#!/usr/bin/env python

"""

Optimise object layouts and generate access instruction plans.

Copyright (C) 2014, 2015, 2016, 2017 Paul Boddie <paul@boddie.org.uk>

This program is free software; you can redistribute it and/or modify it under

the terms of the GNU General Public License as published by the Free Software

Foundation; either version 3 of the License, or (at your option) any later

version.

This program is distributed in the hope that it will be useful, but WITHOUT

ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS

FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more

details.

You should have received a copy of the GNU General Public License along with

this program.  If not, see <http://www.gnu.org/licenses/>.

"""

from common import add_counter_item, get_attrname_from_location, init_item, \

                   sorted_output

from encoders import encode_access_location, encode_instruction, get_kinds

from os.path import exists, join

from os import makedirs

from referencing import Reference

class Optimiser:

    "Optimise objects in a program."

    def __init__(self, importer, deducer, output):

        """

        Initialise an instance using the given 'importer' and 'deducer' that

        will perform the arrangement of attributes for program objects, writing

        the results to the given 'output' directory.

        """

        self.importer = importer

        self.deducer = deducer

        self.output = output

        # Locations/offsets of attributes in objects.

        self.locations = None

        self.attr_locations = None

        self.all_attrnames = None

        # Locations of parameters in parameter tables.

        self.arg_locations = None

        self.param_locations = None

        self.all_paramnames = None

        # Specific attribute access information.

        self.access_instructions = {}

        self.accessor_kinds = {}

        # Object structure information.

        self.structures = {}

        self.attr_table = {}

        # Parameter list information.

        self.parameters = {}

        self.param_table = {}

        # Constant literal information.

        self.constants = []

        self.constant_numbers = {}

        # Optimiser activities.

        self.populate_objects()

        self.position_attributes()

        self.populate_parameters()

        self.position_parameters()

        self.populate_tables()

        self.populate_constants()

        self.initialise_access_instructions()

    def to_output(self):

        "Write the output files using optimisation information."

        if not exists(self.output):

            makedirs(self.output)

        self.write_objects()

    def write_objects(self):

        """

        Write object-related output.

        The locations are a list of positions indicating the attributes residing

        at each position in the different structures in a program.

        ----

        The parameter locations are a list of positions indicating the parameters

        residing at each position in the different parameter lists in a program.

        ----

        Each attribute plan provides attribute details in the following format:

        location " " name " " test " " test type " " base

                 " " traversed attributes " " traversed attribute ambiguity

                 " " traversal access modes

                 " " attributes to traverse " " attribute ambiguity

                 " " context " " access method " " static attribute

        Locations have the following format:

        qualified name of scope "." local name ":" name version

        Traversal access modes are either "class" (obtain accessor class to

        access attribute) or "object" (obtain attribute directly from accessor).

        ----

        The structures are presented as a table in the following format:

        qualified name " " attribute names

        The attribute names are separated by ", " characters and indicate the

        attribute provided at each position in the structure associated with the

        given type. Where no attribute is provided at a particular location

        within a structure, "-" is given.

        ----

        The parameters are presented as a table in the following format:

        qualified name " " parameter details

        The parameter details are separated by ", " characters and indicate

        the parameter name and list position for each parameter described at

        each location in the parameter table associated with the given

        function. Where no parameter details are provided at a particular

        location within a parameter table, "-" is given. The name and list

        position are separated by a colon (":").

        ----

        The attribute table is presented as a table in the following format:

        qualified name " " attribute identifiers

        Instead of attribute names, identifiers defined according to the order

        given in the "attrnames" file are employed to denote the attributes

        featured in each type's structure. Where no attribute is provided at a

        particular location within a structure, "-" is given.

        ----

        The parameter table is presented as a table in the following format:

        qualified name " " parameter details

        Instead of parameter names, identifiers defined according to the order

        given in the "paramnames" file are employed to denote the parameters

        featured in each function's parameter table. Where no parameter is

        provided at a particular location within a table, "-" is given.

        ----

        The ordered list of attribute names is given in the "attrnames" file.

        ----

        The ordered list of parameter names is given in the "paramnames" file.

        ----

        The ordered list of constant literals is given in the "constants" file.

        """

        f = open(join(self.output, "locations"), "w")

        try:

            for attrnames in self.locations:

                print >>f, sorted_output(attrnames)

        finally:

            f.close()

        f = open(join(self.output, "parameter_locations"), "w")

        try:

            for argnames in self.arg_locations:

                print >>f, sorted_output(argnames)

        finally:

            f.close()

        f = open(join(self.output, "instruction_plans"), "w")

        try:

            access_instructions = self.access_instructions.items()

            access_instructions.sort()

            for location, instructions in access_instructions:

                print >>f, encode_access_location(location), "..."

                for instruction in instructions:

                    print >>f, encode_instruction(instruction)

                print >>f

        finally:

            f.close()

        f = open(join(self.output, "structures"), "w")

        try:

            structures = self.structures.items()

            structures.sort()

            for name, attrnames in structures:

                print >>f, name, ", ".join([s or "-" for s in attrnames])

        finally:

            f.close()

        f = open(join(self.output, "parameters"), "w")

        try:

            parameters = self.parameters.items()

            parameters.sort()

            for name, argnames in parameters:

                print >>f, name, ", ".join([s and ("%s:%d" % s) or "-" for s in argnames])

        finally:

            f.close()

        f = open(join(self.output, "attrtable"), "w")

        try:

            attr_table = self.attr_table.items()

            attr_table.sort()

            for name, attrcodes in attr_table:

                print >>f, name, ", ".join([i is not None and str(i) or "-" for i in attrcodes])

        finally:

            f.close()

        f = open(join(self.output, "paramtable"), "w")

        try:

            param_table = self.param_table.items()

            param_table.sort()

            for name, paramcodes in param_table:

                print >>f, name, ", ".join([s and ("%d:%d" % s) or "-" for s in paramcodes])

        finally:

            f.close()

        f = open(join(self.output, "attrnames"), "w")

        try:

            for name in self.all_attrnames:

                print >>f, name

        finally:

            f.close()

        f = open(join(self.output, "paramnames"), "w")

        try:

            for name in self.all_paramnames:

                print >>f, name

        finally:

            f.close()

        f = open(join(self.output, "constants"), "w")

        try:

            constants = []

            for (value, value_type, encoding), n in self.constants.items():

                constants.append((n, value_type, encoding, value))

            constants.sort()

            for n, value_type, encoding, value in constants:

                print >>f, value_type, encoding or "{}", repr(value)

        finally:

            f.close()

    def populate_objects(self):

        "Populate objects using attribute and usage information."

        all_attrs = {}

        # Partition attributes into separate sections so that class and instance

        # attributes are treated separately.

        for source, objtype in [

            (self.importer.all_class_attrs, "<class>"),

            (self.importer.all_instance_attrs, "<instance>"),

            (self.importer.all_module_attrs, "<module>")

            ]:

            for name, attrs in source.items():

                all_attrs[(objtype, name)] = attrs

        self.locations = get_allocated_locations(all_attrs, get_attributes_and_sizes)

    def populate_parameters(self):

        "Populate parameter tables using parameter information."

        self.arg_locations = [set()] + get_allocated_locations(self.importer.function_parameters, get_parameters_and_sizes)

    def position_attributes(self):

        "Position specific attribute references."

        # Reverse the location mappings.

        attr_locations = self.attr_locations = {}

        for i, attrnames in enumerate(self.locations):

            for attrname in attrnames:

                attr_locations[attrname] = i

        # Record the structures.

        for source, objtype in [

            (self.importer.all_class_attrs, "<class>"),

            (self.importer.all_instance_attrs, "<instance>"),

            (self.importer.all_module_attrs, "<module>")

            ]:

            for name, attrnames in source.items():

                key = Reference(objtype, name)

                l = self.structures[key] = [None] * len(attrnames)

                for attrname in attrnames:

                    position = attr_locations[attrname]

                    if position >= len(l):

                        l.extend([None] * (position - len(l) + 1))

                    l[position] = attrname

    def initialise_access_instructions(self):

        "Expand access plans into instruction sequences."

        for access_location, access_plan in self.deducer.access_plans.items():

            # Obtain the access details.

            name, test, test_type, base, \

                traversed, traversal_modes, attrnames, \

                context, context_test, \

                first_method, final_method, \

                origin, accessor_kinds = access_plan

            instructions = []

            emit = instructions.append

            if base:

                original_accessor = base

            else:

                original_accessor = "<expr>" # use a generic placeholder

            # Prepare for any first attribute access.

            if traversed:

                attrname = traversed[0]

                del traversed[0]

            elif attrnames:

                attrname = attrnames[0]

                del attrnames[0]

            # Perform the first access explicitly if at least one operation

            # requires it.

            access_first_attribute = final_method in ("access", "assign") or traversed or attrnames

            # Determine whether the first access involves assignment.

            assigning = not traversed and not attrnames and final_method == "assign"

            set_accessor = assigning and "<set_target_accessor>" or "<set_accessor>"

            stored_accessor = assigning and "<target_accessor>" or "<accessor>"

            # Set the context if already available.

            if context == "base":

                accessor = context_var = (base,)

            elif context == "original-accessor":

                # Prevent re-evaluation of any dynamic expression by storing it.

                if original_accessor == "<expr>":

                    emit((set_accessor, original_accessor))

                    accessor = context_var = (stored_accessor,)

                else:

                    accessor = context_var = (original_accessor,)

            # Assigning does not set the context.

            elif context in ("final-accessor", "unset") and access_first_attribute:

                # Prevent re-evaluation of any dynamic expression by storing it.

                if original_accessor == "<expr>":

                    emit((set_accessor, original_accessor))

                    accessor = (stored_accessor,)

                else:

                    accessor = (original_accessor,)

            # Apply any test.

            if test[0] == "test":

                accessor = ("__%s_%s_%s" % test, accessor, test_type)

            # Perform the first or final access.

            # The access only needs performing if the resulting accessor is used.

            remaining = len(traversed + attrnames)

            if access_first_attribute:

                if first_method == "relative-class":

                    if assigning:

                        emit(("__store_via_class", accessor, attrname, "<assexpr>"))

                    else:

                        accessor = ("__load_via_class", accessor, attrname)

                elif first_method == "relative-object":

                    if assigning:

                        emit(("__store_via_object", accessor, attrname, "<assexpr>"))

                    else:

                        accessor = ("__load_via_object", accessor, attrname)

                elif first_method == "relative-object-class":

                    if assigning:

                        emit(("__get_class_and_store", accessor, attrname, "<assexpr>"))

                    else:

                        accessor = ("__get_class_and_load", accessor, attrname)

                elif first_method == "check-class":

                    if assigning:

                        emit(("__check_and_store_via_class", accessor, attrname, "<assexpr>"))

                    else:

                        accessor = ("__check_and_load_via_class", accessor, attrname)

                elif first_method == "check-object":

                    if assigning:

                        emit(("__check_and_store_via_object", accessor, attrname, "<assexpr>"))

                    else:

                        accessor = ("__check_and_load_via_object", accessor, attrname)

                elif first_method == "check-object-class":

                    if assigning:

                        emit(("__check_and_store_via_any", accessor, attrname, "<assexpr>"))

                    else:

                        accessor = ("__check_and_load_via_any", accessor, attrname)

            # Traverse attributes using the accessor.

            if traversed:

                for attrname, traversal_mode in zip(traversed, traversal_modes):

                    assigning = remaining == 1 and final_method == "assign"

                    # Set the context, if appropriate.

                    if remaining == 1 and final_method != "assign" and context == "final-accessor":

                        emit(("__set_context", accessor))

                        accessor = context_var = "<context>"

                    # Perform the access only if not achieved directly.

                    if remaining > 1 or final_method in ("access", "assign"):

                        if traversal_mode == "class":

                            if assigning:

                                emit(("__store_via_class", accessor, attrname, "<assexpr>"))

                            else:

                                accessor = ("__load_via_class", accessor, attrname)

                        else:

                            if assigning:

                                emit(("__store_via_object", accessor, attrname, "<assexpr>"))

                            else:

                                accessor = ("__load_via_object", accessor, attrname)

                    remaining -= 1

            if attrnames:

                for attrname in attrnames:

                    assigning = remaining == 1 and final_method == "assign"

                    # Set the context, if appropriate.

                    if remaining == 1 and final_method != "assign" and context == "final-accessor":

                        emit(("__set_context", accessor))

                        accessor = context_var = "<context>"

                    # Perform the access only if not achieved directly.

                    if remaining > 1 or final_method in ("access", "assign"):

                        if assigning:

                            emit(("__check_and_store_via_any", accessor, attrname, "<assexpr>"))

                        else:

                            accessor = ("__check_and_load_via_any", accessor, attrname)

                    remaining -= 1

            # Define or emit the means of accessing the actual target.

            if final_method == "static-assign":

                parent, attrname = origin.rsplit(".", 1)

                emit(("__store_via_object", parent, attrname, "<assexpr>"))

            elif final_method in ("static", "static-invoke"):

                parent, attrname = origin.rsplit(".", 1)

                accessor = ("__load_static", parent, origin)

            # Wrap accesses in context operations.

            if context_test == "test":

                emit(("__test_context", context_var, accessor))

            elif context_test == "replace":

                emit(("__update_context", context_var, accessor))

            elif final_method not in ("assign", "static-assign"):

                emit(accessor)

            self.access_instructions[access_location] = instructions

            self.accessor_kinds[access_location] = accessor_kinds

    def get_ambiguity_for_attributes(self, attrnames):

        """

        Return a list of attribute position alternatives corresponding to each

        of the given 'attrnames'.

        """

        ambiguity = []

        for attrname in attrnames:

            position = self.attr_locations[attrname]

            ambiguity.append(len(self.locations[position]))

        return ambiguity

    def position_parameters(self):

        "Position the parameters for each function's parameter table."

        # Reverse the location mappings.

        param_locations = self.param_locations = {}

        for i, argnames in enumerate(self.arg_locations):

            # Position the arguments.

            for argname in argnames:

                param_locations[argname] = i

        for name, argnames in self.importer.function_parameters.items():

            # Allocate an extra context parameter in the table.

            l = self.parameters[name] = [None] + [None] * len(argnames)

            # Store an entry for the name along with the name's position in the

            # parameter list.

            for pos, argname in enumerate(argnames):

                # Position the argument in the table.

                position = param_locations[argname]

                if position >= len(l):

                    l.extend([None] * (position - len(l) + 1))

                # Indicate an argument list position starting from 1 (after the

                # initial context argument).

                l[position] = (argname, pos + 1)

    def populate_tables(self):

        """

        Assign identifiers to attributes and encode structure information using

        these identifiers.

        """

        self.all_attrnames, d = self._get_name_mapping(self.attr_locations)

        # Record the numbers indicating the locations of the names.

        for key, attrnames in self.structures.items():

            l = self.attr_table[key] = []

            for attrname in attrnames:

                if attrname is None:

                    l.append(None)

                else:

                    l.append(d[attrname])

        self.all_paramnames, d = self._get_name_mapping(self.param_locations)

        # Record the numbers indicating the locations of the names.

        for key, values in self.parameters.items():

            l = self.param_table[key] = []

            for value in values:

                if value is None:

                    l.append(None)

                else:

                    name, pos = value

                    l.append((d[name], pos))

    def _get_name_mapping(self, locations):

        """

        Get a sorted list of names from 'locations', then map them to

        identifying numbers. Return the list and the mapping.

        """

        all_names = locations.keys()

        all_names.sort()

        d = {}

        for i, name in enumerate(all_names):

            d[name] = i

        return all_names, d

    def populate_constants(self):

        """

        Obtain a collection of distinct constant literals, building a mapping

        from constant references to those in this collection.

        """

        # Obtain mappings from constant values to identifiers.

        self.constants = {}

        for path, constants in self.importer.all_constants.items():

            # Record constants and obtain a number for them.

            # Each constant is actually (value, value_type, encoding).

            for constant, n in constants.items():

                add_counter_item(self.constants, constant)

        self.constant_numbers = {}

        for name, constant in self.importer.all_constant_values.items():

            self.constant_numbers[name] = self.constants[constant]

def combine_rows(a, b):

    c = []

    for i, j in zip(a, b):

        if i is None or j is None:

            c.append(i or j)

        else:

            return None

    return c

def get_attributes_and_sizes(d):

    """

    Return a matrix of attributes, a list of type names corresponding to columns

    in the matrix, and a list of ranked sizes each indicating...

     * a weighted size depending on the kind of object

     * the minimum size of an object employing an attribute

     * the number of free columns in the matrix for the attribute

     * the attribute name itself

    """

    attrs = {}

    sizes = {}

    objtypes = {}

    for name, attrnames in d.items():

        objtype, _name = name

        for attrname in attrnames:

            # Record each type supporting the attribute.

            init_item(attrs, attrname, set)

            attrs[attrname].add(name)

            # Maintain a record of the smallest object size supporting the given

            # attribute.

            if not sizes.has_key(attrname):

                sizes[attrname] = len(attrnames)

            else:

                sizes[attrname] = min(sizes[attrname], len(attrnames))

            # Record the object types/kinds supporting the attribute.

            init_item(objtypes, attrname, set)

            objtypes[attrname].add(objtype)

    # Obtain attribute details in order of size and occupancy.

    names = d.keys()

    rsizes = []

    for attrname, size in sizes.items():

        priority = "<instance>" in objtypes[attrname] and 0.5 or 1

        occupied = len(attrs[attrname])

        key = (priority * size, size, len(names) - occupied, attrname)

        rsizes.append(key)

    rsizes.sort()

    # Make a matrix of attributes.

    matrix = {}

    for attrname, types in attrs.items():

        row = []

        for name in names:

            if name in types:

                row.append(attrname)

            else:

                row.append(None)

        matrix[attrname] = row

    return matrix, names, rsizes

def get_parameters_and_sizes(d):

    """

    Return a matrix of parameters, a list of functions corresponding to columns

    in the matrix, and a list of ranked sizes each indicating...

     * a weighted size depending on the kind of object

     * the minimum size of a parameter list employing a parameter

     * the number of free columns in the matrix for the parameter

     * the parameter name itself

    This is a slightly simpler version of the above 'get_attributes_and_sizes'

    function.

    """

    params = {}

    sizes = {}

    for name, argnames in d.items():

        for argname in argnames:

            # Record each function supporting the parameter.

            init_item(params, argname, set)

            params[argname].add(name)

            # Maintain a record of the smallest parameter list supporting the

            # given parameter.

            if not sizes.has_key(argname):

                sizes[argname] = len(argnames)

            else:

                sizes[argname] = min(sizes[argname], len(argnames))

    # Obtain attribute details in order of size and occupancy.