#!/usr/bin/env python  """ Encoder functions, producing representations of program objects.  Copyright (C) 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 first, InstructionSequence    # Value digest computation.  from base64 import b64encode from hashlib import sha1  def digest(values):     m = sha1()     for value in values:         m.update(str(value))     return b64encode(m.digest()).replace("+", "__").replace("/", "_").rstrip("=")    # Output encoding and decoding for the summary files.  def encode_attrnames(attrnames):      "Encode the 'attrnames' representing usage."      return ", ".join(attrnames) or "{}"  def encode_constrained(constrained):      "Encode the 'constrained' status for program summaries."      return constrained and "constrained" or "deduced"  def encode_usage(usage):      "Encode attribute details from 'usage'."      all_attrnames = []     for t in usage:         attrname, invocation, assignment = t         all_attrnames.append("%s%s" % (attrname, invocation and "!" or assignment and "=" or ""))     return ", ".join(all_attrnames) or "{}"  def decode_usage(s):      "Decode attribute details from 's'."      all_attrnames = set()     for attrname_str in s.split(", "):         all_attrnames.add((attrname_str.rstrip("!="), attrname_str.endswith("!"), attrname_str.endswith("=")))      all_attrnames = list(all_attrnames)     all_attrnames.sort()     return tuple(all_attrnames)  def encode_access_location(t):      "Encode the access location 't'."      path, name, attrname, version = t     return "%s %s %s:%d" % (path, name or "{}", attrname, version)  def encode_location(t):      "Encode the general location 't' in a concise form."      path, name, attrname, version = t     if name is not None and version is not None:         return "%s %s:%d" % (path, name, version)     elif name is not None:         return "%s %s" % (path, name)     else:         return "%s :%s" % (path, attrname)  def encode_modifiers(modifiers):      "Encode assignment and invocation details from 'modifiers'."      all_modifiers = []     for t in modifiers:         all_modifiers.append(encode_modifier_term(t))     return "".join(all_modifiers)  def encode_modifier_term(t):      "Encode modifier 't' representing an assignment or an invocation."      assignment, invocation = t     if assignment:         return "="     elif invocation is not None:         arguments, keywords = invocation         return "(%d;%s)" % (arguments, ",".join(keywords))     else:         return "_"  def decode_modifiers(s):      "Decode 's' containing modifiers."      i = 0     end = len(s)      modifiers = []      while i < end:         if s[i] == "=":             modifiers.append((True, None))             i += 1         elif s[i] == "(":             j = s.index(";", i)             arguments = int(s[i+1:j])             i = j             j = s.index(")", i)             keywords = s[i+1:j]             keywords = keywords and keywords.split(",") or []             modifiers.append((False, (arguments, keywords)))             i = j + 1         else:             modifiers.append((False, None))             i += 1      return modifiers    # Test generation functions.  def get_kinds(all_types):      """      Return object kind details for 'all_types', being a collection of     references for program types.     """      return map(lambda ref: ref.get_kind(), all_types)  def test_label_for_kind(kind):      "Return the label used for 'kind' in test details."      return kind == "<instance>" and "instance" or "type"  def test_label_for_type(ref):      "Return the label used for 'ref' in test details."      return test_label_for_kind(ref.get_kind())    # Instruction representation encoding.  def encode_instruction(instruction):      """     Encode the 'instruction' - a sequence starting with an operation and     followed by arguments, each of which may be an instruction sequence or a     plain value - to produce a function call string representation.     """      op = instruction[0]     args = instruction[1:]      if args:         a = []         for arg in args:             if isinstance(arg, tuple):                 a.append(encode_instruction(arg))             else:                 a.append(arg or "{}")         argstr = "(%s)" % ", ".join(a)         return "%s%s" % (op, argstr)     else:         return op    # Output program encoding.  attribute_loading_ops = (     "__load_via_class", "__load_via_object", "__get_class_and_load",     )  attribute_ops = attribute_loading_ops + (     "__store_via_object",     )  checked_loading_ops = (     "__check_and_load_via_class", "__check_and_load_via_object", "__check_and_load_via_any",     )  checked_ops = checked_loading_ops + (     "__check_and_store_via_class", "__check_and_store_via_object", "__check_and_store_via_any",     )  typename_ops = (     "__test_common_instance", "__test_common_object", "__test_common_type",     )  type_ops = (     "__test_specific_instance", "__test_specific_object", "__test_specific_type",     )  static_ops = (     "__load_static_ignore", "__load_static_replace", "__load_static_test", "<test_context_static>",     )  context_values = (     "<context>",     )  context_ops = (     "<context>", "<set_context>", "<test_context_revert>", "<test_context_static>",     )  context_op_functions = (     "<test_context_revert>", "<test_context_static>",     )  reference_acting_ops = attribute_ops + checked_ops + typename_ops attribute_producing_ops = attribute_loading_ops + checked_loading_ops  def encode_access_instruction(instruction, subs, context_index):      """     Encode the 'instruction' - a sequence starting with an operation and     followed by arguments, each of which may be an instruction sequence or a     plain value - to produce a function call string representation.      The 'subs' parameter defines a mapping of substitutions for special values     used in instructions.      The 'context_index' parameter defines the position in local context storage     for the referenced context or affected by a context operation.      Return both the encoded instruction and a collection of substituted names.     """      op = instruction[0]     args = instruction[1:]     substituted = set()      # Encode the arguments.      a = []     if args:         converting_op = op         for arg in args:             s, _substituted = encode_access_instruction_arg(arg, subs, converting_op, context_index)             substituted.update(_substituted)             a.append(s)             converting_op = None      # Modify certain arguments.      # Convert attribute name arguments to position symbols.      if op in attribute_ops:         arg = a[1]         a[1] = encode_symbol("pos", arg)      # Convert attribute name arguments to position and code symbols.      elif op in checked_ops:         arg = a[1]         a[1] = encode_symbol("pos", arg)         a.insert(2, encode_symbol("code", arg))      # Convert type name arguments to position and code symbols.      elif op in typename_ops:         arg = encode_type_attribute(args[1])         a[1] = encode_symbol("pos", arg)         a.insert(2, encode_symbol("code", arg))      # Obtain addresses of type arguments.      elif op in type_ops:         a[1] = "&%s" % a[1]      # Obtain addresses of static objects.      elif op in static_ops:         a[-1] = "&%s" % a[-1]      # Add context storage information to certain operations.      if op in context_ops:         a.insert(0, context_index)      # Add the local context array to certain operations.      if op in context_op_functions:         a.append("__tmp_contexts")      # Define any argument string.      if a:         argstr = "(%s)" % ", ".join(map(str, a))     else:         argstr = ""      # Substitute the first element of the instruction, which may not be an     # operation at all.      if subs.has_key(op):         substituted.add(op)          # Break accessor initialisation into initialisation and value-yielding         # parts:          if op == "<set_accessor>" and isinstance(a[0], InstructionSequence):             ops = []             ops += a[0].get_init_instructions()             ops.append("%s(%s)" % (subs[op], a[0].get_value_instruction()))             return ", ".join(map(str, ops)), substituted          op = subs[op]      elif not args:         op = "&%s" % encode_path(op)      return "%s%s" % (op, argstr), substituted  def encode_access_instruction_arg(arg, subs, op, context_index):      """     Encode 'arg' using 'subs' to define substitutions, 'op' to indicate the     operation to which the argument belongs, and 'context_index' to indicate any     affected context storage.      Return a tuple containing the encoded form of 'arg' along with a collection     of any substituted values.     """      if isinstance(arg, tuple):         encoded, substituted = encode_access_instruction(arg, subs, context_index)          # Convert attribute results to references where required.          if op and op in reference_acting_ops and arg[0] in attribute_producing_ops:             return "%s.value" % encoded, substituted         else:             return encoded, substituted      # Special values only need replacing, not encoding.      elif subs.has_key(arg):          # Handle values modified by storage details.          if arg in context_values:             return "%s(%s)" % (subs.get(arg), context_index), set([arg])         else:             return subs.get(arg), set([arg])      # Convert static references to the appropriate type.      elif op and op in reference_acting_ops and arg != "<accessor>":         return "&%s" % encode_path(arg), set()      # Other values may need encoding.      else:         return encode_path(arg), set()  def encode_function_pointer(path):      "Encode 'path' as a reference to an output program function."      return "__fn_%s" % encode_path(path)  def encode_instantiator_pointer(path):      "Encode 'path' as a reference to an output program instantiator."      return "__new_%s" % encode_path(path)  def encode_instructions(instructions):      "Encode 'instructions' as a sequence."      if len(instructions) == 1:         return instructions[0]     else:         return "(\n%s\n)" % ",\n".join(instructions)  def encode_literal_constant(n):      "Encode a name for the literal constant with the number 'n'."      return "__const%s" % n  def encode_literal_constant_size(value):      "Encode a size for the literal constant with the given 'value'."      if isinstance(value, basestring):         return len(value)     else:         return 0  def encode_literal_constant_member(value):      "Encode the member name for the 'value' in the final program."      return "%svalue" % value.__class__.__name__  def encode_literal_constant_value(value):      "Encode the given 'value' in the final program."      if isinstance(value, (int, float)):         return str(value)     else:         l = []          # Encode characters including non-ASCII ones.          for c in str(value):             if c == '"': l.append('\\"')             elif c == '\n': l.append('\\n')             elif c == '\t': l.append('\\t')             elif c == '\r': l.append('\\r')             elif c == '\\': l.append('\\\\')             elif 0x20 <= ord(c) < 0x80: l.append(c)             else: l.append("\\x%02x" % ord(c))          return '"%s"' % "".join(l)  def encode_literal_data_initialiser(style):      """     Encode a reference to a function populating the data for a literal having     the given 'style' ("mapping" or "sequence").     """      return "__newdata_%s" % style  def encode_literal_instantiator(path):      """     Encode a reference to an instantiator for a literal having the given 'path'.     """      return "__newliteral_%s" % encode_path(path)  def encode_literal_reference(n):      "Encode a reference to a literal constant with the number 'n'."      return "__constvalue%s" % n    # Track all encoded paths, detecting and avoiding conflicts.  all_encoded_paths = {}  def encode_path(path):      "Encode 'path' as an output program object, translating special symbols."      if path in reserved_words:         return "__%s" % path     else:         part_encoded = path.replace("#", "__").replace("$", "__")          if "." not in path:             return part_encoded          encoded = part_encoded.replace(".", "_")          # Test for a conflict with the encoding of a different path, re-encoding         # if necessary.          previous = all_encoded_paths.get(encoded)         replacement = "_"          while previous:             if path == previous:                 return encoded             replacement += "_"             encoded = part_encoded.replace(".", replacement)             previous = all_encoded_paths.get(encoded)          # Store any new or re-encoded path.          all_encoded_paths[encoded] = path         return encoded  def encode_predefined_reference(path):      "Encode a reference to a predefined constant value for 'path'."      return "__predefined_%s" % encode_path(path)  def encode_size(kind, path=None):      """     Encode a structure size reference for the given 'kind' of structure, with     'path' indicating a specific structure name.     """      return "__%ssize%s" % (structure_size_prefixes.get(kind, kind), path and "_%s" % encode_path(path) or "")  def encode_symbol(symbol_type, path=None):      "Encode a symbol with the given 'symbol_type' and optional 'path'."      return "__%s%s" % (symbol_type, path and "_%s" % encode_path(path) or "")  def encode_tablename(kind, path):      """     Encode a table reference for the given 'kind' of table structure, indicating     a 'path' for the specific object concerned.     """      return "__%sTable_%s" % (table_name_prefixes[kind], encode_path(path))  def encode_type_attribute(path):      "Encode the special type attribute for 'path'."      return "#%s" % path  def decode_type_attribute(s):      "Decode the special type attribute 's'."      return s[1:]  def is_type_attribute(s):      "Return whether 's' is a type attribute name."      return s.startswith("#")    # A mapping from kinds to structure size reference prefixes.  structure_size_prefixes = {     "<class>" : "c",     "<module>" : "m",     "<instance>" : "i"     }  # A mapping from kinds to table name prefixes.  table_name_prefixes = {     "<class>" : "Class",     "<function>" : "Function",     "<module>" : "Module",     "<instance>" : "Instance"     }    # Output language reserved words.  reserved_words = [     "break", "char", "const", "continue",     "default", "double", "else",     "float", "for",     "if", "int", "long",     "NULL",     "return", "struct",     "typedef",     "void", "while",     ]  # vim: tabstop=4 expandtab shiftwidth=4