1 files changed, 54 insertions, 0 deletions
diff --git a/src/strings.c b/src/strings.c
new file mode 100644
index 0000000..baa433f
--- /dev/null
+++ b/src/strings.c
@@ -0,0 +1,54 @@
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "strings.h"
+
+// new String pointers must be zeroed before being handed to this function
+void init_string(struct String *str, size_t initial_capacity)
+{
+    if (str->data) free(str->data);
+    str->data = malloc(initial_capacity);
+    if (str->data == NULL) {
+        perror("malloc() failed");
+        exit(errno);
+    }
+    str->cap = initial_capacity;
+    str->len = 0;
+    *(str->data) = 0;
+}
+
+void resize_string(struct String *str)
+{
+    str->data = realloc((void*)str->data, str->cap * 2);
+    if (str->data == NULL) {
+        perror("realloc() failed");
+        exit(errno);
+    }
+    str->cap = str->cap * 2;
+}
+
+void append_str(char *input_str, size_t len, struct String *str)
+{
+    while (str->len + len >= str->cap - 1) {
+        resize_string(str);
+    }
+    strcpy(str->data + str->len, input_str);
+    str->len += len;
+}
+
+void append_char(char c, struct String *str)
+{
+    if (str->len >= str->cap - 1) {
+        resize_string(str);
+    }
+    str->data[str->len] = c;
+    str->len += 1;
+    str->data[str->len] = '\0';
+}
+
+void delete_char(struct String *str)
+{
+    str->len -= 1;
+    str->data[str->len] = '\0';
+}