Fix module prefix function mapping for Python imports

[Copilot]

Fixes #104 - Functions with module prefix are not mapped correctly when using imports like from infrastructure import http followed by calls like http.request().

Problem

When analyzing Python code with nested module imports, code2flow was not properly connecting function calls that use module prefixes. For example:

# infrastructure/http.py
def request(method, url):
    pass

# repository/user_repository.py  
from infrastructure import http
from infrastructure.http import request

def get_users():
    http.request("GET", "https://api.example.com/users")  # This call was not mapped

def get_users2():
    request("GET", "https://api.example.com/users")      # This call worked fine

Before the fix:

• Variables showed: http->UNKNOWN_MODULE
• Only direct imports were connected
• Missing edges for module-prefixed calls like http.request()

Root Cause

The issue was in the _resolve_str_variable() function in model.py. When processing from infrastructure import http, it creates a variable with:

• token = "http"
• points_to = "infrastructure.http"

But the file infrastructure/http.py has import_tokens = ["http"]. The function only checked for exact matches between "infrastructure.http" and ["http"], which failed.

Solution

Enhanced _resolve_str_variable() to include a fallback check for module path matching:

# Handle module paths like "infrastructure.http" matching file with import_tokens ["http"]
for file_group in file_groups:
    for node in file_group.all_nodes():
        if any(variable.points_to.endswith('.' + ot) for ot in node.import_tokens):
            return node
    for group in file_group.all_groups():
        if any(variable.points_to.endswith('.' + ot) for ot in group.import_tokens):
            return group

This allows "infrastructure.http" to match files with import token "http" when the variable path ends with ".http".

Results

After the fix:

• Variables now show: http->http (properly resolved)
• All module-prefixed calls are correctly mapped
• Complete call graph includes previously missing edges
• Existing functionality remains unchanged

Testing

• Added comprehensive test case module_prefix_imports to prevent regression
• Verified existing tests still pass (two_file_simple, import_paths, etc.)
• Tested edge cases to ensure no false positive matches
• Full verification with the exact scenario from issue Functions with module prefix are not mapped (Python) #104

The fix is minimal, targeted, and maintains backward compatibility while solving the core mapping issue for module-prefixed function calls.

Warning

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• esm.ubuntu.com
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• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
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