[python] Add a (commented-out) example app

Change-Id: I3b00052bf7a116b4b6e2a785931e6a265cc6031c

Makefile

@@ -69,6 +69,7 @@ endif
 include ion/Makefile
 include kandinsky/Makefile
 include poincare/Makefile
+#include python/Makefile
 include escher/Makefile
 # Executable Makefiles
 include apps/Makefile

apps/main.cpp

@@ -1,7 +1,72 @@
 #include "apps_container.h"
+#define PYTHON_TEST 0
+extern "C" {
+#include <stdlib.h>
+#if PYTHON_TEST
+#include "py/compile.h"
+#include "py/runtime.h"
+#include "py/gc.h"
+#include "py/stackctrl.h"
+#endif
+}
 
 AppsContainer container;
 
+#if PYTHON_TEST
+mp_obj_t execute_from_str(const char *str) {
+    nlr_buf_t nlr;
+    if (nlr_push(&nlr) == 0) {
+        mp_lexer_t *lex = mp_lexer_new_from_str_len(0/*MP_QSTR_*/, str, strlen(str), false);
+        mp_parse_tree_t pt = mp_parse(lex, MP_PARSE_FILE_INPUT);
+        mp_obj_t module_fun = mp_compile(&pt, lex->source_name, MP_EMIT_OPT_NONE, false);
+        mp_call_function_0(module_fun);
+        nlr_pop();
+        return 0;
+    } else {
+        // uncaught exception
+        return (mp_obj_t)nlr.ret_val;
+    }
+}
+
+extern "C"
+void mp_hal_stdout_tx_strn_cooked(const char * str, size_t len) {
+  KDContext * ctx = KDIonContext::sharedContext();
+  ctx->drawString(str, KDPoint(0, 0));
+}
+#endif
+
 void ion_app() {
+#if PYTHON_TEST
+
+    // Initialized stack limit
+    mp_stack_set_limit(40000);
+
+    char * pythonHeap = (char *)malloc(16384);
+
+    gc_init(pythonHeap, pythonHeap + 16384);
+
+    // Initialize interpreter
+    mp_init();
+
+    const char str[] =
+"import kandinsky\n"
+"red = kandinsky.color(255,0,0)\n"
+"blue = kandinsky.color(0,0,255)\n"
+"for i in range(100):\n"
+"  for j in range(100):\n"
+"    if ((i+j)%2 == 0):\n"
+"      kandinsky.set_pixel(i, j, red)\n"
+"    else:\n"
+"      kandinsky.set_pixel(i, j, blue)\n"
+;
+
+    if (execute_from_str(str)) {
+        mp_hal_stdout_tx_strn_cooked("Error", 0);
+    }
+
+  while (1) {
+  }
+#endif
+
   container.run();
 }