Initial commit.

.editorconfig

@@ -0,0 +1,94 @@
+[*.{cs,vb}]
+
+# IDE0028: Simplify collection initialization
+dotnet_diagnostic.IDE0028.severity = silent
+dotnet_style_operator_placement_when_wrapping = beginning_of_line
+tab_width = 4
+indent_size = 4
+end_of_line = crlf
+dotnet_style_coalesce_expression = true:suggestion
+dotnet_style_null_propagation = true:suggestion
+dotnet_style_prefer_is_null_check_over_reference_equality_method = true:suggestion
+dotnet_style_prefer_auto_properties = true:silent
+dotnet_style_object_initializer = true:suggestion
+dotnet_style_prefer_collection_expression = true:suggestion
+dotnet_style_collection_initializer = true:suggestion
+dotnet_style_prefer_simplified_boolean_expressions = true:suggestion
+dotnet_style_prefer_conditional_expression_over_assignment = true:silent
+dotnet_style_prefer_conditional_expression_over_return = true:silent
+dotnet_style_explicit_tuple_names = true:suggestion
+
+[*.cs]
+csharp_indent_labels = one_less_than_current
+csharp_using_directive_placement = outside_namespace:silent
+csharp_prefer_simple_using_statement = true:suggestion
+csharp_prefer_braces = true:silent
+csharp_style_namespace_declarations = file_scoped:suggestion
+csharp_style_prefer_method_group_conversion = true:silent
+csharp_style_prefer_top_level_statements = true:silent
+csharp_style_prefer_primary_constructors = true:suggestion
+csharp_style_expression_bodied_methods = false:silent
+csharp_style_expression_bodied_constructors = false:silent
+csharp_style_expression_bodied_operators = false:silent
+csharp_style_expression_bodied_properties = true:silent
+csharp_style_expression_bodied_indexers = true:silent
+csharp_style_expression_bodied_accessors = true:silent
+csharp_style_expression_bodied_lambdas = true:silent
+csharp_style_expression_bodied_local_functions = false:silent
+csharp_space_around_binary_operators = before_and_after
+
+# IDE0090: Use 'new(...)'
+dotnet_diagnostic.IDE0090.severity = silent
+
+# CA1854: Prefer the 'IDictionary.TryGetValue(TKey, out TValue)' method
+dotnet_diagnostic.CA1854.severity = silent
+
+[*.{cs,vb}]
+#### Naming styles ####
+
+# Naming rules
+
+dotnet_naming_rule.interface_should_be_begins_with_i.severity = suggestion
+dotnet_naming_rule.interface_should_be_begins_with_i.symbols = interface
+dotnet_naming_rule.interface_should_be_begins_with_i.style = begins_with_i
+
+dotnet_naming_rule.types_should_be_pascal_case.severity = suggestion
+dotnet_naming_rule.types_should_be_pascal_case.symbols = types
+dotnet_naming_rule.types_should_be_pascal_case.style = pascal_case
+
+dotnet_naming_rule.non_field_members_should_be_pascal_case.severity = suggestion
+dotnet_naming_rule.non_field_members_should_be_pascal_case.symbols = non_field_members
+dotnet_naming_rule.non_field_members_should_be_pascal_case.style = pascal_case
+
+# Symbol specifications
+
+dotnet_naming_symbols.interface.applicable_kinds = interface
+dotnet_naming_symbols.interface.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.interface.required_modifiers = 
+
+dotnet_naming_symbols.types.applicable_kinds = class, struct, interface, enum
+dotnet_naming_symbols.types.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.types.required_modifiers = 
+
+dotnet_naming_symbols.non_field_members.applicable_kinds = property, event, method
+dotnet_naming_symbols.non_field_members.applicable_accessibilities = public, internal, private, protected, protected_internal, private_protected
+dotnet_naming_symbols.non_field_members.required_modifiers = 
+
+# Naming styles
+
+dotnet_naming_style.begins_with_i.required_prefix = I
+dotnet_naming_style.begins_with_i.required_suffix = 
+dotnet_naming_style.begins_with_i.word_separator = 
+dotnet_naming_style.begins_with_i.capitalization = pascal_case
+
+dotnet_naming_style.pascal_case.required_prefix = 
+dotnet_naming_style.pascal_case.required_suffix = 
+dotnet_naming_style.pascal_case.word_separator = 
+dotnet_naming_style.pascal_case.capitalization = pascal_case
+
+dotnet_naming_style.pascal_case.required_prefix = 
+dotnet_naming_style.pascal_case.required_suffix = 
+dotnet_naming_style.pascal_case.word_separator = 
+dotnet_naming_style.pascal_case.capitalization = pascal_case
+dotnet_style_prefer_inferred_tuple_names = true:suggestion
+dotnet_style_namespace_match_folder = true:suggestion

Mnemonic.sln

@@ -7,6 +7,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "src", "src", "{B09A4292-905
 EndProject
 Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "Solution Items", "Solution Items", "{9D157855-7C1B-4057-AFD1-ABCDC8CF5AC8}"
 	ProjectSection(SolutionItems) = preProject
+		.editorconfig = .editorconfig
 		.gitignore = .gitignore
 		common.props = common.props
 		houseofcat.png = houseofcat.png

common.props

@@ -3,7 +3,7 @@
 	<PropertyGroup>
 
 		<!-- Shared Project Properties -->
-		<TargetFrameworks>net7.0;net8.0</TargetFrameworks>
+		<TargetFrameworks>net8.0</TargetFrameworks>
 		<LangVersion>latest</LangVersion>
 		<NoWarn>1591</NoWarn>
 		<IsWindows Condition="'$([System.Runtime.InteropServices.RuntimeInformation]::IsOSPlatform($([System.Runtime.InteropServices.OSPlatform]::Windows)))' == 'true'">true</IsWindows>

examples/Mnemonic/Program.cs

@@ -1,2 +1,17 @@
-// See https://aka.ms/new-console-template for more information
-Console.WriteLine("Hello, World!");
+using Mnemonic.AhoCorasick;
+using System;
+
+Console.WriteLine("Mnemonic AhoCorasick StringReplace");
+
+var ac = new AhoCorasickStringReplace();
+
+ac.AddPattern("apple is red.", "apple is yellow.");
+ac.AddPattern("apple is green.", "apple is blue.");
+
+ac.BuildFailureLinks();
+
+var input = "My apple is red.";
+var output = ac.Replace(input);
+
+Console.WriteLine("Input: " + input);
+Console.WriteLine("Output: " + output);

src/Mnemonic.AhoCorasick/AhoCorasickStringReplace.cs

@@ -0,0 +1,121 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+
+namespace Mnemonic.AhoCorasick;
+
+public sealed class AhoCorasickStringReplace
+{
+    private readonly TrieNode _root = new TrieNode();
+    private bool _isBuilt = false;
+
+    private static readonly string _mustAddFirstError = $"You can only invoke {nameof(AddPattern)} before invoking {nameof(BuildFailureLinks)}.";
+
+    public void AddPattern(ReadOnlySpan<char> pattern, string replacement)
+    {
+        if (_isBuilt) throw new InvalidOperationException(_mustBuildFirstError);
+
+        var node = _root;
+
+        foreach (char c in pattern)
+        {
+            node.Children.AddIfNotExists(c, new TrieNode { Key = c });
+            node = node.Children[c];
+        }
+
+        node.IsEndOfPattern = true;
+        node.Replacement = replacement;
+    }
+
+    public void BuildFailureLinks()
+    {
+        if (_isBuilt) return;
+
+        var queue = new Queue<TrieNode>();
+
+        foreach (var child in _root.Children.Values)
+        {
+            child.FailureLinkNode = _root;
+            queue.Enqueue(child);
+        }
+
+        while (queue.Count > 0)
+        {
+            BuildFailureLink(queue);
+        }
+
+        _isBuilt = true;
+    }
+
+    private static readonly string _mustBuildFirstError = $"You must invoke {nameof(BuildFailureLinks)} before attempting to invoke {nameof(Replace)}.";
+
+    public string Replace(ReadOnlySpan<char> input)
+    {
+        if (!_isBuilt) throw new InvalidOperationException(_mustBuildFirstError);
+        if (input.Length == 0) return default;
+
+        var result = new StringBuilder();
+        var currentNode = _root;
+        var i = 0;
+
+        while (i < input.Length)
+        {
+            if (currentNode.Children.TryGetValue(input[i], out var nextNode))
+            {
+                currentNode = nextNode;
+                i++;
+            }
+            else if (currentNode == _root)
+            {
+                result.Append(input[i]);
+                i++;
+            }
+            else
+            {
+                currentNode = currentNode.FailureLinkNode;
+            }
+
+            if (currentNode.IsEndOfPattern)
+            {
+                result.Append(currentNode.Replacement);
+                currentNode = _root;
+            }
+        }
+
+        return result.ToString();
+    }
+
+    private void BuildFailureLink(Queue<TrieNode> queue)
+    {
+        var currentNode = queue.Dequeue();
+
+        foreach (var kvp in currentNode.Children)
+        {
+            var currentKey = kvp.Key;
+            var currentChildNode = kvp.Value;
+            var currentFailureLinkeNode = currentNode.FailureLinkNode;
+
+            while (currentFailureLinkeNode != null
+                && !currentFailureLinkeNode.Children.ContainsKey(currentKey))
+            {
+                currentFailureLinkeNode = currentFailureLinkeNode.FailureLinkNode;
+            }
+
+            if (currentFailureLinkeNode == null)
+            {
+                currentChildNode.FailureLinkNode = _root;
+            }
+            else
+            {
+                currentChildNode.FailureLinkNode = currentFailureLinkeNode.Children[currentKey];
+            }
+
+            if (currentChildNode.FailureLinkNode.IsEndOfPattern)
+            {
+                currentChildNode.IsEndOfPattern = true;
+            }
+
+            queue.Enqueue(currentChildNode);
+        }
+    }
+}

src/Mnemonic.AhoCorasick/Extensions.cs

@@ -0,0 +1,42 @@
+using System.Collections.Generic;
+using System.Runtime.CompilerServices;
+using System.Runtime.InteropServices;
+
+namespace Mnemonic.AhoCorasick;
+
+public static class Extensions
+{
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void AddIfNotExists<TKey, TValue>(this Dictionary<TKey, TValue> dictionary, TKey key) where TValue : new()
+    {
+        ref var valOrNew = ref CollectionsMarshal.GetValueRefOrAddDefault(dictionary, key, out var existed);
+        if (!existed) { valOrNew = new(); }
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static void AddIfNotExists<TKey, TValue>(this Dictionary<TKey, TValue> dictionary, TKey key, TValue value)
+    {
+        ref var valOrNew = ref CollectionsMarshal.GetValueRefOrAddDefault(dictionary, key, out var existed);
+        if (!existed) { valOrNew = value; }
+    }
+
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static int GetStableHashCode(this string str)
+    {
+        unchecked
+        {
+            var hash1 = 5381;
+            var hash2 = hash1;
+
+            for (var i = 0; i < str.Length && str[i] != '\0'; i += 2)
+            {
+                hash1 = ((hash1 << 5) + hash1) ^ str[i];
+                if (i == str.Length - 1 || str[i + 1] == '\0')
+                { break; }
+                hash2 = ((hash2 << 5) + hash2) ^ str[i + 1];
+            }
+
+            return hash1 + (hash2 * 1566083941);
+        }
+    }
+}

src/Mnemonic.AhoCorasick/TrieNode.cs

@@ -0,0 +1,14 @@
+using System.Collections.Generic;
+using System.Diagnostics;
+
+namespace Mnemonic.AhoCorasick;
+
+[DebuggerDisplay("{Replacement}", Name = "{Key}")]
+public sealed record TrieNode
+{
+    public char Key { get; set; }
+    public Dictionary<char, TrieNode> Children { get; } = new Dictionary<char, TrieNode>();
+    public TrieNode FailureLinkNode { get; set; }
+    public bool IsEndOfPattern { get; set; }
+    public string Replacement { get; set; }
+}