Properly add the @language annotation (thanks Him188!)

DOCUMENTATION.md

@@ -42,6 +42,8 @@ Usually, the matching process is separated in two steps:
   information on what its associated token type is
 * Match the result of the recognizer with something, usually with a token type.
 
+That is a fairly oversimplified view of the process of making a lexer in Lixy however.
+
 ### My first lexer
 
 ```kotlin

build.gradle

@@ -22,6 +22,11 @@ kotlin {
     }
 
     sourceSets {
+        all {
+            languageSettings {
+                useExperimentalAnnotation("kotlin.RequiresOptIn")
+            }
+        }
         commonMain {
             dependencies {
                 implementation kotlin('stdlib-common')

src/commonMain/kotlin/guru/zoroark/lixy/matchers/RegexPatternRecognizer.kt

@@ -1,6 +1,7 @@
 package guru.zoroark.lixy.matchers
 
 import guru.zoroark.lixy.LixyDslStateEnvironment
+import guru.zoroark.lixy.utils.Language
 
 /**
  * Create a recognizer that recognizes the given regular expression. Use
@@ -9,4 +10,4 @@ import guru.zoroark.lixy.LixyDslStateEnvironment
  *
  * @param pattern The regular expression to use in the recognizer
  */
-expect fun LixyDslStateEnvironment.matches(pattern: String): LixyTokenRecognizer
+expect fun LixyDslStateEnvironment.matches(@Language("RegExp", "", "") pattern: String): LixyTokenRecognizer

src/commonMain/kotlin/guru/zoroark/lixy/utils/Language.kt

@@ -0,0 +1,20 @@
+package guru.zoroark.lixy.utils
+
+import kotlin.annotation.AnnotationTarget.*
+
+
+/**
+ * Mapping to `org.intellij.lang.annotations.Language` on JVM, but no actual
+ * implementations on other platforms.
+ *
+ * Credits to @Him188 on GitHub, thanks!
+ */
+@Retention(AnnotationRetention.BINARY)
+@Target(FUNCTION, FIELD, VALUE_PARAMETER, LOCAL_VARIABLE, ANNOTATION_CLASS)
+@OptIn(ExperimentalMultiplatform::class)
+@OptionalExpectation
+expect annotation class Language(
+    val value: String,
+    val prefix: String, // default values aren't allowed yet
+    val suffix: String
+)

src/jvmMain/kotlin/guru/zoroark/lixy/matchers/JvmRegexRecognizer.kt

@@ -20,6 +20,5 @@ internal class RegexPatternRecognizer(private val pattern: Pattern) :
     }
 }
 
-actual fun LixyDslStateEnvironment.matches(
-    @Language("RegExp") pattern: String
-): LixyTokenRecognizer = RegexPatternRecognizer(Pattern.compile(pattern))
+actual fun LixyDslStateEnvironment.matches(pattern: String): LixyTokenRecognizer =
+    RegexPatternRecognizer(Pattern.compile(pattern))

src/jvmMain/kotlin/guru/zoroark/lixy/utils/Language.kt

@@ -0,0 +1,5 @@
+package guru.zoroark.lixy.utils
+
+import org.intellij.lang.annotations.Language
+
+actual typealias Language = Language

src/nonJvmMain/kotlin/NonJvmRegexRecognizer.kt

@@ -6,6 +6,8 @@ import guru.zoroark.lixy.LixyDslStateEnvironment
  * This version is less optimized than the JVM version due to limitations on the
  * Regex object, which does not have all of the features of the JVM's Matcher and
  * Pattern objects.
+ *
+ * Thanks to @Him188!
  */
 internal class NonJvmRegexPatternRecognizer(private val regex: Regex) :
     LixyTokenRecognizer {