clox/object.c

/**
  ******************************************************************************
  * @file           : object.cpp
  * @author         : simon
  * @brief          : None
  * @attention      : None
  * @date           : 2023/8/23
  ******************************************************************************
  */
#include <stdio.h>
#include <string.h>

#include "memory.h"
#include "table.h"
#include "object.h"
#include "vm.h"

static Obj *allocateObject(size_t size, ObjType type);
static uint32_t hashString(const char *key, int length);

#define ALLOCATE_OBJ(type, objectType) \
  (type *) allocateObject(sizeof(type), objectType)

static ObjString *allocateString(char *chars, int length,
                                 uint32_t hash) {
  ObjString *string = ALLOCATE_OBJ(ObjString, OBJ_STRING);
  string->length = length;
  string->chars = chars;
  string->hash = hash;
  tableSet(&vm.strings, string, NIL_VAL);
  return string;
}

ObjString *copyString(const char *chars, int length) {
  uint32_t hash = hashString(chars, length);
  ObjString *interned = tableFindString(&vm.strings, chars, length, hash);

  if (interned != NULL) return interned;

  char *heapChars = ALLOCATE(char, length + 1);
  memcpy(heapChars, chars, length);
  heapChars[length] = '\0';
  return allocateString(heapChars, length, hash);
}
void printObject(Value value) {
  switch (OBJ_TYPE(value)) {
    case OBJ_STRING:
      printf("%s", AS_CSTRING(value));
      break;
  }
}
ObjString *takeString(char *chars, int length) {
  uint32_t hash = hashString(chars, length);
  ObjString *interned = tableFindString(&vm.strings, chars, length, hash);

  if (interned != NULL) {
    FREE_ARRAY(char, chars, length + 1);
    return interned;
  }

  return allocateString(chars, length, hash);
}

static Obj *allocateObject(size_t size, ObjType type) {
  Obj *object = (Obj *) reallocate(NULL, 0, size);
  object->type = type;

  object->next = vm.objects;
  vm.objects = object;

  return object;
}
/// Hash 函数 -- 使用 FNV-1a 算法
/// \param key
/// \param length
/// \return
static uint32_t hashString(const char *key, int length) {
  uint32_t hash = 2166136261u;
  for (int i = 0; i < length; i++) {
    hash ^= (uint8_t) key[i];
    hash *= 16777619;
  }
  return hash;
}