/* Common operations.  Copyright (C) 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/>. */  #include "gc.h" /* GC_MALLOC, GC_REALLOC */ #include "ops.h" #include "progops.h" /* for raising errors */ #include "progconsts.h" #include "progtypes.h"  /* Direct access and manipulation of static objects. */  __attr __load_static_ignore(__ref obj) {     return (__attr) {.value=obj}; }  __attr __load_static_replace(__ref context, __ref obj) {     return __update_context(context, (__attr) {.value=obj}); }  __attr __load_static_test(__ref context, __ref obj) {     return __test_context(context, (__attr) {.value=obj}); }  /* Direct retrieval operations, returning and setting attributes. */  __attr __load_via_object(__ref obj, int pos) {     return obj->attrs[pos]; }  __attr __load_via_class(__ref obj, int pos) {     return __load_via_object(__get_class(obj), pos); }  __attr __get_class_and_load(__ref obj, int pos) {     if (__is_instance(obj))         return __load_via_class(obj, pos);     else         return __load_via_object(obj, pos); }  /* Direct storage operations. */  int __store_via_object(__ref obj, int pos, __attr value) {     obj->attrs[pos] = value;     return 1; }  int __get_class_and_store(__ref obj, int pos, __attr value) {     /* Forbid class-relative assignments. */      __raise_type_error();     return 0; }  /* Introspection. */  int __is_instance(__ref obj) {     return obj->pos == __INSTANCEPOS; }  int __is_type_instance(__ref obj) {     return __HASATTR(__get_class(obj), __TYPE_CLASS_POS, __TYPE_CLASS_CODE); }  __ref __get_class(__ref obj) {     return __load_via_object(obj, __ATTRPOS(__class__)).value; }  __attr __get_class_attr(__ref obj) {     return __load_via_object(obj, __ATTRPOS(__class__)); }  /* Attribute testing operations. */  __ref __test_specific_instance(__ref obj, __ref type) {     return __get_class(obj) == type ? obj : 0; }  __ref __test_specific_object(__ref obj, __ref type) {     return __test_specific_type(obj, type) || __test_specific_instance(obj, type) ? obj : 0; }  __ref __test_specific_type(__ref obj, __ref type) {     return obj == type ? obj : 0; }  __ref __test_common_instance(__ref obj, int pos, int code) {     return __HASATTR(__get_class(obj), pos, code) ? obj : 0; }  __ref __test_common_object(__ref obj, int pos, int code) {     return __test_common_type(obj, pos, code) || __test_common_instance(obj, pos, code) ? obj : 0; }  __ref __test_common_type(__ref obj, int pos, int code) {     return __HASATTR(obj, pos, code) ? obj : 0; }  /* Attribute testing and retrieval operations. */  __attr __check_and_load_via_object_null(__ref obj, int pos, int code) {     if (__HASATTR(obj, pos, code))         return __load_via_object(obj, pos);     else         return __NULL; }  __attr __check_and_load_via_class(__ref obj, int pos, int code) {     return __check_and_load_via_object(__get_class(obj), pos, code); }  __attr __check_and_load_via_object(__ref obj, int pos, int code) {     if (__HASATTR(obj, pos, code))         return __load_via_object(obj, pos);      __raise_type_error();     return __NULL; }  __attr __check_and_load_via_any(__ref obj, int pos, int code) {     __attr out = __check_and_load_via_object_null(obj, pos, code);     if (out.value == 0)         out = __check_and_load_via_class(obj, pos, code);     return out; }  /* Attribute testing and storage operations. */  int __check_and_store_via_class(__ref obj, int pos, int code, __attr value) {     /* Forbid class-relative assignments. */      __raise_type_error();     return 0; }  int __check_and_store_via_object(__ref obj, int pos, int code, __attr value) {     if (__HASATTR(obj, pos, code))     {         __store_via_object(obj, pos, value);         return 1;     }      /* No suitable attribute. */      __raise_type_error();     return 0; }  int __check_and_store_via_any(__ref obj, int pos, int code, __attr value) {     if (__check_and_store_via_object(obj, pos, code, value))         return 1;      /* Forbid class-relative assignments. */      __raise_type_error();     return 0; }  /* Context-related operations. */  int __test_context_update(__ref context, __attr attr) {     /* Return whether the context should be updated for the attribute. */      __ref attrcontext = __CONTEXT_AS_VALUE(attr).value;      /* Preserve any existing null or instance context. */      if ((attrcontext == 0) || __is_instance(attrcontext))         return 0;      /* Test any instance context against the context employed by the        attribute. */      if (__is_instance(context))     {         /* Obtain the special class attribute position and code identifying the            attribute context's class, inspecting the context instance for            compatibility. */          if (__test_common_instance(context, __TYPEPOS(attrcontext), __TYPECODE(attrcontext)))             return 1;         else             __raise_type_error();     }      /* Test for access to a type class attribute using a type instance. */      if (__test_specific_type(attrcontext, &__TYPE_CLASS_TYPE) && __is_type_instance(context))         return 1;      /* Otherwise, preserve the attribute as retrieved. */      return 0; }  __attr __test_context(__ref context, __attr attr) {     /* Update the context or return the unchanged attribute. */      if (__test_context_update(context, attr))         return __update_context(context, attr);     else         return attr; }  __attr __update_context(__ref context, __attr attr) {     return __new_wrapper(context, attr); }  __attr __test_context_revert(int target, __ref context, __attr attr, __ref contexts[]) {     /* Revert the local context to that employed by the attribute if the        supplied context is not appropriate. */      if (!__test_context_update(context, attr))         contexts[target] = __CONTEXT_AS_VALUE(attr).value;     return attr; }  __attr __test_context_static(int target, __ref context, __ref value, __ref contexts[]) {     /* Set the local context to the specified context if appropriate. */      if (__test_context_update(context, (__attr) {.value=value}))         contexts[target] = context;     return (__attr) {.value=value}; }  /* Context testing for invocations. */  int __type_method_invocation(__ref context, __attr target) {     __ref targetcontext = __CONTEXT_AS_VALUE(target).value;      /* Require instances, not classes, where methods are function instances. */      if (!__is_instance(target.value))         return 0;      /* Access the context of the callable and test if it is the type object. */      return ((targetcontext != 0) && __test_specific_type(targetcontext, &__TYPE_CLASS_TYPE) && __is_type_instance(context)); }  __attr __unwrap_callable(__attr callable) {     __attr value = __check_and_load_via_object_null(callable.value, __ATTRPOS(__value__), __ATTRCODE(__value__));     return value.value ? value : callable; }  __attr (*__get_function(__ref context, __attr target))(__attr[]) {     target = __unwrap_callable(target);      /* Require null or instance contexts for functions and methods respectively,        or type instance contexts for type methods. */      if ((context == 0) || __is_instance(context) || __type_method_invocation(context, target))         return __load_via_object(target.value, __ATTRPOS(__fn__)).fn;     else         return __unbound_method; }  __attr (*__check_and_get_function(__ref context, __attr target))(__attr[]) {     target = __unwrap_callable(target);      /* Require null or instance contexts for functions and methods respectively,        or type instance contexts for type methods. */      if ((context == 0) || __is_instance(context) || __type_method_invocation(context, target))         return __check_and_load_via_object(target.value, __ATTRPOS(__fn__), __ATTRCODE(__fn__)).fn;     else         return __unbound_method; }  /* Basic structure tests. */  int __WITHIN(__ref obj, int pos) {     return pos < obj->table->size; }  int __HASATTR(__ref obj, int pos, int code) {     return __WITHIN(obj, pos) && (obj->table->attrs[pos] == code); }  /* Parameter position operations. */  int __HASPARAM(const __ptable *ptable, int ppos, int pcode) {     __param param;      if (ppos < ptable->size)     {         param = ptable->params[ppos];         if (param.code == pcode)             return param.pos;     }      return -1; }  /* Conversions. */  __attr __CONTEXT_AS_VALUE(__attr attr) {     return __check_and_load_via_object_null(attr.value, __ATTRPOS(__context__), __ATTRCODE(__context__)); }  /* Type testing. */  __ref __ISFUNC(__ref obj) {     return __test_specific_instance(obj, &__FUNCTION_TYPE); }  int __ISNULL(__attr value) {     return (value.value == 0); /* __NULL.value */ }  /* Attribute codes and positions for type objects. */  unsigned int __TYPECODE(__ref obj) {     return obj->table->attrs[obj->pos]; }  unsigned int __TYPEPOS(__ref obj) {     return obj->pos; }  /* Memory allocation. */  void *__ALLOCATE(size_t nmemb, size_t size) {     void *ptr = GC_MALLOC(nmemb * size); /* sets memory to zero */     if (ptr == NULL)         __raise_memory_error();     return ptr; }  void *__REALLOCATE(void *ptr, size_t size) {     void *nptr = GC_REALLOC(ptr, size);     if (nptr == NULL)         __raise_memory_error();     return nptr; }  /* Copying of structures. */  __ref __COPY(__ref obj, int size) {     __ref copy = (__ref) __ALLOCATE(1, size);     memcpy(copy, obj, size);     return copy; }