Fixed nested test coverage

Signed-off-by: Guian Gumpac <guian.gumpac@improving.com>

core/src/main/java/org/opensearch/sql/datasource/model/EmptyDataSourceService.java

@@ -0,0 +1,89 @@
+package org.opensearch.sql.datasource.model;
+
+import com.google.common.collect.ImmutableMap;
+import org.opensearch.sql.data.type.ExprType;
+import org.opensearch.sql.datasource.DataSourceService;
+import org.opensearch.sql.planner.logical.LogicalPlan;
+import org.opensearch.sql.planner.physical.PhysicalPlan;
+import org.opensearch.sql.storage.StorageEngine;
+import org.opensearch.sql.storage.Table;
+
+import java.util.Map;
+import java.util.Set;
+
+import static org.opensearch.sql.analysis.DataSourceSchemaIdentifierNameResolver.DEFAULT_DATASOURCE_NAME;
+import static org.opensearch.sql.data.type.ExprCoreType.STRING;
+
+public class EmptyDataSourceService {
+  private static DataSourceService emptyDataSourceService = new DataSourceService() {
+    @Override
+    public DataSource getDataSource(String dataSourceName) {
+      return new DataSource(DEFAULT_DATASOURCE_NAME, DataSourceType.OPENSEARCH, storageEngine());
+    }
+
+    @Override
+    public Set<DataSourceMetadata> getDataSourceMetadata(boolean isDefaultDataSourceRequired) {
+      return Set.of();
+    }
+
+    @Override
+    public DataSourceMetadata getDataSourceMetadata(String name) {
+      return null;
+    }
+
+    @Override
+    public void createDataSource(DataSourceMetadata metadata) {
+
+    }
+
+    @Override
+    public void updateDataSource(DataSourceMetadata dataSourceMetadata) {
+
+    }
+
+    @Override
+    public void deleteDataSource(String dataSourceName) {
+
+    }
+
+    @Override
+    public Boolean dataSourceExists(String dataSourceName) {
+      return null;
+    }
+  };
+
+  private static StorageEngine storageEngine() {
+    Table table =
+        new Table() {
+          @Override
+          public boolean exists() {
+            return true;
+          }
+
+          @Override
+          public void create(Map<String, ExprType> schema) {
+            throw new UnsupportedOperationException("Create table is not supported");
+          }
+
+          @Override
+          public Map<String, ExprType> getFieldTypes() {
+            return null;
+          }
+
+          @Override
+          public PhysicalPlan implement(LogicalPlan plan) {
+            throw new UnsupportedOperationException();
+          }
+
+          public Map<String, ExprType> getReservedFieldTypes() {
+            return ImmutableMap.of("_test", STRING);
+          }
+        };
+    return (dataSourceSchemaName, tableName) -> table;
+  }
+
+
+  public static DataSourceService getEmptyDataSourceService() {
+    return emptyDataSourceService;
+  }
+}

core/src/main/java/org/opensearch/sql/expression/DSL.java

@@ -25,6 +25,7 @@
 import org.opensearch.sql.expression.parse.RegexExpression;
 import org.opensearch.sql.expression.span.SpanExpression;
 import org.opensearch.sql.expression.window.ranking.RankingWindowFunction;
+import static org.opensearch.sql.datasource.model.EmptyDataSourceService.getEmptyDataSourceService;
 
 public class DSL {
 
@@ -615,6 +616,10 @@ public static FunctionExpression xor(Expression... expressions) {
     return compile(FunctionProperties.None, BuiltinFunctionName.XOR, expressions);
   }
 
+  public static FunctionExpression nested(Expression... expressions) {
+    return compile(FunctionProperties.None, BuiltinFunctionName.NESTED, expressions);
+  }
+
   public static FunctionExpression not(Expression... expressions) {
     return compile(FunctionProperties.None, BuiltinFunctionName.NOT, expressions);
   }
@@ -823,6 +828,10 @@ public static FunctionExpression typeof(Expression value) {
     return compile(FunctionProperties.None, BuiltinFunctionName.TYPEOF, value);
   }
 
+  public static FunctionExpression match_phrase_prefix(Expression... args) {
+    return compile(FunctionProperties.None, BuiltinFunctionName.MATCH_PHRASE_PREFIX, args);
+  }
+
   public static FunctionExpression now(FunctionProperties functionProperties, Expression... args) {
     return compile(functionProperties, BuiltinFunctionName.NOW, args);
   }
@@ -905,7 +914,7 @@ public static FunctionExpression utc_timestamp(
   private static <T extends FunctionImplementation> T compile(
       FunctionProperties functionProperties, BuiltinFunctionName bfn, Expression... args) {
     return (T)
-        BuiltinFunctionRepository.getInstance(null)
+        BuiltinFunctionRepository.getInstance(getEmptyDataSourceService())
             .compile(functionProperties, bfn.getName(), Arrays.asList(args));
   }
 }

core/src/main/java/org/opensearch/sql/expression/function/BuiltinFunctionRepository.java

@@ -67,8 +67,8 @@ public class BuiltinFunctionRepository {
    * @return singleton instance
    */
   public static synchronized BuiltinFunctionRepository getInstance(DataSourceService dataSourceService) {
-    // Create hash code for tests with dataSourceService as null
-    int dataSourceServiceHash = dataSourceService == null ? 0 : dataSourceService.hashCode();
+    // TODO: get hashCode of dataSourceMetadata
+    int dataSourceServiceHash = dataSourceService.hashCode();
 
     // Creates new Repository for every dataSourceService
     if (!instance.containsKey(dataSourceServiceHash)) {
@@ -86,15 +86,15 @@ public static synchronized BuiltinFunctionRepository getInstance(DataSourceServi
       TextFunction.register(repository);
       TypeCastOperator.register(repository);
       SystemFunctions.register(repository);
-
-      if (dataSourceService != null) {
-        for (DataSourceMetadata metadata : dataSourceService.getDataSourceMetadata(true)) {
-          dataSourceService
-              .getDataSource(metadata.getName())
-              .getStorageEngine()
-              .getFunctions()
-              .forEach(repository::register);
-        }
+      // Temporary as part of https://github.com/opensearch-project/sql/issues/811
+      // TODO: remove this resolver when Analyzers are moved to opensearch module
+      repository.register(new NestedFunctionResolver());
+
+      for (DataSourceMetadata metadata : dataSourceService.getDataSourceMetadata(true)) {
+        dataSourceService
+            .getDataSource(metadata.getName())
+            .getStorageEngine().getFunctions().
+            forEach(function -> repository.register(function));
       }
       instance.put(dataSourceServiceHash, repository);
     }

core/src/main/java/org/opensearch/sql/expression/function/NestedFunctionResolver.java

@@ -0,0 +1,37 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.expression.function;
+
+import org.apache.commons.lang3.tuple.Pair;
+import org.opensearch.sql.data.model.ExprValue;
+import org.opensearch.sql.data.type.ExprType;
+import org.opensearch.sql.expression.Expression;
+import org.opensearch.sql.expression.FunctionExpression;
+import org.opensearch.sql.expression.env.Environment;
+
+public class NestedFunctionResolver implements FunctionResolver{
+  @Override
+  public Pair<FunctionSignature, FunctionBuilder> resolve(FunctionSignature unresolvedSignature) {
+    return Pair.of(unresolvedSignature,
+        (functionProperties, arguments) ->
+            new FunctionExpression(BuiltinFunctionName.NESTED.getName(), arguments) {
+              @Override
+              public ExprValue valueOf(Environment<Expression, ExprValue> valueEnv) {
+                return valueEnv.resolve(getArguments().get(0));
+              }
+
+              @Override
+              public ExprType type() {
+                return getArguments().get(0).type();
+              }
+            });
+  }
+
+  @Override
+  public FunctionName getFunctionName() {
+    return BuiltinFunctionName.NESTED.getName();
+  }
+}