Support LCS (#2104)

Adds support for https://redis.io/commands/lcs/ (#2055)

Co-authored-by: slorello89 <[email protected]>
Co-authored-by: Nick Craver <[email protected]>

Author: 3 people

docs/ReleaseNotes.md

@@ -27,6 +27,7 @@
 - Adds: Support for `ZMPOP` with `.SortedSetPop()`/`.SortedSetPopAsync()` ([#2094 by slorello89](https://github.com/StackExchange/StackExchange.Redis/pull/2094))
 - Adds: Support for `XAUTOCLAIM` with `.StreamAutoClaim()`/.`StreamAutoClaimAsync()` and `.StreamAutoClaimIdsOnly()`/.`StreamAutoClaimIdsOnlyAsync()` ([#2095 by ttingen](https://github.com/StackExchange/StackExchange.Redis/pull/2095))
 - Fix [#2071](https://github.com/StackExchange/StackExchange.Redis/issues/2071): Add `.StringSet()`/`.StringSetAsync()` overloads for source compat broken for 1 case in 2.5.61 ([#2098 by NickCraver](https://github.com/StackExchange/StackExchange.Redis/pull/2098))
+- Adds: Support for `LCS` with `.StringLongestCommonSubsequence()`/`.StringLongestCommonSubsequence()`, `.StringLongestCommonSubsequenceLength()`/`.StringLongestCommonSubsequenceLengthAsync()`, and `.StringLongestCommonSubsequenceWithMatches()`/`.StringLongestCommonSubsequenceWithMatchesAsync()` ([#2104 by Avital-Fine](https://github.com/StackExchange/StackExchange.Redis/pull/2104))
 - Adds: Support for `OBJECT FREQ` with `.KeyFrequency()`/`.KeyFrequencyAsync()` ([#2105 by Avital-Fine](https://github.com/StackExchange/StackExchange.Redis/pull/2105))
 - Performance: Avoids allocations when computing cluster hash slots or testing key equality ([#2110 by Marc Gravell](https://github.com/StackExchange/StackExchange.Redis/pull/2110))
 - Adds: Support for `SORT_RO` with `.Sort()`/`.SortAsync()` ([#2111 by slorello89](https://github.com/StackExchange/StackExchange.Redis/pull/2111))

src/StackExchange.Redis/APITypes/LCSMatchResult.cs

@@ -0,0 +1,67 @@
+using System;
+
+namespace StackExchange.Redis;
+
+/// <summary>
+/// The result of a LongestCommonSubsequence command with IDX feature.
+/// Returns a list of the positions of each sub-match.
+/// </summary>
+public readonly struct LCSMatchResult
+{
+    internal static LCSMatchResult Null { get; } = new LCSMatchResult(Array.Empty<LCSMatch>(), 0);
+
+    /// <summary>
+    /// The matched positions of all the sub-matched strings.
+    /// </summary>
+    public LCSMatch[] Matches { get; }
+
+    /// <summary>
+    /// The length of the longest match.
+    /// </summary>
+    public long LongestMatchLength { get; }
+
+    /// <summary>
+    /// Returns a new <see cref="LCSMatchResult"/>.
+    /// </summary>
+    /// <param name="matches">The matched positions in each string.</param>
+    /// <param name="matchLength">The length of the match.</param>
+    internal LCSMatchResult(LCSMatch[] matches, long matchLength)
+    {
+        Matches = matches;
+        LongestMatchLength = matchLength;
+    }
+
+    /// <summary>
+    /// Represents a sub-match of the longest match. i.e first indexes the matched substring in each string.
+    /// </summary>
+    public readonly struct LCSMatch
+    {
+        /// <summary>
+        /// The first index of the matched substring in the first string.
+        /// </summary>
+        public long FirstStringIndex { get; }
+
+        /// <summary>
+        /// The first index of the matched substring in the second string.
+        /// </summary>
+        public long SecondStringIndex { get; }
+
+        /// <summary>
+        /// The length of the match.
+        /// </summary>
+        public long Length { get; }
+
+        /// <summary>
+        /// Returns a new Match.
+        /// </summary>
+        /// <param name="firstStringIndex">The first index of the matched substring in the first string.</param>
+        /// <param name="secondStringIndex">The first index of the matched substring in the second string.</param>
+        /// <param name="length">The length of the match.</param>
+        internal LCSMatch(long firstStringIndex, long secondStringIndex, long length)
+        {
+            FirstStringIndex = firstStringIndex;
+            SecondStringIndex = secondStringIndex;
+            Length = length;
+        }
+    }
+}

src/StackExchange.Redis/Enums/RedisCommand.cs

@@ -86,6 +86,7 @@ internal enum RedisCommand
 
     LASTSAVE,
     LATENCY,
+    LCS,
     LINDEX,
     LINSERT,
     LLEN,
@@ -393,6 +394,7 @@ internal static bool IsPrimaryOnly(this RedisCommand command)
             case RedisCommand.KEYS:
             case RedisCommand.LASTSAVE:
             case RedisCommand.LATENCY:
+            case RedisCommand.LCS:
             case RedisCommand.LINDEX:
             case RedisCommand.LLEN:
             case RedisCommand.LPOS:

src/StackExchange.Redis/Interfaces/IDatabase.cs

@@ -2771,6 +2771,46 @@ IEnumerable<SortedSetEntry> SortedSetScan(RedisKey key,
         /// <remarks><seealso href="https://redis.io/commands/strlen"/></remarks>
         long StringLength(RedisKey key, CommandFlags flags = CommandFlags.None);
 
+        /// <summary>
+        /// Implements the longest common subsequence algorithm between the values at <paramref name="first"/> and <paramref name="second"/>,
+        /// returning a string containing the common sequence.
+        /// Note that this is different than the longest common string algorithm,
+        /// since matching characters in the string does not need to be contiguous.
+        /// </summary>
+        /// <param name="first">The key of the first string.</param>
+        /// <param name="second">The key of the second string.</param>
+        /// <param name="flags">The flags to use for this operation.</param>
+        /// <returns>A string (sequence of characters) of the LCS match.</returns>
+        /// <remarks><seealso href="https://redis.io/commands/lcs"/></remarks>
+        string? StringLongestCommonSubsequence(RedisKey first, RedisKey second, CommandFlags flags = CommandFlags.None);
+
+        /// <summary>
+        /// Implements the longest common subsequence algorithm between the values at <paramref name="first"/> and <paramref name="second"/>,
+        /// returning the legnth of the common sequence.
+        /// Note that this is different than the longest common string algorithm,
+        /// since matching characters in the string does not need to be contiguous.
+        /// </summary>
+        /// <param name="first">The key of the first string.</param>
+        /// <param name="second">The key of the second string.</param>
+        /// <param name="flags">The flags to use for this operation.</param>
+        /// <returns>The length of the LCS match.</returns>
+        /// <remarks><seealso href="https://redis.io/commands/lcs"/></remarks>
+        long StringLongestCommonSubsequenceLength(RedisKey first, RedisKey second, CommandFlags flags = CommandFlags.None);
+
+        /// <summary>
+        /// Implements the longest common subsequence algorithm between the values at <paramref name="first"/> and <paramref name="second"/>,
+        /// returning a list of all common sequences.
+        /// Note that this is different than the longest common string algorithm,
+        /// since matching characters in the string does not need to be contiguous.
+        /// </summary>
+        /// <param name="first">The key of the first string.</param>
+        /// <param name="second">The key of the second string.</param>
+        /// <param name="minLength">Can be used to restrict the list of matches to the ones of a given minimum length.</param>
+        /// <param name="flags">The flags to use for this operation.</param>
+        /// <returns>The result of LCS algorithm, based on the given parameters.</returns>
+        /// <remarks><seealso href="https://redis.io/commands/lcs"/></remarks>
+        LCSMatchResult StringLongestCommonSubsequenceWithMatches(RedisKey first, RedisKey second, long minLength = 0, CommandFlags flags = CommandFlags.None);
+
         /// <inheritdoc cref="StringSet(RedisKey, RedisValue, TimeSpan?, bool, When, CommandFlags)" />
         [Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
         bool StringSet(RedisKey key, RedisValue value, TimeSpan? expiry, When when);

src/StackExchange.Redis/Interfaces/IDatabaseAsync.cs

@@ -2723,6 +2723,46 @@ IAsyncEnumerable<SortedSetEntry> SortedSetScanAsync(RedisKey key,
         /// <remarks><seealso href="https://redis.io/commands/strlen"/></remarks>
         Task<long> StringLengthAsync(RedisKey key, CommandFlags flags = CommandFlags.None);
 
+        /// <summary>
+        /// Implements the longest common subsequence algorithm between the values at <paramref name="first"/> and <paramref name="second"/>,
+        /// returning a string containing the common sequence.
+        /// Note that this is different than the longest common string algorithm,
+        /// since matching characters in the string does not need to be contiguous.
+        /// </summary>
+        /// <param name="first">The key of the first string.</param>
+        /// <param name="second">The key of the second string.</param>
+        /// <param name="flags">The flags to use for this operation.</param>
+        /// <returns>A string (sequence of characters) of the LCS match.</returns>
+        /// <remarks><seealso href="https://redis.io/commands/lcs"/></remarks>
+        Task<string?> StringLongestCommonSubsequenceAsync(RedisKey first, RedisKey second, CommandFlags flags = CommandFlags.None);
+
+        /// <summary>
+        /// Implements the longest common subsequence algorithm between the values at <paramref name="first"/> and <paramref name="second"/>,
+        /// returning the legnth of the common sequence.
+        /// Note that this is different than the longest common string algorithm,
+        /// since matching characters in the string does not need to be contiguous.
+        /// </summary>
+        /// <param name="first">The key of the first string.</param>
+        /// <param name="second">The key of the second string.</param>
+        /// <param name="flags">The flags to use for this operation.</param>
+        /// <returns>The length of the LCS match.</returns>
+        /// <remarks><seealso href="https://redis.io/commands/lcs"/></remarks>
+        Task<long> StringLongestCommonSubsequenceLengthAsync(RedisKey first, RedisKey second, CommandFlags flags = CommandFlags.None);
+
+        /// <summary>
+        /// Implements the longest common subsequence algorithm between the values at <paramref name="first"/> and <paramref name="second"/>,
+        /// returning a list of all common sequences.
+        /// Note that this is different than the longest common string algorithm,
+        /// since matching characters in the string does not need to be contiguous.
+        /// </summary>
+        /// <param name="first">The key of the first string.</param>
+        /// <param name="second">The key of the second string.</param>
+        /// <param name="minLength">Can be used to restrict the list of matches to the ones of a given minimum length.</param>
+        /// <param name="flags">The flags to use for this operation.</param>
+        /// <returns>The result of LCS algorithm, based on the given parameters.</returns>
+        /// <remarks><seealso href="https://redis.io/commands/lcs"/></remarks>
+        Task<LCSMatchResult> StringLongestCommonSubsequenceWithMatchesAsync(RedisKey first, RedisKey second, long minLength = 0, CommandFlags flags = CommandFlags.None);
+
         /// <inheritdoc cref="StringSetAsync(RedisKey, RedisValue, TimeSpan?, bool, When, CommandFlags)" />
         [Browsable(false), EditorBrowsable(EditorBrowsableState.Never)]
         Task<bool> StringSetAsync(RedisKey key, RedisValue value, TimeSpan? expiry, When when);

src/StackExchange.Redis/KeyspaceIsolation/DatabaseWrapper.cs

@@ -299,6 +299,15 @@ public bool LockRelease(RedisKey key, RedisValue value, CommandFlags flags = Com
         public bool LockTake(RedisKey key, RedisValue value, TimeSpan expiry, CommandFlags flags = CommandFlags.None) =>
             Inner.LockTake(ToInner(key), value, expiry, flags);
 
+        public string? StringLongestCommonSubsequence(RedisKey first, RedisKey second, CommandFlags flags = CommandFlags.None) =>
+            Inner.StringLongestCommonSubsequence(ToInner(first), ToInner(second), flags);
+
+        public long StringLongestCommonSubsequenceLength(RedisKey first, RedisKey second, CommandFlags flags = CommandFlags.None) =>
+            Inner.StringLongestCommonSubsequenceLength(ToInner(first), ToInner(second), flags);
+
+        public LCSMatchResult StringLongestCommonSubsequenceWithMatches(RedisKey first, RedisKey second, long minLength = 0, CommandFlags flags = CommandFlags.None) =>
+            Inner.StringLongestCommonSubsequenceWithMatches(ToInner(first), ToInner(second), minLength, flags);
+
         public long Publish(RedisChannel channel, RedisValue message, CommandFlags flags = CommandFlags.None) =>
             Inner.Publish(ToInner(channel), message, flags);
 

src/StackExchange.Redis/KeyspaceIsolation/WrapperBase.cs

@@ -310,6 +310,15 @@ public Task<bool> LockReleaseAsync(RedisKey key, RedisValue value, CommandFlags
         public Task<bool> LockTakeAsync(RedisKey key, RedisValue value, TimeSpan expiry, CommandFlags flags = CommandFlags.None) =>
             Inner.LockTakeAsync(ToInner(key), value, expiry, flags);
 
+        public Task<string?> StringLongestCommonSubsequenceAsync(RedisKey first, RedisKey second, CommandFlags flags = CommandFlags.None) =>
+            Inner.StringLongestCommonSubsequenceAsync(ToInner(first), ToInner(second), flags);
+
+        public Task<long> StringLongestCommonSubsequenceLengthAsync(RedisKey first, RedisKey second, CommandFlags flags = CommandFlags.None) =>
+            Inner.StringLongestCommonSubsequenceLengthAsync(ToInner(first), ToInner(second), flags);
+
+        public Task<LCSMatchResult> StringLongestCommonSubsequenceWithMatchesAsync(RedisKey first, RedisKey second, long minLength = 0, CommandFlags flags = CommandFlags.None) =>
+            Inner.StringLongestCommonSubsequenceWithMatchesAsync(ToInner(first), ToInner(second), minLength, flags);
+
         public Task<long> PublishAsync(RedisChannel channel, RedisValue message, CommandFlags flags = CommandFlags.None) =>
             Inner.PublishAsync(ToInner(channel), message, flags);