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  • What is causing Apache2 to display PHP as plain text in this config file?

    - by rxgx
    I am trying to run PHP and Rails in the same virtual host, however, PHP is being displayed as plain/text. When I create a test host without all the rewrites and proxy-ing, Apache2 will process the PHP as desired. Where in my config file have I gone wrong? <VirtualHost *:80> #ServerName staging.domain.com #ServerAlias www.domain.com DocumentRoot /home/demo/vhosts/domain/public <Directory /> Options FollowSymLinks AllowOverride None </Directory> <Directory /home/demo/vhosts/domain/public> Options Indexes FollowSymLinks MultiViews AllowOverride None Order allow,deny allow from all </Directory> RewriteEngine On <Proxy balancer://thinservers> BalancerMember http://127.0.0.1:5000 BalancerMember http://127.0.0.1:5001 BalancerMember http://127.0.0.1:5002 </Proxy> # Redirect all non-static requests to thin RewriteCond %{DOCUMENT_ROOT}/%{REQUEST_FILENAME} !-f RewriteRule ^/(.*)$ balancer://thinservers%{REQUEST_URI} [P,QSA,L] ProxyPass / balancer://thinservers/ ProxyPassReverse / balancer://thinservers/ ProxyPreserveHost on <Proxy *> Order deny,allow Allow from all </Proxy> # Custom log file locations ErrorLog /home/demo/vhosts/domain/log/error.log CustomLog /home/demo/vhosts/domain/log/access.log combined </VirtualHost>

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  • Double Buffering for Game objects, what's a nice clean generic C++ way?

    - by Gary
    This is in C++. So, I'm starting from scratch writing a game engine for fun and learning from the ground up. One of the ideas I want to implement is to have game object state (a struct) be double-buffered. For instance, I can have subsystems updating the new game object data while a render thread is rendering from the old data by guaranteeing there is a consistent state stored within the game object (the data from last time). After rendering of old and updating of new is finished, I can swap buffers and do it again. Question is, what's a good forward-looking and generic OOP way to expose this to my classes while trying to hide implementation details as much as possible? Would like to know your thoughts and considerations. I was thinking operator overloading could be used, but how do I overload assign for a templated class's member within my buffer class? for instance, I think this is an example of what I want: doublebuffer<Vector3> data; data.x=5; //would write to the member x within the new buffer int a=data.x; //would read from the old buffer's x member data.x+=1; //I guess this shouldn't be allowed If this is possible, I could choose to enable or disable double-buffering structs without changing much code. This is what I was considering: template <class T> class doublebuffer{ T T1; T T2; T * current=T1; T * old=T2; public: doublebuffer(); ~doublebuffer(); void swap(); operator=()?... }; and a game object would be like this: struct MyObjectData{ int x; float afloat; } class MyObject: public Node { doublebuffer<MyObjectData> data; functions... } What I have right now is functions that return pointers to the old and new buffer, and I guess any classes that use them have to be aware of this. Is there a better way?

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  • .net clipboard metadata (or whatever skype quotations use)

    - by Cyclone
    Is it possible to use the Clipboard class to grab all the data from the clipboard, like full skype quotes? They use some kind of metadata I think, which is how it knows when something is a quote or not. How can I access that from the Clipboard class? What functions would I call to set/restore Skype quotations? Thanks for the help!

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  • Debugging into a shared library source from consuming app, using QTCreator

    - by morpheous
    I am using QTCreator (1.3.1) on Ubuntu Karmic. I have built two projects: a shared library an application that links to the shared library I am debugging the application, and need to step into the implementation (i.e. the source) of one of the functions exported by the shared library. Does anyone know how to setup the QTCreator to allow me to step into the source of a shared library?

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  • Convert number into words using flex.

    - by charlie
    Hi I am trying to convert an entry using a numeric stepper in flex into words to display in a textarea. i.e a user uses the stepper to enter "89" as a value and in the text area the words "Eighty nine" are displayed. After much searching i haven't found anything that helps - a few javascript functions but that is all. any help sample code would be much appreciated. thanks in advance.

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  • How To Make Moving News Bar in Windows Forms Application without Timer

    - by Ehab Sutan
    I'm making a desktop application in C# which contains a moving News Bar labels. I'm using a timer to move these labels but the problem is that when i make the interval of this timer low (1-10 for example) the application takes very high percentage of CPU Usage, And when i make it higher(200 -500 ) the movement of the labels becomes intermittent or not smooth movement even that the user may not be able to read the news in Comfortable way. ((More Information)) it is Windows form application. the way i move the labels is as follows : the news items from RSS feeds are represented in a group of linklabels. All these linklabels are added to a flowlayout container. The timer moves the whole flowlayout container. I found this way according to my knowledge the best way to making the news bar. If you have better idea or solution please help

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  • How can I merge properties of two JavaScript objects dynamically?

    - by JC Grubbs
    I need to be able to merge two (very simple) JavaScript objects at runtime. For example I'd like to: var obj1 = { food: 'pizza', car: 'ford' } var obj2 = { animal: 'dog' } obj1.merge(obj2); //obj1 now has three properties: food, car, and animal Does anyone have a script for this or know of a built in way to do this? I do not need recursion, and I do not need to merge functions, just methods on flat objects.

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  • What is a good platform for building a game framework targetting both web and native languages?

    - by fuzzyTew
    I would like to develop (or find, if one is already in development) a framework with support for accelerated graphics and sound built on a system flexible enough to compile to the following: native ppc/x86/x86_64/arm binaries or a language which compiles to them javascript actionscript bytecode or a language which compiles to it (actionscript 3, haxe) optionally java I imagine, for example, creating an API where I can open windows and make OpenGL-like calls and the framework maps this in a relatively efficient manner to either WebGL with a canvas object, 3d graphics in Flash, OpenGL ES 2 with EGL, or desktop OpenGL in an X11, Windows, or Cocoa window. I have so far looked into these avenues: Building the game library in haXe Pros: Targets exist for php, javascript, actionscript bytecode, c++ High level, object oriented language Cons: No support for finally{} blocks or destructors, making resource cleanup difficult C++ target does not allow room for producing highly optimized libraries -- the foreign function interface requires all primitive types be boxed in a wrapper object, as if writing bindings for a scripting language; these feel unideal for real-time graphics and audio, especially exporting low-level functions. Doesn't seem quite yet mature Using the C preprocessor to create a translator, writing programs entirely with macros Pros: CPP is widespread and simple to use Cons: This is an arduous task and probably the wrong tool for the job CPP implementations differ widely in support for features (e.g. xcode cpp has no variadic macros despite claiming C99 compliance) There is little-to-no room for optimization in this route Using llvm's support for multiple backends to target c/c++ to web languages Pros: Can code in c/c++ LLVM is a very mature highly optimizing compiler performing e.g. global inlining Targets exist for actionscript (alchemy) and javascript (emscripten) Cons: Actionscript target is closed source, unmaintained, and buggy. Javascript targets do not use features of HTML5 for appropriate optimization (e.g. linear memory with typed arrays) and are immature An LLVM target must convert from low-level bytecode, so high-level constructs are lost and bloated unreadable code is created from translating individual instructions, which may be more difficult for an unprepared JIT to optimize. "jump" instructions cause problems for languages with no "goto" statements. Using libclang to write a translator from C/C++ to web languages Pros: A beautiful parsing library providing easy access to the code structure Can code in C/C++ Has sponsored developer effort from Apple Cons: Incomplete; current feature set targets IDEs. Basic operators are unexposed and must be manually parsed from the returned AST element to be identified. Translating code prior to compilation may forgo optimizations assumed in c/c++ such as inlining. Creating new code generators for clang to translate into web languages Pros: Can code in C/C++ as libclang Cons: There is no API; code structure is unstable A much larger job than using libclang; the innards of clang are complex Building the game library in Common Lisp Pros: Flexible, ancient, well-developed language Extensive introspection should ease writing translators Translators exist for at least javascript Cons: Unfamiliar language No standardized library functions, widely varying implementations Which of these avenues should I pursue? Do you know of any others, or any systems that might be useful? Does a general project like this exist somewhere already? Thank you for any input.

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  • What happens in memory when a C++ class is instantiated

    - by Jo Bucher
    I'm interested in the nuts and boltw of C++ and I wondered what actually changes when an object is instantiated. I'm particularly interested if the functions are then added to memory, if they are there from runtime or if they are never stored in memory at all. If anyone could direct me to a good site on some of the core bolts of C and C++, I'd love that too. Thanks, Jo

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  • Using the erlang mysql module, how is a database connection closed?

    - by Dan
    In using the erlang mysql module the exposed external functions are: %% External exports -export([start_link/5, start_link/6, start_link/7, start_link/8, start/5, start/6, start/7, start/8, connect/7, connect/8, connect/9, fetch/1, fetch/2, fetch/3, prepare/2, execute/1, execute/2, execute/3, execute/4, unprepare/1, get_prepared/1, get_prepared/2, transaction/2, transaction/3, get_result_field_info/1, get_result_rows/1, get_result_affected_rows/1, get_result_reason/1, encode/1, encode/2, asciz_binary/2 ]). From the this this, it is not apparent how to close a connection. How a connection closed?

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  • How do you get notified of your repos' updates?

    - by furtelwart
    I'm working on several repositories at work and would like to be informed, if anything changes in the SVN repositories. I made a small BAT script (yes, BAT is usefull sometimes) that keeps executing an svn log -r BASE:HEAD on my working copy. It shows all submit comments and revision dates. It works really well but it's not comfortable for different repositories. How do you keep track of changes in your repositories? Do you use a small program you made for yourself? Do you use software someone else made? I'm interested in every approach to this problem. I would like to get notifications and several more information about the commit. The IDE integrated functions are good, but work only if I request the information. I don't want to act to get this information. Platform: Windows, Subversion 1.5 and higher.

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  • SQL query to get latest record for all distinct items in a table

    - by David Buckley
    I have a table of all sales defined like: mysql> describe saledata; +-------------------+---------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------------+---------------------+------+-----+---------+-------+ | SaleDate | datetime | NO | | NULL | | | StoreID | bigint(20) unsigned | NO | | NULL | | | Quantity | int(10) unsigned | NO | | NULL | | | Price | decimal(19,4) | NO | | NULL | | | ItemID | bigint(20) unsigned | NO | | NULL | | +-------------------+---------------------+------+-----+---------+-------+ I need to get the last sale price for all items (as the price may change). I know I can run a query like: SELECT price FROM saledata WHERE itemID = 1234 AND storeID = 111 ORDER BY saledate DESC LIMIT 1 However, I want to be able to get the last sale price for all items (the ItemIDs are stored in a separate item table) and insert them into a separate table. How can I get this data? I've tried queries like this: SELECT storeID, itemID, price FROM saledata WHERE itemID IN (SELECT itemID from itemmap) ORDER BY saledate DESC LIMIT 1 and then wrap that into an insert, but it's not getting the proper data. Is there one query I can run to get the last price for each item and insert that into a table defined like: mysql> describe lastsale; +-------------------+---------------------+------+-----+---------+-------+ | Field | Type | Null | Key | Default | Extra | +-------------------+---------------------+------+-----+---------+-------+ | StoreID | bigint(20) unsigned | NO | | NULL | | | Price | decimal(19,4) | NO | | NULL | | | ItemID | bigint(20) unsigned | NO | | NULL | | +-------------------+---------------------+------+-----+---------+-------+

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  • segfault during __cxa_allocate_exception in SWIG wrapped library

    - by lefticus
    While developing a SWIG wrapped C++ library for Ruby, we came across an unexplained crash during exception handling inside the C++ code. I'm not sure of the specific circumstances to recreate the issue, but it happened first during a call to std::uncaught_exception, then after a some code changes, moved to __cxa_allocate_exception during exception construction. Neither GDB nor valgrind provided any insight into the cause of the crash. I've found several references to similar problems, including: http://wiki.fifengine.de/Segfault_in_cxa_allocate_exception http://forums.fifengine.de/index.php?topic=30.0 http://code.google.com/p/osgswig/issues/detail?id=17 https://bugs.launchpad.net/ubuntu/+source/libavg/+bug/241808 The overriding theme seems to be a combination of circumstances: A C application is linked to more than one C++ library More than one version of libstdc++ was used during compilation Generally the second version of C++ used comes from a binary-only implementation of libGL The problem does not occur when linking your library with a C++ application, only with a C application The "solution" is to explicitly link your library with libstdc++ and possibly also with libGL, forcing the order of linking. After trying many combinations with my code, the only solution that I found that works is the LD_PRELOAD="libGL.so libstdc++.so.6" ruby scriptname option. That is, none of the compile-time linking solutions made any difference. My understanding of the issue is that the C++ runtime is not being properly initialized. By forcing the order of linking you bootstrap the initialization process and it works. The problem occurs only with C applications calling C++ libraries because the C application is not itself linking to libstdc++ and is not initializing the C++ runtime. Because using SWIG (or boost::python) is a common way of calling a C++ library from a C application, that is why SWIG often comes up when researching the problem. Is anyone out there able to give more insight into this problem? Is there an actual solution or do only workarounds exist? Thanks.

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  • Android - read and delete new SMS of a specific sender only

    - by John
    I'm trying to write the next function: 1) Send SMS to a service number 2) Read the response SMS content (the service's auto sent-back message that tells me if I succeed/failed to turn on the service) 3) Delete the service's auto-sent SMS I know how to do the first step, and I should be able to do the second with both: getMessageBody () getOriginatingAddress () but: 1) how can I refer the last incoming message to use the above functions? 2) how can I delete that specific message? Thanks, John

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  • Using Facebook Login to create a user?

    - by andbeyond
    I've read this SO post which led me to this FB policy page, which seemed to include some pertinent information, but I'd like more of a community response, maybe some experienced FB API people who know the limits. My question is if I can use Facebook's Login api to, essentially, create a new user on my website. I really would just like to allow users to easily "transfer" some data from FB in order to more easily create a new account on my site. I realize, first and foremost, that I would obviously announce to the user that by click "submit" in the form, that they are creating a separate account on my site. Pertinent blocks on the policy page state: You may cache data you receive through use of the Facebook API in order to improve your application’s user experience, but you should try to keep the data up to date. This permission does not give you any rights to such data. Which doesn't look good for me, but also this: If you stop using Platform or we disable your application, you must delete all data you have received through use of the Facebook API unless: (a) it is basic account information; or (b) you have received explicit consent from the user to retain their data. Which, in my case, I would be satisfying part B. I would be asking the user's permission to retain the data, as I am simply using Facebook as a conveience to the user when creating an account. I also realize that Facebook has a registration API, but this would require a Facebook styled login form, along with my own sites login form, and I'd rather one interface, as this makes it easier for me on the front and back end. Any thoughts?

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  • A Digg-like rotating homepage of popular content, how to include date as a factor?

    - by Ferdy
    I am building an advanced image sharing web application. As you may expect, users can upload images and others can comments on it, vote on it, and favorite it. These events will determine the popularity of the image, which I capture in a "karma" field. Now I want to create a Digg-like homepage system, showing the most popular images. It's easy, since I already have the weighted Karma score. I just sort on that descendingly to show the 20 most valued images. The part that is missing is time. I do not want extremely popular images to always be on the homepage. I guess an easy solution is to restrict the result set to the last 24 hours. However, I'm also thinking that in order to keep the image rotation occur throughout the day, time can be some kind of variable where its offset has an influence on the image's sorting. Specific questions: Would you recommend the easy scenario (just sort for best images within 24 hours) or the more sophisticated one (use datetime offset as part of the sorting)? If you advise the latter, any help on the mathematical solution to this? Would it be best to run a scheduled service to mark images for the homepage, or would you advise a direct query (I'm using MySQL) As an extra note, the homepage should support paging and on a quiet day should include entries of days before in order to make sure it is always "filled" I'm not asking the community to build this algorithm, just looking for some advise :)

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  • t-sql most efficient row to column? for xml path, pivot

    - by ajberry
    create table _orders ( OrderId int identity(1,1) primary key nonclustered ,CustomerId int ) create table _details ( DetailId int identity(1,1) primary key nonclustered ,OrderId int ,ProductId int ) insert into _orders (CustomerId) select 1 union select 2 union select 3 insert into _details (OrderId,ProductId) select 1,100 union select 1,158 union select 1,234 union select 2,125 union select 3,105 union select 3,101 union select 3,212 union select 3,250 -- select orderid ,REPLACE(( SELECT ' ' + CAST(ProductId as varchar) FROM _details d WHERE d.OrderId = o.OrderId ORDER BY d.OrderId,d.DetailId FOR XML PATH('') ),'&#x20;','') as Products from _orders o I am looking for the most performant way to turn rows into columns. I have a requirement to output the contents of the db (not actual schema above, but concept is similar) in both fixed width and delimited formats. The above FOR XML PATH query gives me the result I want, but when dealing with anything other than small amounts of data, can take awhile. I've looked at pivot but most of the examples I have found are aggregating information. I just to combine the child rows and tack them onto the parent. For example, for an order it would need to output: OrderId,Product1,Product2,Product3,etc Thoughts or suggestions? I am using SQL Server 2k5.

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  • SQL Server - Complex Dynamic Pivot columns

    - by user972255
    I have two tables "Controls" and "ControlChilds" Parent Table Structure: Create table Controls( ProjectID Varchar(20) NOT NULL, ControlID INT NOT NULL, ControlCode Varchar(2) NOT NULL, ControlPoint Decimal NULL, ControlScore Decimal NULL, ControlValue Varchar(50) ) Sample Data ProjectID | ControlID | ControlCode | ControlPoint | ControlScore | ControlValue P001 1 A 30.44 65 Invalid P001 2 C 45.30 85 Valid Child Table Structure: Create table ControlChilds( ControlID INT NOT NULL, ControlChildID INT NOT NULL, ControlChildValue Varchar(200) NULL ) Sample Data ControlID | ControlChildID | ControlChildValue 1 100 Yes 1 101 No 1 102 NA 1 103 Others 2 104 Yes 2 105 SomeValue Output should be in a single row for a given ProjectID with all its Control values first & followed by child control values (based on the ControlCode (i.e.) ControlCode_Child (1, 2, 3...) and it should look like this Also, I tried this PIVOT query and I am able to get the ChildControls table values but I dont know how to get the Controls table values. DECLARE @cols AS NVARCHAR(MAX); DECLARE @query AS NVARCHAR(MAX); select @cols = STUFF((SELECT distinct ',' + QUOTENAME(ControlCode + '_Child' + CAST(ROW_NUMBER() over(PARTITION BY ControlCode ORDER BY ControlChildID) AS Varchar(25))) FROM Controls C INNER JOIN ControlChilds CC ON C.ControlID = CC.ControlID FOR XML PATH(''), TYPE ).value('.', 'NVARCHAR(MAX)') , 1, 1, ''); SELECT @query ='SELECT * FROM ( SELECT (ControlCode + ''_Child'' + CAST(ROW_NUMBER() over(PARTITION BY ControlCode ORDER BY ControlChildID) AS Varchar(25))) As Code, ControlChildValue FROM Controls AS C INNER JOIN ControlChilds AS CC ON C.ControlID = CC.ControlID ) AS t PIVOT ( MAX(ControlChildValue) FOR Code IN( ' + @cols + ' )' + ' ) AS p ; '; execute(@query); Output I am getting: Can anyone please help me on how to get the Controls table values in front of each ControlChilds table values?

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  • Google Analytics - Events versus Pageviews, can you compare them?

    - by Aart Nicolai
    Hi, A mortgage page on our website is accesible by multiple links on one page. In order to determine which of the links on that same page has been clicked on, I use event tracking. All events for these links are being stored under the category: "mortgage" When I look at the total number of pageviews for this mortgage page and the total number of events for the event category "mortgage", the number of pageviews is 10%-20% higher. My questions are: Can I compare pageviews and events? If not, why not? Thanks, Aart Nicolai (funda.nl)

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  • plot matrix missing points in different color using gnuplot

    - by kitt
    I have a file 'matrix.dat': 1 2 3 4 5 5 - 3 4 5 - 4 5 B - 1 B 2 B 3 - 3 2 - 3 I want to plot numbers using palette, '-' using white color and 'B' using black color. In gnuplot, I use this palette (blue - cyan - green - orange - red): set palette model HSV functions 0.666*(1-gray), 1, 1 And set '-' as missing data: set datafile missing "-" plot 'matrix.dat' matrix with image Now I can only plot numbers and '-' in correct colors.

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  • Metatool for automatic xml code generation

    - by iceman
    I want to develop a programming tool for developers which can do automatic xml code generation for specifying a GUI design and its controls. The aim is to allow non-programmers specify GUI controls(which in this case perform higher level task unlike WinForms ) from a GUI. So the xml code generated is essentially an internal representation which programmers can understand and further use in any automatic GUI generator. So the workflow is GUI(non-programmers)-xml(for programmers)-GUI(non-programmers). Is there a Microsoft project similar to this?

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  • C#, Display plain text in a form

    - by daemonfire300
    I ve made this simple drawing to explain my needs: Plain Text in C# I can only find rather "complex" functions, like RTF Text box etc. I couldn't figure out how to display "plain text" in a Form1.cs (I do not talk about HTML to WinForm) (Search did not return any useful results)

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  • Custom language - FOR loop in a clojure interpeter?

    - by Mark
    I have a basic interpreter in clojure. Now i need to implement for (initialisation; finish-test; loop-update) { statements } Implement a similar for-loop for the interpreted language. The pattern will be: (for variable-declarations end-test loop-update do statement) The variable-declarations will set up initial values for variables.The end-test returns a boolean, and the loop will end if end-test returns false. The statement is interpreted followed by the loop-update for each pass of the loop. Examples of use are: (run ’(for ((i 0)) (< i 10) (set i (+ 1 i)) do (println i))) (run ’(for ((i 0) (j 0)) (< i 10) (seq (set i (+ 1 i)) (set j (+ j (* 2 i)))) do (println j))) inside my interpreter. I will attach my interpreter code I got so far. Any help is appreciated. Interpreter (declare interpret make-env) ;; needed as language terms call out to 'interpret' (def do-trace false) ;; change to 'true' to show calls to 'interpret' ;; simple utilities (def third ; return third item in a list (fn [a-list] (second (rest a-list)))) (def fourth ; return fourth item in a list (fn [a-list] (third (rest a-list)))) (def run ; make it easy to test the interpreter (fn [e] (println "Processing: " e) (println "=> " (interpret e (make-env))))) ;; for the environment (def make-env (fn [] '())) (def add-var (fn [env var val] (cons (list var val) env))) (def lookup-var (fn [env var] (cond (empty? env) 'error (= (first (first env)) var) (second (first env)) :else (lookup-var (rest env) var)))) ;; for terms in language ;; -- define numbers (def is-number? (fn [expn] (number? expn))) (def interpret-number (fn [expn env] expn)) ;; -- define symbols (def is-symbol? (fn [expn] (symbol? expn))) (def interpret-symbol (fn [expn env] (lookup-var env expn))) ;; -- define boolean (def is-boolean? (fn [expn] (or (= expn 'true) (= expn 'false)))) (def interpret-boolean (fn [expn env] expn)) ;; -- define functions (def is-function? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'lambda (first expn))))) (def interpret-function ; keep function definitions as they are written (fn [expn env] expn)) ;; -- define addition (def is-plus? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '+ (first expn))))) (def interpret-plus (fn [expn env] (+ (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define subtraction (def is-minus? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '- (first expn))))) (def interpret-minus (fn [expn env] (- (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define multiplication (def is-times? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '* (first expn))))) (def interpret-times (fn [expn env] (* (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define division (def is-divides? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '/ (first expn))))) (def interpret-divides (fn [expn env] (/ (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define equals test (def is-equals? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '= (first expn))))) (def interpret-equals (fn [expn env] (= (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define greater-than test (def is-greater-than? (fn [expn] (and (list? expn) (= 3 (count expn)) (= '> (first expn))))) (def interpret-greater-than (fn [expn env] (> (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define not (def is-not? (fn [expn] (and (list? expn) (= 2 (count expn)) (= 'not (first expn))))) (def interpret-not (fn [expn env] (not (interpret (second expn) env)))) ;; -- define or (def is-or? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'or (first expn))))) (def interpret-or (fn [expn env] (or (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define and (def is-and? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'and (first expn))))) (def interpret-and (fn [expn env] (and (interpret (second expn) env) (interpret (third expn) env)))) ;; -- define print (def is-print? (fn [expn] (and (list? expn) (= 2 (count expn)) (= 'println (first expn))))) (def interpret-print (fn [expn env] (println (interpret (second expn) env)))) ;; -- define with (def is-with? (fn [expn] (and (list? expn) (= 3 (count expn)) (= 'with (first expn))))) (def interpret-with (fn [expn env] (interpret (third expn) (add-var env (first (second expn)) (interpret (second (second expn)) env))))) ;; -- define if (def is-if? (fn [expn] (and (list? expn) (= 4 (count expn)) (= 'if (first expn))))) (def interpret-if (fn [expn env] (cond (interpret (second expn) env) (interpret (third expn) env) :else (interpret (fourth expn) env)))) ;; -- define function-application (def is-function-application? (fn [expn env] (and (list? expn) (= 2 (count expn)) (is-function? (interpret (first expn) env))))) (def interpret-function-application (fn [expn env] (let [function (interpret (first expn) env)] (interpret (third function) (add-var env (first (second function)) (interpret (second expn) env)))))) ;; the interpreter itself (def interpret (fn [expn env] (cond do-trace (println "Interpret is processing: " expn)) (cond ; basic values (is-number? expn) (interpret-number expn env) (is-symbol? expn) (interpret-symbol expn env) (is-boolean? expn) (interpret-boolean expn env) (is-function? expn) (interpret-function expn env) ; built-in functions (is-plus? expn) (interpret-plus expn env) (is-minus? expn) (interpret-minus expn env) (is-times? expn) (interpret-times expn env) (is-divides? expn) (interpret-divides expn env) (is-equals? expn) (interpret-equals expn env) (is-greater-than? expn) (interpret-greater-than expn env) (is-not? expn) (interpret-not expn env) (is-or? expn) (interpret-or expn env) (is-and? expn) (interpret-and expn env) (is-print? expn) (interpret-print expn env) ; special syntax (is-with? expn) (interpret-with expn env) (is-if? expn) (interpret-if expn env) ; functions (is-function-application? expn env) (interpret-function-application expn env) :else 'error))) ;; tests of using environment (println "Environment tests:") (println (add-var (make-env) 'x 1)) (println (add-var (add-var (add-var (make-env) 'x 1) 'y 2) 'x 3)) (println (lookup-var '() 'x)) (println (lookup-var '((x 1)) 'x)) (println (lookup-var '((x 1) (y 2)) 'x)) (println (lookup-var '((x 1) (y 2)) 'y)) (println (lookup-var '((x 3) (y 2) (x 1)) 'x)) ;; examples of using interpreter (println "Interpreter examples:") (run '1) (run '2) (run '(+ 1 2)) (run '(/ (* (+ 4 5) (- 2 4)) 2)) (run '(with (x 1) x)) (run '(with (x 1) (with (y 2) (+ x y)))) (run '(with (x (+ 2 4)) x)) (run 'false) (run '(not false)) (run '(with (x true) (with (y false) (or x y)))) (run '(or (= 3 4) (> 4 3))) (run '(with (x 1) (if (= x 1) 2 3))) (run '(with (x 2) (if (= x 1) 2 3))) (run '((lambda (n) (* 2 n)) 4)) (run '(with (double (lambda (n) (* 2 n))) (double 4))) (run '(with (sum-to (lambda (n) (if (= n 0) 0 (+ n (sum-to (- n 1)))))) (sum-to 100))) (run '(with (x 1) (with (f (lambda (n) (+ n x))) (with (x 2) (println (f 3))))))

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