Astor

A Python library for reading, rewriting, and writing Python Abstract Syntax Trees (ASTs). Astor enables programmatic manipulation of Python source code through AST transformations, providing round-trip conversion between source code and AST representations while preserving code readability.

Package Information

• Package Name: astor
• Language: Python
• Installation: pip install astor

Core Imports

import astor

Most commonly used functions:

from astor import to_source, parse_file, dump_tree

Basic Usage

import ast
import astor

# Parse Python source code into an AST
source_code = """
def hello(name):
    print(f"Hello, {name}!")
    return name.upper()
"""

# Parse source to AST
tree = ast.parse(source_code)

# Convert AST back to source code
generated_source = astor.to_source(tree)
print(generated_source)

# Parse a file directly
tree = astor.parse_file('example.py')

# Pretty-print AST structure for debugging
print(astor.dump_tree(tree))

Architecture

Astor provides a comprehensive AST manipulation framework with several key components:

• Source Generation: Core functionality for converting AST nodes back to readable Python source code
• Tree Walking: Efficient recursive and non-recursive AST traversal mechanisms
• Node Utilities: Tools for inspecting, comparing, and modifying AST structures
• File Operations: High-level interfaces for parsing files and managing code objects
• Operator Handling: Utilities for working with Python operators and precedence rules

The library is designed for maximum utility in code generation tools, static analysis frameworks, refactoring utilities, and any application requiring programmatic Python code manipulation.

Capabilities

AST to Source Conversion

Core functionality for converting Python AST nodes back to readable source code with customizable formatting options and pretty-printing capabilities.

def to_source(node, indent_with=' ' * 4, add_line_information=False, 
              pretty_string=pretty_string, pretty_source=pretty_source, 
              source_generator_class=None):
    """Convert AST node tree to Python source code."""

AST to Source

Tree Manipulation

Tools for walking, inspecting, dumping, and modifying AST structures. Includes utilities for tree traversal, node comparison, and AST pretty-printing.

def dump_tree(node, name=None, initial_indent='', indentation='    ', 
              maxline=120, maxmerged=80):
    """Dump AST in pretty-printed format with indentation."""

def iter_node(node, name='', unknown=None):
    """Iterate over AST node attributes or list items."""

def strip_tree(node):
    """Strip AST by removing all attributes not in _fields."""

Tree Manipulation

File Operations

High-level interfaces for parsing Python files into ASTs and managing code objects with caching support.

def parse_file(fname):
    """Parse Python file into AST."""

class CodeToAst:
    """Convert modules/functions to AST with caching support."""

File Operations

Operator Utilities

Utilities for working with Python operators, including symbol extraction and precedence handling for proper expression formatting.

def get_op_symbol(obj, fmt='%s'):
    """Return symbol string for AST operator node."""

def get_op_precedence(obj):
    """Return precedence value for AST operator node."""

Operator Utilities

Version Information

__version__: str = "0.8.1"