "goodbye" && 100 < 101 I know that there are tons of questions like this on SO already, but I'm asking this one because I've tried the most common answer to this question, BeanShell, and it allows for the evaluation of statements like this one "hello" == 100 with no trouble at all. Does anyone know of a FOSS parser that throws errors for things like operand mismatch? Or is there a setting in BeanShell that will help me out? I've already tried Interpreter.setStrictJava(true). Here's the code that I'm using currently: Interpreter interpreter = new Interpreter(); interpreter.setStrictJava(true); String testableCondition = "100 == \"hello\""; try { interpreter.eval("boolean result = ("+ testableCondition + ")"); System.out.println("result: "+interpreter.get("result")); if(interpreter.get("result") == null){ throw new ValidationFailure("Result was null"); } } catch (EvalError e) { e.printStackTrace(); throw new ValidationFailure("Eval error while parsing the condition"); }

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  • How to convert int to char in JSP expression language?

    - by james.bunt
    I need to display incremented single characters to denote footnotes in a table of data in a JSP. In Java I would normally have a char variable and just increment it, or convert an int to a char by casting it (e.g. (char)(i + 97) to convert a 0-based index to a-z). I can't figure out how to do this in expression language short of writing my own JSTL function. Does anyone know how to convert an int to char in EL? Or how to increment a char variable in EL? Or possibly even a better technique to do what I'm trying to do in JSP/EL? Example of what I need to be able to produce: a mydata b myotherdata ... a first footnote b second footnote

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  • How do you match only valid roman numerals with a regular expression?

    - by Daniel Magliola
    Thinking about my other problem, i decided I can't even create a regular expression that will match roman numerals (let alone a context-free grammar that will generate them) The problem is matching only valid roman numerals. Eg, 990 is NOT "XM", it's "CMXC" My problem in making the regex for this is that in order to allow or not allow certain characters, I need to look back. Let's take thousands and hundreds, for example. I can allow M{0,2}C?M (to allow for 900, 1000, 1900, 2000, 2900 and 3000). However, If the match is on CM, I can't allow following characters to be C or D (because I'm already at 900). How can I express this in a regex? If it's simply not expressible in a regex, is it expressible in a context-free grammar? Thanks for any pointers!

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  • WPF: Is it possible to nest TreeView items with a binding expression?

    - by John Gietzen
    Lets say I have the following data: <XmlDataProvider x:Key="Values"> <x:XData> <folder name="C:"> <folder name="stuff" /> <folder name="things" /> <folder name="windows"> <folder name="system32" /> </folder> </folder> </x:XData> </XmlDataProvider> How can I get that into a treeview? I can't seem to grok hierarchical binding... I know that I can get it in there in C# code, but I wanted to do it with a binding expression.

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