Add minimal 'dynamic array' library using macros

This is a one-file library built on C-macros to declare and use
dynamically allocated, growing arrays, which is most of the data
structures you'll ever need.

build/Makefile.in

@@ -227,6 +227,7 @@ HEADERS = src/moar.h \
           src/core/exceptions.h \
           src/core/interp.h \
           src/core/alloc.h \
+          src/core/dynar.h \
           src/core/frame.h \
           src/core/callstack.h \
           src/core/compunit.h \

src/core/dynar.h

@@ -0,0 +1,32 @@
+/* An as-small-as-possible dynamic array implementation. */
+#define MVM_DYNAR_DECL(type, x) type *x; \
+    size_t x ## _num; \
+    size_t x ## _alloc;
+
+#define MVM_DYNAR_INIT(x, size) do { \
+        x = MVM_malloc((size)*sizeof(*x));    \
+        x ## _num = 0; \
+        x ## _alloc = (size); \
+    } while (0)
+
+#define MVM_DYNAR_GROW(x, size) do {\
+        x = MVM_realloc(x, (size)*sizeof(*x));   \
+        x ## _alloc = (size); \
+    } while (0)
+
+#define MVM_DYNAR_ENSURE(x, space) \
+    if (((x ## _num) + (space)) >= (x ## _alloc)) {     \
+        MVM_DYNAR_GROW(x, (x ## _alloc)*2); \
+    }
+
+#define MVM_DYNAR_PUSH(x, value) do { \
+        MVM_DYNAR_ENSURE(x, 1); \
+        x[x ## _num++] = (value); \
+    } while(0)
+
+#define MVM_DYNAR_APPEND(x, ar, len) do { \
+        MVM_DYNAR_ENSURE(x, len); \
+        memcpy(x + x ## _num, ar, (len) * sizeof(x[0]));        \
+        x ## _num += len; \
+    } while(0)
+

src/moar.h

@@ -101,6 +101,7 @@ MVM_PUBLIC const MVMint32 MVM_jit_support(void);
 #include "core/args.h"
 #include "core/exceptions.h"
 #include "core/alloc.h"
+#include "core/dynar.h"
 #include "core/frame.h"
 #include "core/callstack.h"
 #include "core/validation.h"