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Created April 21, 2022 19:36
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Use Python to Parse Python Files with Abstract Syntax Tree

Parsing a Python File using Python and the Abstract Syntax Tree

This comes in handy often. I want to do something based on a Python file. Maybe I want to pull all the docstrings out and make a markdown file. Maybe I want generate a script that calls all the functions in a python file. Whatever it is, the abstract syntax tree can help. Here is an example for the first use case: I pull out all the docstrings. We used this to create the documentation for hackathon at Clear Technologies a few years ago.

import ast
import os
view_path = "./folder_with_python_files_in_it"
docs_dir = "doc"
docs_path = os.path.join(view_path, docs_dir)
undocumented_count = 0
if not os.path.exists(docs_path):
only_files = [f for f in os.listdir(view_path) if os.path.isfile(os.path.join(view_path, f))]
new_md_file = open('', "w+")
md_content = '<style>' \
'.body {margin:14px; font-family: verdana, san-serif; font-size: 18px;}\n' \
'h1, h2, h3, h4, h5, p, li {font-family: verdana, sans-serif;}\n' \
'.verb {width:64px; height:22px; text-align: center; padding-top: 4px; padding-bottom: 2px; ' \
'font-family: verdana, sans-serif; font-weight: bold;}\n' \
'.get {color: white; background-color: green;}\n' \
'.post {color: white; background-color: orange;}\n' \
'.put {color:white; background-color: blue;}\n' \
'.delete {color: white; background-color: red;}\n' \
md_content += '![logo](\n'
md_content += '# API Documentation\n---\n\n'
md_content += "### <a id='toc' /> Table of Contents:\n"
md_content += "- [Business Unit Views](#business_units)\n"
md_content += "- [Admin Views](#admin_views)\n"
for file in only_files:
if "_views" in file:
with open(os.path.join(view_path, file)) as fd:
file_contents =
module = ast.parse(file_contents)
function_defs = [node for node in module.body if isinstance(node, ast.FunctionDef)]
anchor ='/')[2][:-3]
md_content += "## <a id='" + anchor + "' />" +'/')[2][:-3].replace("_", " ").title() + "\r\n"
for f in function_defs:
docstring = ast.get_docstring(f)
if docstring is not None and len(f.decorator_list) != 0:
for i in range(len(f.decorator_list)):
for dec_str in f.decorator_list[i].args:
section = ast.dump(dec_str).split("\'")[1].replace("<", "").replace(">", "")
md_content += "### " + section + "\n"
for keyword in f.decorator_list[i].keywords:
verb = ast.dump(keyword).split(",")[1].split("\'")[1]
md_content += "<div class='verb " + verb.lower() + "'>" + verb + "</div>\n"
if len(f.decorator_list[0].keywords) == 0:
md_content += "#### Verbs: GET \n"
docstring = docstring.replace(":param ", "\n- ")
docstring = docstring.replace(":return:", "\n#### Returns: ")
md_content += (docstring + "\n [Back to Top](#toc)\n\n---\n")
elif len(f.decorator_list) != 0:
undocumented_count += 1
print("Undocumented endpoint: " +
if len(f.decorator_list) == 0:
print("Function " + + " is not an endpoint.")
print("You have " + str(undocumented_count) + " undocumented endpoints.")
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