Improve app result ranking

core/base/src/main/java/de/mm20/launcher2/licenses/OpenSourceLicenses.kt

@@ -220,4 +220,12 @@ val OpenSourceLicenses = arrayOf(
         url = "https://github.com/woheller69/AndroidAddressFormatter",
         copyrightNote = "Copyright (c) 2022 woheller69",
     ),
+    OpenSourceLibrary(
+        name = "String Similarity for Kotlin",
+        description = "A library that implements various measures of string similarity and distance.",
+        licenseName = R.string.mit_license_name,
+        licenseText = R.raw.license_mit,
+        url = "https://github.com/aallam/string-similarity-kotlin",
+        copyrightNote = "Copyright (c) 2023 Mouaad Aallam",
+    ),
 )

core/base/src/main/java/de/mm20/launcher2/search/ResultScore.kt

@@ -0,0 +1,94 @@
+package de.mm20.launcher2.search
+
+import com.aallam.similarity.JaroWinkler
+import de.mm20.launcher2.ktx.normalize
+
+@JvmInline
+value class ResultScore private constructor(private val packed: Long) : Comparable<ResultScore> {
+    constructor(
+        isPrefix: Boolean,
+        isSubstring: Boolean,
+        isPrimary: Boolean,
+        similarity: Float,
+    ) : this(
+        (similarity.toRawBits().toLong()) or
+                (if (isPrefix) (1L shl 32) else 0) or
+                (if (isSubstring) (1L shl 33) else 0) or
+                (if (isPrimary) (1L shl 34) else 0)
+    )
+
+    /**
+     * Whether the query is a literal prefix of the result.
+     */
+    val isPrefix: Boolean
+        get() = (packed and (1L shl 32)) != 0L
+
+    /**
+     * Whether the query is a substring of the result.
+     */
+    val isSubstring: Boolean
+        get() = (packed and (1L shl 33)) != 0L
+
+    /**
+     * Whether the query was matched against a primary field.
+     */
+    val isPrimary: Boolean
+        get() = (packed and (1L shl 34)) != 0L
+
+    /**
+     * The Jaro-Winkler similarity between the query and the result.
+     */
+    val similarity: Float
+        get() = Float.fromBits((packed and 0xffffffffL).toInt())
+
+    /**
+     * A total score for the result, combining the similarity with additional factors.
+     */
+    val score: Float
+        get() = (similarity + (if (isPrefix) 0.8f else 0f) + (if (isSubstring) 0.8f else 0f)) * (if (isPrimary) 1f else 0.5f)
+
+    override fun compareTo(other: ResultScore): Int {
+        return score.compareTo(other.score)
+    }
+
+    companion object {
+        operator fun invoke(
+            query: String,
+            primaryFields: Iterable<String> = emptyList(),
+            secondaryFields: Iterable<String> = emptyList(),
+        ): ResultScore {
+            val normalizedQuery = query.normalize()
+            val jaroWinkler = JaroWinkler()
+            val bestPrimaryScore = primaryFields.maxOfOrNull {
+                val normalizedTerm = it.normalize()
+                val sim = jaroWinkler.similarity(normalizedQuery, normalizedTerm).toFloat()
+                ResultScore(
+                    isPrefix = normalizedTerm.startsWith(normalizedQuery),
+                    isSubstring = normalizedQuery in normalizedTerm,
+                    isPrimary = true,
+                    similarity = sim
+                )
+            } ?: Zero
+            val bestSecondaryScore = secondaryFields.maxOfOrNull {
+                val normalizedTerm = it.normalize()
+                val sim = jaroWinkler.similarity(normalizedQuery, normalizedTerm).toFloat()
+                ResultScore(
+                    isPrefix = normalizedTerm.startsWith(normalizedQuery),
+                    isSubstring = normalizedQuery in normalizedTerm,
+                    isPrimary = false,
+                    similarity = sim
+                )
+            } ?: Zero
+
+            return maxOf(bestPrimaryScore, bestSecondaryScore)
+        }
+
+        val Zero = ResultScore(
+            isPrefix = false,
+            isSubstring = false,
+            isPrimary = false,
+            similarity = 0f
+        )
+    }
+
+}

core/base/src/main/java/de/mm20/launcher2/search/Searchable.kt

@@ -2,4 +2,7 @@ package de.mm20.launcher2.search
 
 import kotlinx.coroutines.Deferred
 
-interface Searchable
+interface Searchable {
+    val score: ResultScore
+        get() = ResultScore.Zero
+}