1 files changed, 269 insertions, 0 deletions
diff --git a/exec/java-exec/src/main/java/org/apache/drill/exec/record/metadata/schema/parser/SchemaVisitor.java b/exec/java-exec/src/main/java/org/apache/drill/exec/record/metadata/schema/parser/SchemaVisitor.java
new file mode 100644
index 000000000..7c7663a71
--- /dev/null
+++ b/exec/java-exec/src/main/java/org/apache/drill/exec/record/metadata/schema/parser/SchemaVisitor.java
@@ -0,0 +1,269 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you 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 org.apache.drill.exec.record.metadata.schema.parser;
+
+import org.antlr.v4.runtime.tree.TerminalNode;
+import org.apache.drill.common.types.TypeProtos;
+import org.apache.drill.common.types.Types;
+import org.apache.drill.exec.record.MaterializedField;
+import org.apache.drill.exec.record.metadata.ColumnMetadata;
+import org.apache.drill.exec.record.metadata.MapBuilder;
+import org.apache.drill.exec.record.metadata.MetadataUtils;
+import org.apache.drill.exec.record.metadata.RepeatedListBuilder;
+import org.apache.drill.exec.record.metadata.TupleMetadata;
+import org.apache.drill.exec.record.metadata.TupleSchema;
+
+import java.util.List;
+
+/**
+ * Visits schema and stores metadata about its columns into {@link TupleMetadata} class.
+ */
+public class SchemaVisitor extends SchemaParserBaseVisitor<TupleMetadata> {
+
+  @Override
+  public TupleMetadata visitSchema(SchemaParser.SchemaContext ctx) {
+    return visitColumns(ctx.columns());
+  }
+
+  @Override
+  public TupleMetadata visitColumns(SchemaParser.ColumnsContext ctx) {
+    TupleMetadata schema = new TupleSchema();
+    ColumnVisitor columnVisitor = new ColumnVisitor();
+    ctx.column().forEach(
+      c -> schema.addColumn(c.accept(columnVisitor))
+    );
+    return schema;
+  }
+
+  /**
+   * Visits various types of columns (primitive, map, array) and stores their metadata
+   * into {@link ColumnMetadata} class.
+   */
+  public static class ColumnVisitor extends SchemaParserBaseVisitor<ColumnMetadata> {
+
+    @Override
+    public ColumnMetadata visitPrimitive_column(SchemaParser.Primitive_columnContext ctx) {
+      String name = ctx.column_id().accept(new IdVisitor());
+      TypeProtos.DataMode mode = ctx.nullability() == null ? TypeProtos.DataMode.OPTIONAL : TypeProtos.DataMode.REQUIRED;
+      return ctx.simple_type().accept(new TypeVisitor(name, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitSimple_array_column(SchemaParser.Simple_array_columnContext ctx) {
+      String name = ctx.column_id().accept(new IdVisitor());
+      return ctx.simple_array_type().accept(new ArrayTypeVisitor(name));
+    }
+
+    @Override
+    public ColumnMetadata visitMap_column(SchemaParser.Map_columnContext ctx) {
+      String name = ctx.column_id().accept(new IdVisitor());
+      // Drill does not distinguish between nullable and not null map, by default they are not null
+      return ctx.map_type().accept(new TypeVisitor(name, TypeProtos.DataMode.REQUIRED));
+    }
+
+    @Override
+    public ColumnMetadata visitComplex_array_column(SchemaParser.Complex_array_columnContext ctx) {
+      String name = ctx.column_id().accept(new IdVisitor());
+      ColumnMetadata child = ctx.complex_array_type().complex_type().accept(new ArrayTypeVisitor(name));
+      RepeatedListBuilder builder = new RepeatedListBuilder(null, name);
+      builder.addColumn(child);
+      return builder.buildColumn();
+    }
+
+  }
+
+  /**
+   * Visits ID and QUOTED_ID, returning their string representation.
+   */
+  private static class IdVisitor extends SchemaParserBaseVisitor<String> {
+
+    @Override
+    public String visitId(SchemaParser.IdContext ctx) {
+      return ctx.ID().getText();
+    }
+
+    @Override
+    public String visitQuoted_id(SchemaParser.Quoted_idContext ctx) {
+      String text = ctx.QUOTED_ID().getText();
+      // first substring first and last symbols (backticks)
+      // then find all chars that are preceding with the backslash and remove the backslash
+      return text.substring(1, text.length() -1).replaceAll("\\\\(.)", "$1");
+    }
+  }
+
+  /**
+   * Visits simple and map types, storing their metadata into {@link ColumnMetadata} holder.
+   */
+  private static class TypeVisitor extends SchemaParserBaseVisitor<ColumnMetadata> {
+
+    private final String name;
+    private final TypeProtos.DataMode mode;
+
+    TypeVisitor(String name, TypeProtos.DataMode mode) {
+      this.name = name;
+      this.mode = mode;
+    }
+
+    @Override
+    public ColumnMetadata visitInt(SchemaParser.IntContext ctx) {
+      return constructColumn(Types.withMode(TypeProtos.MinorType.INT, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitBigint(SchemaParser.BigintContext ctx) {
+      return constructColumn(Types.withMode(TypeProtos.MinorType.BIGINT, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitFloat(SchemaParser.FloatContext ctx) {
+      return constructColumn(Types.withMode(TypeProtos.MinorType.FLOAT4, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitDouble(SchemaParser.DoubleContext ctx) {
+      return constructColumn(Types.withMode(TypeProtos.MinorType.FLOAT8, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitDecimal(SchemaParser.DecimalContext ctx) {
+      TypeProtos.MajorType type = Types.withMode(TypeProtos.MinorType.VARDECIMAL, mode);
+
+      List<TerminalNode> numbers = ctx.NUMBER();
+      if (!numbers.isEmpty()) {
+        int precision = Integer.parseInt(numbers.get(0).getText());
+        int scale = numbers.size() == 2 ? Integer.parseInt(numbers.get(1).getText()) : 0;
+        type = type.toBuilder().setPrecision(precision).setScale(scale).build();
+      }
+
+      return constructColumn(type);
+    }
+
+    @Override
+    public ColumnMetadata visitBoolean(SchemaParser.BooleanContext ctx) {
+      return constructColumn(Types.withMode(TypeProtos.MinorType.BIT, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitVarchar(SchemaParser.VarcharContext ctx) {
+      TypeProtos.MajorType type = Types.withMode(TypeProtos.MinorType.VARCHAR, mode);
+
+      if (ctx.NUMBER() != null) {
+        type = type.toBuilder().setPrecision(Integer.parseInt(ctx.NUMBER().getText())).build();
+      }
+
+      return constructColumn(type);
+    }
+
+    @Override
+    public ColumnMetadata visitBinary(SchemaParser.BinaryContext ctx) {
+      TypeProtos.MajorType type = Types.withMode(TypeProtos.MinorType.VARBINARY, mode);
+
+      if (ctx.NUMBER() != null) {
+        type = type.toBuilder().setPrecision(Integer.parseInt(ctx.NUMBER().getText())).build();
+      }
+
+      return constructColumn(type);
+    }
+
+    @Override
+    public ColumnMetadata visitTime(SchemaParser.TimeContext ctx) {
+      TypeProtos.MajorType type = Types.withMode(TypeProtos.MinorType.TIME, mode);
+
+      if (ctx.NUMBER() != null) {
+        type = type.toBuilder().setPrecision(Integer.parseInt(ctx.NUMBER().getText())).build();
+      }
+
+      return constructColumn(type);
+    }
+
+    @Override
+    public ColumnMetadata visitDate(SchemaParser.DateContext ctx) {
+      return constructColumn(Types.withMode(TypeProtos.MinorType.DATE, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitTimestamp(SchemaParser.TimestampContext ctx) {
+      TypeProtos.MajorType type = Types.withMode(TypeProtos.MinorType.TIMESTAMP, mode);
+
+      if (ctx.NUMBER() != null) {
+        type = type.toBuilder().setPrecision(Integer.parseInt(ctx.NUMBER().getText())).build();
+      }
+
+      return constructColumn(type);
+    }
+
+    @Override
+    public ColumnMetadata visitInterval_year(SchemaParser.Interval_yearContext ctx) {
+      return constructColumn(Types.withMode(TypeProtos.MinorType.INTERVALYEAR, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitInterval_day(SchemaParser.Interval_dayContext ctx) {
+      return constructColumn(Types.withMode(TypeProtos.MinorType.INTERVALDAY, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitInterval(SchemaParser.IntervalContext ctx) {
+      return constructColumn(Types.withMode(TypeProtos.MinorType.INTERVAL, mode));
+    }
+
+    @Override
+    public ColumnMetadata visitMap_type(SchemaParser.Map_typeContext ctx) {
+      MapBuilder builder = new MapBuilder(null, name, mode);
+      ColumnVisitor visitor = new ColumnVisitor();
+      ctx.columns().column().forEach(
+        c -> builder.addColumn(c.accept(visitor))
+      );
+      return builder.buildColumn();
+    }
+
+    private ColumnMetadata constructColumn(TypeProtos.MajorType type) {
+      MaterializedField field = MaterializedField.create(name, type);
+      return MetadataUtils.fromField(field);
+    }
+
+  }
+
+  /**
+   * Visits array type: simple (which has only on nested element: array<int>)
+   * or complex (which has several nested elements: array<int<int>>).
+   */
+  private static class ArrayTypeVisitor extends SchemaParserBaseVisitor<ColumnMetadata> {
+
+    private final String name;
+
+    ArrayTypeVisitor(String name) {
+      this.name = name;
+    }
+
+    @Override
+    public ColumnMetadata visitSimple_array_type(SchemaParser.Simple_array_typeContext ctx) {
+      TypeVisitor visitor = new TypeVisitor(name, TypeProtos.DataMode.REPEATED);
+      return ctx.map_type() == null ? ctx.simple_type().accept(visitor) : ctx.map_type().accept(visitor);
+    }
+
+    @Override
+    public ColumnMetadata visitComplex_array_type(SchemaParser.Complex_array_typeContext ctx) {
+      RepeatedListBuilder childBuilder = new RepeatedListBuilder(null, name);
+      ColumnMetadata child = ctx.complex_type().accept(new ArrayTypeVisitor(name));
+      childBuilder.addColumn(child);
+      return childBuilder.buildColumn();
+    }
+  }
+
+}