Constrain custom selectors and operators (axuno#172)

* Custom selector chars can be added, if not disallowed or in use as an operator char
* Custom operator chars can be added, if not disallowed or in use as a selector char
* Added corresponding unit tests
* Alphanumeric selector chars are the only option now and cannot be degraded to pure numeric chars
* `PlaceholderBeginChar`, `PlaceholderEndChar`, `FormatterOptionsBeginChar` and `FormatterOptionsEndChar` now only have getters
* Removed obsolete `formatter.Parser.AddOperators("[]");` from the `ListFormatter` CTOR.

src/SmartFormat.Tests/Core/ParserTests.cs

@@ -617,5 +617,55 @@ public void Parse_Unicode(string formatString, string unicodeLiteral, int itemIn
             else
                 Assert.That(() => literal.ToString(), Throws.ArgumentException.And.Message.Contains(unicodeLiteral));
         }
+
+        [TestCase("{A }", ' ')]
+        [TestCase("{B§}", '§')]
+        [TestCase("{?C}", '?')]
+        public void Selector_With_Custom_Selector_Character(string formatString, char customChar)
+        {
+            var parser = GetRegularParser();
+            parser.Settings.Parser.AddCustomSelectorChars(new[]{customChar});
+            var result = parser.ParseFormat(formatString, new[] {"d"});
+
+            var placeholder = result.Items[0] as Placeholder;
+            Assert.That(placeholder, Is.Not.Null);
+            Assert.That(placeholder.Selectors.Count, Is.EqualTo(1));
+            Assert.That(placeholder.Selectors[0].ToString(), Is.EqualTo(formatString.Substring(1,2)));
+        }
+
+        [TestCase("{a b}", ' ')]
+        [TestCase("{a°b}", '°')]
+        public void Selectors_With_Custom_Operator_Character(string formatString, char customChar)
+        {
+            var parser = GetRegularParser();
+            parser.Settings.Parser.AddCustomOperatorChars(new[]{customChar});
+            var result = parser.ParseFormat(formatString, new[] {"d"});
+
+            var placeholder = result.Items[0] as Placeholder;
+            Assert.That(placeholder, Is.Not.Null);
+            Assert.That(placeholder.Selectors.Count, Is.EqualTo(2));
+            Assert.That(placeholder.Selectors[0].ToString(), Is.EqualTo(formatString.Substring(1,1)));
+            Assert.That(placeholder.Selectors[1].ToString(), Is.EqualTo(formatString.Substring(3, 1)));
+            Assert.That(placeholder.Selectors[1].Operator, Is.EqualTo(formatString.Substring(2,1)));
+        }
+
+        [TestCase("{C?.D}", '?')] 
+        [TestCase("{C..D}", '.')] 
+        public void Selector_With_Contiguous_Operator_Characters(string formatString, char customChar)
+        {
+            // contiguous operators '?.' are parsed as ONE
+
+            var parser = GetRegularParser();
+            // adding '.' is ignored, as it's the standard operator
+            parser.Settings.Parser.AddCustomOperatorChars(new[]{customChar});
+            var result = parser.ParseFormat(formatString, new[] {"d"});
+
+            var placeholder = result.Items[0] as Placeholder;
+            Assert.That(placeholder, Is.Not.Null);
+            Assert.That(placeholder.Selectors.Count, Is.EqualTo(2));
+            Assert.That(placeholder.Selectors[0].ToString(), Is.EqualTo(formatString.Substring(1,1)));
+            Assert.That(placeholder.Selectors[1].ToString(), Is.EqualTo(formatString.Substring(4,1)));
+            Assert.That(placeholder.Selectors[1].Operator, Is.EqualTo(formatString.Substring(2,2)));
+        }
     }
 }

src/SmartFormat.Tests/Core/SettingsTests.cs

@@ -0,0 +1,104 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text;
+using System.Threading.Tasks;
+using NUnit.Framework;
+using SmartFormat.Core.Settings;
+
+namespace SmartFormat.Tests.Core
+{
+    [TestFixture]
+    public class SettingsTests
+    {
+        [Test]
+        public void TryingToAddDisallowedSelectorCharacters_Should_Throw()
+        {
+            var settings = new SmartSettings();
+            Assert.That(() => settings.Parser.AddCustomSelectorChars(new[] {settings.Parser.PlaceholderBeginChar}),
+                Throws.ArgumentException.And.Message.Contains($"{settings.Parser.PlaceholderBeginChar}"));
+        }
+
+        [Test]
+        public void ExistingSelectorCharacter_Should_Not_Be_Added()
+        {
+            var settings = new SmartSettings();
+            settings.Parser.AddCustomSelectorChars(new[] {'A', ' '});
+            settings.Parser.AddCustomSelectorChars(new[] {' '});
+
+            Assert.That(settings.Parser.CustomSelectorChars.Count(c => c == 'A'), Is.EqualTo(0));
+            Assert.That(settings.Parser.CustomSelectorChars.Count(c => c == ' '), Is.EqualTo(1));
+        }
+
+        [Test]
+        public void TryingToAddDisallowedOperatorCharacters_Should_Throw()
+        {
+            var settings = new SmartSettings();
+            Assert.That(() => settings.Parser.AddCustomOperatorChars(new[] {settings.Parser.PlaceholderBeginChar}),
+                Throws.ArgumentException.And.Message.Contains($"{settings.Parser.PlaceholderBeginChar}"));
+        }
+
+        [Test]
+        public void ExistingOperatorCharacter_Should_Not_Be_Added()
+        {
+            var settings = new SmartSettings();
+            settings.Parser.AddCustomOperatorChars(new[] {settings.Parser.OperatorChars[0], '°'});
+            settings.Parser.AddCustomOperatorChars(new[] {'°'});
+
+            Assert.That(settings.Parser.CustomOperatorChars.Count(c => c == settings.Parser.OperatorChars[0]), Is.EqualTo(0));
+            Assert.That(settings.Parser.CustomOperatorChars.Count(c => c == '°'), Is.EqualTo(1));
+        }
+
+        [Test]
+        public void GetCaseSensitivityComparison()
+        {
+            var settings = new SmartSettings();
+            foreach (var name in Enum.GetNames(typeof(CaseSensitivityType)))
+            {
+                settings.CaseSensitivity = (CaseSensitivityType) Enum.Parse(typeof(CaseSensitivityType), name);
+                Assert.DoesNotThrow(() => settings.GetCaseSensitivityComparison());
+            }
+
+            settings.CaseSensitivity = (CaseSensitivityType) int.MaxValue;
+            Assert.Throws<InvalidOperationException>(() => settings.GetCaseSensitivityComparison());
+        }
+
+        [Test]
+        public void CaseSensitivityComparer()
+        {
+            var settings = new SmartSettings();
+            foreach (var name in Enum.GetNames(typeof(CaseSensitivityType)))
+            {
+                settings.CaseSensitivity = (CaseSensitivityType) Enum.Parse(typeof(CaseSensitivityType), name);
+                Assert.DoesNotThrow(() => settings.GetCaseSensitivityComparer());
+            }
+
+            settings.CaseSensitivity = (CaseSensitivityType) int.MaxValue;
+            Assert.Throws<InvalidOperationException>(() => settings.GetCaseSensitivityComparer());
+        }
+
+        [TestCase('°')] // a custom char
+        [TestCase('A')] // a standard selector char
+        public void Add_CustomOperator_Used_As_Seperator_Should_Throw(char operatorChar)
+        {
+            var settings = new SmartSettings();
+            settings.Parser.AddCustomSelectorChars(new[] {operatorChar}); // reserve as selector char
+
+            // try to add the same char as operator
+            Assert.That(() => settings.Parser.AddCustomOperatorChars(new[] {operatorChar}),
+                Throws.ArgumentException.And.Message.Contains($"{operatorChar}"));
+        }
+
+        [TestCase('°')] // a custom char
+        [TestCase('.')] // a standard operator char
+        public void Add_CustomSelector_Used_As_Operator_Should_Throw(char selectorChar)
+        {
+            var settings = new SmartSettings();
+            settings.Parser.AddCustomOperatorChars(new[] {selectorChar}); // reserve as operator char
+
+            // try to add the same char as selector
+            Assert.That(() => settings.Parser.AddCustomSelectorChars(new[] {selectorChar}),
+                Throws.ArgumentException.And.Message.Contains($"{selectorChar}"));
+        }
+    }
+}

src/SmartFormat/Core/Parsing/Parser.cs

@@ -55,10 +55,10 @@ internal Parser(SmartSettings smartSettings)
         /// <summary>
         /// Includes a-z and A-Z in the list of allowed selector chars.
         /// </summary>
-        [Obsolete("Use 'ParserSettings.AllowAlphanumericSelectors' instead.")]
+        [Obsolete("Alphanumeric selectors are always enabled")]
         public void AddAlphanumericSelectors()
         {
-            _parserSettings.AllowAlphanumericSelectors = true;
+            // Do nothing - this is the standard behavior
         }
 
         /// <summary>
@@ -116,8 +116,7 @@ public void UseBraceEscaping()
         [Obsolete("This feature has been removed", true)]
         public void UseAlternativeBraces(char opening, char closing)
         {
-            _parserSettings.PlaceholderBeginChar = opening;
-            _parserSettings.PlaceholderEndChar = opening;
+            throw new NotImplementedException("This feature has been removed");
         }
 
         #endregion
@@ -565,7 +564,7 @@ private void ParseSelector(string inputFormat, ref Format currentFormat, ref Ind
             }
 
             var inputChar = inputFormat[index.Current];
-            if (_parserSettings.OperatorChars.Contains(inputChar))
+            if (_parserSettings.OperatorChars.Contains(inputChar) || _parserSettings.CustomOperatorChars.Contains(inputChar))
             {
                 // Add the selector:
                 if (index.Current != index.LastEnd)
@@ -675,8 +674,7 @@ private void ParseFormatOptions(string inputFormat, ref IndexContainer index)
         }
 
         /// <summary>
-        /// Checks whether the selector character is valid,
-        /// depending on <see cref="ParserSettings.AllowAlphanumericSelectors"/> and <see cref="ParserSettings.CustomSelectorChars"/>.
+        /// Checks whether the selector character is valid.
         /// </summary>
         /// <param name="c">The character to check.</param>
         /// <returns><see langword="true"/> if the character is valid, else <see langword="false"/>.</returns>
@@ -685,11 +683,10 @@ internal bool IsValidSelectorChar(char c)
         {
             // C# variables: LetterOrDigit and "_"
             // Required for Alignment: "-" and ","
-            return _parserSettings.AllowAlphanumericSelectors
-                ? _parserSettings.AlphanumericSelectorChars.Contains(c) || _parserSettings.OperatorChars.Contains(c) || _parserSettings.CustomSelectorChars.Contains(c)
-                : _parserSettings.NumericSelectorChars.Contains(c) || _parserSettings.OperatorChars.Contains(c);
+            return _parserSettings.AlphanumericSelectorChars.Contains(c) || _parserSettings.OperatorChars.Contains(c) ||
+                   _parserSettings.CustomSelectorChars.Contains(c);
         }
-        
+
         private static bool FormatterNameExists(string name, string[] formatterExtensionNames)
         {
             return formatterExtensionNames.Any(n => n == name);

src/SmartFormat/Core/Settings/ParserSettings.cs

@@ -3,6 +3,7 @@
 // Licensed under the MIT license.
 //
 
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using SmartFormat.Core.Parsing;
@@ -15,7 +16,6 @@ namespace SmartFormat.Core.Settings
     public class ParserSettings
     {
         private readonly IList<char> _alphanumericSelectorChars = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ_-".ToCharArray();
-        private readonly IList<char> _numericSelectorChars = "0123456789-".ToCharArray();
 
         private readonly IList<char> _customSelectorChars = new List<char>();
         private readonly IList<char> _customOperatorChars = new List<char>();
@@ -26,64 +26,69 @@ public class ParserSettings
         /// </summary>
         public ParseErrorAction ErrorAction { get; set; } = ParseErrorAction.ThrowError;
 
-        /// <summary>
-        /// If <see langword="true"/>, selectors can be alpha-numeric: They may contain
-        /// letters, digits, and the underscore character (_), like it is for C# variable names.
-        /// If <see langword="false"/>, only digits are allowed as selectors. Default is <see langword="true"/>.
-        /// </summary>
-        public bool AllowAlphanumericSelectors { get; set; } = true;
-
         /// <summary>
         /// The list of alphanumeric selector characters.
         /// </summary>
         public IReadOnlyList<char> AlphanumericSelectorChars => (IReadOnlyList<char>) _alphanumericSelectorChars;
 
         /// <summary>
-        /// The list of numeric selector characters.
+        /// Gets a read-only list of the custom selector characters, which were set with <see cref="AddCustomSelectorChars"/>.
         /// </summary>
-        public IReadOnlyList<char> NumericSelectorChars => (IReadOnlyList<char>) _numericSelectorChars;
+        public IReadOnlyList<char> CustomSelectorChars => (IReadOnlyList<char>) _customSelectorChars;
 
         /// <summary>
-        /// Gets a read-only list of the custom selector characters, which were set with <see cref="AddCustomSelectorChars"/>.
+        /// Gets a list of characters which are not allowed in a selector.
         /// </summary>
-        public IReadOnlyList<char> CustomSelectorChars => (IReadOnlyList<char>) _customSelectorChars;
+        public IReadOnlyList<char> DisallowedSelectorChars
+        {
+            get
+            {
+                var chars = new List<char> {
+                    CharLiteralEscapeChar, FormatterNameSeparator, AlignmentOperator, SelectorOperator,
+                    PlaceholderBeginChar, PlaceholderEndChar, FormatterOptionsBeginChar, FormatterOptionsEndChar
+                };
+                chars.AddRange(OperatorChars);
+                return chars;
+            }
+        }
 
         /// <summary>
         /// Gets a read-only list of the custom operator characters, which were set with <see cref="AddCustomSelectorChars"/>.
+        /// Contiguous operator characters are parsed as one operator (e.g. '?.').
         /// </summary>
         public IReadOnlyList<char> CustomOperatorChars => (IReadOnlyList<char>) _customOperatorChars;
 
         /// <summary>
-        /// Add a list of allowable selector characters on top of the <see cref="AllowAlphanumericSelectors"/> setting.
+        /// Add a list of allowable selector characters on top of the <see cref="AlphanumericSelectorChars"/> setting.
         /// This can be useful to support additional selector syntax such as math.
-        ///  </summary>
+        /// Characters in <see cref="DisallowedSelectorChars"/> cannot be added.
+        /// Operator chars and selector chars must be different.
+        /// </summary>
         public void AddCustomSelectorChars(IList<char> characters)
         {
-            if (AllowAlphanumericSelectors)
-            {
-                foreach (var c in characters)
-                {
-                    if (!_customSelectorChars.Contains(c) && !_alphanumericSelectorChars.Contains(c))
-                        _customSelectorChars.Add(c);
-                }
-            }
-            else
+            foreach (var c in characters)
             {
-                foreach (var c in characters)
-                {
-                    if (!_customSelectorChars.Contains(c) && !_numericSelectorChars.Contains(c))
-                        _customSelectorChars.Add(c);
-                }
+                if (DisallowedSelectorChars.Contains(c) || _customOperatorChars.Contains(c))
+                    throw new ArgumentException($"Cannot add '{c}' as a custom selector character. It is disallowed or in use as an operator.");
+
+                if (!_customSelectorChars.Contains(c) && !_alphanumericSelectorChars.Contains(c))
+                    _customSelectorChars.Add(c);
             }
         }
 
         /// <summary>
         /// Add a list of allowable operator characters on top of the standard <see cref="OperatorChars"/> setting.
+        /// Characters in <see cref="DisallowedSelectorChars"/> cannot be added.
+        /// Operator chars and selector chars must be different.
         ///  </summary>
         public void AddCustomOperatorChars(IList<char> characters)
         {
             foreach (var c in characters)
             {
+                if (DisallowedSelectorChars.Where(_ => OperatorChars.All(ch => ch != c)).Contains(c) ||
+                    _alphanumericSelectorChars.Contains(c) || _customSelectorChars.Contains(c))
+                    throw new ArgumentException($"Cannot add '{c}' as a custom operator character. It is disallowed or in use as a selector.");
+
                 if (!OperatorChars.Contains(c) && !_customOperatorChars.Contains(c))
                     _customOperatorChars.Add(c);
             }
@@ -114,42 +119,43 @@ public void AddCustomOperatorChars(IList<char> characters)
         /// The character which separates the formatter name (if any exists) from other parts of the placeholder.
         /// E.g.: {Variable:FormatterName:argument} or {Variable:FormatterName}
         /// </summary>
-        internal char FormatterNameSeparator { get; set; } = ':';
+        internal char FormatterNameSeparator { get; } = ':';
 
         /// <summary>
         /// The standard operator characters.
+        /// Contiguous operator characters are parsed as one operator (e.g. '?.').
         /// </summary>
         internal IReadOnlyList<char> OperatorChars => new List<char> {SelectorOperator, AlignmentOperator, '[', ']'};
 
         /// <summary>
         /// The character which separates the selector for alignment. <c>E.g.: Smart.Format("Name: {name,10}")</c>
         /// </summary>
-        internal char AlignmentOperator { get; set; } = ',';
+        internal char AlignmentOperator { get; } = ',';
 
         /// <summary>
         /// The character which separates two or more selectors <c>E.g.: "First.Second.Third"</c>
         /// </summary>
-        internal char SelectorOperator { get; set; } = '.';
+        internal char SelectorOperator { get; } = '.';
 
         /// <summary>
         /// Gets the character indicating the start of a <see cref="Placeholder"/>.
         /// </summary>
-        public char PlaceholderBeginChar { get; internal set; } = '{';
+        public char PlaceholderBeginChar { get; } = '{';
 
         /// <summary>
         /// Gets the character indicating the end of a <see cref="Placeholder"/>.
         /// </summary>
-        public char PlaceholderEndChar { get; internal set; } = '}';
+        public char PlaceholderEndChar { get; } = '}';
 
         /// <summary>
         /// Gets the character indicating the begin of formatter options.
         /// </summary>
-        public char FormatterOptionsBeginChar { get; internal set; } = '(';
+        public char FormatterOptionsBeginChar { get; } = '(';
 
         /// <summary>
         /// Gets the character indicating the end of formatter options.
         /// </summary>
-        public char FormatterOptionsEndChar { get; internal set; } = ')';
+        public char FormatterOptionsEndChar { get; } = ')';
 
         /// <summary>
         /// Characters which terminate parsing of format options.

src/SmartFormat/Extensions/ListFormatter.cs

@@ -41,7 +41,7 @@ public class ListFormatter : IFormatter, ISource
 
         public ListFormatter(SmartFormatter formatter)
         {
-            formatter.Parser.AddOperators("[]()");
+            formatter.Parser.AddOperators("[]");
             _smartSettings = formatter.Settings;
         }