Python Libcst: Unable to generate code from the node in visitor class

问题

I am searching for a way to get code from the node in the visitor. Example:

import libcst

code_example = """
from ast import parse
threshold  =  1
print(threshold)
"""

class CodeVisitor(libcst.CSTVisitor):
    def visit_Assign(self, node: libcst.Assign) -> bool:
        print(node)
        return True


demo = libcst.parse_module(code_example)
demo.visit(CodeVisitor())

In the above code I want to get the code(i.e. threshold = 1) of the node . But it seems like libcst doesn't provide that support. I further looked around and figured out a function name code_for_node(node: libcst._nodes.base.CSTNode) → str libcst.Module.code_for_node which belongs to the Module . But I didn't able to find enough help to use this in my code.

Looking forward for the help. Thanks in advance!

回答1:

After spending sometime, I figured out the way to solve the problem. Here is the code.

Code:

import libcst as cst

code_example = """
from ast import parse
threshold  =  1
print(threshold)
"""

class CodeVisitor(cst.CSTVisitor):
    def visit_Assign(self, node: cst.Assign) -> bool:
        print("--> NODE TREE: \n{}".format(node))
        print("--> CODE LINE FROM NODE TREE: \n{}".format(cst.parse_module("").code_for_node(node)))
        return True


demo = cst.parse_module(code_example)
_ = demo.visit(CodeVisitor())

Output:

--> NODE TREE: 
Assign(
    targets=[
        AssignTarget(
            target=Name(
                value='threshold',
                lpar=[],
                rpar=[],
            ),
            whitespace_before_equal=SimpleWhitespace(
                value='  ',
            ),
            whitespace_after_equal=SimpleWhitespace(
                value='  ',
            ),
        ),
    ],
    value=Integer(
        value='1',
        lpar=[],
        rpar=[],
    ),
    semicolon=MaybeSentinel.DEFAULT,
)
--> CODE LINE FROM NODE TREE: 
threshold  =  1

来源：https://stackoverflow.com/questions/62771691/python-libcst-unable-to-generate-code-from-the-node-in-visitor-class

标签

python-3.x

abstract-syntax-tree

libcst