In the following example one class property is of type Gstrv.
With ObjectClass.list_properties() one can query the Paramspec of all properties, and with get_property() all properties can be requested as GLib.Value. How would I access the Value of type GStrv and convert it to a GLib.Variant?
My GLib version is slightly outdated, so I do not have the GLib.Value.to_variant() function available yet :( .
public class Foo: GLib.Object {
public GLib.HashTable<string, int32> bar;
public Foo() {
bar = new GLib.HashTable<string, int32>(str_hash, str_equal);
}
public string[] bar_keys { owned get { return bar.get_keys_as_array(); } }
}
int main() {
var foo = new Foo();
Type type = foo.get_type();
ObjectClass ocl = (ObjectClass) type.class_ref ();
foreach (ParamSpec spec in ocl.list_properties ()) {
print ("%s\n", spec.get_name ());
Value property_value = Value(spec.value_type);
print ("%s\n", property_value.type_name ());
foo.get_property(spec.name, ref property_value);
// next: convert GLib.Value -> GLib.Variant :(
}
foo.bar.set("baz", 42);
return 0;
}
Output:
bar-keys
GStrv
Using GLib.Value.get_boxed() seems to be working.
Example:
// compile simply with: valac valacode.vala
public class Foo: GLib.Object {
public GLib.HashTable<string, int32> bar;
public Foo() {
bar = new GLib.HashTable<string, int32>(str_hash, str_equal);
}
public string[] bar_keys { owned get { return bar.get_keys_as_array(); } }
}
public Variant first_gstrv_property_as_variant(Object obj)
{
Type class_type = obj.get_type();
ObjectClass ocl = (ObjectClass) class_type.class_ref ();
foreach (ParamSpec spec in ocl.list_properties ()) {
print ("%s\n", spec.get_name ());
Value property_value = Value(spec.value_type);
print ("%s\n", property_value.type_name ());
obj.get_property(spec.name, ref property_value);
// next: convert GLib.Value -> GLib.Variant
if(property_value.type_name () == "GStrv") {
return new GLib.Variant.strv((string[])property_value.get_boxed());
}
}
return new GLib.Variant("s", "No property of type GStrv found");
}
int main() {
var foo = new Foo();
print("%s\n", first_gstrv_property_as_variant(foo).print(true));
foo.bar.set("baz", 42);
print("%s\n", first_gstrv_property_as_variant(foo).print(true));
foo.bar.set("zot", 3);
print("%s\n", first_gstrv_property_as_variant(foo).print(true));
return 0;
}
Output:
bar-keys
GStrv
#as []
bar-keys
GStrv
['baz']
bar-keys
GStrv
['baz', 'zot']
In the generated c-code this looks as follows:
_tmp18_ = g_value_get_boxed (&property_value);
_tmp19_ = g_variant_new_strv ((gchar**) _tmp18_, -1);
Passing -1 as length to g_variant_new_strv() means the string array is considered as null terminated. Inside g_variant_new_strv() the g_strv_length() function is used to determine the length.
Hopefully it will be useful to someone else someday. :-)
Related
im trying to make a miniJava parser but im having trouble figuring out a way to parse method declarations that have no formal parameters.
e.g public int getNumber()
The code that i have right now works for parameters of one or more, but im not sure how to return an empty formal object as clearly the problem lies with the line returning null.
Is there a way to skip the return statement altogether and return nothing?
public Formal nt_FormalList() :
{
Type t;
Token s;
LinkedList<Formal> fl = new LinkedList<Formal>();
Formal f;
}
{
t = nt_Type() s = <IDENTIFIER> (f = nt_FormalRest() {fl.add(f);})*
{ return new Formal(t, s.image); }
| {}
{ return null; }
}
.....
public class Formal {
public final Type t;
public final String i;
public Formal(Type at, String ai) {
t = at;
i = ai;
}
I'd suggest that you return list of Formals from nt_FormalList.
public List<Formal> nt_FormalList() :
{
LinkedList<Formal> fl = new LinkedList<Formal>();
Formal f;
}
{
[ f = nt_Formal() {fl.add(f);}
(<COMMA> f = nt_Formal() {fl.add(f);})*
]
{ return fl; }
}
Dart allows variables of types: Type type = SomeType; But for what purpose?
For example, foo bar baz are misapplications:
class A {
Type type = List;
foo() => new type();
type bar() {
return new List();
}
type baz = new List();
}
void main() {
Type type = String;
var str = "Hello Dart";
print(type == str.runtimeType);//true
print(str is String);//true
print(str is type); //type error.
}
I think this one is pretty neat:
void main() {
foo(Type t) {
switch (t){
case int: return 5;
case List: return [1,2,3]; // This one gets me every time :(
case String: return "Hello Dart!";
default: return "default";
}}
print(foo(10.runtimeType)); //5
print(foo([2,4,6].runtimeType)); //default
print(foo("lalala".runtimeType)); //Hello Dart!
print(foo(foo.runtimeType)); //default
}
Is its sole purpose to be the return type for methods like runtimeType and type matching ?
I don't think you can use it for generics. There you need type literals. But you can use it for reflection.
Just one simple example:
import 'dart:mirrors' as mirr;
class A {
String s;
A(this.s);
#override
String toString() => s;
}
void main() {
Type type = A;
var str = "Hello Dart";
mirr.ClassMirror cm = mirr.reflectType(type);
var s = cm.newInstance(new Symbol(''), [str]).reflectee;
print(s);
}
You could also create a Map with registered factories for different types to avoid the need for reflection.
(not tested)
class A {
String s;
int a = 0;
int b = 0;
int c = 0;
A(this.s);
A.extended(this.s, this.a, this.b, this.c);
#override
String toString() => '${super.toString()}: $s, $a, $b, $c';
}
void main(args) {
Type t = A;
registerType(t, (List args) => new A.extended(args[0], args[1], args[2], args[3]));
...
var a = getInstance(t, ['hallo', 1, 2, 3]);
}
Map<Type,Function> _factories = {};
void registerType(Type t, Function factory) {
_factories[t] = factory;
}
void getNewInstance(Type t, List args) {
return _factories[t](args);
}
Have an issue in the below chunk of code.
class Events
{
// some member variables
}
class SVList
{
String name;
int contentLen;
List<Events> listEvents;
SVList()
{
this.name = "";
this.contentLen = 0;
this.listEvents = new List<Events>();
}
}
class GList
{
List<SVList> listSVList;
GList(int Num)
{
this.listSVList = new List<SvList>(num);
}
}
function f1 ()
{
//array of class objects
GList gList = new GList(num);
}
Not able to find "listEvents" member after GList constructor is called. Am I missing anything here.
Referencing glist.listSVList[index] --> do not find member variable 'listEvents'. Any pointers appreciated.
To elaborate , no member variable with 'glist.listSVList[index].listEvents' is found.
you have a typo here:
this.listSVList = new List<SvList>(num); // <== SVList not SvList
function seems wrong here
function f1 () { ... }
in this case you use function as a return type
another typo:
GList(int Num) // <== Num (uppercase)
{
this.listSVList = new List<SvList>(num); // <== num (lowercase)
}
this code worked:
class Events {
// some member variables
}
class SVList {
String name;
int contentLen;
List<Events> listEvents;
SVList() {
this.name = "";
this.contentLen = 0;
this.listEvents = new List<Events>();
}
}
class GList {
List<SVList> listSVList;
GList(int num) {
this.listSVList = new List<SVList>(num);
}
}
main() {
//array of class objects
GList gList = new GList(5);
gList.listSVList[0] = new SVList();
gList.listSVList[0].listEvents.add(new Events());
print(gList.listSVList[0].listEvents.length);
}
What editor are you using?
DartEditor showed all errors immediately after I pasted your code.
Lists in Dart can now be stated as
List<Object> array = []
Using Dart here.
As the above title suggests, I have a class (shown below) that has three bool instance variables. What I want to do is create a function that inspects the identifier names of these instance variables and prints each of them out in a string. The .declarations getter that comes with the ClassMirror class ALMOST does this, except it also gives me the name of the Constructor and any other methods I have in the class. This is no good. So really what I want is a way to filter by type (i.e., only give me the boolean identifiers as strings.) Any way to do this?
class BooleanHolder {
bool isMarried = false;
bool isBoard2 = false;
bool isBoard3 = false;
List<bool> boolCollection;
BooleanHolder() {
}
void boolsToStrings() {
ClassMirror cm = reflectClass(BooleanHolder);
Map<Symbol, DeclarationMirror> map = cm.declarations;
for (DeclarationMirror dm in map.values) {
print(MirrorSystem.getName(dm.simpleName));
}
}
}
OUTPUT IS:
isMarried
isBoard2
isBoard3
boolsToStrings
BooleanHolder
Sample code.
import "dart:mirrors";
void main() {
var type = reflectType(Foo);
var found = filter(type, [reflectType(bool), reflectType(int)]);
for(var element in found) {
var name = MirrorSystem.getName(element.simpleName);
print(name);
}
}
List<VariableMirror> filter(TypeMirror owner, List<TypeMirror> types) {
var result = new List<VariableMirror>();
if (owner is ClassMirror) {
for (var declaration in owner.declarations.values) {
if (declaration is VariableMirror) {
var declaredType = declaration.type;
for (var type in types) {
if (declaredType.isSubtypeOf(type)) {
result.add(declaration);
}
}
}
}
}
return result;
}
class Foo {
bool bool1 = true;
bool bool2;
int int1;
int int2;
String string1;
String string2;
}
Output:
bool1
bool2
int1
int2
I need to allow my content pipeline extension to use a pattern similar to a factory. I start with a dictionary type:
public delegate T Mapper<T>(MapFactory<T> mf, XElement d);
public class MapFactory<T>
{
Dictionary<string, Mapper<T>> map = new Dictionary<string, Mapper<T>>();
public void Add(string s, Mapper<T> m)
{
map.Add(s, m);
}
public T Get(XElement xe)
{
if (xe == null) throw new ArgumentNullException(
"Invalid document");
var key = xe.Name.ToString();
if (!map.ContainsKey(key)) throw new ArgumentException(
key + " is not a valid key.");
return map[key](this, xe);
}
public IEnumerable<T> GetAll(XElement xe)
{
if (xe == null) throw new ArgumentNullException(
"Invalid document");
foreach (var e in xe.Elements())
{
var val = e.Name.ToString();
if (map.ContainsKey(val))
yield return map[val](this, e);
}
}
}
Here is one type of object I want to store:
public partial class TestContent
{
// Test type
public string title;
// Once test if true
public bool once;
// Parameters
public Dictionary<string, object> args;
public TestContent()
{
title = string.Empty;
args = new Dictionary<string, object>();
}
public TestContent(XElement xe)
{
title = xe.Name.ToString();
args = new Dictionary<string, object>();
xe.ParseAttribute("once", once);
}
}
XElement.ParseAttribute is an extension method that works as one might expect. It returns a boolean that is true if successful.
The issue is that I have many different types of tests, each of which populates the object in a way unique to the specific test. The element name is the key to MapFactory's dictionary. This type of test, while atypical, illustrates my problem.
public class LogicTest : TestBase
{
string opkey;
List<TestBase> items;
public override bool Test(BehaviorArgs args)
{
if (items == null) return false;
if (items.Count == 0) return false;
bool result = items[0].Test(args);
for (int i = 1; i < items.Count; i++)
{
bool other = items[i].Test(args);
switch (opkey)
{
case "And":
result &= other;
if (!result) return false;
break;
case "Or":
result |= other;
if (result) return true;
break;
case "Xor":
result ^= other;
break;
case "Nand":
result = !(result & other);
break;
case "Nor":
result = !(result | other);
break;
default:
result = false;
break;
}
}
return result;
}
public static TestContent Build(MapFactory<TestContent> mf, XElement xe)
{
var result = new TestContent(xe);
string key = "Or";
xe.GetAttribute("op", key);
result.args.Add("key", key);
var names = mf.GetAll(xe).ToList();
if (names.Count() < 2) throw new ArgumentException(
"LogicTest requires at least two entries.");
result.args.Add("items", names);
return result;
}
}
My actual code is more involved as the factory has two dictionaries, one that turns an XElement into a content type to write and another used by the reader to create the actual game objects.
I need to build these factories in code because they map strings to delegates. I have a service that contains several of these factories. The mission is to make these factory classes available to a content processor. Neither the processor itself nor the context it uses as a parameter have any known hooks to attach an IServiceProvider or equivalent.
Any ideas?
I needed to create a data structure essentially on demand without access to the underlying classes as they came from a third party, in this case XNA Game Studio. There is only one way to do this I know of... statically.
public class TestMap : Dictionary<string, string>
{
private static readonly TestMap map = new TestMap();
private TestMap()
{
Add("Logic", "LogicProcessor");
Add("Sequence", "SequenceProcessor");
Add("Key", "KeyProcessor");
Add("KeyVector", "KeyVectorProcessor");
Add("Mouse", "MouseProcessor");
Add("Pad", "PadProcessor");
Add("PadVector", "PadVectorProcessor");
}
public static TestMap Map
{
get { return map; }
}
public IEnumerable<TestContent> Collect(XElement xe, ContentProcessorContext cpc)
{
foreach(var e in xe.Elements().Where(e => ContainsKey(e.Name.ToString())))
{
yield return cpc.Convert<XElement, TestContent>(
e, this[e.Name.ToString()]);
}
}
}
I took this a step further and created content processors for each type of TestBase:
/// <summary>
/// Turns an imported XElement into a TestContent used for a LogicTest
/// </summary>
[ContentProcessor(DisplayName = "LogicProcessor")]
public class LogicProcessor : ContentProcessor<XElement, TestContent>
{
public override TestContent Process(XElement input, ContentProcessorContext context)
{
var result = new TestContent(input);
string key = "Or";
input.GetAttribute("op", key);
result.args.Add("key", key);
var items = TestMap.Map.Collect(input, context);
if (items.Count() < 2) throw new ArgumentNullException(
"LogicProcessor requires at least two items.");
result.args.Add("items", items);
return result;
}
}
Any attempt to reference or access the class such as calling TestMap.Collect will generate the underlying static class if needed. I basically moved the code from LogicTest.Build to the processor. I also carry out any needed validation in the processor.
When I get to reading these classes I will have the ContentService to help.