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  • Theory of formal languages - Automaton

    - by dader51
    Hi everybody ! I'm wondering about formal languages. I have a kind of parser : It reads à xml-like serialized tree structure and turn it into a multidimmensionnal array. I figured out that i need at least three variables to achieve the job : $tree = array(); // a new array $pTree = array(&$tree); // a new array which the first element points to $tree; $deep = 0; plus the one containing the sentence splitted into words. My point is on the similarities between the algorithm deing used and the differents kinds of automatons ( state machines turing machines stack ... ). The $words variable is the "tape" of the automaton, the test/conditions of the algorithm are transitions, $deep is the state and $tree is the output. I cannont figure what is $pTree. So the question is : which is the automaton I implictly use here, and to which formal languages family does it fit ? And what's about recursion ?

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  • TicTacToe AI Making Incorrect Decisions

    - by Chris Douglass
    A little background: as a way to learn multinode trees in C++, I decided to generate all possible TicTacToe boards and store them in a tree such that the branch beginning at a node are all boards that can follow from that node, and the children of a node are boards that follow in one move. After that, I thought it would be fun to write an AI to play TicTacToe using that tree as a decision tree. TTT is a solvable problem where a perfect player will never lose, so it seemed an easy AI to code for my first time trying an AI. Now when I first implemented the AI, I went back and added two fields to each node upon generation: the # of times X will win & the # of times O will win in all children below that node. I figured the best solution was to simply have my AI on each move choose and go down the subtree where it wins the most times. Then I discovered that while it plays perfect most of the time, I found ways where I could beat it. It wasn't a problem with my code, simply a problem with the way I had the AI choose it's path. Then I decided to have it choose the tree with either the maximum wins for the computer or the maximum losses for the human, whichever was more. This made it perform BETTER, but still not perfect. I could still beat it. So I have two ideas and I'm hoping for input on which is better: 1) Instead of maximizing the wins or losses, instead I could assign values of 1 for a win, 0 for a draw, and -1 for a loss. Then choosing the tree with the highest value will be the best move because that next node can't be a move that results in a loss. It's an easy change in the board generation, but it retains the same search space and memory usage. Or... 2) During board generation, if there is a board such that either X or O will win in their next move, only the child that prevents that win will be generated. No other child nodes will be considered, and then generation will proceed as normal after that. It shrinks the size of the tree, but then I have to implement an algorithm to determine if there is a one move win and I think that can only be done in linear time (making board generation a lot slower I think?) Which is better, or is there an even better solution?

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  • How to bind "rest" variables to list of values in macro in Scheme

    - by Slartibartfast
    I want to make a helper macro for writing match-extensions. I have something like this: (define-match-expander my-expander (? (stx) (let* ([dat (cdr (syntax-e stx))] [var1 (car dat))] [var2 (cadr dat)]) ;transformer goes here ))) So I wanted a macro that will do this let binding. I've started with something like this: (define-syntax-rule (define-my-expander (id vars ...) body) (define-match-expander id (? (stx) (match-let ([(vars ...) (cdr (syntax-e stx))]) body)))) but match-let isn't defined in transformation time. First question would be is there any other way of doing this (making this expanders, I mean)? Maybe there is already something similar in plt-scheme that I'm not aware of, or I'm doing it wrong in some way. Regardless of answer on the first question, if I ever want to bound list of variables to list of values inside of a macro, how should I do it? EDIT: In combination with Eli's answer macro now looks like this: (define-syntax-rule (define-my-expander (id vars ...) body) (define-match-expander id (? (stx) (syntax-case stx () [(_ vars ...) body]))))

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  • Python constructor does weird things with optional parameters

    - by christangrant
    Can you help me understand of the behaviour and implications of the python __init__ constructor. It seems like when there is an optional parameter and you try and set an existing object to a new object the optional value of the existing object is preserved and copied. Ok that was confusing... so look at an example I concocted below. In the code below I am trying to make a tree structure with nodes and possibly many children . In the first class NodeBad, the constructor has two parameters, the value and any possible children. The second class NodeGood only takes the value of the node as a parameter. Both have an addchild method to add a child to a node. When creating a tree with the NodeGood class, it works as expected. However, when doing the same thing with the NodeBad class, it seems as though a child can only be added once! The code below will result in the following output: Good Tree 1 2 3 [< 3 >] Bad Tree 1 2 2 [< 2 >, < 3 >] Que Pasa? Here is the Example: #!/usr/bin/python class NodeBad: def __init__(self, value, c=[]): self.value = value self.children = c def addchild(self, node): self.children.append(node) def __str__(self): return '< %s >' % self.value def __repr__(self): return '< %s >' % self.value class NodeGood: def __init__(self, value): self.value = value self.children = [] def addchild(self, node): self.children.append(node) def __str__(self): return '< %s >' % self.value def __repr__(self): return '< %s >' % self.value if __name__ == '__main__': print 'Good Tree' ng = NodeGood(1) # Root Node rootgood = ng ng.addchild(NodeGood(2)) # 1nd Child ng = ng.children[0] ng.addchild(NodeGood(3)) # 2nd Child print rootgood.value print rootgood.children[0].value print rootgood.children[0].children[0].value print rootgood.children[0].children print 'Bad Tree' nb = NodeBad(1) # Root Node rootbad = nb nb.addchild(NodeBad(2)) # 1st Child nb = nb.children[0] nb.addchild(NodeBad(3)) # 2nd Child print rootbad.value print rootbad.children[0].value print rootbad.children[0].children[0].value print rootbad.children[0].children

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  • Questions about linux root file system.

    - by smwikipedia
    I read the manual page of the "mount" command, at it reads as below: All files accessible in a Unix system are arranged in one big tree, the file hierarchy, rooted at /. These files can be spread out over several devices. The mount command serves to attach the file system found on some device to the big file tree. My questions are: Where is this "big tree" located? Suppose I have 2 disks, if I mount them onto some point in the "big tree", does linux place some "special marks" in the mount point to indicate that these 2 "mount directories" are indeed seperate disks?

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  • protection points in survivable mutlicast network

    - by wantobegeek
    I am working on a project on survivable multicasting.I want to propose a hybrid scheme(protection and restoration) for that purpose.Can anyone help me with an approach to decide protection points in a multicast tree??(The protection points will be those points upto which there will be an alternate path from the multicast source(protection) and from protection point to the multicast destination the path will be dynamically restored.).Pls suggest an approach to find the protection points.I found an approach name caterpillar tree which assigns the nodes on the spine of caterpillar tree as protection points.Is there any other such approach..?

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  • EXT JS toLayout on Viewport doesnt show anything...

    - by Nazariy
    After reading many example about adding new components in to existing container without reloading whole page I run in to small problem while combining tree and tabs inside Viewport component. What I'm trying to do is to register on click event to tree node and load in to content container new component, depending on node type it can be tabpanel, gridpanel or any other available component. here is short example of tree object: { xtype: 'treepanel', id: 'tree-panel', listeners: { click: function(n) { var content = Ext.getCmp('content-panel'); content.setTitle(n.attributes.qtip); //remove all components from content-panel content.removeAll(); content.add(dummy_tabs2); content.doLayout(); return; } }} All DOM manipulation went fine, everything registered properly, new Title shown, but dummy_tabs2 are not shown. I did try to set various properties for doLayout(true|false, true|false) but nothing happens. Am I doing something wrong?

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  • WPF TreeView PreviewMouseDown on TreeViewItem

    - by imekon
    If I handle the PreviewMouseDown event on TreeViewItem, I get events for everything I click on that TreeViewItem include the little +/- box to the left (Windows XP). How can I distinguish that? I tried the following: // We've had a single click on a tree view item // Unfortunately this is the WHOLE tree item, including the +/- // symbol to the left. The tree doesn't do a selection, so we // have to filter this out... MouseDevice device = e.Device as MouseDevice; // This is bad. The whole point of WPF is for the code // not to know what the UI has - yet here we are testing for // it as a workaround. Sigh... // This is broken - if you click on the +/- on a item, it shouldn't // go on to be processed by OnTreeSingleClick... ho hum! if (device.DirectlyOver.GetType() != typeof(Path)) { OnTreeSingleClick(sender); } What I'm after is just single click on the tree view item excluding the extra bits it seems to include.

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  • JTree keep expanding problem

    - by newbie123
    I want to keep my jTree file expanded. I using below code to expand the jTree : public void expandAll(JTree tree) { int row = 0; while (row < tree.getRowCount()) { tree.expandRow(row); row++; } } It works, but when I add in new file or delete file the jtree collapse back. How can keep the jTree expanded?

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  • Using Python, what's the best way to create a set of files on disk for testing?

    - by Chris R
    I'm looking for a way to create a tree of test files to unit test a packaging tool. Basically, I want to create some common file system structures -- directories, nested directories, symlinks within the selected tree, symlinks outside the tree, &c. Ideally I want to do this with as little boilerplate as possible. Of course, I could hand-write the set of files I want to see, but I'm thinking that somebody has to have automated this for a test suite somewhere. Any suggestions?

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  • What does the "=>" mean?

    - by quakkels
    Hey SO, I've got a pretty noob question for ya. I keep seeing this syntax: <%= Html.LabelFor(model => model.Email) %> ...and I have no idea what the = means. I thought it was syntax for linq2sql or ado.net entity framework but I'm just using straight ado.net. I don't understand why the VWD used that syntax when generating the Create form. What does = mean?

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  • Pass a Delphi class to a C++ function/method that expects a class with __thiscall methods.

    - by Alan G.
    I have some MSVC++ compiled DLL's for which I have created COM-like (lite) interfaces (abstract Delphi classes). Some of those classes have methods that need pointers to objects. These C++ methods are declared with the __thiscall calling convention (which I cannot change), which is just like __stdcall, except a this pointer is passed on the ECX register. I create the class instance in Delphi, then pass it on to the C++ method. I can set breakpoints in Delphi and see it hitting the exposed __stdcall methods in my Delphi class, but soon I get a STATUS_STACK_BUFFER_OVERRUN and the app has to exit. Is it possible to emulate/deal with __thiscall on the Delphi side of things? If I pass an object instantiated by the C++ system then all is good, and that object's methods are called (as would be expected), but this is useless - I need to pass Delphi objects. Edit 2010-04-19 18:12 This is what happens in more detail: The first method called (setLabel) exits with no error (though its a stub method). The second method called (init), enters then dies when it attempts to read the vol parameter. C++ Side #define SHAPES_EXPORT __declspec(dllexport) // just to show the value class SHAPES_EXPORT CBox { public: virtual ~CBox() {} virtual void init(double volume) = 0; virtual void grow(double amount) = 0; virtual void shrink(double amount) = 0; virtual void setID(int ID = 0) = 0; virtual void setLabel(const char* text) = 0; }; Delphi Side IBox = class public procedure destroyBox; virtual; stdcall; abstract; procedure init(vol: Double); virtual; stdcall; abstract; procedure grow(amount: Double); virtual; stdcall; abstract; procedure shrink(amount: Double); virtual; stdcall; abstract; procedure setID(val: Integer); virtual; stdcall; abstract; procedure setLabel(text: PChar); virtual; stdcall; abstract; end; TMyBox = class(IBox) protected FVolume: Double; FID: Integer; FLabel: String; // public constructor Create; destructor Destroy; override; // BEGIN Virtual Method implementation procedure destroyBox; override; stdcall; // empty - Dont need/want C++ to manage my Delphi objects, just call their methods procedure init(vol: Double); override; stdcall; // FVolume := vol; procedure grow(amount: Double); override; stdcall; // Inc(FVolume, amount); procedure shrink(amount: Double); override; stdcall; // Dec(FVolume, amount); procedure setID(val: Integer); override; stdcall; // FID := val; procedure setLabel(text: PChar); override; stdcall; // Stub method; empty. // END Virtual Method implementation property Volume: Double read FVolume; property ID: Integer read FID; property Label: String read FLabel; end; I would have half expected using stdcall alone to work, but something is messing up, not sure what, perhaps something to do with the ECX register being used? Help would be greatly appreciated. Edit 2010-04-19 17:42 Could it be that the ECX register needs to be preserved on entry and restored once the function exits? Is the this pointer required by C++? I'm probably just reaching at the moment based on some intense Google searches. I found something related, but it seems to be dealing with the reverse of this issue.

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  • ignoring folders in mercurial

    - by damian
    Caveat: I try all the posibilities listed here: http://stackoverflow.com/questions/254002/how-can-i-ignore-everything-under-a-folder-in-mercurial. None works as I hope. I want to ignore every thing under the folder test. But not ignore srcProject\test\TestManager I try syntax: glob test/** And it ignores test and srcProject\test\TestManager With: syntax: regexp ^/test/ It's the same thing. Also with: syntax: regexp test\\* I have install TortoiseHG 0.4rc2 with Mercurial-626cb86a6523+tortoisehg, Python-2.5.1, PyGTK-2.10.6, GTK-2.10.11 in Windows

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  • What does the "=>" mean in asp.net mvc?

    - by quakkels
    Hey SO, I've got a pretty noob question for ya. I keep seeing this syntax: <%= Html.LabelFor(model => model.Email) %> ...and I have no idea what the = means. I thought it was syntax for linq2sql or ado.net entity framework but I'm just using straight ado.net. I don't understand why the VWD used that syntax when generating the Create form. What does = mean?

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  • g_tree_insert overwrites all data

    - by pechenie
    I wonder how I should use the GTree (from GLib) to store data? Every new value I insert into GTree with g_tree_insert routine is overwrite the previous one! GTree *tree; //init tree = g_tree_new( g_str_equal ); //"g_str_equal" is a GLib default compare func //... for( i = 0; i < 100; ++i ) g_tree_insert( tree, random_key(), random_value() ); //insert some random vals // printf( "%d", g_tree_nnodes( tree ) ); //should be 100? NO! Prints "1"!!! What am I doing wrong? Thank you.

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  • Problem in setting backgound color to my TreeCellRenderer

    - by Sunil Kumar Sahoo
    Hi I have cretaed my own renderer. I want the back ground should be blue. I have set background color as blue also. But I donot know what is tha problem that the background color of my renderer always seems to be white. I have post the code. please help where I am wrong so that the background color becomes white. class CheckTreeCellRenderer extends JPanel implements TreeCellRenderer { private CheckTreeSelectionModel selectionModel; private MyRenderer delegate; private TristateCheckBox checkBox = new TristateCheckBox("", null, true); public static final State NOT_SELECTED = new State(); public static final State SELECTED = new State(); public static final State DONT_CARE = new State(); public CheckTreeCellRenderer(MyRenderer delegate, CheckTreeSelectionModel selectionModel) { this.delegate = delegate; this.selectionModel = selectionModel; setLayout(new BorderLayout()); setOpaque(true); setBackground(new Color(207, 219, 234)); checkBox.setState(Boolean.TRUE); checkBox.setOpaque(true); checkBox.setBackground(new Color(207, 219, 234)); } public Component getTreeCellRendererComponent(JTree tree, Object value, boolean selected, boolean expanded, boolean leaf, int row, boolean hasFocus) { Component renderer = delegate.getTreeCellRendererComponent(tree, value, selected, expanded, leaf, row, hasFocus); TreePath path = tree.getPathForRow(row); if (path != null) { if (selectionModel.isPathSelected(path, true)) { checkBox.setState(Boolean.TRUE); } else { checkBox.setState(selectionModel.isPartiallySelected(path) ? null : Boolean.FALSE); } } renderer.setBackground(new Color(207, 219, 234)); tree.setOpaque(true); tree.setBackground(new Color(207, 219, 234)); this.setOpaque(true); this.setBackground(new Color(207, 219, 234)); add(checkBox, BorderLayout.WEST); add(renderer, BorderLayout.CENTER); return this; } }

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  • JSF 2.0: Preserving component state across multiple views

    - by tlind
    The web application I am developing using MyFaces 2.0.3 / PrimeFaces 2.2RC2 is divided into a content and a navigation area. In the navigation area, which is included into multiple pages using templating (i.e. <ui:define>), there are some widgets (e.g. a navigation tree, collapsible panels etc.) of which I want to preserve the component state across views. For example, let's say I am on the home page. When I navigate to a product details page by clicking on a product in the navigation tree, my Java code triggers a redirect using navigationHandler.handleNavigation(context, null, "/detailspage.jsf?faces-redirect=true") Another way of getting to that details page would be by directly clicking on a product teaser that is shown on the home page. The corresponding <h:link> would lead us to the details page. In both cases, the expansion state of my navigation tree (a PrimeFaces tree component) and my collapsible panels is lost. I understand this is because the redirect / h:link results in the creation of a new view. What is the best way of dealing with this? I am already using MyFaces Orchestra in my project along with its conversation scope, but I am not sure if this is of any help here (since I'd have to bind the expansion/collapsed state of the widgets to a backing bean... but as far as I know, this is not possible). Is there a way of telling JSF which component states to propagate to the next view, assuming that the same component exists in that view? I guess I could need a pointer into the right direction here. Thanks! Update 1: I just tried binding the panels and the tree to a session-scoped bean, but this seems to have no effect. Also, I guess I would have to bind all child components (if any) manually, so this doesn't seem like the way to go. Update 2: Binding UI components to non-request scoped beans is not a good idea (see link I posted in a comment below). If there is no easier approach, I might have to proceed as follows: When a panel is collapsed or the tree is expanded, save the current state in a session-scoped backing bean (!= the UI component itself) The components' states are stored in a map. The map key is the component's (hopefully) unique, relative ID. I cannot use the whole absolute component path here, since the IDs of the parent naming containers might change if the view changes, assuming these IDs are generated programmatically. As soon as a new view gets constructed, retrieve the components' states from the map and apply them to the components. For example, in case of the panels, I can set the collapsed attribute to a value retrieved from my session-scoped backing bean.

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  • Thread-safety of read-only memory access

    - by Edmund
    I've implemented the Barnes-Hut gravity algorithm in C as follows: Build a tree of clustered stars. For each star, traverse the tree and apply the gravitational forces from each applicable node. Update the star velocities and positions. Stage 2 is the most expensive stage, and so is implemented in parallel by dividing the set of stars. E.g. with 1000 stars and 2 threads, I have one thread processing the first 500 stars and the second thread processing the second 500. In practice this works: it speeds the computation by about 30% with two threads on a two-core machine, compared to the non-threaded version. Additionally, it yields the same numerical results as the original non-threaded version. My concern is that the two threads are accessing the same resource (namely, the tree) simultaneously. I have not added any synchronisation to the thread workers, so it's likely they will attempt to read from the same location at some point. Although access to the tree is strictly read-only I am not 100% sure it's safe. It has worked when I've tested it but I know this is no guarantee of correctness! Questions Do I need to make a private copy of the tree for each thread? Even if it is safe, are there performance problems of accessing the same memory from multiple threads?

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  • How to upgrade internal php version of Zend Studio / Eclipse

    - by Moak
    I was following this tutorial when typing up this code: public function search($term){ $filter = function($tag) use ($term){ if(stristr($tag,$term)) return true; return false; }; return array_filter($this->_tags,$filter); } I get following errors in Zend Studio 8 syntax error, unexpected '{' syntax error, unexpected 'function' syntax error, unexpected 'use' However the code works fine on my Xampp with php 5.3.1 - How can I find the version of PHP in Zend Studio, and how can I upgrade it?

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  • Selective Checkout or a View, on a project in repository

    - by Yossi Zach
    I have a bunch of interconnected projects which share the same project tree. I'm looking for a version control system which provides a possibility to checkout a subset of the project tree. If my the full project tree looks like this: Project Root |-Feature1 | |-SubFeature11 | \-SubFeature12 |-Feature2 | |-SubFeature21 | \-SubFeature22 |-file1 \-file2 I want be able to checkout only subset like this: Project Root |-Feature1 | \-SubFeature12 |-Feature2 | \-SubFeature22 |-file1 \-file2 So do you know any version control system that allows to do selective checkout or a view on a repository?

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  • How to adjust a JScrollPane to its contained JTree

    - by spuas
    Hello, here I have a swing size question: I have a JTree which is contained inside a JScrollPane (which is contained in a custom component which extends JXPanel from swingx, but I think that has nothing to do with this question). Doesn't matter how many rows the tree has, the scrollpane is always bigger (the tree is dinamic but not designed to have many rows) but what I would like is the JScrollPane to adjust to the tree initial height and then show the vertical scroll when some of the nodes are expanded. I have tried without setting any size at all, setting tree preferred size to null and setting scrollpane preferred size to null as well but nothing changes. I DO NOT WANT to set the size manually... Is there a way to do this? Thanks

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  • Incorrect emacs indentation in a C++ class with DLL export specification

    - by Michael Daum
    I often write classes with a DLL export/import specification, but this seems to confuse emacs' syntax parser. I end up with something like: class myDllSpec Foo { public: Foo( void ); }; Notice that the "public:" access spec is indented incorrectly, as well as everything that follows it. When I ask emacs to describe the syntax at the beginning of the line containing public, I get a return of: ((label 352)) If I remove the myDllSpec, the indentation is correct, and emacs tells me that the syntax there is: ((inclass 352) (access-label 352)) Which seems correct and reasonable. So I conclude that the syntax parser is not able to handle the DLL export spec, and that this is what's causing my indentation trouble. Unfortunately, I don't know how to teach the parser about my labels. Seems that this is pretty common practice, so I'm hoping there's a way around it.

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