treeloom 0.2.3

Language-agnostic Code Property Graph library — weave syntax trees into queryable, analyzable graphs

treeloom

A language-agnostic Code Property Graph (CPG) library for Python. treeloom parses source code via tree-sitter, builds a unified graph combining AST, control flow, data flow, and call graph layers, and provides query and analysis APIs on top of it.

Features

• Multi-language parsing -- Python, JavaScript, TypeScript, Go, Java, C, C++, and Rust via tree-sitter grammars
• Unified graph model -- AST structure, control flow, data flow, and call graphs in a single queryable graph
• Taint analysis -- generic label-propagation engine for tracking data flow from sources to sinks, with sanitizer support
• Pattern matching -- chain-based pattern queries for finding code patterns across the graph
• Visualization -- export to JSON, Graphviz DOT, or interactive HTML (Cytoscape.js)
• Consumer annotations -- attach arbitrary metadata to nodes without modifying the structural graph
• Overlay system -- inject visual styling for domain-specific visualization (e.g., security analysis results)
• Serialization -- full round-trip JSON serialization including annotations

Quick Start

from pathlib import Path
from treeloom import CPGBuilder, NodeKind, EdgeKind

# Build a CPG from a directory of source files
cpg = CPGBuilder().add_directory(Path("src/")).build()

# Inspect the graph
print(f"{cpg.node_count} nodes, {cpg.edge_count} edges")
print(f"Files: {[str(f) for f in cpg.files]}")

# Find all function definitions
for func in cpg.nodes(kind=NodeKind.FUNCTION):
    print(f"  {func.name} at {func.location}")

# Find all call sites targeting a specific function
for call in cpg.nodes(kind=NodeKind.CALL):
    if call.name == "eval":
        print(f"  eval() called at {call.location}")

# Query: what nodes are reachable from a function via data flow?
func_node = next(cpg.nodes(kind=NodeKind.FUNCTION))
reachable = cpg.query().reachable_from(
    func_node.id, edge_kinds=frozenset({EdgeKind.DATA_FLOWS_TO})
)

Installation

pip install treeloom              # core only (networkx + tree-sitter)
pip install treeloom[languages]   # with all language grammars
pip install treeloom[all]         # everything (grammars + dev tools)

For development:

git clone https://github.com/rdwj/treeloom.git
cd treeloom
pip install -e ".[all]"

Supported Languages

Language	Extensions	Grammar Package
Python	.py, .pyi	tree-sitter-python
JavaScript	.js, .mjs, .cjs	tree-sitter-javascript
TypeScript	.ts, .tsx	tree-sitter-typescript
Go	.go	tree-sitter-go
Java	.java	tree-sitter-java
C	.c, .h	tree-sitter-c
C++	.cpp, .cc, ...	tree-sitter-cpp
Rust	.rs	tree-sitter-rust

Grammar packages are optional dependencies. The core library works without them -- you just can't parse files without the appropriate grammar installed. Missing grammars produce clear error messages, not crashes.

Architecture

treeloom builds a Code Property Graph -- a single directed graph that unifies four views of source code.

AST layer. Module, class, function, parameter, variable, call, and literal nodes connected by containment edges (CONTAINS, HAS_PARAMETER). This gives you the structural hierarchy of the code.

Control flow layer. Statement-level flow between nodes within functions. FLOWS_TO edges represent sequential execution; BRANCHES_TO edges represent conditional or loop branching.

Data flow layer. Tracks where variables are defined and used, and how data propagates through assignments, function calls, and return values. Edges: DATA_FLOWS_TO, DEFINED_BY, USED_BY.

Call graph layer. Links call sites to their resolved function definitions. CALLS edges connect a call node to the function it invokes. Resolution is best-effort (no full type inference).

API Overview

Class / Function	Purpose
CPGBuilder	Fluent builder -- add files/directories, call build()
CodePropertyGraph	Central graph object -- node/edge access, annotations, traversal, serialization
GraphQuery	Path queries, reachability, subgraph extraction, pattern matching
TaintPolicy	Consumer-defined source/sink/sanitizer callbacks
TaintResult	Taint analysis output -- paths, labels, filtering
ChainPattern	Declarative pattern for matching node chains
Overlay	Per-node/edge visual styling for HTML export
to_json / from_json	JSON serialization with full round-trip support
to_dot	Graphviz DOT export
generate_html	Interactive HTML visualization with Cytoscape.js

For full API details, see CLAUDE.md.

Taint Analysis

treeloom's taint engine propagates labels through data flow edges. It is generic -- the labels can represent anything (security-sensitive data, PII, environment variables). What they mean is up to you.

from treeloom import (
    CPGBuilder, CodePropertyGraph, TaintPolicy, TaintLabel, NodeKind,
)
from pathlib import Path

cpg = CPGBuilder().add_directory(Path("myapp/")).build()

# Define what constitutes a source, sink, and sanitizer
policy = TaintPolicy(
    sources=lambda node: (
        TaintLabel("user_input", node.id)
        if node.kind == NodeKind.PARAMETER and node.name == "user_data"
        else None
    ),
    sinks=lambda node: (
        node.kind == NodeKind.CALL and node.name in ("exec", "eval", "os.system")
    ),
    sanitizers=lambda node: (
        node.kind == NodeKind.CALL and node.name == "sanitize"
    ),
)

result = cpg.taint(policy)

for path in result.unsanitized_paths():
    print(f"Unsanitized: {path.source.name} -> {path.sink.name}")
    print(f"  Labels: {[l.name for l in path.labels]}")
    for node in path.intermediates:
        print(f"    {node.kind.value}: {node.name} at {node.location}")

Export and Visualization

JSON

Full round-trip serialization, including annotations:

from treeloom import to_json, from_json

json_str = to_json(cpg)
restored = from_json(json_str)  # equivalent graph

Graphviz DOT

from treeloom import to_dot, EdgeKind

# Full graph
dot = to_dot(cpg)

# Only data flow edges
dot = to_dot(cpg, edge_kinds=frozenset({EdgeKind.DATA_FLOWS_TO}))

with open("graph.dot", "w") as f:
    f.write(dot)

Interactive HTML

Self-contained HTML with Cytoscape.js. Includes layer toggles, search, click-to-inspect, and overlay support.

from treeloom import generate_html, Overlay, OverlayStyle

html = generate_html(cpg, title="My Project CPG")

with open("cpg.html", "w") as f:
    f.write(html)

Development

Set up a local development environment:

python -m venv .venv
source .venv/bin/activate
pip install -e ".[all]"

Run tests:

pytest
pytest --cov=treeloom --cov-report=html

Lint and type-check:

ruff check src/ tests/
mypy src/treeloom/

Changelog

Version 0.2.3

• Fixed data flow through chained method calls (.format().fetchone() pattern)
• New treeloom edges command for querying edges by kind, source/target name
• treeloom diff --match-by-basename and --strip-prefix for cross-directory comparison
• treeloom query --scope, --count, --annotation, --annotation-value filters
• Fixed --json-errors flag (errors now propagate to main handler for JSON formatting)
• Build --progress skips unsupported file types, --language filter restricts parsing
• DOT --edge-kind filter prunes disconnected nodes
• Import nodes hidden by default in HTML visualization (togglable "Imports" layer)
• treeloom viz --exclude-kind for consumer-controlled node filtering
• Large graph warning (>500 nodes) suggesting subgraph extraction
• 821 tests

Version 0.2.2

• Fixed data flow tracking through string formatting (.format(), % operator, f-strings)
• Fixed parameter references not generating data flow edges (root cause of taint false negatives)
• Implemented CFG edge generation (flows_to, branches_to) connecting statements within functions
• Implemented inter-procedural data flow: call-site arguments flow to callee parameters, return values flow back
• Taint analysis on vulpy (deliberately vulnerable Flask app) went from 0 to 12 findings including cross-file HTTP-input-to-SQL-injection traces
• 776 tests

Version 0.2.1

• New CLI commands: annotate, diff, pattern, subgraph, watch, serve, completions
• --json-errors global flag for machine-readable error output
• --progress flag for build command
• Multiple --policy files for taint policy composition
• TaintResult.apply_to(cpg) stamps taint annotations onto the graph
• --apply flag for taint command writes annotated CPG directly
• Fixed variable scoping in all visitors (ScopeStack replaces flat dict)
• Fixed import alias capture in Python, JavaScript, TypeScript visitors
• Fixed taint sanitizer tracking on convergent paths (per-origin intersection)
• Shell completions for bash, zsh, fish
• HTTP JSON API server (treeloom serve) with query, node, edges, subgraph endpoints
• 750 tests

Version 0.2.0

• CLI with 7 subcommands: build, info, query, taint, viz, dot, config
• YAML-based taint policies for CLI-driven analysis (sources, sinks, sanitizers, propagators)
• Project and user configuration via .treeloom.yaml and ~/.config/treeloom/config.yaml
• Works with pip install treeloom, uvx treeloom, and uv tool install treeloom
• 585 tests

Version 0.1.0

• Initial release
• Code Property Graph with four layers: AST, control flow, data flow, call graph
• Language visitors: Python, JavaScript, TypeScript/TSX, Go, Java, C, C++, Rust
• Worklist-based taint analysis engine with inter-procedural propagation
• Pattern matching query API with wildcard support
• Export to JSON (round-trip), Graphviz DOT, and interactive HTML (Cytoscape.js)
• Consumer annotation and overlay system for domain-specific visualization
• 539 tests

License

Apache-2.0