LocalStrBuilder

#pragma once

#include <stdlib.h>

#define LOCALSTRBUILDER_NCHARS 7

typedef struct
{
  char* c_str;
  int size;
  int capacity;
  char chars[LOCALSTRBUILDER_NCHARS + 1];

} LocalStrBuilder;


void LocalStrBuilder_Init(LocalStrBuilder* p);

void LocalStrBuilder_Swap(LocalStrBuilder* pA, LocalStrBuilder* pB);

void LocalStrBuilder_Destroy(LocalStrBuilder* p);

void LocalStrBuilder_Reserve(LocalStrBuilder* p, int nelements);

void LocalStrBuilder_Print(LocalStrBuilder* p);

void LocalStrBuilder_Clear(LocalStrBuilder* p);

void LocalStrBuilder_Grow(LocalStrBuilder* p, int nelements);

void LocalStrBuilder_Append(LocalStrBuilder* p, const char* source);
void LocalStrBuilder_AppendChar(LocalStrBuilder* p, char ch);
void LocalStrBuilder_Set(LocalStrBuilder* p, const char* source);

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "LocalStrBuilder.h"


void LocalStrBuilder_Init(LocalStrBuilder* p)
{
  p->capacity = LOCALSTRBUILDER_NCHARS;
  p->size = 0;
  p->c_str = p->chars;
}

void LocalStrBuilder_Swap(LocalStrBuilder* pA, LocalStrBuilder* pB)
{
  int bA = (pA->c_str == pA->chars);
  int bB = (pB->c_str == pB->chars);

  LocalStrBuilder temp = *pA;
  *pA = *pB;
  *pB = temp;

  if (bA)
  {
    pB->c_str = pB->chars;
  }
  if (bB)
  {
    pA->c_str = pA->chars;
  }
}

void LocalStrBuilder_Destroy(LocalStrBuilder* p)
{
  if (p->c_str != p->chars)
  {
    free(p->c_str);
  }
}

void LocalStrBuilder_Reserve(LocalStrBuilder* p, int nelements)
{
  if (nelements > p->capacity)
  {
    char* pnew = NULL;
    if (nelements <= LOCALSTRBUILDER_NCHARS)
    {
      pnew = p->chars;
      p->capacity = LOCALSTRBUILDER_NCHARS;
      p->c_str = pnew;
    }
    else
    {
      if (p->capacity <= LOCALSTRBUILDER_NCHARS)
      {
        pnew = (char*)malloc((nelements + 1) * sizeof(char));
        memcpy(pnew, p->chars, LOCALSTRBUILDER_NCHARS);
      }
      else
      {
        pnew = (char*)realloc(p->c_str, (nelements + 1) * sizeof(char));
      }

      p->c_str = pnew;

      if (p->size == 0)
      {
        pnew[0] = '\0';
      }
      p->capacity = nelements;
    }
  }
}

void LocalStrBuilder_Print(LocalStrBuilder* p)
{
  printf("size = %d, capacity = %d, c_str = '%s', internal buffer = %s \n",
    (int)p->size,
    (int)p->capacity,
    p->c_str,
    (p->c_str == p->chars ? "yes" : "no"));
}

void LocalStrBuilder_Clear(LocalStrBuilder* p)
{
  if (p->c_str)
  {
    p->c_str[0] = 0;
  }
  p->size = 0;
}

void LocalStrBuilder_Grow(LocalStrBuilder* p, int nelements)
{
  if (nelements > p->capacity)
  {
    int new_nelements = p->capacity + p->capacity / 2;

    if (new_nelements < nelements)
    {
      new_nelements = nelements;
    }

    LocalStrBuilder_Reserve(p, new_nelements);
  }
}

void LocalStrBuilder_Append(LocalStrBuilder* p, const char* source)
{
  while (*source)
  {
    LocalStrBuilder_AppendChar(p, *source);
    source++;
  }
}


void LocalStrBuilder_Set(LocalStrBuilder* p, const char* source)
{
  LocalStrBuilder_Clear(p);
  while (*source)
  {
    LocalStrBuilder_AppendChar(p, *source);
    source++;
  }
}



void LocalStrBuilder_AppendChar(LocalStrBuilder* p, char ch)
{
  LocalStrBuilder_Grow(p, p->size + 1);

  p->c_str[p->size] = ch;
  p->c_str[p->size + 1] = 0;
  p->size++;
}