More file system checking functions:

- Stat#isFile
- Stat#isDirectory
- Directory.exists()
- File.exists()

src/module/io.c

@@ -442,6 +442,18 @@ void statUser(WrenVM* vm)
   wrenSetSlotDouble(vm, 0, (double)stat->st_uid);
 }
 
+void statIsDirectory(WrenVM* vm)
+{
+  uv_stat_t* stat = (uv_stat_t*)wrenGetSlotForeign(vm, 0);
+  wrenSetSlotBool(vm, 0, S_ISDIR(stat->st_mode));
+}
+
+void statIsFile(WrenVM* vm)
+{
+  uv_stat_t* stat = (uv_stat_t*)wrenGetSlotForeign(vm, 0);
+  wrenSetSlotBool(vm, 0, S_ISREG(stat->st_mode));
+}
+
 static void allocCallback(uv_handle_t* handle, size_t suggestedSize,
                           uv_buf_t* buf)
 {

src/module/io.wren

@@ -6,6 +6,18 @@ class Directory {
     if (!(path is String)) Fiber.abort("Path must be a string.")
   }
 
+  static exists(path) {
+    ensurePath_(path)
+    var stat
+    Fiber.new {
+      stat = Stat.path(path)
+    }.try()
+
+    // If we can't stat it, there's nothing there.
+    if (stat == null) return false
+    return stat.isDirectory
+  }
+
   static list(path) {
     ensurePath_(path)
     list_(path, Fiber.current)
@@ -31,11 +43,23 @@ foreign class File {
   }
 
   static delete(path) {
-    File.ensurePath_(path)
+    ensurePath_(path)
     delete_(path, Fiber.current)
     return Scheduler.runNextScheduled_()
   }
 
+  static exists(path) {
+    ensurePath_(path)
+    var stat
+    Fiber.new {
+      stat = Stat.path(path)
+    }.try()
+
+    // If we can't stat it, there's nothing there.
+    if (stat == null) return false
+    return stat.isFile
+  }
+
   static open(path) { openWithFlags(path, FileFlags.readOnly) }
 
   static open(path, fn) { openWithFlags(path, FileFlags.readOnly, fn) }
@@ -43,8 +67,8 @@ foreign class File {
   // TODO: Add named parameters and then call this "open(_,flags:_)"?
   // TODO: Test.
   static openWithFlags(path, flags) {
-    File.ensurePath_(path)
-    File.ensureInt_(flags, "Flags")
+    ensurePath_(path)
+    ensureInt_(flags, "Flags")
     open_(path, flags, Fiber.current)
     var fd = Scheduler.runNextScheduled_()
     return new_(fd)
@@ -68,7 +92,7 @@ foreign class File {
   }
 
   static size(path) {
-    File.ensurePath_(path)
+    ensurePath_(path)
     sizePath_(path, Fiber.current)
     return Scheduler.runNextScheduled_()
   }
@@ -175,6 +199,10 @@ foreign class Stat {
   foreign size
   foreign specialDevice
   foreign user
+
+  foreign isFile
+  foreign isDirectory
+  // TODO: Other mode checks.
 }
 
 class Stdin {

src/module/io.wren.inc

@@ -8,6 +8,18 @@ static const char* ioModuleSource =
 "    if (!(path is String)) Fiber.abort(\"Path must be a string.\")\n"
 "  }\n"
 "\n"
+"  static exists(path) {\n"
+"    ensurePath_(path)\n"
+"    var stat\n"
+"    Fiber.new {\n"
+"      stat = Stat.path(path)\n"
+"    }.try()\n"
+"\n"
+"    // If we can't stat it, there's nothing there.\n"
+"    if (stat == null) return false\n"
+"    return stat.isDirectory\n"
+"  }\n"
+"\n"
 "  static list(path) {\n"
 "    ensurePath_(path)\n"
 "    list_(path, Fiber.current)\n"
@@ -33,11 +45,23 @@ static const char* ioModuleSource =
 "  }\n"
 "\n"
 "  static delete(path) {\n"
-"    File.ensurePath_(path)\n"
+"    ensurePath_(path)\n"
 "    delete_(path, Fiber.current)\n"
 "    return Scheduler.runNextScheduled_()\n"
 "  }\n"
 "\n"
+"  static exists(path) {\n"
+"    ensurePath_(path)\n"
+"    var stat\n"
+"    Fiber.new {\n"
+"      stat = Stat.path(path)\n"
+"    }.try()\n"
+"\n"
+"    // If we can't stat it, there's nothing there.\n"
+"    if (stat == null) return false\n"
+"    return stat.isFile\n"
+"  }\n"
+"\n"
 "  static open(path) { openWithFlags(path, FileFlags.readOnly) }\n"
 "\n"
 "  static open(path, fn) { openWithFlags(path, FileFlags.readOnly, fn) }\n"
@@ -45,8 +69,8 @@ static const char* ioModuleSource =
 "  // TODO: Add named parameters and then call this \"open(_,flags:_)\"?\n"
 "  // TODO: Test.\n"
 "  static openWithFlags(path, flags) {\n"
-"    File.ensurePath_(path)\n"
-"    File.ensureInt_(flags, \"Flags\")\n"
+"    ensurePath_(path)\n"
+"    ensureInt_(flags, \"Flags\")\n"
 "    open_(path, flags, Fiber.current)\n"
 "    var fd = Scheduler.runNextScheduled_()\n"
 "    return new_(fd)\n"
@@ -70,7 +94,7 @@ static const char* ioModuleSource =
 "  }\n"
 "\n"
 "  static size(path) {\n"
-"    File.ensurePath_(path)\n"
+"    ensurePath_(path)\n"
 "    sizePath_(path, Fiber.current)\n"
 "    return Scheduler.runNextScheduled_()\n"
 "  }\n"
@@ -177,6 +201,10 @@ static const char* ioModuleSource =
 "  foreign size\n"
 "  foreign specialDevice\n"
 "  foreign user\n"
+"\n"
+"  foreign isFile\n"
+"  foreign isDirectory\n"
+"  // TODO: Other mode checks.\n"
 "}\n"
 "\n"
 "class Stdin {\n"