solc-ast

A tool for exploring the Solidity abstrax syntrax tree as generated by the solc compiler.

Installation

You can install the latest release via pip:

$ pip install py-solc-ast

Or clone the repo and use setuptools:

$ python setup.py install

Usage

First, use py-solc-x to compile your contracts to the standard JSON output format.

>>> import json
>>> import solcx
>>> input_json = json.load(open('input.json'))
>>> output_json = solcx.compile_standard(input_json)

Next, import solcast and initialize using from_standard_output_json or from_standard_output. This returns a list of SourceUnit objects, which each represent the base node in a Solidity AST.

>>> import solcast
>>> nodes = solcast.from_standard_output(output_json)

From the initial objects, you can explore the AST:

>>> nodes
[<SourceUnit iterable object 'contracts/Token.sol'>]
>>> s = nodes[0]
>>> s
<SourceUnit iterable object 'contracts/Token.sol'>

>>> s.keys()
['children', 'contract_id', 'contracts', 'depth', 'keys', 'name', 'node_type', 'offset', 'parent', 'path', 'value']

>>> s.contracts
[<ContractDefinition iterable 'Token'>]

>>> s[0]
<ContractDefinition iterable 'Token'>

>>> s['Token']
<ContractDefinition iterable 'Token'>

>>> s['Token'].keys()
['children', 'contract_id', 'depth', 'functions', 'keys', 'name', 'node_class', 'node_type', 'offset', 'parent', 'value']

>>> s['Token'].functions
[<FunctionDefinition iterable '<constructor>'>, <FunctionDefinition iterable '<fallback>'>, <FunctionDefinition iterable 'balanceOf'>, <FunctionDefinition iterable 'allowance'>, <FunctionDefinition iterable 'approve'>, <FunctionDefinition iterable 'transfer'>, <FunctionDefinition iterable 'transferFrom'>]

>>> s['Token']['transfer']
<FunctionDefinition iterable 'transfer'>

>>> s['Token']['transfer'].statements
[<ExpressionStatement.FunctionCall 'require(balances[msg.sender] >= _value, Insufficient Balance)'>, <ExpressionStatement.Assignment iterable uint256 'balances[msg.sender] = balances[msg.sender].sub(_value)'>, <ExpressionStatement.Assignment iterable uint256 'balances[_to] = balances[_to].add(_value)'>, <EmitStatement.FunctionCall 'Transfer'>, <Return.Literal bool 'true'>]

Use the Node.children and Node.parents methods to access and filter related nodes:

>>> node = s['Token']['transfer']

>>> node.children(depth=1)
[<ExpressionStatement.FunctionCall 'require(balances[msg.sender] >= _value, Insufficient Balance)'>, <ExpressionStatement.Assignment iterable uint256 'balances[msg.sender] = balances[msg.sender].sub(_value)'>, <ExpressionStatement.Assignment iterable uint256 'balances[_to] = balances[_to].add(_value)'>, <EmitStatement.FunctionCall 'Transfer'>, <Return.Literal bool 'true'>]

>>> node.children(include_children=False, filters={'node_type': "FunctionCall", 'name': "require"})
[<ExpressionStatement.FunctionCall 'require(balances[msg.sender] >= _value, Insufficient Balance)'>]

>>> node.parents()
[<ContractDefinition iterable 'Token'>, <SourceUnit iterable object 'contracts/Token.sol'>]

Calling help on either of these methods provides a more detailed explanation of their functionality.

Development

This project is still in development and should be considered an early alpha. All feedback and contributions are welcomed!

Not all nodes have been implemented yet. From any object, you can use the Node._unimplemented method to get a list of keys that contain AST nodes that have not yet been included. The raw json data is stored at Node._node.

>>> s['Token']['transfer']._unimplemented()
['parameters', 'returnParameters']

>>> s['Token']['transfer']._node['returnParameters']
{'id': 328, 'nodeType': 'ParameterList', 'parameters': [{'constant': False, 'id': 327, 'name': '', 'nodeType': 'VariableDeclaration', 'scope': 373, 'src': '1573:4:2', 'stateVariable': False, 'storageLocation': 'default', 'typeDescriptions': {'typeIdentifier': 't_bool', 'typeString': 'bool'}, 'typeName': {'id': 326, 'name': 'bool', 'nodeType': 'ElementaryTypeName', 'src': '1573:4:2', 'typeDescriptions': {'typeIdentifier': 't_bool', 'typeString': 'bool'}}, 'value': None, 'visibility': 'internal'}], 'src': '1572:6:2'}

See the Solidity documentation for information about the AST grammar.

License

This project is licensed under the MIT license.