wrenReturn___() -> wrenSlotSet___().

This turns those functions into general-purpose functions for writing
raw C values into slots on the foreign call stack.

Writing a return just means writing a value to slot 0.

test/api/benchmark.c

@@ -11,7 +11,7 @@ static void arguments(WrenVM* vm)
   result += wrenGetSlotDouble(vm, 3);
   result += wrenGetSlotDouble(vm, 4);
 
-  wrenReturnDouble(vm, result);
+  wrenSetSlotDouble(vm, 0, result);
 }
 
 WrenForeignMethodFn benchmarkBindMethod(const char* signature)

test/api/foreign_class.c

@@ -7,7 +7,7 @@ static int finalized = 0;
 
 static void apiFinalized(WrenVM* vm)
 {
-  wrenReturnDouble(vm, finalized);
+  wrenSetSlotDouble(vm, 0, finalized);
 }
 
 static void counterAllocate(WrenVM* vm)
@@ -27,7 +27,7 @@ static void counterIncrement(WrenVM* vm)
 static void counterValue(WrenVM* vm)
 {
   double value = *(double*)wrenGetSlotForeign(vm, 0);
-  wrenReturnDouble(vm, value);
+  wrenSetSlotDouble(vm, 0, value);
 }
 
 static void pointAllocate(WrenVM* vm)
@@ -64,7 +64,7 @@ static void pointToString(WrenVM* vm)
   char result[100];
   sprintf(result, "(%g, %g, %g)",
       coordinates[0], coordinates[1], coordinates[2]);
-  wrenReturnString(vm, result, (int)strlen(result));
+  wrenSetSlotString(vm, 0, result);
 }
 
 static void resourceAllocate(WrenVM* vm)

test/api/main.c

@@ -7,7 +7,7 @@
 #include "benchmark.h"
 #include "call.h"
 #include "foreign_class.h"
-#include "returns.h"
+#include "slots.h"
 #include "value.h"
 
 // The name of the currently executing API test.
@@ -36,7 +36,7 @@ static WrenForeignMethodFn bindForeignMethod(
   method = foreignClassBindMethod(fullName);
   if (method != NULL) return method;
   
-  method = returnsBindMethod(fullName);
+  method = slotsBindMethod(fullName);
   if (method != NULL) return method;
   
   method = valueBindMethod(fullName);

test/api/returns.c

@@ -1,51 +0,0 @@
-#include <string.h>
-
-#include "returns.h"
-
-static void implicitNull(WrenVM* vm)
-{
-  // Do nothing.
-}
-
-static void returnInt(WrenVM* vm)
-{
-  wrenReturnDouble(vm, 123456);
-}
-
-static void returnFloat(WrenVM* vm)
-{
-  wrenReturnDouble(vm, 123.456);
-}
-
-static void returnTrue(WrenVM* vm)
-{
-  wrenReturnBool(vm, true);
-}
-
-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 Returns.implicitNull") == 0) return implicitNull;
-  if (strcmp(signature, "static Returns.returnInt") == 0) return returnInt;
-  if (strcmp(signature, "static Returns.returnFloat") == 0) return returnFloat;
-  if (strcmp(signature, "static Returns.returnTrue") == 0) return returnTrue;
-  if (strcmp(signature, "static Returns.returnFalse") == 0) return returnFalse;
-  if (strcmp(signature, "static Returns.returnString") == 0) return returnString;
-  if (strcmp(signature, "static Returns.returnBytes") == 0) return returnBytes;
-
-  return NULL;
-}

test/api/returns.h

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

test/api/returns.wren

@@ -1,23 +0,0 @@
-class Returns {
-  foreign static implicitNull
-
-  foreign static returnInt
-  foreign static returnFloat
-
-  foreign static returnTrue
-  foreign static returnFalse
-
-  foreign static returnString
-  foreign static returnBytes
-}
-
-System.print(Returns.implicitNull == null) // expect: true
-
-System.print(Returns.returnInt)  // expect: 123456
-System.print(Returns.returnFloat) // expect: 123.456
-
-System.print(Returns.returnTrue)  // expect: true
-System.print(Returns.returnFalse) // expect: false
-
-System.print(Returns.returnString) // expect: a string
-System.print(Returns.returnBytes.bytes.toList) // expect: [97, 0, 98, 0, 99]

test/api/slots.c

@@ -0,0 +1,83 @@
+#include <string.h>
+
+#include "slots.h"
+
+static void noSet(WrenVM* vm)
+{
+  // Do nothing.
+}
+
+static void getSlots(WrenVM* vm)
+{
+  bool result = true;
+  if (wrenGetSlotBool(vm, 1) != true) result = false;
+  // TODO: Test wrenGetSlotForeign().
+  
+  int length;
+  const char* bytes = wrenGetSlotBytes(vm, 2, &length);
+  if (length != 5) result = false;
+  if (memcmp(bytes, "by\0te", length) != 0) result = false;
+
+  if (wrenGetSlotDouble(vm, 3) != 12.34) result = false;
+  if (strcmp(wrenGetSlotString(vm, 4), "str") != 0) result = false;
+  
+  WrenValue* value = wrenGetSlotValue(vm, 5);
+
+  if (result)
+  {
+    // Otherwise, return the value so we can tell if we captured it correctly.
+    wrenSetSlotValue(vm, 0, value);
+    wrenReleaseValue(vm, value);
+  }
+  else
+  {
+    // If anything failed, return false.
+    wrenSetSlotBool(vm, 0, false);
+  }
+}
+
+static void setSlots(WrenVM* vm)
+{
+  WrenValue* value = wrenGetSlotValue(vm, 1);
+  
+  wrenSetSlotBool(vm, 1, true);
+  wrenSetSlotBytes(vm, 2, "by\0te", 5);
+  wrenSetSlotDouble(vm, 3, 12.34);
+  wrenSetSlotString(vm, 4, "str");
+  
+  // TODO: wrenSetSlotNull().
+  
+  // Read the slots back to make sure they were set correctly.
+  
+  bool result = true;
+  if (wrenGetSlotBool(vm, 1) != true) result = false;
+  
+  int length;
+  const char* bytes = wrenGetSlotBytes(vm, 2, &length);
+  if (length != 5) result = false;
+  if (memcmp(bytes, "by\0te", length) != 0) result = false;
+  
+  if (wrenGetSlotDouble(vm, 3) != 12.34) result = false;
+  if (strcmp(wrenGetSlotString(vm, 4), "str") != 0) result = false;
+
+  if (result)
+  {
+    // Move the value into the return position.
+    wrenSetSlotValue(vm, 0, value);
+    wrenReleaseValue(vm, value);
+  }
+  else
+  {
+    // If anything failed, return false.
+    wrenSetSlotBool(vm, 0, false);
+  }
+}
+
+WrenForeignMethodFn slotsBindMethod(const char* signature)
+{
+  if (strcmp(signature, "static Slots.noSet") == 0) return noSet;
+  if (strcmp(signature, "static Slots.getSlots(_,_,_,_,_)") == 0) return getSlots;
+  if (strcmp(signature, "static Slots.setSlots(_,_,_,_)") == 0) return setSlots;
+
+  return NULL;
+}

test/api/slots.h

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

test/api/slots.wren

@@ -0,0 +1,16 @@
+class Slots {
+  foreign static noSet
+
+  foreign static getSlots(bool, num, string, bytes, value)
+
+  foreign static setSlots(a, b, c, d)
+}
+
+// If nothing is set in the return slot, it retains its previous value, the
+// receiver.
+System.print(Slots.noSet == Slots) // expect: true
+
+var value = ["value"]
+System.print(Slots.getSlots(true, "by\0te", 12.34, "str", value) == value) // expect: true
+
+System.print(Slots.setSlots(value, 0, 0, 0) == value) // expect: true

test/api/value.c

@@ -11,7 +11,7 @@ static void setValue(WrenVM* vm)
 
 static void getValue(WrenVM* vm)
 {
-  wrenReturnValue(vm, value);
+  wrenSetSlotValue(vm, 0, value);
   wrenReleaseValue(vm, value);
 }