module_info.py

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# Author J. Henrichs, Bureau of Meteorology
 
'''This module contains the ModuleInfo class, which is used to store
and cache information about a module: the filename, source code (if requested)
and the fparser tree (if requested), and information about any routines it
includes, and external symbol usage.
'''
 
import os
 
from fparser.common.readfortran import FortranStringReader
from fparser.two.Fortran2003 import (Function_Subprogram, Interface_Block,
                                     Interface_Stmt, Procedure_Stmt,
                                     Subroutine_Subprogram, Use_Stmt)
from fparser.two.parser import ParserFactory
from fparser.two.utils import FortranSyntaxError, walk
 
from psyclone.errors import InternalError, PSycloneError
from psyclone.psyir.frontend.fparser2 import Fparser2Reader
from psyclone.psyir.nodes import Container, FileContainer
from psyclone.psyir.symbols import SymbolError
 
 
# ============================================================================
class ModuleInfoError(PSycloneError):
    '''
    PSyclone-specific exception for use when an error with the module manager
    happens - typically indicating that some module information cannot be
    found.
 
    :param str value: the message associated with the error.
 
    '''
    def __init__(self, value):
        PSycloneError.__init__(self, value)
        self.valuevaluevalue = "ModuleInfo error: "+str(value)
 
 
# ============================================================================
class ModuleInfo:
    # pylint: disable=too-many-instance-attributes
    '''This class stores mostly cached information about modules: it stores
    the original filename, if requested it will read the file and then caches
    the plain text file, and if required it will parse the file, and then
    cache the fparser AST.
 
    :param str name: the module name.
    :param str filename: the name of the source file that stores this module \
        (including path).
 
    '''
 
    def __init__(self, name, filename):
        self._name_name = name
        self._filename_filename = filename
        # A cache for the source code:
        self._source_code_source_code = None
 
        # A cache for the fparser tree
        self._parse_tree_parse_tree = None
 
        # A cache for the PSyIR representation
        self._psyir_psyir = None
 
        # A cache for the module dependencies: this is just a set
        # of all modules used by this module. Type: set[str]
        self._used_modules_used_modules = None
 
        # This is a dictionary containing the sets of symbols imported from
        # each module, indexed by the module names: dict[str, set[str]].
        self._used_symbols_from_module_used_symbols_from_module = None
 
        # This variable will be a set that stores the name of all routines
        # (based on fparser), so we can test is a routine is defined
        # without having to convert the AST to PSyIR. It is initialised with
        # None so we avoid trying to parse a file more than once (parsing
        # errors would cause routine_names to be empty, so we can test
        # if routine_name is None vs if routine_names is empty)
        # TODO #2435: To be changed once we have support for interfaces
        self._routine_names_routine_names = None
 
        # This map contains the list of routine names that are part
        # of the same generic interface.
        # TODO #2435: To be changed once we have support for interfaces
        self._generic_interfaces_generic_interfaces = {}
 
        self._processor_processor = Fparser2Reader()
 
    # ------------------------------------------------------------------------
    @property
    def name(self):
        ''':returns: the name of this module.
        :rtype: str
 
        '''
        return self._name_name
 
    # ------------------------------------------------------------------------
    @property
    def filename(self):
        ''':returns: the filename that contains the source code for this \
            module.
        :rtype: str
 
        '''
        return self._filename_filename
 
    # ------------------------------------------------------------------------
    def get_source_code(self):
        '''Returns the source code for the module. The first time, it
        will be read from the file, but the data is then cached.
 
        :returns: the source code.
        :rtype: str
 
        :raises ModuleInfoError: when the file cannot be read.
 
        '''
        if self._source_code_source_code is None:
            try:
                with open(self._filename_filename, "r", encoding='utf-8') as file_in:
                    self._source_code_source_code = file_in.read()
            except FileNotFoundError as err:
                raise ModuleInfoError(
                    f"Could not find file '{self._filename}' when trying to "
                    f"read source code for module '{self._name}'") from err
 
        return self._source_code_source_code
 
    # ------------------------------------------------------------------------
    def get_parse_tree(self):
        '''Returns the fparser AST for this module. The first time, the file
        will be parsed by fparser using the Fortran 2008 standard. The AST is
        then cached for any future uses.
 
        :returns: the fparser AST for this module.
        :rtype: :py:class:`fparser.two.Fortran2003.Program`
 
        '''
        if self._parse_tree_parse_tree is None:
            # Set routine_names to be an empty set (it was None before).
            # This way we avoid that any other function might trigger to
            # parse this file again (in case of parsing errors).
            self._routine_names_routine_names = set()
 
            reader = FortranStringReader(self.get_source_codeget_source_code())
            parser = ParserFactory().create(std="f2008")
            self._parse_tree_parse_tree = parser(reader)
 
            # First collect information about all subroutines/functions.
            # Store information about generic interface to be handled later
            # (so we only walk the tree once):
            # TODO #2478: once generic interfaces are supported, use PSyIR
            # instead of fparser here.
            all_generic_interfaces = []
            for routine in walk(self._parse_tree_parse_tree, (Function_Subprogram,
                                                   Subroutine_Subprogram,
                                                   Interface_Block)):
                if isinstance(routine, Interface_Block):
                    all_generic_interfaces.append(routine)
                else:
                    routine_name = str(routine.content[0].items[1])
                    self._routine_names_routine_names.add(routine_name)
 
            # Then handle all generic interfaces and add them to
            # _generic_interfaces:
            for interface in all_generic_interfaces:
                # TODO #2422 This code does not support all potential
                # interface statements. After #2422 we can use PSyIR here.
                # Get the name of the interface from the Interface_Stmt:
                name = str(walk(interface, Interface_Stmt)[0].items[0]).lower()
                self._routine_names_routine_names.add(name)
 
                # Collect all specific functions for this generic interface
                routine_names = []
                for proc_stmt in walk(interface, Procedure_Stmt):
                    # Convert the items to strings:
                    routine_names.extend([str(i) for i in
                                          proc_stmt.items[0].items])
                self._generic_interfaces_generic_interfaces[name] = routine_names
 
        return self._parse_tree_parse_tree
 
    # ------------------------------------------------------------------------
    def contains_routine(self, routine_name):
        ''':returns: whether the specified routine name is part of this
            module or not. It will also return False if the file could
            not be parsed.
        :rtype: bool
 
        '''
        # TODO #2422 and TODO #2478: Once we parse everything to PSyIR (esp.
        # generic interfaces), this routine can just be replaced with
        # get_psyir().get_routine_psyir(routine_name)
        if self._routine_names_routine_names is None:
            # This will trigger adding routine information
            try:
                self.get_parse_treeget_parse_tree()
            except FortranSyntaxError:
                return False
 
        return routine_name.lower() in self._routine_names_routine_names
 
    # ------------------------------------------------------------------------
    def _extract_import_information(self):
        '''This internal function analyses a given module source file and
        caches which modules are imported (in self._used_modules), and which
        symbol is imported from each of these modules (in
        self._used_symbols_from_module).
 
        '''
        # Initialise the caches:
        self._used_modules_used_modules = set()
        self._used_symbols_from_module_used_symbols_from_module = {}
 
        try:
            parse_tree = self.get_parse_treeget_parse_tree()
        except FortranSyntaxError:
            # TODO #11: Add proper logging
            # TODO #2120: Handle error
            print(f"[ModuleInfo._extract_import_information] Syntax error "
                  f"parsing '{self._filename} - ignored")
            # Hide syntax errors
            return
        for use in walk(parse_tree, Use_Stmt):
            # Ignore intrinsic modules:
            if str(use.items[0]) == "INTRINSIC":
                continue
 
            mod_name = str(use.items[2])
            self._used_modules_used_modules.add(mod_name)
            all_symbols = set()
 
            only_list = use.items[4]
            # If there is no only_list, then the set of symbols
            # will stay empty
            if only_list:
                # Parse the only list:
                for symbol in only_list.children:
                    all_symbols.add(str(symbol))
 
            self._used_symbols_from_module_used_symbols_from_module[mod_name] = all_symbols
 
    # ------------------------------------------------------------------------
    def get_used_modules(self):
        '''This function returns a set of all modules `used` in this
        module. Fortran `intrinsic` modules will be ignored. The information
        is based on the fparser parse tree of the module (since fparser can
        handle more files than PSyir, like LFRic's `constants_mod` which has
        pre-processor directives).
 
        :returns: a set with all imported module names.
        :rtype: set[str]
 
        '''
        if self._used_modules_used_modules is None:
            self._extract_import_information_extract_import_information()
 
        return self._used_modules_used_modules
 
    # ------------------------------------------------------------------------
    def get_used_symbols_from_modules(self):
        '''This function returns information about which modules are used by
        this module, and also which symbols are imported. The return value is
        a dictionary with the used module name as key, and a set of all
        imported symbol names as value.
 
        :returns: a dictionary that gives for each module name the set \
            of symbols imported from it.
        :rtype: dict[str, set[str]]
 
        '''
        if self._used_symbols_from_module_used_symbols_from_module is None:
            self._extract_import_information_extract_import_information()
 
        return self._used_symbols_from_module_used_symbols_from_module
 
    # ------------------------------------------------------------------------
    def get_psyir(self):
        '''Returns the PSyIR representation of this module. This is based
        on the fparser tree (see get_parse_tree), and the information is
        cached. If the PSyIR must be modified, it needs to be copied,
        otherwise the modified tree will be returned from the cache in the
        future.
        If the conversion to PSyIR fails, a dummy FileContainer with an
        empty Container (module) is returned, which avoids additional error
        handling in many other subroutines.
        #TODO 2120: This should be revisited when improving on the error
        handling.
 
        :param routine_name: optional the name of a routine.
        :type routine_name: Optional[str]
 
        :returns: PSyIR representing this module.
        :rtype: list[:py:class:`psyclone.psyir.nodes.Node`]
 
        '''
        if self._psyir_psyir is None:
            try:
                self._psyir_psyir = \
                    self._processor_processor.generate_psyir(self.get_parse_treeget_parse_tree())
            except (KeyError, SymbolError, InternalError,
                    FortranSyntaxError) as err:
                print(f"Error trying to parse '{self.filename}': '{err}'")
                # TODO #11: Add proper logging
                # TODO #2120: Handle error better. Long term we should not
                # just ignore errors.
                # Create a dummy FileContainer with a dummy module. This avoids
                # additional error handling in other subroutines, since they
                # will all return 'no information', whatever you ask for
                self._psyir_psyir = FileContainer(os.path.basename(self._filename_filename))
                module = Container("invalid-module")
                self._psyir_psyir.children.append(module)
 
        # TODO #2462: needs to be fixed to properly support multiple modules
        # in one file
        # Return the actual module Container (not the FileContainer)
        return self._psyir_psyir.children[0]
 
    # ------------------------------------------------------------------------
    def resolve_routine(self, routine_name):
        '''This function returns a list of function names that might be
        actually called when the routine `name` is called. In most cases
        this is exactly name, but in case of a generic subroutine the
        name might change. For now (since we cannot resolve generic
        interfaces yet), we return the list of all possible functions that
        might be called.
 
        :param str routine_name: the name of the routine to resolve
 
        :returns: list of routine name(s) that could be called.
        :rtype: list[str]
 
        '''
        # TODO #2422: once #2422 is done, this can be moved into the PSyIR
        if self._psyir_psyir is None:
            self.get_psyirget_psyir()
        routine_name = routine_name.lower()
        if routine_name not in self._generic_interfaces_generic_interfaces:
            return [routine_name]
 
        # If a generic interface name is queried, return a copy
        # of all possible routine names that might be called:
        return self._generic_interfaces_generic_interfaces[routine_name][:]