Update reader APIs

ion-schema/src/main/kotlin/com/amazon/ionschema/reader/IonSchemaReader.kt

@@ -1,18 +1,20 @@
 package com.amazon.ionschema.reader
 
+import com.amazon.ion.IonSymbol
 import com.amazon.ion.IonValue
+import com.amazon.ionschema.IonSchemaVersion
 import com.amazon.ionschema.model.ExperimentalIonSchemaModel
-import com.amazon.ionschema.model.NamedTypeDefinition
 import com.amazon.ionschema.model.SchemaDocument
-import com.amazon.ionschema.model.TypeDefinition
+import com.amazon.ionschema.reader.internal.IonSchemaReaderV2_0
 import com.amazon.ionschema.reader.internal.ReadError
+import com.amazon.ionschema.reader.internal.VersionedIonSchemaReader
 import com.amazon.ionschema.util.IonSchemaResult
 
 /**
  * Reads IonValues into the Ion Schema model.
  */
 @ExperimentalIonSchemaModel
-interface IonSchemaReader {
+object IonSchemaReader {
     /**
      * Attempts to read a [SchemaDocument]. Returns an [IonSchemaResult] containing either a [SchemaDocument] or a list
      * of [ReadError]s that were encountered.
@@ -21,44 +23,31 @@ interface IonSchemaReader {
      * the given Ion. Reporting all errors is a best-effort attempt because the presence of one error can mask other
      * errors.
      */
-    fun readSchema(document: Iterable<IonValue>, failFast: Boolean = false): IonSchemaResult<SchemaDocument, List<ReadError>>
+    @JvmStatic
+    @JvmOverloads
+    fun readSchema(document: Iterable<IonValue>, failFast: Boolean = false): IonSchemaResult<SchemaDocument, List<ReadError>> {
+        val maybeVersion = document
+            .firstOrNull {
+                (it is IonSymbol && !it.isNullValue && IonSchemaVersion.fromIonSymbolOrNull(it) != null) ||
+                    it.hasTypeAnnotation("schema_header") ||
+                    it.hasTypeAnnotation("schema_footer") ||
+                    it.hasTypeAnnotation("type")
+            }
+
+        val version = maybeVersion
+            ?.let { if (it is IonSymbol) IonSchemaVersion.fromIonSymbolOrNull(it) else null }
+            ?: IonSchemaVersion.v1_0
+
+        val delegate: VersionedIonSchemaReader = when (version) {
+            IonSchemaVersion.v1_0 -> TODO("IonSchemaReader does not support Ion Schema 1.0 yet.")
+            IonSchemaVersion.v2_0 -> IonSchemaReaderV2_0
+        }
+        return delegate.readSchema(document, failFast)
+    }
 
     /**
      * Reads a [SchemaDocument], throwing an [InvalidSchemaException][com.amazon.ionschema.InvalidSchemaException]
      * if the Ion value is not a valid Ion Schema Language schema document.
      */
     fun readSchemaOrThrow(document: List<IonValue>) = readSchema(document, true).unwrap()
-
-    /**
-     * Reads an orphaned [TypeDefinition]—that is an anonymous type definition that does not belong to any schema.
-     * Returns an [IonSchemaResult] containing either a [TypeDefinition] or a list of [ReadError]s that were encountered.
-     *
-     * If [failFast] is true, returns once a single error has been detected. Otherwise, attempts to report all errors in
-     * the given Ion. Reporting all errors is a best-effort attempt because the presence of one error can mask other
-     * errors.
-     */
-    fun readType(ion: IonValue, failFast: Boolean = false): IonSchemaResult<TypeDefinition, List<ReadError>>
-
-    /**
-     * Reads an orphaned [TypeDefinition]—that is an anonymous type definition that does not belong to any schema—
-     * throwing an [InvalidSchemaException][com.amazon.ionschema.InvalidSchemaException] if the Ion value is not a valid
-     * Ion Schema type definition.
-     */
-    fun readTypeOrThrow(ion: IonValue) = readType(ion, true).unwrap()
-
-    /**
-     * Reads a [NamedTypeDefinition]. Returns an [IonSchemaResult] containing either a [NamedTypeDefinition] or a list
-     * of [ReadError]s that were encountered.
-     *
-     * If [failFast] is true, returns once a single error has been detected. Otherwise, attempts to report all errors in
-     * the given Ion. Reporting all errors is a best-effort attempt because the presence of one error can mask other
-     * errors.
-     */
-    fun readNamedType(ion: IonValue, failFast: Boolean = false): IonSchemaResult<NamedTypeDefinition, List<ReadError>>
-
-    /**
-     * Reads a [NamedTypeDefinition], throwing an [InvalidSchemaException][com.amazon.ionschema.InvalidSchemaException]
-     * if the Ion value is not a valid Ion Schema named type definition.
-     */
-    fun readNamedTypeOrThrow(ion: IonValue) = readNamedType(ion, true).unwrap()
 }

ion-schema/src/main/kotlin/com/amazon/ionschema/reader/IonSchemaReaderV2_0.kt → ion-schema/src/main/kotlin/com/amazon/ionschema/reader/internal/IonSchemaReaderV2_0.kt

@@ -1,4 +1,7 @@
-package com.amazon.ionschema.reader
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package com.amazon.ionschema.reader.internal
 
 import com.amazon.ion.IonValue
 import com.amazon.ionschema.InvalidSchemaException
@@ -9,20 +12,10 @@ import com.amazon.ionschema.model.ExperimentalIonSchemaModel
 import com.amazon.ionschema.model.NamedTypeDefinition
 import com.amazon.ionschema.model.SchemaDocument
 import com.amazon.ionschema.model.TypeDefinition
-import com.amazon.ionschema.reader.internal.FooterReader
-import com.amazon.ionschema.reader.internal.HeaderReader
-import com.amazon.ionschema.reader.internal.ReadError
-import com.amazon.ionschema.reader.internal.ReaderContext
-import com.amazon.ionschema.reader.internal.TypeReaderV2_0
-import com.amazon.ionschema.reader.internal.isFooter
-import com.amazon.ionschema.reader.internal.isHeader
-import com.amazon.ionschema.reader.internal.isTopLevelOpenContent
-import com.amazon.ionschema.reader.internal.isType
-import com.amazon.ionschema.reader.internal.readCatching
 import com.amazon.ionschema.util.IonSchemaResult
 
 @OptIn(ExperimentalIonSchemaModel::class)
-class IonSchemaReaderV2_0 : IonSchemaReader {
+internal object IonSchemaReaderV2_0 : VersionedIonSchemaReader {
     private val typeReader = TypeReaderV2_0()
     private val headerReader = HeaderReader(IonSchemaVersion.v2_0)
     private val footerReader = FooterReader { it in userReservedFields.footer || !IonSchema_2_0.RESERVED_WORDS_REGEX.matches(it) }

ion-schema/src/main/kotlin/com/amazon/ionschema/reader/internal/VersionedIonSchemaReader.kt

@@ -0,0 +1,66 @@
+// Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+// SPDX-License-Identifier: Apache-2.0
+
+package com.amazon.ionschema.reader.internal
+
+import com.amazon.ion.IonValue
+import com.amazon.ionschema.model.ExperimentalIonSchemaModel
+import com.amazon.ionschema.model.NamedTypeDefinition
+import com.amazon.ionschema.model.SchemaDocument
+import com.amazon.ionschema.model.TypeDefinition
+import com.amazon.ionschema.util.IonSchemaResult
+
+/**
+ * Reads IonValues into the Ion Schema model.
+ */
+@ExperimentalIonSchemaModel
+interface VersionedIonSchemaReader {
+    /**
+     * Attempts to read a [SchemaDocument]. Returns an [IonSchemaResult] containing either a [SchemaDocument] or a list
+     * of [ReadError]s that were encountered.
+     *
+     * If [failFast] is true, returns once a single error has been detected. Otherwise, attempts to report all errors in
+     * the given Ion. Reporting all errors is a best-effort attempt because the presence of one error can mask other
+     * errors.
+     */
+    fun readSchema(document: Iterable<IonValue>, failFast: Boolean = false): IonSchemaResult<SchemaDocument, List<ReadError>>
+
+    /**
+     * Reads a [SchemaDocument], throwing an [InvalidSchemaException][com.amazon.ionschema.InvalidSchemaException]
+     * if the Ion value is not a valid Ion Schema Language schema document.
+     */
+    fun readSchemaOrThrow(document: List<IonValue>) = readSchema(document, true).unwrap()
+
+    /**
+     * Reads an orphaned [TypeDefinition]—that is an anonymous type definition that does not belong to any schema.
+     * Returns an [IonSchemaResult] containing either a [TypeDefinition] or a list of [ReadError]s that were encountered.
+     *
+     * If [failFast] is true, returns once a single error has been detected. Otherwise, attempts to report all errors in
+     * the given Ion. Reporting all errors is a best-effort attempt because the presence of one error can mask other
+     * errors.
+     */
+    fun readType(ion: IonValue, failFast: Boolean = false): IonSchemaResult<TypeDefinition, List<ReadError>>
+
+    /**
+     * Reads an orphaned [TypeDefinition]—that is an anonymous type definition that does not belong to any schema—
+     * throwing an [InvalidSchemaException][com.amazon.ionschema.InvalidSchemaException] if the Ion value is not a valid
+     * Ion Schema type definition.
+     */
+    fun readTypeOrThrow(ion: IonValue) = readType(ion, true).unwrap()
+
+    /**
+     * Reads a [NamedTypeDefinition]. Returns an [IonSchemaResult] containing either a [NamedTypeDefinition] or a list
+     * of [ReadError]s that were encountered.
+     *
+     * If [failFast] is true, returns once a single error has been detected. Otherwise, attempts to report all errors in
+     * the given Ion. Reporting all errors is a best-effort attempt because the presence of one error can mask other
+     * errors.
+     */
+    fun readNamedType(ion: IonValue, failFast: Boolean = false): IonSchemaResult<NamedTypeDefinition, List<ReadError>>
+
+    /**
+     * Reads a [NamedTypeDefinition], throwing an [InvalidSchemaException][com.amazon.ionschema.InvalidSchemaException]
+     * if the Ion value is not a valid Ion Schema named type definition.
+     */
+    fun readNamedTypeOrThrow(ion: IonValue) = readNamedType(ion, true).unwrap()
+}

ion-schema/src/main/kotlin/com/amazon/ionschema/util/SchemaSymbolsUtil.kt

@@ -13,7 +13,7 @@ import com.amazon.ionschema.model.SchemaDocument
 import com.amazon.ionschema.model.TypeArgument
 import com.amazon.ionschema.model.TypeDefinition
 import com.amazon.ionschema.model.ValidValue
-import com.amazon.ionschema.reader.IonSchemaReaderV2_0
+import com.amazon.ionschema.reader.internal.IonSchemaReaderV2_0
 import java.io.File
 
 /**
@@ -66,7 +66,7 @@ object SchemaSymbolsUtil {
     @JvmStatic
     @OptIn(ExperimentalIonSchemaModel::class)
     fun getSymbolsTextForSchema(schema: Schema): Set<String> {
-        return IonSchemaReaderV2_0().readSchemaOrThrow(schema.isl).getAllSymbolsText()
+        return IonSchemaReaderV2_0.readSchemaOrThrow(schema.isl).getAllSymbolsText()
     }
 
     /**

ion-schema/src/test/kotlin/com/amazon/ionschema/reader/IonSchemaReaderV2_0Tests.kt

@@ -14,6 +14,7 @@ import com.amazon.ionschema.model.SchemaHeader
 import com.amazon.ionschema.model.TypeArgument
 import com.amazon.ionschema.model.TypeDefinition
 import com.amazon.ionschema.model.UserReservedFields
+import com.amazon.ionschema.reader.internal.IonSchemaReaderV2_0
 import com.amazon.ionschema.util.emptyBag
 import org.junit.jupiter.api.Assertions.assertTrue
 import org.junit.jupiter.api.Test
@@ -24,7 +25,7 @@ import kotlin.test.assertEquals
 class IonSchemaReaderV2_0Tests {
 
     val ION = IonSystemBuilder.standard().build()
-    val reader = IonSchemaReaderV2_0()
+    private val reader = IonSchemaReaderV2_0
     val typeTextWithMultipleErrors = """
             type::{
               valid_values: until_recently::["Ni!"],

ion-schema/src/test/kotlin/com/amazon/ionschema/reader/ReaderTests.kt

@@ -11,6 +11,8 @@ import com.amazon.ionschema.TestFactory
 import com.amazon.ionschema.asDocument
 import com.amazon.ionschema.getTextField
 import com.amazon.ionschema.model.ExperimentalIonSchemaModel
+import com.amazon.ionschema.reader.internal.IonSchemaReaderV2_0
+import com.amazon.ionschema.reader.internal.VersionedIonSchemaReader
 import org.junit.jupiter.api.DynamicContainer
 import org.junit.jupiter.api.DynamicNode
 import org.junit.jupiter.api.DynamicTest
@@ -44,15 +46,15 @@ class ReaderTests {
     @Nested
     inner class IonSchema_2_0 : TestFactory by ReaderTestsRunner(
         version = IonSchemaVersion.v2_0,
-        reader = IonSchemaReaderV2_0(),
+        reader = IonSchemaReaderV2_0,
         testNameFilter = { it !in ISL_2_0_EXPECTED_TO_NOT_PASS }
     )
 }
 
 @ExperimentalIonSchemaModel
 class ReaderTestsRunner(
     val version: IonSchemaVersion,
-    val reader: IonSchemaReader,
+    val reader: VersionedIonSchemaReader,
     additionalFileFilter: (File) -> Boolean = { true },
     private val testNameFilter: (String) -> Boolean = { true },
 ) : TestFactory {

ion-schema/src/test/kotlin/com/amazon/ionschema/writer/WriterTests.kt

@@ -14,8 +14,8 @@ import com.amazon.ionschema.TestFactory
 import com.amazon.ionschema.asDocument
 import com.amazon.ionschema.getTextField
 import com.amazon.ionschema.model.ExperimentalIonSchemaModel
-import com.amazon.ionschema.reader.IonSchemaReader
-import com.amazon.ionschema.reader.IonSchemaReaderV2_0
+import com.amazon.ionschema.reader.internal.IonSchemaReaderV2_0
+import com.amazon.ionschema.reader.internal.VersionedIonSchemaReader
 import com.amazon.ionschema.writer.internal.IonSchemaWriterV2_0
 import com.amazon.ionschema.writer.internal.VersionedIonSchemaWriter
 import org.junit.jupiter.api.Assertions.assertEquals
@@ -32,15 +32,15 @@ class WriterTests {
     @Nested
     inner class IonSchema_2_0 : TestFactory by WriterTestsRunner(
         version = IonSchemaVersion.v2_0,
-        reader = IonSchemaReaderV2_0(),
+        reader = IonSchemaReaderV2_0,
         writer = IonSchemaWriterV2_0,
     )
 }
 
 @ExperimentalIonSchemaModel
 class WriterTestsRunner(
     val version: IonSchemaVersion,
-    val reader: IonSchemaReader,
+    val reader: VersionedIonSchemaReader,
     val writer: VersionedIonSchemaWriter,
     additionalFileFilter: (File) -> Boolean = { true },
     private val testNameFilter: (String) -> Boolean = { true },