Better embedding API support (and tests!) for strings with null bytes.

- Test that a foreign method can return strings.
- Test that a foreign method can return a string with null bytes.
- Test wrenCall().
- Allow passing NULL for "v" to wrenCall().
- Allow "a" for passing an explicit length byte array to wrenCall().

src/cli/vm.c

@@ -172,7 +172,7 @@ static void initVM()
 static void freeVM()
 {
   schedulerReleaseMethods();
-
+  
   uv_loop_close(loop);
   free(loop);
 
@@ -259,8 +259,8 @@ uv_loop_t* getLoop()
   return loop;
 }
 
-void setForeignCallbacks(
-    WrenBindForeignMethodFn bindMethod, WrenBindForeignClassFn bindClass)
+void setTestCallbacks(WrenBindForeignMethodFn bindMethod,
+                      WrenBindForeignClassFn bindClass)
 {
   bindMethodFn = bindMethod;
   bindClassFn = bindClass;

src/cli/vm.h

@@ -22,7 +22,7 @@ uv_loop_t* getLoop();
 //
 // Used by the API test executable to let it wire up its own foreign functions.
 // This must be called before calling [createVM()].
-void setForeignCallbacks(WrenBindForeignMethodFn bindMethod,
-                         WrenBindForeignClassFn bindClass);
+void setTestCallbacks(WrenBindForeignMethodFn bindMethod,
+                      WrenBindForeignClassFn bindClass);
 
 #endif

src/include/wren.h

@@ -213,8 +213,15 @@ WrenValue* wrenGetMethod(WrenVM* vm, const char* module, const char* variable,
 //         will allocate its own string and copy the characters from this, so
 //         you don't have to worry about the lifetime of the string you pass to
 //         Wren.
+// - "a" - An array of bytes converted to a Wren String. This requires two
+//         consecutive arguments in the argument list: `const char*` pointing
+//         to the array of bytes, followed by an `int` defining the length of
+//         the array. This is used when the passed string may contain null
+//         bytes, or just to avoid the implicit `strlen()` call of "s" if you
+//         happen to already know the length.
 // - "v" - A previously acquired WrenValue*. Passing this in does not implicitly
-//         release the value.
+//         release the value. If the passed argument is NULL, this becomes a
+//         Wren NULL.
 //
 // [method] must have been created by a call to [wrenGetMethod]. If [result] is
 // not `NULL`, the return value of the method will be stored in a new
@@ -302,9 +309,12 @@ void wrenReturnDouble(WrenVM* vm, double value);
 // Provides a string return value for a foreign call.
 //
 // The [text] will be copied to a new string within Wren's heap, so you can
-// free memory used by it after this is called. If [length] is non-zero, Wren
-// will copy that many bytes from [text]. If it is -1, then the length of
-// [text] will be calculated using `strlen()`.
+// free memory used by it after this is called.
+//
+// If [length] is non-zero, Wren copies that many bytes from [text], including
+// any null bytes. If it is -1, then the length of [text] is calculated using
+// `strlen()`. If the string may contain any null bytes in the middle, then you
+// must pass an explicit length.
 void wrenReturnString(WrenVM* vm, const char* text, int length);
 
 // Provides the return value for a foreign call.

src/vm/wren_vm.c

@@ -1334,17 +1334,29 @@ WrenInterpretResult wrenCall(WrenVM* vm, WrenValue* method, WrenValue** result,
     Value value = NULL_VAL;
     switch (*argType)
     {
+      case 'a':
+      {
+        const char* bytes = va_arg(argList, const char*);
+        int length = va_arg(argList, int);
+        value = wrenNewString(vm, bytes, (size_t)length);
+        break;
+      }
+        
       case 'b': value = BOOL_VAL(va_arg(argList, int)); break;
       case 'd': value = NUM_VAL(va_arg(argList, double)); break;
       case 'i': value = NUM_VAL((double)va_arg(argList, int)); break;
       case 'n': value = NULL_VAL; va_arg(argList, void*); break;
       case 's':
-      {
         value = wrenStringFormat(vm, "$", va_arg(argList, const char*));
         break;
-      }
 
-      case 'v': value = va_arg(argList, WrenValue*)->value; break;
+      case 'v':
+      {
+        // Allow a NULL value pointer for Wren null.
+        WrenValue* wrenValue = va_arg(argList, WrenValue*);
+        if (wrenValue != NULL) value = wrenValue->value;
+        break;
+      }
 
       default:
         ASSERT(false, "Unknown argument type.");

test/api/call.c

@@ -0,0 +1,50 @@
+#include <string.h>
+
+#include "call.h"
+#include "vm.h"
+
+static void runTests(WrenVM* vm)
+{
+  WrenValue* noParams = wrenGetMethod(vm, "main", "Api", "noParams");
+  WrenValue* zero = wrenGetMethod(vm, "main", "Api", "zero()");
+  WrenValue* one = wrenGetMethod(vm, "main", "Api", "one(_)");
+  WrenValue* two = wrenGetMethod(vm, "main", "Api", "two(_,_)");
+  
+  // Different arity.
+  wrenCall(vm, noParams, NULL, "");
+  wrenCall(vm, zero, NULL, "");
+  wrenCall(vm, one, NULL, "i", 1);
+  wrenCall(vm, two, NULL, "ii", 1, 2);
+
+  WrenValue* getValue = wrenGetMethod(vm, "main", "Api", "getValue(_)");
+  
+  // Returning a value.
+  WrenValue* value = NULL;
+  wrenCall(vm, getValue, &value, "v", NULL);
+  
+  // Different argument types.
+  wrenCall(vm, two, NULL, "bb", true, false);
+  wrenCall(vm, two, NULL, "dd", 1.2, 3.4);
+  wrenCall(vm, two, NULL, "ii", 3, 4);
+  wrenCall(vm, two, NULL, "ss", "string", "another");
+  wrenCall(vm, two, NULL, "vv", NULL, value);
+  
+  // Truncate a string, or allow null bytes.
+  wrenCall(vm, two, NULL, "aa", "string", 3, "b\0y\0t\0e", 7);
+  
+  wrenReleaseValue(vm, noParams);
+  wrenReleaseValue(vm, zero);
+  wrenReleaseValue(vm, one);
+  wrenReleaseValue(vm, two);
+  wrenReleaseValue(vm, getValue);
+  wrenReleaseValue(vm, value);
+}
+
+
+WrenForeignMethodFn callBindMethod(const char* signature)
+{
+  if (strcmp(signature, "static Api.runTests()") == 0) return runTests;
+
+  return NULL;
+}
+

test/api/call.h

@@ -0,0 +1,3 @@
+#include "wren.h"
+
+WrenForeignMethodFn callBindMethod(const char* signature);

test/api/call.wren

@@ -0,0 +1,45 @@
+class Api {
+  static noParams {
+    System.print("noParams")
+  }
+
+  static zero() {
+    System.print("zero")
+  }
+
+  static one(one) {
+    System.print("one " + one.toString)
+  }
+
+  static two(one, two) {
+    // Don't print null bytes.
+    if (two is String && two.bytes.contains(0)) {
+      two = two.bytes.toList
+    }
+
+    System.print("two " + one.toString + " " + two.toString)
+  }
+
+  static getValue(value) {
+    // Return a new value if we aren't given one.
+    if (value == null) return ["a", "b"]
+
+    // Otherwise print it.
+    System.print(value)
+  }
+
+  foreign static runTests()
+}
+
+Api.runTests()
+// expect: noParams
+// expect: zero
+// expect: one 1
+// expect: two 1 2
+
+// expect: two true false
+// expect: two 1.2 3.4
+// expect: two 3 4
+// expect: two string another
+// expect: two null [a, b]
+// expect: two str [98, 0, 121, 0, 116, 0, 101]

test/api/main.c

@@ -4,6 +4,7 @@
 #include "vm.h"
 #include "wren.h"
 
+#include "call.h"
 #include "foreign_class.h"
 #include "returns.h"
 #include "value.h"
@@ -35,6 +36,7 @@ static WrenForeignMethodFn bindForeignMethod(
   strcat(fullName, ".");
   strcat(fullName, signature);
 
+  REGISTER_METHOD(call, call);
   REGISTER_METHOD(foreign_class, foreignClass);
   REGISTER_METHOD(returns, returns);
   REGISTER_METHOD(value, value);
@@ -56,7 +58,6 @@ static WrenForeignClassMethods bindForeignClass(
   return methods;
 }
 
-
 int main(int argc, const char* argv[])
 {
   if (argc != 2)
@@ -73,7 +74,7 @@ int main(int argc, const char* argv[])
   strcat(testPath, testName);
   strcat(testPath, ".wren");
 
-  setForeignCallbacks(bindForeignMethod, bindForeignClass);
+  setTestCallbacks(bindForeignMethod, bindForeignClass);
   runFile(testPath);
   return 0;
 }

test/api/returns.c

@@ -27,6 +27,16 @@ static void returnFalse(WrenVM* vm)
   wrenReturnBool(vm, false);
 }
 
+static void returnString(WrenVM* vm)
+{
+  wrenReturnString(vm, "a string", -1);
+}
+
+static void returnBytes(WrenVM* vm)
+{
+  wrenReturnString(vm, "a\0b\0c", 5);
+}
+
 WrenForeignMethodFn returnsBindMethod(const char* signature)
 {
   if (strcmp(signature, "static Api.implicitNull") == 0) return implicitNull;
@@ -34,6 +44,8 @@ WrenForeignMethodFn returnsBindMethod(const char* signature)
   if (strcmp(signature, "static Api.returnFloat") == 0) return returnFloat;
   if (strcmp(signature, "static Api.returnTrue") == 0) return returnTrue;
   if (strcmp(signature, "static Api.returnFalse") == 0) return returnFalse;
+  if (strcmp(signature, "static Api.returnString") == 0) return returnString;
+  if (strcmp(signature, "static Api.returnBytes") == 0) return returnBytes;
 
   return NULL;
 }

test/api/returns.wren

@@ -6,6 +6,9 @@ class Api {
 
   foreign static returnTrue
   foreign static returnFalse
+
+  foreign static returnString
+  foreign static returnBytes
 }
 
 System.print(Api.implicitNull == null) // expect: true
@@ -15,3 +18,6 @@ System.print(Api.returnFloat) // expect: 123.456
 
 System.print(Api.returnTrue)  // expect: true
 System.print(Api.returnFalse) // expect: false
+
+System.print(Api.returnString) // expect: a string
+System.print(Api.returnBytes.bytes.toList) // expect: [97, 0, 98, 0, 99]

util/xcode/wren.xcodeproj/project.pbxproj

@@ -20,6 +20,7 @@
 		29205C9D1AB4E6430073018D /* wren_utils.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C961AB4E6430073018D /* wren_utils.c */; };
 		29205C9E1AB4E6430073018D /* wren_value.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C971AB4E6430073018D /* wren_value.c */; };
 		29205C9F1AB4E6430073018D /* wren_vm.c in Sources */ = {isa = PBXBuildFile; fileRef = 29205C981AB4E6430073018D /* wren_vm.c */; };
+		293D46961BB43F9900200083 /* call.c in Sources */ = {isa = PBXBuildFile; fileRef = 293D46941BB43F9900200083 /* call.c */; };
 		29512C811B91F8EB008C10E6 /* libuv.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 29512C801B91F8EB008C10E6 /* libuv.a */; };
 		29512C821B91F901008C10E6 /* libuv.a in Frameworks */ = {isa = PBXBuildFile; fileRef = 29512C801B91F8EB008C10E6 /* libuv.a */; };
 		29729F311BA70A620099CA20 /* io.c in Sources */ = {isa = PBXBuildFile; fileRef = 29729F2E1BA70A620099CA20 /* io.c */; };
@@ -75,6 +76,8 @@
 		29205CA61AB4E65E0073018D /* wren_utils.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_utils.h; path = ../../src/vm/wren_utils.h; sourceTree = "<group>"; };
 		29205CA71AB4E65E0073018D /* wren_value.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_value.h; path = ../../src/vm/wren_value.h; sourceTree = "<group>"; };
 		29205CA81AB4E65E0073018D /* wren_vm.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_vm.h; path = ../../src/vm/wren_vm.h; sourceTree = "<group>"; };
+		293D46941BB43F9900200083 /* call.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; name = call.c; path = ../../test/api/call.c; sourceTree = "<group>"; };
+		293D46951BB43F9900200083 /* call.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = call.h; path = ../../test/api/call.h; sourceTree = "<group>"; };
 		29512C7F1B91F86E008C10E6 /* api_test */ = {isa = PBXFileReference; explicitFileType = "compiled.mach-o.executable"; includeInIndex = 0; path = api_test; sourceTree = BUILT_PRODUCTS_DIR; };
 		29512C801B91F8EB008C10E6 /* libuv.a */ = {isa = PBXFileReference; lastKnownFileType = archive.ar; name = libuv.a; path = ../../build/libuv.a; sourceTree = "<group>"; };
 		296371B31AC713D000079FDA /* wren_opcodes.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = wren_opcodes.h; path = ../../src/vm/wren_opcodes.h; sourceTree = "<group>"; };
@@ -201,6 +204,8 @@
 			isa = PBXGroup;
 			children = (
 				29D009A61B7E3993000CE58C /* main.c */,
+				293D46941BB43F9900200083 /* call.c */,
+				293D46951BB43F9900200083 /* call.h */,
 				29D009A81B7E39A8000CE58C /* foreign_class.c */,
 				29D009A91B7E39A8000CE58C /* foreign_class.h */,
 				29D009AA1B7E39A8000CE58C /* returns.c */,
@@ -310,6 +315,7 @@
 				29729F341BA70A620099CA20 /* io.wren.inc in Sources */,
 				291647C81BA5EC5E006142EE /* modules.c in Sources */,
 				29729F321BA70A620099CA20 /* io.c in Sources */,
+				293D46961BB43F9900200083 /* call.c in Sources */,
 				291647D21BA5ED26006142EE /* timer.wren.inc in Sources */,
 				291647D01BA5ED26006142EE /* scheduler.wren.inc in Sources */,
 			);