eric6/DebugClients/Python/ModuleLoader.py

# -*- coding: utf-8 -*-

# Copyright (c) 2020 Detlev Offenbach <detlev@die-offenbachs.de>
#

"""
Module implementing an import hook patching modules to support debugging.
"""

import sys
import importlib


class ModuleLoader(object):
    """
    Class implementing an import hook patching modules to support debugging.
    """
    def __init__(self, debugClient):
        """
        Constructor
        
        @param debugClient reference to the debug client object
        @type DebugClient
        """
        self.__dbgClient = debugClient
        
        self.__enableImportHooks = True
        
        # TODO: check if needed
        if sys.version_info[0] == 2:
            self.threadModName = 'thread'
        else:
            self.threadModName = '_thread'
        
        # reset already imported thread module to apply hooks at next import
        for moduleName in ("thread", "_thread", "threading"):
            if moduleName in sys.modules:
                del sys.modules[moduleName]
        
        self.__modulesToPatch = (
                'thread', '_thread', 'threading',
                'greenlet',
                'PyQt4.QtCore', 'PyQt5.QtCore',
                'PySide.QtCore', 'PySide2.QtCore',
        )
        
        sys.meta_path.insert(0, self)
    
    def __loadModule(self, fullname):
        """
        Public method to load a module.
        
        @param fullname name of the module to be loaded
        @type str
        @return reference to the loaded module
        @rtype module
        """
        module = importlib.import_module(fullname)
        sys.modules[fullname] = module
        
        ## Add hook for _thread.start_new_thread
        if (
            fullname in ('thread', '_thread') and
            not hasattr(module, 'eric6_patched')
        ):
            module.eric6_patched = True
            self.__dbgClient.patchPyThread(module)
        
        ## Add hook for threading.run()
        elif (
            fullname == "threading" and
            not hasattr(module, 'eric6_patched')
        ):
            module.eric6_patched = True
            self.__dbgClient.patchPyThreading(module)
        
        ## greenlet support
        elif (
            fullname == 'greenlet' and
            not hasattr(module, 'eric6_patched')
        ):
            if self.__dbgClient.patchGreenlet(module):
                module.eric6_patched = True
        
        ## Add hook for *.QThread
        elif (
            fullname in ('PyQt4.QtCore', 'PyQt5.QtCore',
                         'PySide.QtCore', 'PySide2.QtCore') and
            not hasattr(module, 'eric6_patched')
        ):
            module.eric6_patched = True
            self.__dbgClient.patchQThread(module)
        
        self.__enableImportHooks = True
        return module
    
    if sys.version_info >= (3, 4):
        def find_spec(self, fullname, path, target=None):
            """
            Public method returning the module spec.
            
            @param fullname name of the module to be loaded
            @type str
            @param path path to resolve the module name
            @type str
            @param target module object to use for a more educated guess
                about what spec to return
            @type module
            @return module spec object pointing to the module loader
            @type ModuleSpec
            """
            if fullname in sys.modules or not self.__dbgClient.debugging:
                return None
            
            if (
                fullname in self.__modulesToPatch and
                self.__enableImportHooks
            ):
                # Disable hook to be able to import original module
                self.__enableImportHooks = False
                return importlib.machinery.ModuleSpec(fullname, self)
            
            return None
        
        def create_module(self, spec):
            """
            Public method to create a module based on the passed in spec.
            
            @param spec module spec object for loading the module
            @type ModuleSpec
            @return created and patched module
            @rtype module
            """
            return self.__loadModule(spec.name)
        
        def exec_module(self, module):
            """
            Public method to execute the created module
            
            @param module module to be executed
            @type module
            """
            pass
    
    else:
        def find_module(self, fullname, path=None):
            """
            Public method returning the module loader.
            
            @param fullname name of the module to be loaded
            @type str
            @param path path to resolve the module name
            @type str
            @return module loader object
            @rtype object
            """
            if fullname in sys.modules or not self.__dbgClient.debugging:
                return None
            
            if (
                fullname in self.__modulesToPatch and
                self.__enableImportHooks
            ):
                # Disable hook to be able to import original module
                self.__enableImportHooks = False
                return self
            
            return None
        
        def load_module(self, fullname):
            """
            Public method to load a module.
            
            @param fullname name of the module to be loaded
            @type str
            @return reference to the loaded module
            @rtype module
            """
            return self.__loadModule(fullname)