Index.kt
/*
* Copyright (C) 2017 The Android Open Source Project
*
* 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 androidx.room.vo
import androidx.room.migration.bundle.BundleUtil
import androidx.room.migration.bundle.IndexBundle
private typealias IndexOrder = androidx.room.Index.Order
/**
* Represents a processed index.
*/
data class Index(
val name: String,
val unique: Boolean,
override val fields: Fields,
val orders: List<IndexOrder>
) : HasSchemaIdentity, HasFields {
companion object {
// should match the value in TableInfo.Index.DEFAULT_PREFIX
const val DEFAULT_PREFIX = "index_"
}
constructor(
name: String,
unique: Boolean,
fields: List<Field>,
orders: List<IndexOrder>
) : this(name, unique, Fields(fields), orders)
override fun getIdKey() = buildString {
append("$unique-$name-${columnNames.joinToString(",")}")
// orders was newly added; it should affect the ID only when declared.
if (orders.isNotEmpty()) {
append("-${orders.joinToString(",")}")
}
}
fun createQuery(tableName: String): String {
val indexSQL = if (unique) {
"UNIQUE INDEX"
} else {
"INDEX"
}
val columns = if (orders.isNotEmpty()) {
columnNames.mapIndexed { index, columnName -> "`$columnName` ${orders[index]}" }
} else {
columnNames.map { "`$it`" }
}.joinToString(", ")
return """
CREATE $indexSQL IF NOT EXISTS `$name`
ON `$tableName` ($columns)
""".trimIndent().replace("\n", " ")
}
fun toBundle(): IndexBundle = IndexBundle(
name, unique, columnNames, orders.map { it.name },
createQuery(BundleUtil.TABLE_NAME_PLACEHOLDER)
)
}