PyPosAST 1.6.1

Description:

PyPosAST 1.6.1

PyPosAST
This project extends Python ast nodes with positional informations, such as where the ast node starts and finishes in the code.
I (João Felipe Pimentel) started this library to help me with ast analysis to help me with ast analises on noWorkflow.
Installing and using PyPosAST is simple and easy. Please check our installation and basic usage guidelines below.
This package currently supports Python 2.7, 3.6, 3.7, 3.8, 3.9, 3.10, 3.11, 3.12, 3.13.0b2
Differences between Python AST positions and PyPosAST positions.
This project was originally created before Python 3.9 added end_lineno and end_col_offset with the goal of fully identifying the AST nodes in the code. Thus, it enrinches the existing AST nodes with different attributes:


Attribute
AST
PyPosAST


Start line

node.lineno


node.first_line



Start column

node.col_offset


node.first_col



End line

node.end_lineno


node.last_line



End column

node.end_lineno


node.last_col



There are also some key differences on the interpretation of what is the start and the end of a node.

In function definitions and class definitions that have decorators, PyPosAST considers the start of the FunctionDef node as the start of the first decorator, while Python AST uses the start of def/class.
In expressions surrounded by parentheses, PyPosAST includes the parentheses in the position of the node.
In match_case nodes, PyPosAST includes the case keyword as part of the node to be consistent with other types of nodes.

Moreover, PyPosAST extracts some positions that the Python AST does not extract (e.g., positions of identifier nodes, which are str on the ast). Some of them are available on pseudo-nodes (node.name_node, node.op_pos, ...), while other positions are integrated on the nodes themselves.
The following table presents some of these differences.


Code
Node
Tool
Start line
Start column
End line
End column



@dec
def f():
pass


FunctionDef
AST
2
0
3
7


PyPosAST
1
0
3
7


FunctionDef.name_node
PyPosAST
2
4
2
5



(a.b)


Attribute
AST
1
1
1
4


PyPosAST
1
0
1
5



match x:
case y:
pass


match_case
AST
2
9
-
-


PyPosAST
2
4
3
12


Limitation: PyPosAST currently only works with unicode code, since it parses the script again to obtain the position of all elements.
Quick Installation
To install PyPosAST, you should follow these basic instructions:
If you have pip, just run:
$ pip install pyposast

If you do not have pip, but already have Git (to clone our repository) and Python:
$ git clone [email protected]:JoaoFelipe/pyposast.git
$ cd pyposast
$ ./setup.py install

This installs PyPosAST on your system.
Usage
Just use the 'parse' from pyposast it instead of ast.parse:
import pyposast
code = ("variable = 1234\n"
"if variable:\n"
" result = 2 + 2\n"
"else:\n"
" result = 1")
tree = pyposast.parse(code, filename='__main__', mode='exec')

This will add the fields first_line, first_col, last_line, last_col, uid, op_pos to the nodes as following:
Module -> first_line=1, first_col=0, last_line=5, last_col=14, uid=(5, 14)
body[0]=Assign: firts_line=1, first_col=0, last_line=1, last_col=15, uid=(1, 15)
targets[0]=Name: id='variable', first_line=1, firts_col=0, last_line=1, last_col=8, uid=(1, 8)
op_pos[0]=Node: first_line=1, first_col=9, last_line=1, last_col=10, uid=(1, 10)
value=Num: n=1234, first_line=1, first_col=11, last_line=1, last_col=15, uid=(1, 15)
body[1]=If: first_line=2, first_col=0, last_line=5, last_col=14, uid=(2, 2)
test=Name: id='variable', first_line=2, first_col=3, last_line=2, last_col=11, uid=(2, 11)
body[0]=Assign: first_line=3, first_col=4, last_line=3, last_col=20, uid=(3, 20)
targets[0]=Name: id='result', first_line=3, first_col=4, last_line=3, last_col=10, uid=(3, 10)
op_pos[0]=Node: first_line=3, first_col=11, last_line=3, last_col=12, uid=(3, 12)
value=BinOp: first_line=3, first_col=13, last_line=3, last_col=18, uid=(3, 18)
op=Add()
left=Num: n=2, first_line=3, first_col=13, last_line=3, last_col=14, uid=(3, 14)
right=Num: n=2, first_line=3, first_col=17, last_line=3, last_col=18, uid=(3, 18)
op_pos=Node: first_line=3, first_col=15, last_line=3, last_col=16, uid=(3, 16)
orelse[0]=Assign: first_line=5, first_col=4, last_line=5, last_col=14, uid=(5, 14)
targets[0]=Name: id='result', first_line=5, first_col=4, last_line=5, last_col=10, uid=(5, 10)
op_pos[0]=Node: first_line=5, first_col=11, last_line=5, last_col=12, uid=(5, 12)
value=Num: n=1, first_line=5, first_col=13, last_line=5, last_col=14, uid=(5, 14)

The resulting tree can be used as usual with any AST visitor
Contact
Do not hesitate to contact me:

João Felipe Pimentel [email protected]

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