another helper for strings

all.h

@@ -684,6 +684,8 @@ fn u32 stringCountLines(String s);
 fn u32 stringLineLen(String s, u32 line_number);
 fn u32 stringLineStartByteOffset(String s, u32 line_number);
 fn bool stringInsertBytesAt(String* s, str bytes, u32 at);
+fn bool stringInsertBytesAtMaybeAlloc(Arena* a, String* s, str bytes, u32 at);
+fn u32 stringFindNextCharPosFrom(String s, u32 from, u8 c);
 
 ///// OS-wrapped apis
 void      osInit();

string.c

@@ -472,8 +472,10 @@ fn bool stringInsertBytesAt(String* s, str bytes, u32 at) {
     return false;
   }
   for (u32 i = 0; i < len; i++) {
-    // move the original byte over by `len`
+    // shift all the following bytes over by one, starting from the end and working toward `at`
-    s->bytes[at + i + len] = s->bytes[at + i];
+    for (u32 ii = s->length; ii > at+i; ii--) {
+      s->bytes[ii] = s->bytes[ii-1];
+    }
     // copy the new byte in
     s->bytes[at + i] = bytes[i];
     s->length += 1;
@@ -481,3 +483,25 @@ fn bool stringInsertBytesAt(String* s, str bytes, u32 at) {
   return true;
 }
 
+// will alloc a new string over top of s.bytes if it didnt have enough space
+// this is destructive of the pointer
+// may cause mem-leak if you arent clearing the arena correctly
+fn bool stringInsertBytesAtMaybeAlloc(Arena* a, String* s, str bytes, u32 at) {
+  bool is_already_enough_space = stringInsertBytesAt(s, bytes, at);
+  if (!is_already_enough_space) {
+    ptr old_bytes = s->bytes;
+    s->bytes = arenaAllocZero(a, s->capacity + 64);
+    MemoryCopy(s->bytes, old_bytes, s->length);
+    return stringInsertBytesAt(s, bytes, at);
+  }
+  return true;
+}
+
+fn u32 stringFindNextCharPosFrom(String s, u32 from, u8 c) {
+  for (u32 i = from; i < s.length; i++) {
+    if (s.bytes[i] == c) {
+      return i;
+    }
+  }
+  return s.length;
+}