Python Abstract Syntax Tree Tutorial | Abstract Syntax Tree In Python

Python Abstract syntax tree is an important function used by programmers to solve different problems easily. Learn all about the module here.

Python Abstract syntax: Analyze functions in a python script

This analyzes a python script and, for each defined function, reports the line number where the function began, where the signature ends, where the docstring ends, and where the function definition ends.

!/usr/local/bin/python3

import ast
import sys
The data we collect. Each key is a function name; each value is a dict with keys: firstline, sigend, docend, and lastline and values of line numbers where that happens. """
functions = {}
def process(functions):
""" Handle the function data stored in functions. """
for funcname,data in functions.items():
print("function:",funcname)
print("\tstarts at line:",data['firstline'])
print("\tsignature ends at line:",data['sigend'])
if ( data['sigend'] < data['docend'] ):
print("\tdocstring ends at line:",data['docend'])
else:
print("\tno docstring")
print("\tfunction ends at line:",data['lastline'])
print()
class FuncLister(ast.NodeVisitor):
def visit_FunctionDef(self, node):
Recursively visit all functions, determining where each function starts, where its signature ends, where the docstring ends, and where the function ends. """
functions[node.name] = {'firstline':node.lineno} sigend = max(node.lineno,lastline(node.args)) functions[node.name]['sigend'] = sigend docstring = ast.get_docstring(node)
docstringlength = len(docstring.split('\n')) if docstring else -1 functions[node.name]['docend'] = sigend+docstringlength functions[node.name]['lastline'] = lastline(node) self.generic_visit(node)
def lastline(node):
""" Recursively find the last line of a node """
return max( [ node.lineno if hasattr(node,'lineno') else -1 , ] +[lastline(child) for child in ast.iter_child_nodes(node)] )
def readin(pythonfilename):
""" Read the file name and store the function data into functions. """
with open(pythonfilename) as f:
code = f.read()
FuncLister().visit(ast.parse(code))
def analyze(file,process):
""" Read the file and process the function data. """
readin(file)
process(functions)
if name == 'main':
if len(sys.argv)>1:
for file in sys.argv[1:]:
analyze(file,process)
else:
analyze(sys.argv[0],process)

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