parsing - Convert a simple command into an AST in python -

i function in python converts string command ast (abstract syntax tree).

the syntax command follows:

commandname(3, "hello", 5.0, x::int) 

a command can accept number of comma separated values can either

1. integers
2. strings
3. floats
4. types

suppose function called convert_to_ast, then

convert_to_ast('commandname(3, "hello", 5.0, x::int)') 

should yield following ast:

{    'type': 'command',   'name': 'commandname',   'args': [{     'type': 'int',     'value': 3   }, {     'type': 'str',     'value': 'hello'   }, {     'type': 'float',     'value': 5.0   }, {     'type': 'var',     'kind': 'int',     'name': 'x   }] 

seems evaluate string , pick off types there:

>>> items = ast.literal_eval('(404.5, "hello", 5)') >>> [{'type': type(item).__name__, 'value': item} item in items] [{'type': 'float', 'value': 404.5}, {'type': 'str', 'value': 'hello'}, {'type': 'int', 'value': 5}] 

of course, if want more interesting things, can access ast directly:

>>> ast.dump(ast.parse('(404.5, "hello", 5)')) "module(body=[expr(value=tuple(elts=[num(n=404.5), str(s='hello'), num(n=5)], ctx=load()))])" >>> ast.parse('(404.5, "hello", 5)').body[0].value.elts [<_ast.num object @ 0x107fa1250>, <_ast.str object @ 0x107fa1290>, <_ast.num object @ 0x107fa12d0>] 

for more general thing parsing tuple (as you've added question), still can use python's ast parse (as long syntax is valid python). in case, we'll create ast.nodevisitor pull out information visits each node of python ast care about. in case, care call, num, str , name nodes:

import ast  class parser(ast.nodevisitor):      def __init__(self):         self.calls = []         self.current_command = none      def visit_call(self, node):         name = node.func.id         self.current_command = {             'type': 'command',             'name': name,             'args': []         }         self.calls.append(self.current_command)         arg in node.args:             self.visit(arg)         self.current_command = none      def visit_num(self, node):         if not self.current_command:             return         args = self.current_command['args']         arg = {             'type': type(node.n).__name__,             'value': node.n         }         args.append(arg)      def visit_str(self, node):         if not self.current_command:             return         args = self.current_command['args']         arg = {             'type': 'str',             'value': node.s         }         args.append(arg)      def visit_name(self, node):         if not self.current_command:             return         args = self.current_command['args']         arg = {             'type': 'type',             'kind': node.id          }         args.append(arg)   s = 'commandname(3, "hello", 5.0, int)'  tree = ast.parse(s) p = parser() p.visit(tree) print p.calls