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Refactor parsing in python by adding node visitor class. Performs same

tasks as previous version, but is more concise.
Add:
    bitshift/parser/python.py:
        Add PyTreeCutter class to perform actions on specific nodes.
tags/v1.0^2
Benjamin Attal 10 years ago
parent
commit
b77db873c1
1 changed files with 67 additions and 55 deletions
  1. +67
    -55
      bitshift/parser/python.py

+ 67
- 55
bitshift/parser/python.py View File

@@ -1,15 +1,20 @@
import ast

def _serialize(tree):
class PyTreeCutter(ast.NodeVisitor):
"""
Private function to serialize an abstract syntax tree so it is indexable by the database.
Local node visitor for python abstract syntax trees.

:param tree: The syntax tree to be serialized.

:type tree: list or ast.AST
:ivar accum: (dict) Relevant data accumulated from an abstract syntax tree.
"""

def _start_n_end(big_node):
def __init__(self):
"""
Create a PyTreeCutter instance.
"""

self.accum = {'vars': {}, 'functions': {}, 'classes': {}}

def start_n_end(self, big_node):
"""
Helper function to get the start and end lines of a code node.

@@ -27,57 +32,63 @@ def _serialize(tree):
end_line = temp_node.lineno
return (start_line, end_line)

def _helper(cur_node, accum):
def visit_Assign(self, node):
"""
Visits Assign nodes in a tree. Adds relevant data about them to accum.

:param node: The current node.

:type node: ast.Assign

.. todo::
Add value and type metadata to accum.
"""
Helper function for _serialize which recursively updates the 'vars', 'functions', and 'classes' in the parsed version of the tree.

:param cur_node: The node in the syntax tree currently being parsed.
:param accum: Dicitonary holding parsed version of the tree.
for t in node.targets:
if isinstance(t, ast.Tuple):
for n in t.elts:
line, col = n.lineno, n.col_offset
self.accum['vars'][n.id] = {'ln': line, 'col': col}
else:
line, col = t.lineno, t.col_offset
self.accum['vars'][t.id] = {'ln': line, 'col': col}

:type cur_node: list or ast.AST
:type accum: dict
self.generic_visit(node)

def visit_FunctionDef(self, node):
"""
Visits FunctionDef nodes in a tree. Adds relevant data about them to accum.

:param node: The current node.

if isinstance(cur_node, list):
for node in cur_node:
_helper(node, accum)

elif isinstance(cur_node, ast.Assign):
# return name
# return col and line offset
# in the future add value and type metadata
for t in cur_node.targets:
if isinstance(t, ast.Tuple):
for n in t.elts:
line, col = n.lineno, n.col_offset
accum['vars'][n.id] = {'ln': line, 'col': col}
else:
line, col = t.lineno, t.col_offset
accum['vars'][t.id] = {'ln': line, 'col': col}


elif isinstance(cur_node, ast.FunctionDef):
# return name
# return start and end of the function
# in the future add arguments and decorators metadata
start_line, end_line = _start_n_end(cur_node)
accum['functions'][cur_node.name] = {'start_ln': start_line , 'end_ln': end_line}

elif isinstance(cur_node, ast.ClassDef):
# return name
# return start and end of the class
# in the future add arguments, inherits, and decorators metadata
start_line, end_line = _start_n_end(cur_node)
accum['classes'][cur_node.name] = {'start_ln': start_line , 'end_ln': end_line}

if isinstance(cur_node, ast.AST):
for k in cur_node.__dict__.keys():
node = cur_node.__dict__[k]
_helper(node, accum)

accum = {'vars': {}, 'functions': {}, 'classes': {}}
_helper(tree, accum)
return accum
:type node: ast.FunctionDef

.. todo::
Add arguments and decorators metadata to accum.
"""

start_line, end_line = self.start_n_end(node)
self.accum['functions'][node.name] = {'start_ln': start_line,
'end_ln': end_line}

self.generic_visit(node)

def visit_ClassDef(self, node):
"""
Visits ClassDef nodes in a tree. Adds relevant data about them to accum.

:param node: The current node.

:type node: ast.ClassDef

.. todo::
Add arguments, inherits, and decorators metadata to accum.
"""
start_line, end_line = self.start_n_end(node)
self.accum['functions'][node.name] = {'start_ln': start_line,
'end_ln': end_line}

self.generic_visit(node)

def parse_py(codelet):
"""
@@ -87,7 +98,8 @@ def parse_py(codelet):

:type code: Codelet
"""

tree = ast.parse(codelet.code)
symbols = _serialize(tree)
codelet.symbols = symbols
print symbols
cutter = PyTreeCutter()
cutter.visit(tree)
codelet.symbols = cutter.accum

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