Add an API to load a top-level variable into a slot.

src/include/wren.h

@@ -384,4 +384,9 @@ void wrenSetSlotValue(WrenVM* vm, int slot, WrenValue* value);
 // an element, use `-1` for the index.
 void wrenInsertInList(WrenVM* vm, int listSlot, int index, int elementSlot);
 
+// Looks up the top level variable with [name] in [module] and stores it in
+// [slot].
+void wrenGetVariable(WrenVM* vm, const char* module, const char* name,
+                     int slot);
+
 #endif

src/vm/wren_vm.c

@@ -1789,3 +1789,25 @@ void wrenInsertInList(WrenVM* vm, int listSlot, int index, int elementSlot)
   
   wrenListInsert(vm, list, vm->foreignStackStart[elementSlot], index);
 }
+
+void wrenGetVariable(WrenVM* vm, const char* module, const char* name,
+                     int slot)
+{
+  ASSERT(module != NULL, "Module cannot be NULL.");
+  ASSERT(module != NULL, "Variable name cannot be NULL.");  
+  validateForeignSlot(vm, slot);
+  
+  Value moduleName = wrenStringFormat(vm, "$", module);
+  wrenPushRoot(vm, AS_OBJ(moduleName));
+  
+  ObjModule* moduleObj = getModule(vm, moduleName);
+  ASSERT(moduleObj != NULL, "Could not find module.");
+  
+  wrenPopRoot(vm); // moduleName.
+
+  int variableSlot = wrenSymbolTableFind(&moduleObj->variableNames,
+                                         name, strlen(name));
+  ASSERT(variableSlot != -1, "Could not find variable.");
+  
+  setSlot(vm, slot, moduleObj->variables.data[variableSlot]);
+}

test/api/get_variable.c

@@ -0,0 +1,44 @@
+#include <string.h>
+
+#include "get_variable.h"
+
+static void beforeDefined(WrenVM* vm)
+{
+  wrenGetVariable(vm, "main", "A", 0);
+}
+
+static void afterDefined(WrenVM* vm)
+{
+  wrenGetVariable(vm, "main", "A", 0);
+}
+
+static void afterAssigned(WrenVM* vm)
+{
+  wrenGetVariable(vm, "main", "A", 0);
+}
+
+static void otherSlot(WrenVM* vm)
+{
+  wrenEnsureSlots(vm, 3);
+  wrenGetVariable(vm, "main", "B", 2);
+  
+  // Move it into return position.
+  const char* string = wrenGetSlotString(vm, 2);
+  wrenSetSlotString(vm, 0, string);
+}
+
+static void otherModule(WrenVM* vm)
+{
+  wrenGetVariable(vm, "get_variable_module", "Variable", 0);
+}
+
+WrenForeignMethodFn getVariableBindMethod(const char* signature)
+{
+  if (strcmp(signature, "static GetVariable.beforeDefined()") == 0) return beforeDefined;
+  if (strcmp(signature, "static GetVariable.afterDefined()") == 0) return afterDefined;
+  if (strcmp(signature, "static GetVariable.afterAssigned()") == 0) return afterAssigned;
+  if (strcmp(signature, "static GetVariable.otherSlot()") == 0) return otherSlot;
+  if (strcmp(signature, "static GetVariable.otherModule()") == 0) return otherModule;
+
+  return NULL;
+}

test/api/get_variable.h

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

test/api/get_variable.wren

@@ -0,0 +1,24 @@
+import "get_variable_module"
+
+class GetVariable {
+  foreign static beforeDefined()
+  foreign static afterDefined()
+  foreign static afterAssigned()
+  foreign static otherSlot()
+  foreign static otherModule()
+}
+
+System.print(GetVariable.beforeDefined()) // expect: null
+
+var A = "a"
+
+System.print(GetVariable.afterDefined()) // expect: a
+
+A = "changed"
+
+System.print(GetVariable.afterAssigned()) // expect: changed
+
+var B = "b"
+System.print(GetVariable.otherSlot()) // expect: b
+
+System.print(GetVariable.otherModule()) // expect: value

test/api/get_variable_module.wren

@@ -0,0 +1,3 @@
+// nontest
+
+var Variable = "value"

test/api/main.c

@@ -6,6 +6,7 @@
 
 #include "benchmark.h"
 #include "call.h"
+#include "get_variable.h"
 #include "foreign_class.h"
 #include "lists.h"
 #include "slots.h"
@@ -33,7 +34,10 @@ static WrenForeignMethodFn bindForeignMethod(
   
   method = benchmarkBindMethod(fullName);
   if (method != NULL) return method;
-  
+
+  method = getVariableBindMethod(fullName);
+  if (method != NULL) return method;
+
   method = foreignClassBindMethod(fullName);
   if (method != NULL) return method;
   

util/xcode/wren.xcodeproj/project.pbxproj

@@ -19,6 +19,7 @@
 		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 */; };
+		2949AA8D1C2F14F000B106BA /* get_variable.c in Sources */ = {isa = PBXBuildFile; fileRef = 2949AA8B1C2F14F000B106BA /* get_variable.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 */; };
@@ -98,6 +99,8 @@
 		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>"; };
+		2949AA8B1C2F14F000B106BA /* get_variable.c */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.c; name = get_variable.c; path = ../../test/api/get_variable.c; sourceTree = "<group>"; };
+		2949AA8C1C2F14F000B106BA /* get_variable.h */ = {isa = PBXFileReference; fileEncoding = 4; lastKnownFileType = sourcecode.c.h; name = get_variable.h; path = ../../test/api/get_variable.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>"; };
@@ -252,6 +255,8 @@
 				293D46951BB43F9900200083 /* call.h */,
 				29D009A81B7E39A8000CE58C /* foreign_class.c */,
 				29D009A91B7E39A8000CE58C /* foreign_class.h */,
+				2949AA8B1C2F14F000B106BA /* get_variable.c */,
+				2949AA8C1C2F14F000B106BA /* get_variable.h */,
 				29932D521C210F8D00099DEE /* lists.c */,
 				29932D531C210F8D00099DEE /* lists.h */,
 				29D009AA1B7E39A8000CE58C /* slots.c */,
@@ -365,6 +370,7 @@
 				29729F321BA70A620099CA20 /* io.c in Sources */,
 				29932D541C210F8D00099DEE /* lists.c in Sources */,
 				291647C81BA5EC5E006142EE /* modules.c in Sources */,
+				2949AA8D1C2F14F000B106BA /* get_variable.c in Sources */,
 				29DC14A11BBA2FEC008A8274 /* scheduler.c in Sources */,
 				29A427391BDBE435001E6E22 /* wren_opt_random.c in Sources */,
 				29932D511C20D8C900099DEE /* benchmark.c in Sources */,