I like to take the v8 engine and to transform its code to other programming language
based on this for example if i understand it right first step i need to get the parse tree
my question is :
can i get it already from v8 or do i need to generate it from the js code .
what is the easer way ?
It looks hard to get the AST (Annotated Syntax Tree, the Parse tree) from V8 itself but there are plenty of other parsers for JavaScript that will do what you're looking for. I'd recommend having a look at Esprima (http://esprima.org/) which is a JavaScript parser written in JavaScript. This allows you to give some JavaScript source code and get back a JavaScript object version of the AST which you can transform into another language if you want (or modify then transform back into JavaScript or use for some other reason).
They've got some great online demos that should give you a feel for what it can do: http://esprima.org/demo/index.html
Related
I want to make a small "library" to be used by my future maxima scripts, but I am not quite sure on how to proceed (I use wxMaxima). Maxima's documentation covers the save(), load() and loadFile() functions, yet does not provide examples. Therefore, I am not sure whether I am using the proper/best way or not. My current solution, which is based on this post, stores my library in the *.lisp format.
As a simple example, let's say that my library defines the cosSin(x) function. I open a new session and define this function as
(%i0) cosSin(x) := cos(x) * sin(x);
I then save it to a lisp file located in the /tmp/ directory.
(%i1) save("/tmp/lib.lisp");
I then open a new instance of maxima and load the library
(%i0) loadfile("/tmp/lib.lisp");
The cosSin(x) is now defined and can be called
(%i1) cosSin(%pi/4)
(%o1) 1/2
However, I noticed that a substantial number of the libraries shipped with maxima are of *.mac format: the /usr/share/maxima/5.37.2/share/ directory contains 428 *.mac files and 516 *.lisp files. Is it a better format? How would I generate such files?
More generally, what are the different ways a library can be saved and loaded? What is the recommended approach?
Usually people put the functions they need in a file name something.mac and then load("something.mac"); loads the functions into Maxima.
A file can contain any number of functions. A file can load other files, so if you have somethingA.mac and somethingB.mac, then you can have another file that just says load("somethingA.mac"); load("somethingB.mac");.
One can also create Lisp files and load them too, but it is not required to write functions in Lisp.
Unless you are specifically interested in writing Lisp functions, my advice is to write your functions in the Maxima language and put them in a file, using an ordinary text editor. Also, I recommend that you don't use save to save the functions to a file as Lisp code; just type the functions into a file, as Maxima code, with a plain text editor.
Take a look at the files in share to get a feeling for how other people have gone about it. I am looking right now at share/contrib/ggf.mac and I see it has a lengthy comment header describing its purpose -- such comments are always a good idea.
For principiants, like me,
Menu Edit:configure:Startup commands
Copy all the functions you have verified in the first box (this will write your wxmaxima-init.mac in the location indicated below)
Restart Wxmaxima.
Now you can access the functions whitout any load() command
Im looking for a DOM parser for the lua language that works similar to the great PPI parser for perl.
Basically i have a lot of lua scripts bound to specific entities - i want to evaluate some specific function calls within these scripts to show some generic information about a script (generate a report for example).
E.g.
function func1()
....
if(check(1,4))
end
end
In this case, i want the dom parser to find the function call check with a number of arguments.
I dont want to use regexp or similar tools, a DOM parser would be the best.
LuaInspect is what you want.
LuaInspect builds an AST (what you are calling a DOM) from Lua code, and can perform static analysis on it. It can generate an HTML report, and is also used to for code completion in some editors.
command.lua is LuaInspect's main file, which uses ast.lua to build the AST, etc.
In the documentation it says, 'source' can be either str or AST object
When trying to compile my ast root:
dl = compile(newRoot, '<string>', 'eval')
I get this Exception:
expected str, got Module
I am using the last version of IronPython.
Is there an idea why this does not work? all the examples I found seem to do it this way with no issues.
Is there a workaround to compile an AST object?
Thanks!!!!
PD: I found this issue but seems to have no activity: http://ironpython.codeplex.com/workitem/32526
First off, IronPython does not support this.
It's actually quite hard to support in IronPython (and I didn't know it needed to be supported until today). IronPython's _ast module is a wrapper around its own AST, and currently only implements conversion from IronPython AST => CPython AST, but not the reverse. It's a fair bit of (honestly, quite tedious) work, so I'm not sure when it will get fixed.
If there's a popular program or library that's broken because of this that moves it up the priority list, and patches are always welcome.
hi every body
i'm new to xercses C++dom parser.can anyone tell me
can we write our own getElementsBytagName,GetNodeValue etc function ?
how to write these function and use them in my code ?
can anybody explain me the process of Dom parsing?
xerces provides methods like getElementsBytagName so you can use them in your application.
Have a look at xerces programming guide you can find there how to parse xml file and how to get elements and attributes.
When doing J2EE development, I find it handy for debugging to view the Java classes that are generated by the JSP compiler.
How can I do the equivalent in Ruby? Since it is all in memory, it won't generate a file that I can view. I believe it's the ERB module that generates the corresponding object for a template, so how can I actually view the object? Can I drop a debugger statement somewhere and use rdb? Is there some configuration value I can tell it to dump the object definition? I'm using rails, in case that makes a difference.
I don't think rails generates a class for your view. It basically calls eval after processing the file. Or do you mean inspecting the erb object while it's parsing your template?
If it's the latter you can find erb.rb in lib\ruby\1.9.1 I'd imagine you could just drop a debugger statement throughout that file.
I always make a habit of adding the following to my views (layout) which allows me to inspect or debug the parameters being used by the view in question.
<%= debug(params) %>
This will format all the parameters in yaml and display them in a Hash format.
Have a look at the method in the source code to get a better understanding. SOURCE
There are some differences compared with the Java way due to language differences.
Most template libraries for Ruby follow these steps when compiling/optimizing:
The template is compiled into Ruby source code -- not a class but a long procedure that appends to a string buffer while traversing the logic of the original template.
This ruby code is evaluated in order to be bound for later reference, preferably within a method body. This way, it is only parsed once by the interpreter.
The method (or other context) containing the logic of the parsed template is invoked to render it.
Anyway, the compiled template code therefore looks a lot like a much noisier version of your original template, and will generally not help you debugging, unless you're debugging the template language itself.
Anyone interested in template language implementation might enjoy a look around the Tilt code (use different template languages with the same rendering interface and optimization), and Temple (a great template language meta-implementation).