reorganized build-ins and implement a circular queue as an example

src/lib/builtins/string.c

@@ -0,0 +1,71 @@
+#include <string.h>
+#include <stdlib.h>
+#include "string.h"
+#include "../utils/defs.h"
+#include "../runtime/runtime.h"
+
+static int bin_cat(Runtime *runtime, Object **argv, unsigned int argc, Object *rets[static MAX_RETS], Error *error)
+{
+    unsigned int total_count = 0;
+
+    for(unsigned int i = 0; i < argc; i += 1)
+    {
+        if(!Object_IsString(argv[i]))
+        {
+            Error_Report(error, 0, "Argument #%d is not a string", i+1);
+            return -1;
+        }
+
+        total_count += Object_Count(argv[i], error);
+
+        if(error->occurred)
+            return -1;
+    }
+
+    char starting[128];
+    char *buffer = starting;
+
+    if(total_count > sizeof(starting)-1)
+    {
+        buffer = malloc(total_count+1);
+
+        if(buffer == NULL)
+        {
+            Error_Report(error, 1, "No memory");
+            return -1;
+        }
+    }
+
+    Object *result = NULL;
+
+    for(unsigned int i = 0, written = 0; i < argc; i += 1)
+    {
+        int n;
+        const char *s = Object_ToString(argv[i], &n, 
+            Runtime_GetHeap(runtime), error);
+
+        if(error->occurred)
+            goto done;
+
+        memcpy(buffer + written, s, n);
+        written += n;
+    }
+
+    buffer[total_count] = '\0';
+
+    result = Object_FromString(buffer, total_count, Runtime_GetHeap(runtime), error);
+
+done:
+    if(starting != buffer)
+        free(buffer);
+
+    if(result == NULL)
+        return -1;
+
+    rets[0] = result;
+    return 1;
+}
+
+StaticMapSlot bins_string[] = {
+    { "cat", SM_FUNCT, .as_funct = bin_cat, .argc = -1 },
+};