Added new method checkIfIndexExists(in:indexName:)

Author: denissimon

Sources/SQLiteAdapter/SQLiteAdapter.swift

@@ -51,6 +51,7 @@ public protocol SQLiteType {
     func dropTable(_ tableName: String, vacuum: Bool) throws
     func deleteAllRows(in tableName: String, vacuum: Bool, resetAutoincrement: Bool) throws
     func addIndex(to tableName: String, forColumn columnName: String, unique: Bool, order: SQLOrder) throws
+    func checkIfIndexExists(in tableName: String, indexName: String) throws -> Bool
     func dropIndex(in tableName: String, forColumn columnName: String) throws
     func beginTransaction() throws
     func endTransaction() throws
@@ -268,6 +269,15 @@ open class SQLite: SQLiteType {
         log("successfully added index \(indexName)")
     }
 
+    public func checkIfIndexExists(in tableName: String, indexName: String) throws -> Bool {
+        if let count = try? getRowCountWithCondition(sql: "SELECT count(*) FROM sqlite_schema WHERE type='index' AND tbl_name='\(tableName)' AND name='\(indexName)';", valuesToBind: nil) {
+            let result = count == 1 ? true : false
+            log("successfully checked if index \(indexName) exists: \(result)")
+            return result
+        }
+        throw SQLiteError.Other(getErrorMessage(dbPointer: dbPointer))
+    }
+    
     public func dropIndex(in tableName: String, forColumn columnName: String) throws {
         let indexName = "\(tableName)_\(columnName)_idx"
         let sql = "DROP INDEX IF EXISTS \"\(indexName)\";"