Use inline class for ngrams to reduce memory footprint (#101)

pemistahl · May 16, 2022 · 8f61113 · 8f61113
1 parent 0f18387
commit 8f61113
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diff --git a/src/main/kotlin/com/github/pemistahl/lingua/internal/Ngram.kt b/src/main/kotlin/com/github/pemistahl/lingua/internal/Ngram.kt
@@ -23,8 +23,9 @@ import kotlinx.serialization.descriptors.PrimitiveSerialDescriptor
 import kotlinx.serialization.encoding.Decoder
 import kotlinx.serialization.encoding.Encoder
 
+@JvmInline
 @Serializable(with = NgramSerializer::class)
-internal data class Ngram(val value: String) : Comparable<Ngram> {
+internal value class Ngram(val value: String) : Comparable<Ngram> {
     init {
         require(value.length in 0..5) {
             "length of ngram '$value' is not in range 0..5"

diff --git a/src/test/kotlin/com/github/pemistahl/lingua/api/LanguageDetectorTest.kt b/src/test/kotlin/com/github/pemistahl/lingua/api/LanguageDetectorTest.kt
@@ -212,17 +212,17 @@ class LanguageDetectorTest {
     // ngram probability lookup
 
     private fun ngramProbabilityProvider() = listOf(
-        arguments(ENGLISH, Ngram("a"), 0.01),
-        arguments(ENGLISH, Ngram("lt"), 0.12),
-        arguments(ENGLISH, Ngram("ter"), 0.21),
-        arguments(ENGLISH, Ngram("alte"), 0.25),
-        arguments(ENGLISH, Ngram("alter"), 0.29),
-
-        arguments(GERMAN, Ngram("t"), 0.08),
-        arguments(GERMAN, Ngram("er"), 0.18),
-        arguments(GERMAN, Ngram("alt"), 0.22),
-        arguments(GERMAN, Ngram("lter"), 0.28),
-        arguments(GERMAN, Ngram("alter"), 0.30)
+        arguments(ENGLISH, "a", 0.01),
+        arguments(ENGLISH, "lt", 0.12),
+        arguments(ENGLISH, "ter", 0.21),
+        arguments(ENGLISH, "alte", 0.25),
+        arguments(ENGLISH, "alter", 0.29),
+
+        arguments(GERMAN, "t", 0.08),
+        arguments(GERMAN, "er", 0.18),
+        arguments(GERMAN, "alt", 0.22),
+        arguments(GERMAN, "lter", 0.28),
+        arguments(GERMAN, "alter", 0.30)
     )
 
     @ParameterizedTest