Added cached implementation (#2)

Author: chermenin

src/main/kotlin/ru/chermenin/ua/CachedUserAgentParser.kt

@@ -0,0 +1,36 @@
+package ru.chermenin.ua
+
+/**
+ * Implementation of the parser with cached values.
+ *
+ * @param initialEntries initial size of the cache
+ * @param maxEntries max count of entries in the cache
+ */
+class CachedUserAgentParser(initialEntries: Int = 1000, maxEntries: Int = 5000) {
+
+    private val cache = LRUCache<String, UserAgent>(initialEntries, maxEntries)
+
+    /**
+     * Method to parse user agent string and return [UserAgent] object.
+     *
+     * @param userAgentString user agent string to parse
+     * @return [UserAgent] object for the defined string
+     */
+    fun parse(userAgentString: String): UserAgent {
+        return cache.getOrPut(userAgentString) { UserAgent.parse(userAgentString) }
+    }
+}
+
+/**
+ * Simple implementation of LRU cache class.
+ *
+ * @param initialEntries initial size of the cache
+ * @param maxEntries max count of entries in the cache
+ */
+private class LRUCache<K, V>(private val initialEntries: Int, private val maxEntries: Int) :
+    LinkedHashMap<K, V>(initialEntries, 0.8f, true) {
+
+    override fun removeEldestEntry(eldest: Map.Entry<K, V>?): Boolean {
+        return size > maxEntries
+    }
+}

src/main/kotlin/ru/chermenin/ua/UserAgent.kt

@@ -99,4 +99,24 @@ class UserAgent private constructor(private val userAgentString: String) {
     override fun toString(): String {
         return "$device / $os / $browser"
     }
+
+    override fun equals(other: Any?): Boolean {
+        if (this === other) return true
+        if (javaClass != other?.javaClass) return false
+
+        other as UserAgent
+
+        if (os != other.os) return false
+        if (browser != other.browser) return false
+        if (device != other.device) return false
+
+        return true
+    }
+
+    override fun hashCode(): Int {
+        var result = os.hashCode()
+        result = 31 * result + browser.hashCode()
+        result = 31 * result + (device.hashCode())
+        return result
+    }
 }

src/test/kotlin/ru/chermenin/ua/CachedUserAgentParserTest.kt

@@ -0,0 +1,33 @@
+package ru.chermenin.ua
+
+import org.junit.Test
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class CachedUserAgentParserTest {
+
+    private val iPhoneString = "Mozilla/5.0 (iPhone; CPU iPhone OS 5_1 like Mac OS X) AppleWebKit/534.46 (KHTML, like Gecko) Version/5.1 Mobile/9B179 Safari/7534.48.3"
+    private val iPadString = "Mozilla/5.0(iPad; U; CPU iPhone OS 3_2 like Mac OS X; en-us) AppleWebKit/531.21.10 (KHTML, like Gecko) Version/4.0.4 Mobile/7B314 Safari/531.21.10"
+    private val galaxyTabString = "Mozilla/5.0 (Linux; U; Android 2.2; en-us; SCH-I800 Build/FROYO) AppleWebKit/533.1 (KHTML, like Gecko) Version/4.0 Mobile Safari/533.1"
+    private val galaxyS3String = "Mozilla/5.0 (Linux; U; Android 4.0.4; en-gb; GT-I9300 Build/IMM76D) AppleWebKit/534.30 (KHTML, like Gecko) Version/4.0 Mobile Safari/534.30"
+
+    @Test
+    fun testCachedParser() {
+        val parser = CachedUserAgentParser(1, 3)
+
+        val iPhone = parser.parse(iPhoneString)
+        val iPad = parser.parse(iPadString)
+        val galaxyTab = parser.parse(galaxyTabString)
+
+        assertTrue("iPhone UA object must be the same") { iPhone === parser.parse(iPhoneString) }
+        assertTrue("iPad UA object must be the same") { iPad === parser.parse(iPadString) }
+        assertTrue("galaxyTab UA object must be the same") { galaxyTab === parser.parse(galaxyTabString) }
+
+        val galaxyS3 = parser.parse(galaxyS3String)
+
+        assertTrue("iPad UA object must be the same") { iPad === parser.parse(iPadString) }
+        assertTrue("galaxyTab UA object must be the same") { galaxyTab === parser.parse(galaxyTabString) }
+        assertTrue("galaxyS3 UA object must be the same") { galaxyS3 === parser.parse(galaxyS3String) }
+        assertFalse("iPhone UA object already must not be the same") { iPhone === parser.parse(iPhoneString) }
+    }
+}