abstract-syntax-tree

Is there a way to convert a given Python abstract syntax tree (AST) to a source code? Here is a good example of how to use Python's ast module, specifically a NodeTransformer . I was looking for a way to convert the resulting AST back to source, so the changes can be inspected visually. Ned Batchelder The Python source tree contains an implementation of this: unparse.py in the Demo/parser directory: https://github.com/python/cpython/blob/master/Tools/parser/unparse.py Have a look at http://pypi.python.org/pypi/sourcecodegen/0.6.14 A nice third-party library I found: astunparse which is based

Python AST nodes have lineno and col_offset attributes, which indicate the beginning of respective code range. Is there an easy way to get also the end of the code range? A 3rd party library? EDIT: Latest code (tested in Python 3.5-3.7) is here: https://bitbucket.org/plas/thonny/src/master/thonny/ast_utils.py As I didn't find an easy way, here's a hard (and probably not optimal) way. Might crash and/or work incorrectly if there are more lineno/col_offset bugs in Python parser than those mentioned (and worked around) in the code. Tested in Python 3.3: def mark_code_ranges(node, source): """

I said "live code" because I mean not from text source files or source strings, but from partialFunctions / lambdas. (I know Ruby1.8's parseTree and C# linq can do it) consider a partialFunction f: val f = (i: Int, j: Int) => (i + j) * 2 I hope there is some tool works like this: getBodyAstFrom(f) //=> (Infix('*'), (Infix('+'), Id('i'), Id('j')), Val('2')) I don't care the semantic things (context parsing and implicits are too complex, and unnecessary for me), I just need the syntax tree from live code, is it possible? There may be issues with inspecting other people's code, but what about my

I have to write a visitor pattern to navigate the AST. Can anyone tell me more how would I start writing it? As far as I understand, each Node in AST would have visit() method (?) that would somehow get called (from where?). That about concludes my understanding. To simplify everything, suppose I have nodes Root, Expression, Number, Op and the tree looks like this: Root | Op(+) / \ / \ Number(5) \ Op(*) / \ / \ / \ Number(2) Number(444) Pattern visitor is a design pattern that allows you to implement arbitrary operations (implemented as visitors) on the parse tree( eg. Type-checking ) without

Original question: Executing mathematical user code on a python web server, what is the simplest secure way? I want to be able to run user submitted code on a python webserver. The code will be simple and mathematical in nature. As such a small subset of Python is required, my current approach is to whitelist allowable syntax by traversing Python's abstract syntax tree. Functions and names get special treatment; only explicitly whitelisted functions are allowed, and only unused names. import ast allowed_functions = set([ #math library 'acos', 'acosh', 'asin', 'asinh', 'atan', 'atan2', 'atanh',

Is there a Scala library that parses Scala and creates an Abstract Syntax Tree (AST)? Ideally I am interested in a Scala library. Plan B would be a Java library. (I know I could leverage the EBNF from the Scala Syntax Summary .) Mitch Blevins I would think the best way to access the AST is with a compiler plugin. You should read a soft introduction before diving in deep . A few existing parsers: The offical Scala compiler . The IntelliJ IDEA Scala plugin has a parser written in Scala against IntelliJ's PsiBuilder API. The Scala Netbeans plugin used a parser implemented in Rats! (which

I managed to compile successfully clang for windows with cmake and visual studio 10. I would like to get an XML file as AST representation of the source code. There is one option that provides the result with clang with gcc under linux (ubuntu) but doesn't work on the windows box: clang -cc1 -ast-print-xml source.c However, this is invoking the compilation stage (which I would like to avoid). Digging in the source code didn't help me so far as I am quite new to clang. I could manage to generate the binary version of the AST by using: clang -emit-ast source.c Unfortunately, this format is