/// <summary>
/// Supports navigation into <see cref="JToken"/> return types.
/// </summary>
/// <param name="expression"></param>
/// <param name="name"></param>
/// <param name="navigate"></param>
/// <returns></returns>
public static Expression JTokenNavigateFunc(Expression expression, string name, NavigateFunc navigate)
{
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
if (navigate == null)
{
throw new ArgumentNullException(nameof(navigate));
}
// source expression is a JToken; it might really be a JObject
if (typeof(JToken).IsAssignableFrom(expression.Type))
{
return(Expression.Condition(
Expression.TypeEqual(expression, typeof(JObject)),
navigate(Expression.Convert(expression, typeof(JObject)), name, navigate),
Expression.Constant(JValue.CreateUndefined(), typeof(JToken))));
}
return(null);
}
/// <summary>
/// Supports navigation into <see cref="JObject"/> return types.
/// </summary>
/// <param name="expression"></param>
/// <param name="name"></param>
/// <param name="navigate"></param>
/// <returns></returns>
public static Expression JObjectNavigateFunc(Expression expression, string name, NavigateFunc navigate)
{
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
// source expression is a JObject
if (typeof(JObject).IsAssignableFrom(expression.Type))
{
return(Expression.Condition(
Expression.ReferenceEqual(expression, Expression.Constant(null, expression.Type)),
Expression.Constant(JValue.CreateUndefined(), typeof(JToken)),
InvokeIndexer(expression, typeof(JObject), Expression.Constant(name), typeof(string))));
}
return(null);
}
/// <summary>
/// Supports navigation into <see cref="JArray"/> return types.
/// </summary>
/// <param name="expression"></param>
/// <param name="name"></param>
/// <param name="navigate"></param>
/// <returns></returns>
public static Expression JArrayNavigateFunc(Expression expression, string name, NavigateFunc navigate)
{
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
// cannot navigate into any JArray
if (typeof(JArray).IsAssignableFrom(expression.Type))
{
return(Expression.Constant(JValue.CreateUndefined()));
}
return(null);
}
/// <summary>
/// Default NavigateFunc. Handles standard .NET properties and <see cref="JToken"/> traversal.
/// </summary>
/// <param name="expression"></param>
/// <param name="name"></param>
/// <param name="navigate"></param>
/// <returns></returns>
public static Expression DefaultNavigateFunc(Expression expression, string name, NavigateFunc navigate)
{
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
// returns the nullable version of the type
Type NullableOfType(Type type) =>
type.IsValueType ? typeof(Nullable <>).MakeGenericType(type) : type;
// returns a nullable version of the given type
Expression NullableExpressionOfType(Type type) =>
Expression.Default(NullableOfType(type));
// ensure the result is nullable
Expression NullableExpression(Expression expr) =>
Expression.Convert(expr, NullableOfType(expr.Type));
// resolve member
var member = expression.Type.GetPropertyOrField(name);
// member is a property
if (member is PropertyInfo property)
{
return(Expression.Condition(
Expression.Equal(expression, NullableExpressionOfType(expression.Type)),
NullableExpressionOfType(property.PropertyType),
NullableExpression(Expression.Property(expression, property))));
}
// member is a field
if (member is FieldInfo field)
{
return(Expression.Condition(
Expression.Equal(expression, NullableExpressionOfType(expression.Type)),
NullableExpressionOfType(field.FieldType),
NullableExpression(Expression.Field(expression, field))));
}
// source expression implements a generic dictionary
if (typeof(IEnumerable).IsAssignableFrom(expression.Type) && // early breakout
expression.Type.GetAssignableTypes().FirstOrDefault(i => i.IsGenericType && i.GetGenericTypeDefinition() == typeof(IDictionary <,>)) is Type iface)
{
// invoke get_Item on dictionary, with key type as described by interface
// conditional is used to prevent index missing exceptions
var keyType = iface.GetGenericArguments()[0];
var valType = iface.GetGenericArguments()[1];
// if key type is supported, use it, else try to change type
var keyExpr = Expression.Convert(
keyType.IsInstanceOfType(name) ?
(Expression)Expression.Constant(name, keyType) :
Expression.Call(typeof(Convert).GetMethod(nameof(Convert.ChangeType)), Expression.Constant(name), Expression.Constant(keyType)),
keyType);
// if null, return nullable; else invoke ContainsKey before trying get_Item; convert result to nullable
return(Expression.Condition(
Expression.Equal(expression, Expression.Constant(null, expression.Type)),
NullableExpressionOfType(valType),
Expression.Condition(
Expression.Call(expression, iface.GetMethod("ContainsKey", new[] { keyType }), keyExpr),
NullableExpression(InvokeIndexer(expression, iface, keyExpr, keyType)),
NullableExpressionOfType(valType))));
}
// no way to navigate found, use untyped null
return(NullableExpressionOfType(typeof(object)));
}
/// <summary>
/// Navigates to the root <see cref="JToken"/> of the object as expressed by the '^' path syntax.
/// </summary>
/// <param name="expression"></param>
/// <param name="name"></param>
/// <param name="navigate"></param>
/// <returns></returns>
public static Expression JTokenRootNavigateFunc(Expression expression, string name, NavigateFunc navigate)
{
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
if (name != "^")
{
return(null);
}
if (typeof(JToken).IsAssignableFrom(expression.Type) == false)
{
throw new NotSupportedException("Unable to use root navigation on non-JToken.");
}
return(Expression.Condition(
Expression.ReferenceEqual(expression, Expression.Constant(null, expression.Type)),
Expression.Constant(null, typeof(JToken)),
Expression.Property(expression, nameof(JToken.Root))));
}
/// <summary>
/// Navigates to the parent <see cref="JObject"/> as expressed by the '<' path syntax.
/// </summary>
/// <param name="expression"></param>
/// <param name="name"></param>
/// <param name="navigate"></param>
/// <returns></returns>
public static Expression JTokenParentNavigateFunc(Expression expression, string name, NavigateFunc navigate)
{
if (expression == null)
{
throw new ArgumentNullException(nameof(expression));
}
if (name == null)
{
throw new ArgumentNullException(nameof(name));
}
if (name != "<")
{
return(null);
}
if (typeof(JToken).IsAssignableFrom(expression.Type) == false)
{
throw new NotSupportedException("Unable to use root navigation on non-JToken.");
}
// parent of incoming token
var parent = Expression.Condition(
Expression.ReferenceEqual(expression, Expression.Constant(null, expression.Type)),
Expression.Constant(null, typeof(JContainer)),
Expression.Property(expression, nameof(JToken.Parent)));
// step up to object if on property
return(Expression.Condition(
Expression.TypeIs(parent, typeof(JProperty)),
Expression.Property(parent, nameof(JProperty.Parent)),
parent));
}
/// <summary>
/// Loads a specific track number.
/// </summary>
public void LoadTrack(int track_number, NavigateFunc navFunc)
{
nav_func = navFunc;
if (!validEngine ())
return;
if (current_media == null || !current_media.StartsWith ("cdda://"))
{
Stop ();
MediaEngine.Load ("cdda://");
}
current_media = "cdda://" + track_number;
MediaEngine.SeekToTrack (track_number);
if (MediaEngine.CurrentStatus != MediaStatus.Playing)
Play ();
}
/// <summary>
/// Load the specified file into the media engine and navigate using navFunc.
/// </summary>
public void LoadMedia(string path, NavigateFunc navFunc)
{
nav_func = navFunc;
if (!validEngine ())
return;
if (System.IO.File.Exists (path))
{
switch_engines = !switch_engines;
Stop ();
MediaEngine.Load (path);
current_media = path;
fadePlay ();
}
else
fuse.ThrowError ("The file doesn't exist:\n\n" + path);
}
