Create buffer util

src/main/c/util/buffer.c

@@ -0,0 +1,181 @@
+#ifndef _HDR_HYPERBUILD_UTIL_BUFFER
+#define _HDR_HYPERBUILD_UTIL_BUFFER
+
+#include <stddef.h>
+
+#define INITIAL_BUFFER_SIZE 20
+#define BUFFER_GROWTH_RATE 1.5
+
+typedef struct hbu_buffer_s {
+  char *data;
+  size_t length;
+  size_t size;
+} *hbu_buffer_t;
+
+hbu_buffer_t hbu_buffer_create(void) {
+  hbu_buffer_t buf = malloc(sizeof(struct hbu_buffer_s));
+  buf->data = calloc(INITIAL_BUFFER_SIZE, sizeof(char));
+  buf->length = 0;
+  buf->size = INITIAL_BUFFER_SIZE;
+}
+
+void hbu_buffer_destroy(hbu_buffer_t buf) {
+  free(buf->data);
+  free(buf);
+}
+
+int hbu_buffer_valid_index(hbu_buffer_t buf, size_t idx) {
+  return idx >= 0 && idx < buf->length;
+}
+
+char hbu_buffer_get(hbu_buffer_t buf, size_t idx) {
+  if (!hbu_buffer_valid_index(buf, idx)) {
+    return '\0';
+  }
+
+  return buf->data[idx];
+}
+
+void hbu_buffer_set(hbu_buffer_t buf, size_t idx, char c) {
+  if (!hbu_buffer_valid_index(buf, idx)) {
+    return;
+  }
+
+  buf->data[idx] = c;
+}
+
+void hbu_buffer_size_expand(hbu_buffer_t buf, size_t new_size) {
+  size_t old_size = buf->size;
+
+  if (old_size >= new_size) {
+    return;
+  }
+
+  char *new_data = realloc(buf->data, sizeof(char) * new_size);
+  for (size_t i = old_size; i < new_size; i++) {
+    new_data[i] = '\0';
+  }
+
+  free(buf->data);
+
+  buf->data = new_data;
+  buf->size = new_size;
+}
+
+void hbu_buffer_size_shrink(hbu_buffer_t buf, size_t new_size) {
+  size_t old_size = buf->size;
+
+  if (old_size <= new_size) {
+    return;
+  }
+
+  char *new_data = malloc(sizeof(char) * new_size);
+  memcpy(new_data, buf->data, sizeof(char) * (new_size) - 1);
+  new_data[new_size - 1] = '\0';
+
+  free(buf->data);
+
+  buf->data = new_data;
+  buf->size = new_size;
+}
+
+void hbu_buffer_size_adjust(hbu_buffer_t buf, size_t new_size) {
+  size_t old_size = buf->size;
+
+  if (new_size > old_size) {
+    hbu_buffer_size_expand(buf, new_size);
+
+  } else if (new_size < old_size) {
+    hbu_buffer_size_shrink(buf, new_size);
+  }
+}
+
+void hbu_buffer_size_collapse(hbu_buffer_t buf) {
+  size_t length = buf->length;
+  size_t desired_size = length + 1;
+
+  if (buf->size > desired_size) {
+    hbu_buffer_size_shrink(buf, desired_size);
+  }
+}
+
+void hbu_buffer_ensure_length(hbu_buffer_t buf, size_t length) {
+  size_t desired_size = length + 1;
+
+  if (buf->size < desired_size) {
+    hbu_buffer_size_expand(buf, desired_size);
+  }
+}
+
+void hbu_buffer_append(hbu_buffer_t buf, char tail) {
+  size_t next_idx = buf->length;
+
+  if (next_idx >= buf->size - 1) {
+    size_t old_size = buf->size;
+    size_t new_size = old_size * BUFFER_GROWTH_RATE + 1; // +1 to always guarantee an increase
+
+    hbu_buffer_size_expand(buf, new_size);
+  }
+
+  buf->data[next_idx] = tail;
+  buf->length++;
+}
+
+void hbu_buffer_extend_str(hbu_buffer_t buf, char *ext, size_t ext_len) {
+  hbu_buffer_ensure_length(buf, buf->length + ext_len);
+  for (size_t i = 0; i < ext_len; i++) {
+    hbu_buffer_append(buf, ext[i]);
+  }
+}
+
+void hbu_buffer_extend_buf(hbu_buffer_t buf, hbu_buffer_t ext) {
+  hbu_buffer_ensure_length(buf, buf->length + ext->length);
+  for (size_t i = 0; i < buf->length; i++) {
+    hbu_buffer_append(buf, buf->data[i]);
+  }
+}
+
+char hbu_buffer_shift(hbu_buffer_t buf) {
+  if (buf->length == 0) {
+    return '\0';
+  }
+
+  char f = buf->data[0];
+
+  for (size_t i = 1; i < buf->length; i++) {
+    buf->data[i - 1] = buf->data[i];
+  }
+
+  buf->data[buf->length] = '\0';
+  buf->length--;
+
+  return f;
+}
+
+void hbu_buffer_unshift(hbu_buffer_t buf, char head) {
+  hbu_buffer_append(buf, '\0'); // Use append instead of ensure_length to grow rather than crawl
+
+  for (size_t i = 0; i < buf->length - 1; i++) { // -1 to skip last appended '\0'
+    buf->data[i + 1] = buf->data[i];
+  }
+
+  buf->data[0] = head;
+  // length already adjusted thanks to initial append
+}
+
+char hbu_buffer_pop(hbu_buffer_t buf) {
+  if (buf->length == 0) {
+    return '\0';
+  }
+
+  size_t idx = buf->length - 1;
+
+  char l = buf->data[idx];
+
+  buf->data[idx] = '\0';
+  buf->length--;
+
+  return l;
+}
+
+#endif