code.kerkeslager.com Git - fur/blob - templates/environment.c

   1 struct _EnvironmentNode;
   2 typedef struct _EnvironmentNode _EnvironmentNode;
   3 struct _EnvironmentNode {
   4   const char* symbol;
   5   Object value;
   6   _EnvironmentNode* next;
   7 };
   8
   9 struct Environment {
  10   size_t referenceCount;
  11   Environment* shadowed;
  12   _EnvironmentNode* top;
  13 };
  14
  15 struct Environment_get_Result;
  16 typedef struct Environment_get_Result Environment_get_Result;
  17 struct Environment_get_Result {
  18   bool found;
  19   Object result;
  20 };
  21
  22 void Environment_initialize(Environment* self, Environment* shadowed) {
  23   self->referenceCount = 1;
  24   self->shadowed = shadowed;
  25   self->top = NULL;
  26 }
  27
  28 void Environment_deinitialize(Environment* self) {
  29   assert(self->referenceCount == 0);
  30
  31   while(self->top != NULL) {
  32     _EnvironmentNode* en = self->top;
  33     self->top = en->next;
  34     Object_deinitialize(&(en->value));
  35     free(en);
  36   }
  37 }
  38
  39 Environment* Environment_construct(Environment* shadowed) {
  40   Environment* result = malloc(sizeof(Environment));
  41   Environment_initialize(result, shadowed);
  42   return result;
  43 }
  44
  45 Environment* Environment_reference(Environment* self) {
  46   self->referenceCount++; // TODO Do we need to make this thread safe?
  47   return self;
  48 }
  49
  50 void Environment_destruct(Environment* self) {
  51   self->referenceCount--; // TODO Do we need to make this thread safe?
  52   if(self->referenceCount == 0) {
  53     Environment_deinitialize(self);
  54     free(self);
  55   }
  56 }
  57
  58 Environment_get_Result Environment_getShallow(Environment* self, char* symbol) {
  59   for(_EnvironmentNode* current = self->top; current != NULL; current = current->next) {
  60     if(strcmp(current->symbol, symbol) == 0) {
  61       return (Environment_get_Result) { true, current->value };
  62     }
  63   }
  64   return (Environment_get_Result) { false, BUILTIN_NIL };
  65 }
  66
  67 Environment_get_Result Environment_get(Environment* self, char* symbol) {
  68   for(; self != NULL; self = self->shadowed) {
  69     Environment_get_Result result = Environment_getShallow(self, symbol);
  70     if(result.found) return result;
  71   }
  72   return (Environment_get_Result) { false, BUILTIN_NIL };
  73 }
  74
  75 void Environment_set(Environment* self, char* symbol, Object value) {
  76   assert(!(Environment_getShallow(self, symbol).found));
  77
  78   _EnvironmentNode* en = malloc(sizeof(_EnvironmentNode));
  79   en->symbol = symbol;
  80   en->value = value;
  81   en->next = self->top;
  82   self->top = en;
  83 }