Add FirstMatchHighlighter

Co-authored-by: Sam Pillsworth <[email protected]>

core/src/main/scala/pink/cozydev/protosearch/highlight/FirstMatchHighlighter.scala

@@ -0,0 +1,46 @@
+/*
+ * Copyright 2022 CozyDev
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package pink.cozydev.protosearch.highlight
+
+case class FirstMatchHighlighter(
+    formatter: FragmentFormatter
+) {
+
+  val lookBackWindowSize: Int = formatter.maxSize / 2
+
+  def trim(str: String): String = {
+    val trimmed = str.trim()
+    if (trimmed.size > formatter.maxSize)
+      trimmed.take(formatter.maxSize) + "..."
+    else trimmed
+  }
+
+  def highlight(str: String, queryStr: String): String = {
+    val offset = str.indexOf(queryStr)
+    if (offset == -1)
+      trim(str)
+    else {
+      val start = Math.max(0, offset - lookBackWindowSize)
+      val nearby = str.indexWhere(c => " \n\t.".contains(c), start)
+      val slice = if (str.size < formatter.maxSize) str else str.drop(nearby)
+      val newOffset = if (str.size < formatter.maxSize) offset else offset - nearby
+      val fStr = formatter.format(slice, List(newOffset, queryStr.size))
+      trim(fStr)
+    }
+  }
+
+}

core/src/main/scala/pink/cozydev/protosearch/highlight/FragmentFormatter.scala

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2022 CozyDev
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package pink.cozydev.protosearch.highlight
 
 case class FragmentFormatter(

core/src/test/scala/pink/cozydev/protosearch/highlight/FirstMatchHighlighterSuite.scala

@@ -0,0 +1,57 @@
+/*
+ * Copyright 2022 CozyDev
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package pink.cozydev.protosearch.highlight
+
+class FirstMatchHighlighterSuite extends munit.FunSuite {
+  val formatter = FragmentFormatter(36, "<b>", "</b>")
+  val highlighter = FirstMatchHighlighter(formatter)
+
+  test("no highlight on no match") {
+    val s = "hello world"
+    val actual = highlighter.highlight(s, "cat")
+    val expected = "hello world"
+    assertEquals(actual, expected)
+  }
+
+  test("highlights simple substring") {
+    val s = "hello world"
+    val actual = highlighter.highlight(s, "world")
+    val expected = "hello <b>world</b>"
+    assertEquals(actual, expected)
+  }
+
+  test("highlights only first match") {
+    val s = "hello world, you, nice world, you"
+    val actual = highlighter.highlight(s, "world")
+    val expected = "hello <b>world</b>, you, nice world, you"
+    assertEquals(actual, expected)
+  }
+
+  test("highlights matches near end of long doc") {
+    val s = List.fill(100)("hello cat,").mkString("", " ", " world")
+    val actual = highlighter.highlight(s, "world")
+    val expected = "cat, hello cat, hello cat, <b>world</b>"
+    assertEquals(actual, expected)
+  }
+
+  test("long docs get trimmed with ellipses") {
+    val s = List.fill(100)("hello cat,").mkString("", " ", " world")
+    val actual = highlighter.highlight(s, "fake")
+    val expected = s.take(formatter.maxSize) + "..."
+    assertEquals(actual, expected)
+  }
+}

core/src/test/scala/pink/cozydev/protosearch/highlight/FragmentFormatterSuite.scala

@@ -1,3 +1,19 @@
+/*
+ * Copyright 2022 CozyDev
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
 package pink.cozydev.protosearch.highlight
 
 import munit.FunSuite