A lightweight program-structure engine.

Astars parses source code into an AST-like structure, lets users inspect and query that structure, and maps nodes back to their original source spans and source text. Astars is intended to be a small engine that downstream packages can build on, rather than a full analysis product by itself.

Astars 0.1.0 provides the first v0 public API.

The current v0 scope is intentionally small:

• parse Python source code
• inspect AST-like nodes without touching parser-specific objects
• find nodes by kind
• map nodes to byte spans and source text
• provide a stable entry point for downstream astars-* packages

The following are outside the v0 scope:

• source editing primitives
• semantic analysis
• multi-language support
• metrics, code review, pruning, or LLM-specific policies
• stable compatibility for legacy AParser, APruner, or ATraverser APIs

Astars currently requires Python 3.10 or newer.

For the released package:

pip install astars

To try the development version from this repository:

git clone https://github.com/xwasoux/astars.git
cd astars
pip install -e .

import astars

source = "def hello(name):\n    return name\n"

unit = astars.parse_str(source, lang="python")

print(unit.lang)
print(unit.root.kind)

function = unit.find(kind="FunctionDef")[0]

print(unit.span_of(function))
print(unit.source_of(function))
print(unit.node_at(4).kind)

Expected output:

python
Module
SourceSpan(start_byte=0, end_byte=32, start_point=(0, 0), end_point=(1, 15))
def hello(name):
    return name
Identifier

Astars exposes the v0 API from the top-level astars package:

import astars

unit = astars.parse_file("example.py", lang="python")
unit = astars.parse_str("x = 1\n", lang="python")
unit = astars.parse_bytes(b"x = 1\n", lang="python")

Each parse function returns a SourceUnit.

root = unit.root
diagnostics = unit.diagnostics

for node in unit.walk():
    print(node.kind)

functions = unit.find(kind="FunctionDef")
node = unit.node_at(byte_offset=4)

span = unit.span_of(functions[0])
source_text = unit.source_of(functions[0])

Important public objects:

• astars.SourceUnit
• astars.SourceSpan
• astars.Diagnostic
• astars.AstarsError
• astars.UnsupportedLanguageError
• astars.ParserUnavailableError

Astars is an engine layer. It should answer questions such as:

• What is the program structure of this source file?
• Which nodes match this structural query?
• Where did this node come from in the original source?
• What source text corresponds to this node?

Astars should not decide what a metric means, whether a code review finding is important, or which LLM evaluation policy should be applied. Those decisions belong in downstream packages such as astars-metrics, astars-code-review, or astars-llm-eval.

Run the test suite with:

python -m pytest

The v0 public API is covered by tests/test_public_api.py.

The current strategy and architecture notes are maintained in Japanese:

• Strategy
• API Strategy
• Concepts
• Architecture
• Migration
• Release Strategy
• v0 Plan