language implementation - Page 680

Hashtable is that fast

- by Costa

Hi s[0]*31^(n-1) + s[1]*31^(n-2) + ... + s[n-1]. Is the hash function of the java string, I assume the rest of languages is similar or close to this implementation. If we have hash-Table and a list of 50 elements. each element is 7 chars ABCDEF1, ABCDEF2, ABCDEF3..... ABCDEFn If each bucket of hashtable contains 5 strings (I think this function will make it one string per bucket, but let us assume it is 5). If we call col.Contains("ABCDEFn"); // will do 6 comparisons and discover the difference on the 7th. The hash-table will take around 70 operations (multiplication and additions) to get the hashcode and to compare with 5 strings in bucket. and BANG it found. For list it will take around 300 comparisons to find it. for the case that there is only 10 elements, the list will take around 70 operations but the Hashtable will take around 50 operations. and note that hashtable operations are more time consuming (it is multiplications). I conclude that HybirdDictionary in .Net probably is the best choice for that most cases that require Hashtable with unknown size, because it will let me use a list till the list becomes more than 10 elements. still need something like HashSet rather than a Dictionary of keys and values, I wonder why there is no HybirdSet!! So what do u think? Thanks

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How to develop Online Shopping Portal Application using PHP ?

- by Sarang

I do not know PHP & I have to develop a Shopping Portal with following Definition : Scenario: Online Shopping Portal XYZ.com wants to create an online shopping portal for managing its registered customers and their shopping. The customers need to register themselves first before they do shopping using the shopping portal. However, everyone, whether registered or not, can view the various products along with the prices listed in the portal. The registered customers, after logging in, are allowed to place order for one or more products from the products listed in the portal. Once the order is placed, the customer gets a reference order number and the order status should be “order in process”. The customers can track their order using the given reference number. The management of XYZ.com should be able to modify the order status of a particular reference order number to “shipped” once the products are shipped to the shipping address entered by the customer at the time of placing the order. The Functionalities required are : Create the interface for the XYZ.com shopping portal using HTML/XHTML and CSS. Implement the client side validations using JavaScript. Create the tables using MySQL. Implement the functionality using the server side scripting language, PHP. Integrate all the above tasks and make the XYZ.com shopping portal functional. How do I develop this application with following proper steps of development ?

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"Access is denied" by executing .hta file with JScript on Windows XP x64

- by mem64k

I have a simple HTML (as HTA) application that shows strange behavior on Windows XP x64 machine. I getting periodically (not every time) error message "Access is denied." when i start the application. The same application on Windows XP 32bit runs just fine... Does somebody has any idea or explanation? Error message: Line: 18 Char: 6 Error: Access is denied. Code: 0 URL: file:///D:/test_j.hta Here is the code of my "test_j.hta": <html> <head> <title>Test J</title> <HTA:APPLICATION ID="objTestJ" APPLICATIONNAME="TestJ" SCROLL="no" SINGLEINSTANCE="yes" WINDOWSTATE="normal" > <script language="JScript"> function main() { //window.alert("test"); window.resizeTo(500, 300); } function OnExit() { window.close(); } </script> </head> <body onload="main()"> <input type="button" value="Exit" name="Exit" onClick="OnExit()" title="Exit"> </body> </html>

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Changing <object> height and width works in Chrome but not Firefox or IE. Why?

- by Michael Hopkins

I am making a site with two Youtube videos. These videos use the raw embed code from Youtube. The site's design doesn't work with any of the default Youtube sizes, so I am writing code to automatically resize the video. Here is my code. There will never be more than these two tags on the page, otherwise I'd do a better job selecting the videos. <script language='JavaScript' type='text/javascript'> var x=document.getElementsByTagName('object'); x.[0].width='350'; x.[0].height='350'; x.[1].width='350'; x.[1].height='350'; </script> For reference, here's a sample default Youtube embed that the code might alter: <object width="480" height="385"> <param name="movie" value="http://www.youtube-nocookie.com/v/zSgiXGELjbc&hl=en_US&fs=1&rel=0"></param> <param name="allowFullScreen" value="true"></param> <param name="allowscriptaccess" value="always"></param> <embed src="http://www.youtube-nocookie.com/v/zSgiXGELjbc&hl=en_US&fs=1&rel=0" type="application/x-shockwave-flash" allowscriptaccess="always" allowfullscreen="true" width="480" height="385"></embed> </object> In Chrome, the video players sit perfectly in a 350x350 box. In IE and FF (latest versions), the videos are the unchanged, normal size. I cannot find anything in Google that explans why this won't work. I have tried using setattribute, for loops, adjusting both and , single-quotes and double-quotes, etc. Any ideas what is going wrong?

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How do I attach a link (to a View) to an image in ASP.NET MVC?

- by Ryan Pitts

Ok, so here is my situation. I am creating a web application using ASP.NET MVC 2 using the C# language. I have programmed in HTML, CSS, and PHP for several years and I am very new to ASP.NET. The part that I am having trouble with is the image gallery. The setup: I have a link on the navigation bar that goes to a "Galleries" page. This page will show a list of galleries. Each gallery has a title, an image, and a description. All of this information is pulled from an XML file. I'm using the XML file like a database. I wanted to use this method so that i could easily update the list of galleries and have the updated XML file automatically be reflected by the website. Now, the galleries should link to an "Images" page. This page will display a list of images within the gallery based on what gallery was selected. This page will also pull from an XML file. The problem: I cannot seem to attach a dynamic link to the image? I am also stuck and not sure how to get the correct View to display. I know I need to do something with the controllers and models, right? I have some code if needed? I would greatly appreciate any help or direction for this! Thanks!

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Rtti data manipulation and consistency in Delphi 2010

- by Coco

Has anyone an idea, how I can make TValue using a reference to the original data? In my serialization project, I use (as suggested in XML-Serialization) a generic serializer which stores TValues in an internal tree-structure (similar to the MemberMap in the example). This member-tree should also be used to create a dynamic setup form and manipulate the data. My idea was to define a property for the Data: TDataModel <T> = class {...} private FData : TValue; function GetData : T; procedure SetData (Value : T); public property Data : T read GetData write SetData; end; The implementation of the GetData, SetData Methods: procedure TDataModel <T>.SetData (Value : T); begin FData := TValue.From <T> (Value); end; procedure TDataModel <T>.GetData : T; begin Result := FData.AsType <T>; end; Unfortunately, the TValue.From method always makes a copy of the original data. So whenever the application makes changes to the data, the DataModel is not updated and vice versa if I change my DataModel in a dynamic form, the original data is not affected. Sure I could always use the Data property before and after changing anything, but as I use lot of Rtti inside my DataModel, I do not realy want to do this anytime. Perhaps someone has a better suggestion?

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How do common web frameworks (Django, Rails, Symfony, etc) handle multiple instances of the same plu

- by Steven Wei

Do any of the popular web frameworks solve this problem well? Here's an example: suppose you're running one of these web frameworks and you want to install a blog plugin. Except instead of a single blog, you need to run two separate instances of the blog plugin, and you want to keep them segregated. Or say you want to install multiple instances of a user authentication plugin, because you want to segregate your administrative users from your customer user accounts. Or say you want to install multiple instances of a wiki plugin for different parts of your site, or multiple instances of a comments plugin, or whatever else. It seems to me that at the basic level, each instance of plugin would need to be able to configured with a different set of database tables, and would need to be 'installed' at a different URL path. My experience is mostly with Django and Symfony, and I haven't seen a clean solution to this problem in either of them. They both tend to assume that each plugin (or app, in Django's case) is only ever going to be installed once. I'm curious if the Rails folks have figured out a clean solution to this problem, or any other framework authors (in any language). And if you were going to design a solution to this problem, what would it look like?

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Recursive QuickSort suffering a StackOverflowException -- Need fresh eyes

- by jon

I am working on a Recursive QuickSort method implementation in a GenericList Class. I will have a second method that accepts a compareDelegate to compare different types, but for development purposes I'm sorting a GenericList<int I am recieving stackoverflow areas in different places depending on the list size. I've been staring at and tracing through this code for hours and probably just need a fresh pair of (more experienced)eyes. Definitely wanting to learn why it is broken, not just how to fix it. public void QuickSort() { int i, j, lowPos, highPos, pivot; GenericList<T> leftList = new GenericList<T>(); GenericList<T> rightList = new GenericList<T>(); GenericList<T> tempList = new GenericList<T>(); lowPos = 1; highPos = this.Count; if (lowPos < highPos) { pivot = (lowPos + highPos) / 2; for (i = 1; i <= highPos; i++) { if (this[i].CompareTo(this[pivot]) <= 0) leftList.Add(this[i]); else rightList.Add(this[i]); } leftList.QuickSort(); rightList.QuickSort(); for(i=1;i<=leftList.Count;i++) tempList.Add(leftList[i]); for(i=1;i<=rightList.Count;i++) tempList.Add(rightList[i]); this.items = tempList.items; this.count = tempList.count; } }

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Spring Integration 1.0 RC2: Streaming file content?

- by gdm

I've been trying to find information on this, but due to the immaturity of the Spring Integration framework I haven't had much luck. Here is my desired work flow: New files are placed in an 'Incoming' directory Files are picked up using a file:inbound-channel-adapter The file content is streamed, N lines at a time, to a 'Stage 1' channel, which parses the line into an intermediary (shared) representation. This parsed line is routed to multiple 'Stage 2' channels. Each 'Stage 2' channel does its own processing on the N available lines to convert them to a final representation. This channel must have a queue which ensures no Stage 2 channel is overwhelmed in the event that one channel processes significantly slower than the others. The final representation of the N lines is written to a file. There will be as many output files as there were routing destinations in step 4. *'N' above stands for any reasonable number of lines to read at a time, from [1, whatever I can fit into memory reasonably], but is guaranteed to always be less than the number of lines in the full file. How can I accomplish streaming (steps 3, 4, 5) in Spring Integration? It's fairly easy to do without streaming the files, but my files are large enough that I cannot read the entire file into memory. As a side note, I have a working implementation of this work flow without Spring Integration, but since we're using Spring Integration in other places in our project, I'd like to try it here to see how it performs and how the resulting code compares for length and clarity.

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Most Elegant Way to write isPrime in java

- by Anantha Kumaran

public class Prime { public static boolean isPrime1(int n) { if (n <= 1) { return false; } if (n == 2) { return true; } for (int i = 2; i <= Math.sqrt(n) + 1; i++) { if (n % i == 0) { return false; } } return true; } public static boolean isPrime2(int n) { if (n <= 1) { return false; } if (n == 2) { return true; } if (n % 2 == 0) { return false; } for (int i = 3; i <= Math.sqrt(n) + 1; i = i + 2) { if (n % i == 0) { return false; } } return true; } } public class PrimeTest { public PrimeTest() { } @Test public void testIsPrime() throws IllegalArgumentException, IllegalAccessException, InvocationTargetException { Prime prime = new Prime(); TreeMap<Long, String> methodMap = new TreeMap<Long, String>(); for (Method method : Prime.class.getDeclaredMethods()) { long startTime = System.currentTimeMillis(); int primeCount = 0; for (int i = 0; i < 1000000; i++) { if ((Boolean) method.invoke(prime, i)) { primeCount++; } } long endTime = System.currentTimeMillis(); Assert.assertEquals(method.getName() + " failed ", 78498, primeCount); methodMap.put(endTime - startTime, method.getName()); } for (Entry<Long, String> entry : methodMap.entrySet()) { System.out.println(entry.getValue() + " " + entry.getKey() + " Milli seconds "); } } } I am trying to find the fastest way to check whether the given number is prime or not. This is what is finally came up with. Is there any better way than the second implementation(isPrime2).

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Circular dependency with generics

- by devoured elysium

I have defined the following interface: public interface IStateSpace<State, Action> where State : IState where Action : IAction<State, Action> // <-- this is the line that bothers me { void SetValueAt(State state, Action action); Action GetValueAt(State state); } Basically, an IStateSpace interface should be something like a chess board, and in each position of the chess board you have a set of possible movements to do. Those movements here are called IActions. I have defined this interface this way so I can accommodate for different implementations: I can then define concrete classes that implement 2D matrix, 3D matrix, graphs, etc. public interface IAction<State, Action> { IStateSpace<State, Action> StateSpace { get; } } An IAction, would be to move up(this is, if in (2, 2) move to (2, 1)), move down, etc. Now, I'll want that each action has access to a StateSpace so it can do some checking logic. Is this implementation correct? Or is this a bad case of a circular dependence? If yes, how to accomplish "the same" in a different way? Thanks

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Reversible numerical calculations in Prolog

- by user8472

While reading SICP I came across logic programming chapter 4.4. Then I started looking into the Prolog programming language and tried to understand some simple assignments in Prolog. I found that Prolog seems to have troubles with numerical calculations. Here is the computation of a factorial in standard Prolog: f(0, 1). f(A, B) :- A > 0, C is A-1, f(C, D), B is A*D. The issues I find is that I need to introduce two auxiliary variables (C and D), a new syntax (is) and that the problem is non-reversible (i.e., f(5,X) works as expected, but f(X,120) does not). Naively, I expect that at the very least C is A-1, f(C, D) above may be replaced by f(A-1,D), but even that does not work. My question is: Why do I need to do this extra "stuff" in numerical calculations but not in other queries? I do understand (and SICP is quite clear about it) that in general information on "what to do" is insufficient to answer the question of "how to do it". So the declarative knowledge in (at least some) math problems is insufficient to actually solve these problems. But that begs the next question: How does this extra "stuff" in Prolog help me to restrict the formulation to just those problems where "what to do" is sufficient to answer "how to do it"?

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Why does this program take up so much memory?

- by Adrian

I am learning Objective-C. I am trying to release all of the memory that I use. So, I wrote a program to test if I am doing it right: #import <Foundation/Foundation.h> #define DEFAULT_NAME @"Unknown" @interface Person : NSObject { NSString *name; } @property (copy) NSString * name; @end @implementation Person @synthesize name; - (void) dealloc { [name release]; [super dealloc]; } - (id) init { if (self = [super init]) { name = DEFAULT_NAME; } return self; } @end int main (int argc, const char * argv[]) { NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init]; Person *person = [[Person alloc] init]; NSString *str; int i; for (i = 0; i < 1e9; i++) { str = [NSString stringWithCString: "Name" encoding: NSUTF8StringEncoding]; person.name = str; [str release]; } [person release]; [pool drain]; return 0; } I am using a mac with snow leopard. To test how much memory this is using, I open Activity Monitor at the same time that it is running. After a couple of seconds, it is using gigabytes of memory. What can I do to make it not use so much?

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Getting random record from database with group by

- by Saif Bechan

Hello i have a question on picking random entries from a database. I have 4 tables, products, bids and autobids, and users. Products ------- id 20,21,22,23,24(prime_key) price........... etc........... users ------- id(prim_key) name user1,user2,user3 etc bids ------- product_id user_id created autobids -------- user_id product_id Now a multiple users can have an autobid on an product. So for the next bidder I want to select a random user from the autobid table example of the query in language: for each product in the autobid table I want a random user, which is not the last bidder. On product 20 has user1,user2,user3 an autobidding. On product 21 has user1,user2,user3 an autobidding Then I want a resultset that looks for example like this 20 – user2 21 – user3 Just a random user. I tried miximg the GOUP BY (product_id) and making it RAND(), but I just can't get the right values from it. Now I am getting a random user, but all the values that go with it don't match. Can someone please help me construct this query, I am using php and mysql

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NSOperations or NSThread for bursts of smaller tasks that continuously cancel each other?

- by RickiG

Hi I would like to see if I can make a "search as you type" implementation, against a web service, that is optimized enough for it to run on an iPhone. The idea is that the user starts typing a word; "Foo", after each new letter I wait XXX ms. to see if they type another letter, if they don't, I call the web service using the word as a parameter. The web service call and the subsequent parsing of the result I would like to move to a different thread. I have written a simple SearchWebService class, it has only one public method: - (void) searchFor:(NSString*) str; This method tests if a search is already in progress (the user has had a XXX ms. delay in their typing) and subsequently stops that search and starts a new one. When a result is ready a delegate method is called: - (NSArray*) resultsReady; I can't figure out how to get this functionality 'threaded'. If I keep spawning new threads each time a user has a XXX ms. delay in the typing I end up in a bad spot with many threads, especially because I don't need any other search, but the last one. Instead of spawning threads continuously, I have tried keeping one thread running in the background all the time by: - (void) keepRunning { NSAutoreleasePool *pool = [[NSAutoreleasePool alloc] init]; SearchWebService *searchObj = [[SearchWebService alloc] init]; [[NSRunLoop currentRunLoop] run]; //keeps it alive [searchObj release]; [pool release]; } But I can't figure out how to access the "searchFor" method in the "searchObj" object, so the above code works and keeps running. I just can't message the searchObj or retrieve the resultReady objects? Hope someone could point me in the right direction, threading is giving me grief:) Thank you.

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Problem with Boost::Asio for C++

- by Martin Lauridsen

Hi there, For my bachelors thesis, I am implementing a distributed version of an algorithm for factoring large integers (finding the prime factorisation). This has applications in e.g. security of the RSA cryptosystem. My vision is, that clients (linux or windows) will download an application and compute some numbers (these are independant, thus suited for parallelization). The numbers (not found very often), will be sent to a master server, to collect these numbers. Once enough numbers have been collected by the master server, it will do the rest of the computation, which cannot be easily parallelized. Anyhow, to the technicalities. I was thinking to use Boost::Asio to do a socket client/server implementation, for the clients communication with the master server. Since I want to compile for both linux and windows, I thought windows would be as good a place to start as any. So I downloaded the Boost library and compiled it, as it said on the Boost Getting Started page: bootstrap .\bjam It all compiled just fine. Then I try to compile one of the tutorial examples, client.cpp, from Asio, found (here.. edit: cant post link because of restrictions). I am using the Visual C++ compiler from Microsoft Visual Studio 2008, like this: cl /EHsc /I D:\Downloads\boost_1_42_0 client.cpp But I get this error: /out:client.exe client.obj LINK : fatal error LNK1104: cannot open file 'libboost_system-vc90-mt-s-1_42.lib' Anyone have any idea what could be wrong, or how I could move forward? I have been trying pretty much all week, to get a simple client/server socket program for c++ working, but with no luck. Serious frustration kicking in. Thank you in advance.

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XMLHttpRequst return null on Chrome

- by BoltBait

I have the following code that works fine in IE: <HTML> <BODY> <script language="JavaScript"> text=""; req = new XMLHttpRequest(); if (req) { req.onreadystatechange = processStateChange; req.open("GET", "http://www.boltbait.com", true); req.send(); } function processStateChange() { // is the data ready for use? if (req.readyState == 4) { // process my data alert(req.status); alert(req.responseText); } } </script> </BODY> </HTML> In IE, the first alert returns 200, the second returns the web page. However, in Chrome the first alert returns 0 and the second returns the empty string. My intent is to grab a web page into a string for processing. If I'm not doing this right, how should I be doing this? Thanks.

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Does/Will autofac's ASP.NET integration support PreInit or Init events?

- by David Rubin

I see from poking around in the 1.4.4 source that Autofac's ASP.NET integration (via Autofac.Integration.Web) peforms injection of properties on the Page as part of the HttpContext.PreRequestHandlerExecute event handling, but that the page's child controls don't get their properties injected until Page.PreLoad. What this means, though is that the injected properties of child controls are unavailable for use in the OnInit event handler. For example, this works fine: HelloWorld.aspx: <%@ Page Language="C#" AutoEventWireup="true" CodeBehind="HelloWorld.aspx.cs" Inherits="HelloWorld" %> <html> <body> <asp:Label runat="server" id="lblMsg" OnInit="HandleInit"/> </body> </html> HelloWorld.aspx.cs: ... protected void HandleInit() { lblMsg.Text = _msgProvider.GetMessage(); } public IMsgProvider _msgProvider { private get; set; } // <-- Injected But changing the HelloWorld Page to a UserControl (.acsx) and putting the UserControl in another page doesn't work because _msgProvider isn't injected early enough. Is there a way to make Autofac inject properties of child controls earlier? Or is this something that can be addressed in a future build? Thanks!

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Why do Scala maps have poor performance relative to Java?

- by Mike Hanafey

I am working on a Scala app that consumes large amounts of CPU time, so performance matters. The prototype of the system was written in Python, and performance was unacceptable. The application does a lot with inserting and manipulating data in maps. Rex Kerr's Thyme was used to look at the performance of updating and retrieving data from maps. Basically "n" random Ints were stored in maps, and retrieved from the maps, with the time relative to java.util.HashMap used as a reference. The full results for a range of "n" are here. Sample (n=100,000) performance relative to java, smaller is worse: Update Read Mutable 16.06% 76.51% Immutable 31.30% 20.68% I do not understand why the scala immutable map beats the scala mutable map in update performance. Using the sizeHint on the mutable map does not help (it appears to be ignored in the tested implementation, 2.10.3). Even more surprisingly the immutable read performance is worse than the mutable read performance, more significantly so with larger maps. The update performance of the scala mutable map is surprisingly bad, relative to both scala immutable and plain Java. What is the explanation?

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how to send on users profile page on selecting username( using json autosuggest script)

- by I Like PHP

i m using auto suggest using Ajax Json . now when a user select a user name , i want to send user on the link of that user name my json data is coming in this way { query:'hel', suggestions:["hello world","hell boy ","bac to hell"], data:["2","26","34"] } now what i want that user goes to http://userProfile.php?uid=26 on select username(suppose user select "hell boy") how to do this?? UPDATE: i describe what i m doing step by step i m using a searchbox using jquery ajax, when user write some text on input box , we show (suggest) value regarading their search STEP 1. when user write atleast(2 letter) <input type="text" name="q" id="query" />then a function(below) in invoked in which i send the value written on text box(eg. hell). <script type="text/javascript" language="javascript"> var options, a; jQuery(function(){ options = { serviceUrl:'rpc.php' }; var a = $('#query').autocomplete({ serviceUrl:'rpc.php', minChars:3, delimiter: /(,|;)\s*/, // regex or character maxHeight:400, width:300, zIndex: 9999, deferRequestBy: 0, //miliseconds }); }); </script> STEP 3: on rpc.php, i collect the data and show using JSON my final data come in below format { query:'hell', suggestions:["hello world","hell boy ","bac to hell"], data:["2","26","34"] } where suggestion list having username and data is userid( from user_tables). above data comes in a div (on frontend) where user name displayed in a list STEP 4: now if i select any username using uparrow, downarrow then that name is filled in input box, STEP 5: now what i want that when user select usename then page automatically goes to that user's profile section ( userprofile.php?uid=2)

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Getting Preferred, Varied Products -- Tough Pseudocode Question

- by Volomike

I have a Dallas client who has given me a tough process to work out. I'm seeking your advice. I use PHP, but the language doesn't matter. We can work this out in pseudocode. In a nutshell, this involves showing products on a page based on matching keyword phrases, and using a preferred product provider, but varying this up so that I try to show products from each provider as much as possible when I can. He has 3 product companies: Amazon, eBay, and Overstock. I already have worked out with the API to get products back in an array via a function. He wants to give the user the preference of which one to use primarily -- so a priority number on each. He wants to display anywhere from 1 to 6 products on a page from them. Let's go with 6 for now in this example to start with. Let's assume Amazon first, then eBay, then Overstock as far as priority. He wants me to attempt to take a keyword phrase and find relevant products (all the keywords found in product title) from Amazon, eBay, and Overstock. If we find 1 product from each provider, he wants me to only display one product from each. But if we run out of a particular provider with a matching product, I start over again and grab another product from another provider until we reach 6 products. If there just aren't 6 relevant products, then I do the best I can -- even if I only display one product. If no relevant products, then I don't display anything.

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Indexing and Searching Over Word Level Annotation Layers in Lucene

- by dmcer

I have a data set with multiple layers of annotation over the underlying text, such as part-of-tags, chunks from a shallow parser, name entities, and others from various natural language processing (NLP) tools. For a sentence like The man went to the store, the annotations might look like: Word POS Chunk NER ==== === ===== ======== The DT NP Person man NN NP Person went VBD VP - to TO PP - the DT NP Location store NN NP Location I'd like to index a bunch of documents with annotations like these using Lucene and then perform searches across the different layers. An example of a simple query would be to retrieve all documents where Washington is tagged as a person. While I'm not absolutely committed to the notation, syntactically end-users might enter the query as follows: Query: Word=Washington,NER=Person I'd also like to do more complex queries involving the sequential order of annotations across different layers, e.g. find all the documents where there's a word tagged person followed by the words arrived at followed by a word tagged location. Such a query might look like: Query: "NER=Person Word=arrived Word=at NER=Location" What's a good way to go about approaching this with Lucene? Is there anyway to index and search over document fields that contain structured tokens?

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How to easily map c++ enums to strings

- by Roddy

I have a bunch of enum types in some library header files that I'm using, and I want to have a way of converting enum values to user strings - and vice-versa. RTTI won't do it for me, because the 'user strings' need to be a bit more readable than the enumerations. A brute force solution would be a bunch of functions like this, but I feel that's a bit too C-like. enum MyEnum {VAL1, VAL2,VAL3}; String getStringFromEnum(MyEnum e) { switch e { case VAL1: return "Value 1"; case VAL2: return "Value 2"; case VAL1: return "Value 3"; default: throw Exception("Bad MyEnum"); } } I have a gut feeling that there's an elegant solution using templates, but I can't quite get my head round it yet. UPDATE: Thanks for suggestions - I should have made clear that the enums are defined in a third-party library header, so I don't want to have to change the definition of them. My gut feeling now is to avoid templates and do something like this: char * MyGetValue(int v, char *tmp); // implementation is trivial #define ENUM_MAP(type, strings) char * getStringValue(const type &T) \ { \ return MyGetValue((int)T, strings); \ } ; enum eee {AA,BB,CC}; - exists in library header file ; enum fff {DD,GG,HH}; ENUM_MAP(eee,"AA|BB|CC") ENUM_MAP(fff,"DD|GG|HH") // To use... eee e; fff f; std::cout<< getStringValue(e); std::cout<< getStringValue(f);

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Endianness and C API's: Specifically OpenSSL.

- by Hassan Syed

I have an algorithm that uses the following OpenSSL calls: HMAC_update() / HMAC_final() // ripe160 EVP_CipherUpdate() / EVP_CipherFinal() // cbc_blowfish These algorithm take a unsigned char * into the "plain text". My input data is comes from a C++ std::string::c_str() which originate from a protocol buffer object as a encoded UTF-8 string. UTF-8 strings are meant to be endian neutrial. However I'm a bit paranoid about how OpenSSL may perform operations on the data. My understanding is that encryption algorithms work on 8-bit blocks of data, and if a unsigned char * is used for pointer arithmetic when the operations are performed the algorithms should be endian neutral and I do not need to worry about anything. My uncertainty is compounded by the fact that I am working on a little-endian machine and have never done any real cross-architecture programming. My beliefs/reasoning are/is based on the following two properties std::string (not wstring) internally uses a 8-bit ptr and a the resulting c_str() ptr will itterate the same way regardless of the CPU architecture. Encryption algorithms are either by design, or by implementation, endian neutral. I know the best way to get a definitive answer is to use QEMU and do some cross-platform unit tests (which I plan to do). My question is a request for comments on my reasoning, and perhaps will assist other programmers when faced with similar problems.

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Problem with writing mobilesubstrate plugins for iOS

- by overboming

I am trying to hooking message sending for iOS 3.2, I implement my own hook on a working ExampleHook program I find on the web. But my hook apparently caused segmentation fault everytime it hooks and I don't know why. I want to hook to [NSURL initWithString:(NSString *)URLString relativeToURL:(NSURL *)baseURL; and here is my related implementation static id __$GFWInterceptor_NSURL_initWithString2(NSURL<GFWInterceptor> *_NSURL, NSString *URLString, NSURL* baseURL){ NSLog(@"We have intercepted this url: %@",URLString); [_NSURL __HelloNSURL_initWithString:URLString relativeToURL:baseURL]; establish hook Class _$NSURL = objc_getClass("NSURL"); MSHookMessage(_$NSURL, @selector(initWithString:relativeToURL:), (IMP) &__$GFWInterceptor_NSURL_initWithString2, "__HelloNSURL_"); original method declaration - (void)__HelloNSURL_initWithString:(NSString *)URLString relativeToURL:(NSURL *)baseURL; and here is my gdb backtrace Program received signal EXC_BAD_ACCESS, Could not access memory. Reason: KERN_INVALID_ADDRESS at address: 0x74696e71 0x335625f8 in objc_msgSend () (gdb) bt 0 0x335625f8 in objc_msgSend () 1 0x32c05b1a in CFStringGetLength () 2 0x32c108a8 in _CFStringIsLegalURLString () 3 0x32b1c32a in -[NSURL initWithString:relativeToURL:] () 4 0x000877c0 in __$GFWInterceptor_NSURL_initWithString2 () 5 0x32b1c220 in +[NSURL URLWithString:relativeToURL:] () 6 0x32b1c1f4 in +[NSURL URLWithString:] () 7 0x3061c614 in createUniqueWebDataURL () 8 0x3061c212 in +[WebFrame(WebInternal) _createMainFrameWithSimpleHTMLDocumentWithPage:frameView:withStyle:editable:] () and apparently it hooks, but there is some memory issue there and I can't find anything to blame now

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