Improvement default value handling (#107)

shibayan · Feb 17, 2021 · 030bb9a · 030bb9a
1 parent 1fea914
commit 030bb9a
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Showing 7 changed files with 47 additions and 18 deletions.
diff --git a/Sharprompt/Forms/FormRenderer.cs b/Sharprompt/Forms/FormRenderer.cs
@@ -77,7 +77,7 @@ private void ClearAll()
         {
             var bottom = _screenBuffer.CursorBottom;
 
-            for (int i = 0; i < _screenBuffer.LineCount; i++)
+            for (var i = 0; i < _screenBuffer.LineCount; i++)
             {
                 ConsoleDriver.ClearLine(bottom - i);
             }

diff --git a/Sharprompt/Forms/Input.cs b/Sharprompt/Forms/Input.cs
@@ -10,15 +10,15 @@ namespace Sharprompt.Forms
 {
     internal class Input<T> : FormBase<T>
     {
-        public Input(string message, object defaultValue, IList<Func<object, ValidationResult>> validators)
+        public Input(string message, Optional<T> defaultValue, IList<Func<object, ValidationResult>> validators)
         {
             _message = message;
             _defaultValue = defaultValue;
             _validators = validators;
         }
 
         private readonly string _message;
-        private readonly object _defaultValue;
+        private readonly Optional<T> _defaultValue;
         private readonly IList<Func<object, ValidationResult>> _validators;
 
         private readonly Type _targetType = typeof(T);
@@ -41,7 +41,7 @@ protected override bool TryGetResult(out T result)
                     {
                         if (string.IsNullOrEmpty(input))
                         {
-                            if (_targetType.IsValueType && _underlyingType == null && _defaultValue == null)
+                            if (_targetType.IsValueType && _underlyingType == null && _defaultValue.HasValue)
                             {
                                 Renderer.SetValidationResult(new ValidationResult("Value is required"));
 
@@ -50,7 +50,7 @@ protected override bool TryGetResult(out T result)
                                 return false;
                             }
 
-                            result = (T)_defaultValue;
+                            result = _defaultValue;
                         }
                         else
                         {
@@ -121,7 +121,7 @@ protected override void InputTemplate(ScreenBuffer screenBuffer)
         {
             screenBuffer.WritePrompt(_message);
 
-            if (_defaultValue != null)
+            if (_defaultValue.HasValue)
             {
                 screenBuffer.Write($"({_defaultValue}) ");
             }

diff --git a/Sharprompt/Forms/MultiSelect.cs b/Sharprompt/Forms/MultiSelect.cs
@@ -25,7 +25,7 @@ public MultiSelect(string message, IEnumerable<T> items, int? pageSize, int mini
             }
 
             _message = message;
-            _selector = new Selector<T>(items, pageSize, null, valueSelector);
+            _selector = new Selector<T>(items, pageSize, Optional<T>.Empty, valueSelector);
             _minimum = minimum;
             _maximum = maximum;
             _valueSelector = valueSelector;
@@ -115,7 +115,7 @@ protected override void InputTemplate(ScreenBuffer screenBuffer)
 
             var subset = _selector.ToSubset();
 
-            foreach (T item in subset)
+            foreach (var item in subset)
             {
                 var value = _valueSelector(item);
 

diff --git a/Sharprompt/Forms/Select.cs b/Sharprompt/Forms/Select.cs
@@ -9,7 +9,7 @@ namespace Sharprompt.Forms
 {
     internal class Select<T> : FormBase<T>
     {
-        public Select(string message, IEnumerable<T> items, int? pageSize, object defaultValue, Func<T, string> valueSelector)
+        public Select(string message, IEnumerable<T> items, int? pageSize, Optional<T> defaultValue, Func<T, string> valueSelector)
             : base(false)
         {
             _message = message;
@@ -79,7 +79,7 @@ protected override void InputTemplate(ScreenBuffer screenBuffer)
 
             var subset = _selector.ToSubset();
 
-            foreach (T item in subset)
+            foreach (var item in subset)
             {
                 var value = _valueSelector(item);
 

diff --git a/Sharprompt/Internal/Optional.cs b/Sharprompt/Internal/Optional.cs
@@ -0,0 +1,29 @@
+namespace Sharprompt.Internal
+{
+    internal readonly struct Optional<T>
+    {
+        public Optional(T value)
+        {
+            HasValue = true;
+            Value = value;
+        }
+
+        public bool HasValue { get; }
+
+        public T Value { get; }
+
+        public static implicit operator T(Optional<T> optional) => optional.Value;
+
+        public static readonly Optional<T> Empty = new Optional<T>();
+
+        public static Optional<T> Create(T value)
+        {
+            return value == null ? Empty : new Optional<T>(value);
+        }
+
+        public static Optional<T> Create(object value)
+        {
+            return value == null ? Empty : new Optional<T>((T)value);
+        }
+    }
+}
diff --git a/Sharprompt/Internal/Selector.cs b/Sharprompt/Internal/Selector.cs
@@ -6,7 +6,7 @@ namespace Sharprompt.Internal
 {
     internal class Selector<T>
     {
-        public Selector(IEnumerable<T> items, int? pageSize, object defaultValue, Func<T, string> valueSelector)
+        public Selector(IEnumerable<T> items, int? pageSize, Optional<T> defaultValue, Func<T, string> valueSelector)
         {
             _items = items.ToArray();
             _pageSize = pageSize ?? _items.Length;
@@ -88,18 +88,18 @@ private void InitializeCollection()
             _pageCount = (_filteredSource.Length - 1) / _pageSize + 1;
         }
 
-        private void InitializeDefaults(object defaultValue)
+        private void InitializeDefaults(Optional<T> defaultValue)
         {
             InitializeCollection();
 
-            if (defaultValue == null)
+            if (!defaultValue.HasValue)
             {
                 return;
             }
 
-            for (int i = 0; i < _filteredSource.Length; i++)
+            for (var i = 0; i < _filteredSource.Length; i++)
             {
-                if (EqualityComparer<T>.Default.Equals(_filteredSource[i], (T)defaultValue))
+                if (EqualityComparer<T>.Default.Equals(_filteredSource[i], defaultValue))
                 {
                     _selectedIndex = i % _pageSize;
                     _selectedPage = i / _pageSize;

diff --git a/Sharprompt/Prompt.cs b/Sharprompt/Prompt.cs
@@ -12,7 +12,7 @@ public static class Prompt
     {
         public static T Input<T>(string message, object defaultValue = null, IList<Func<object, ValidationResult>> validators = null)
         {
-            using var form = new Input<T>(message, defaultValue, validators);
+            using var form = new Input<T>(message, Optional<T>.Create(defaultValue), validators);
 
             return form.Start();
         }
@@ -35,14 +35,14 @@ public static T Select<T>(string message, int? pageSize = null, T? defaultValue
         {
             var items = EnumValue<T>.GetValues();
 
-            using var form = new Select<EnumValue<T>>(message, items, pageSize, (EnumValue<T>)defaultValue, x => x.DisplayName);
+            using var form = new Select<EnumValue<T>>(message, items, pageSize, Optional<EnumValue<T>>.Create(defaultValue), x => x.DisplayName);
 
             return form.Start().Value;
         }
 
         public static T Select<T>(string message, IEnumerable<T> items, int? pageSize = null, object defaultValue = null, Func<T, string> valueSelector = null)
         {
-            using var form = new Select<T>(message, items, pageSize, defaultValue, valueSelector ?? (x => x.ToString()));
+            using var form = new Select<T>(message, items, pageSize, Optional<T>.Create(defaultValue), valueSelector ?? (x => x.ToString()));
 
             return form.Start();
         }