Fix part of #4044: Add AlgebraicExpressionInput classifiers

app/BUILD.bazel

@@ -189,7 +189,7 @@ VIEW_MODELS_WITH_RESOURCE_IMPORTS = [
     "src/main/java/org/oppia/android/app/onboarding/OnboardingViewModel.kt",
     "src/main/java/org/oppia/android/app/ongoingtopiclist/OngoingTopicItemViewModel.kt",
     "src/main/java/org/oppia/android/app/options/TextSizeItemViewModel.kt",
-    "src/main/java/org/oppia/android/app/parser/StringToFractionParser.kt",
+    "src/main/java/org/oppia/android/app/parser/FractionParsingUiError.kt",
     "src/main/java/org/oppia/android/app/parser/StringToNumberParser.kt",
     "src/main/java/org/oppia/android/app/parser/StringToRatioParser.kt",
     "src/main/java/org/oppia/android/app/player/state/itemviewmodel/DragDropInteractionContentViewModel.kt",
@@ -546,8 +546,8 @@ android_library(
         ":views",
         "//app/src/main/java/org/oppia/android/app/translation:app_language_activity_injector_provider",
         "//app/src/main/java/org/oppia/android/app/translation:app_language_resource_handler",
-        "//model:interaction_object_java_proto_lite",
-        "//model:thumbnail_java_proto_lite",
+        "//model/src/main/proto:interaction_object_java_proto_lite",
+        "//model/src/main/proto:thumbnail_java_proto_lite",
         "//third_party:androidx_annotation_annotation",
         "//third_party:androidx_constraintlayout_constraintlayout",
         "//third_party:androidx_core_core",
@@ -578,8 +578,8 @@ kt_android_library(
     deps = [
         ":dagger",
         "//domain/src/main/java/org/oppia/android/domain/audio:cellular_audio_dialog_controller",
-        "//model:question_java_proto_lite",
-        "//model:topic_java_proto_lite",
+        "//model/src/main/proto:question_java_proto_lite",
+        "//model/src/main/proto:topic_java_proto_lite",
         "//third_party:androidx_recyclerview_recyclerview",
     ],
 )
@@ -658,6 +658,7 @@ kt_android_library(
         "//utility/src/main/java/org/oppia/android/util/extensions:context_extensions",
         "//utility/src/main/java/org/oppia/android/util/logging/firebase:debug_event_logger",
         "//utility/src/main/java/org/oppia/android/util/logging/firebase:debug_module",
+        "//utility/src/main/java/org/oppia/android/util/math:fraction_parser",
         # TODO(#59): Remove 'debug_util_module' once we completely migrate to Bazel from Gradle as
         # we can then directly exclude debug files from the build and thus won't be requiring this module.
         "//utility/src/main/java/org/oppia/android/util/networking:debug_util_module",
@@ -686,7 +687,7 @@ android_library(
         ":view_models",
         "//app/src/main/java/org/oppia/android/app/translation:app_language_activity_injector_provider",
         "//app/src/main/java/org/oppia/android/app/translation:app_language_resource_handler",
-        "//model:thumbnail_java_proto_lite",
+        "//model/src/main/proto:thumbnail_java_proto_lite",
         "//third_party:androidx_annotation_annotation",
         "//third_party:androidx_constraintlayout_constraintlayout",
         "//third_party:androidx_lifecycle_lifecycle-livedata-core",
@@ -738,8 +739,8 @@ kt_android_library(
         "//domain/src/main/java/org/oppia/android/domain/oppialogger:startup_listener",
         "//domain/src/main/java/org/oppia/android/domain/oppialogger/exceptions:logger_module",
         "//domain/src/main/java/org/oppia/android/domain/oppialogger/loguploader:worker_module",
+        "//model/src/main/proto:arguments_java_proto_lite",
         "//domain/src/main/java/org/oppia/android/domain/profile:profile_management_controller",
-        "//model:arguments_java_proto_lite",
         "//app/src/main/java/org/oppia/android/app/testing/activity:test_activity",
         "//third_party:androidx_databinding_databinding-adapters",
         "//third_party:androidx_databinding_databinding-common",

app/src/main/java/org/oppia/android/app/activity/BUILD.bazel

@@ -75,6 +75,6 @@ kt_android_library(
         "//app:app_visibility",
     ],
     deps = [
-        "//model:profile_java_proto_lite",
+        "//model/src/main/proto:profile_java_proto_lite",
     ],
 )

app/src/main/java/org/oppia/android/app/customview/interaction/FractionInputInteractionView.kt

@@ -20,6 +20,8 @@ import org.oppia.android.app.utility.KeyboardHelper.Companion.showSoftKeyboard
 //  background="@drawable/edit_text_background"
 //  maxLength="200".
 
+// TODO(#4135): Add a dedicated test suite for this class.
+
 /** The custom EditText class for fraction input interaction view. */
 class FractionInputInteractionView @JvmOverloads constructor(
   context: Context,

app/src/main/java/org/oppia/android/app/parser/FractionParsingUiError.kt

@@ -0,0 +1,45 @@
+package org.oppia.android.app.parser
+
+import androidx.annotation.StringRes
+import org.oppia.android.R
+import org.oppia.android.app.translation.AppLanguageResourceHandler
+import org.oppia.android.util.math.FractionParser.FractionParsingError
+
+/** Enum to store the errors of [FractionInputInteractionView]. */
+enum class FractionParsingUiError(@StringRes private var error: Int?) {
+  /** Corresponds to [FractionParsingError.VALID]. */
+  VALID(error = null),
+
+  /** Corresponds to [FractionParsingError.INVALID_CHARS]. */
+  INVALID_CHARS(error = R.string.fraction_error_invalid_chars),
+
+  /** Corresponds to [FractionParsingError.INVALID_FORMAT]. */
+  INVALID_FORMAT(error = R.string.fraction_error_invalid_format),
+
+  /** Corresponds to [FractionParsingError.DIVISION_BY_ZERO]. */
+  DIVISION_BY_ZERO(error = R.string.fraction_error_divide_by_zero),
+
+  /** Corresponds to [FractionParsingError.NUMBER_TOO_LONG]. */
+  NUMBER_TOO_LONG(error = R.string.fraction_error_larger_than_seven_digits);
+
+  /**
+   * Returns the string corresponding to this error's string resources, or null if there is none.
+   */
+  fun getErrorMessageFromStringRes(resourceHandler: AppLanguageResourceHandler): String? =
+    error?.let(resourceHandler::getStringInLocale)
+
+  companion object {
+    /**
+     * Returns the [FractionParsingUiError] corresponding to the specified [FractionParsingError].
+     */
+    fun createFromParsingError(parsingError: FractionParsingError): FractionParsingUiError {
+      return when (parsingError) {
+        FractionParsingError.VALID -> VALID
+        FractionParsingError.INVALID_CHARS -> INVALID_CHARS
+        FractionParsingError.INVALID_FORMAT -> INVALID_FORMAT
+        FractionParsingError.DIVISION_BY_ZERO -> DIVISION_BY_ZERO
+        FractionParsingError.NUMBER_TOO_LONG -> NUMBER_TOO_LONG
+      }
+    }
+  }
+}

app/src/main/java/org/oppia/android/app/parser/StringToNumberParser.kt

@@ -3,7 +3,7 @@ package org.oppia.android.app.parser
 import androidx.annotation.StringRes
 import org.oppia.android.R
 import org.oppia.android.app.translation.AppLanguageResourceHandler
-import org.oppia.android.domain.util.normalizeWhitespace
+import org.oppia.android.util.extensions.normalizeWhitespace
 
 /**
  * This class contains methods that help to parse string to number, check realtime and submit time

app/src/main/java/org/oppia/android/app/parser/StringToRatioParser.kt

@@ -4,8 +4,8 @@ import androidx.annotation.StringRes
 import org.oppia.android.R
 import org.oppia.android.app.model.RatioExpression
 import org.oppia.android.app.translation.AppLanguageResourceHandler
-import org.oppia.android.domain.util.normalizeWhitespace
-import org.oppia.android.domain.util.removeWhitespace
+import org.oppia.android.util.extensions.normalizeWhitespace
+import org.oppia.android.util.extensions.removeWhitespace
 
 /**
  * Utility for parsing [RatioExpression]s from strings and validating strings can be parsed

app/src/main/java/org/oppia/android/app/player/state/itemviewmodel/FractionInteractionViewModel.kt

@@ -9,12 +9,13 @@ import org.oppia.android.app.model.Interaction
 import org.oppia.android.app.model.InteractionObject
 import org.oppia.android.app.model.UserAnswer
 import org.oppia.android.app.model.WrittenTranslationContext
-import org.oppia.android.app.parser.StringToFractionParser
+import org.oppia.android.app.parser.FractionParsingUiError
 import org.oppia.android.app.player.state.answerhandling.AnswerErrorCategory
 import org.oppia.android.app.player.state.answerhandling.InteractionAnswerErrorOrAvailabilityCheckReceiver
 import org.oppia.android.app.player.state.answerhandling.InteractionAnswerHandler
 import org.oppia.android.app.translation.AppLanguageResourceHandler
 import org.oppia.android.domain.translation.TranslationController
+import org.oppia.android.util.math.FractionParser
 
 /** [StateItemViewModel] for the fraction input interaction. */
 class FractionInteractionViewModel(
@@ -32,7 +33,7 @@ class FractionInteractionViewModel(
   var errorMessage = ObservableField<String>("")
 
   val hintText: CharSequence = deriveHintText(interaction)
-  private val stringToFractionParser: StringToFractionParser = StringToFractionParser()
+  private val fractionParser = FractionParser()
 
   init {
     val callback: Observable.OnPropertyChangedCallback =
@@ -52,7 +53,7 @@ class FractionInteractionViewModel(
     if (answerText.isNotEmpty()) {
       val answerTextString = answerText.toString()
       answer = InteractionObject.newBuilder().apply {
-        fraction = stringToFractionParser.parseFractionFromString(answerTextString)
+        fraction = fractionParser.parseFractionFromString(answerTextString)
       }.build()
       plainAnswer = answerTextString
       this.writtenTranslationContext = [email protected]
@@ -63,14 +64,18 @@ class FractionInteractionViewModel(
   override fun checkPendingAnswerError(category: AnswerErrorCategory): String? {
     if (answerText.isNotEmpty()) {
       when (category) {
-        AnswerErrorCategory.REAL_TIME ->
+        AnswerErrorCategory.REAL_TIME -> {
           pendingAnswerError =
-            stringToFractionParser.getRealTimeAnswerError(answerText.toString())
-              .getErrorMessageFromStringRes(resourceHandler)
-        AnswerErrorCategory.SUBMIT_TIME ->
+            FractionParsingUiError.createFromParsingError(
+              fractionParser.getRealTimeAnswerError(answerText.toString())
+            ).getErrorMessageFromStringRes(resourceHandler)
+        }
+        AnswerErrorCategory.SUBMIT_TIME -> {
           pendingAnswerError =
-            stringToFractionParser.getSubmitTimeError(answerText.toString())
-              .getErrorMessageFromStringRes(resourceHandler)
+            FractionParsingUiError.createFromParsingError(
+              fractionParser.getSubmitTimeError(answerText.toString())
+            ).getErrorMessageFromStringRes(resourceHandler)
+        }
       }
       errorMessage.set(pendingAnswerError)
     }

app/src/main/java/org/oppia/android/app/player/state/itemviewmodel/RatioExpressionInputInteractionViewModel.kt

@@ -16,7 +16,7 @@ import org.oppia.android.app.player.state.answerhandling.InteractionAnswerHandle
 import org.oppia.android.app.translation.AppLanguageResourceHandler
 import org.oppia.android.app.utility.toAccessibleAnswerString
 import org.oppia.android.domain.translation.TranslationController
-import org.oppia.android.domain.util.toAnswerString
+import org.oppia.android.util.math.toAnswerString
 
 /** [StateItemViewModel] for the ratio expression input interaction. */
 class RatioExpressionInputInteractionViewModel(

app/src/sharedTest/java/org/oppia/android/app/testing/InputInteractionViewTestActivityTest.kt

@@ -122,6 +122,8 @@ class InputInteractionViewTestActivityTest {
     ApplicationProvider.getApplicationContext<TestApplication>().inject(this)
   }
 
+  // TODO(#4135): Move fraction input tests to a dedicated test suite.
+
   @Test
   fun testFractionInput_withNoInput_hasCorrectPendingAnswerType() {
     val activityScenario = ActivityScenario.launch(