content: /*
   * 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.calcite.rel.type;
  
  import org.apache.calcite.sql.SqlCollation;
  import org.apache.calcite.sql.SqlIdentifier;
  import org.apache.calcite.sql.SqlIntervalQualifier;
  import org.apache.calcite.sql.parser.SqlParserPos;
  import org.apache.calcite.sql.type.BasicSqlType;
  import org.apache.calcite.sql.type.SqlTypeName;
  import org.apache.calcite.util.Pair;
  import org.apache.calcite.util.Util;
  
  import com.google.common.collect.ImmutableList;
  import com.google.common.collect.Iterables;
  
  import org.checkerframework.checker.initialization.qual.UnknownInitialization;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  import java.io.Serializable;
  import java.nio.charset.Charset;
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Map;
  import java.util.Objects;
  
  import static org.apache.calcite.linq4j.Nullness.castNonNull;
  
  import static java.util.Objects.requireNonNull;
  
  /**
   * RelDataTypeImpl is an abstract base for implementations of
   * {@link RelDataType}.
   *
   * <p>Identity is based upon the {@link #digest} field, which each derived class
   * should set during construction.
   */
  public abstract class RelDataTypeImpl
      implements RelDataType, RelDataTypeFamily {
  
    /**
     * Suffix for the digests of non-nullable types.
     */
    public static final String NON_NULLABLE_SUFFIX = " NOT NULL";
  
    //~ Instance fields --------------------------------------------------------
  
    protected final @Nullable List<RelDataTypeField> fieldList;
    protected @Nullable String digest;
  
    //~ Constructors -----------------------------------------------------------
  
    /**
     * Creates a RelDataTypeImpl.
     *
     * @param fieldList List of fields
     */
    protected RelDataTypeImpl(@Nullable List<? extends RelDataTypeField> fieldList) {
      if (fieldList != null) {
        // Create a defensive copy of the list.
        this.fieldList = ImmutableList.copyOf(fieldList);
      } else {
        this.fieldList = null;
      }
    }
  
    /**
     * Default constructor, to allow derived classes such as
     * {@link BasicSqlType} to be {@link Serializable}.
     *
     * <p>(The serialization specification says that a class can be serializable
     * even if its base class is not serializable, provided that the base class
     * has a public or protected zero-args constructor.)
     */
    protected RelDataTypeImpl() {
      this(null);
    }
  
    //~ Methods ----------------------------------------------------------------
  
    @Override public @Nullable RelDataTypeField getField(String fieldName,
        boolean caseSensitive, boolean elideRecord) {
      if (fieldList == null) {
        throw new IllegalStateException("Trying to access field " + fieldName
            + " in a type with no fields: " + this);
      }
      final Map<String, RelDataTypeField> fieldMap = getFieldMap();
      if (caseSensitive && fieldMap != null) {
        RelDataTypeField field = fieldMap.get(fieldName);
        if (field != null) {
          return field;
        }
      } else {
        for (RelDataTypeField field : fieldList) {
          if (Util.matches(caseSensitive, field.getName(), fieldName)) {
            return field;
          }
        }
      }
      if (elideRecord) {
        final List<Slot> slots = new ArrayList<>();
        getFieldRecurse(slots, this, 0, fieldName, caseSensitive);
      loop:
        for (Slot slot : slots) {
          switch (slot.count) {
          case 0:
            break; // no match at this depth; try deeper
          case 1:
            return slot.field;
          default:
            break loop; // duplicate fields at this depth; abandon search
          }
        }
      }
      // Extra field
      if (!fieldList.isEmpty()) {
        final RelDataTypeField lastField = Iterables.getLast(fieldList);
        if (lastField.getName().equals("_extra")) {
          return new RelDataTypeFieldImpl(
              fieldName, -1, lastField.getType());
        }
      }
  
      // a dynamic * field will match any field name.
      if (fieldMap != null) {
        return fieldMap.get("");
      } else {
        for (RelDataTypeField field : fieldList) {
          if (field.isDynamicStar()) {
            // the requested field could be in the unresolved star
            return field;
          }
        }
      }
  
      return null;
    }
  
    /** Returns a map from field names to fields.
     *
     * <p>Matching is case-sensitive.
     *
     * <p>If several fields have the same name, the map contains the first.
     *
     * <p>A {@link RelDataTypeField#isDynamicStar() dynamic star field} is indexed
     * under its own name and "" (the empty string).
     *
     * <p>If the map is null, the type must do lookup the long way.
     */
    protected @Nullable Map<String, RelDataTypeField> getFieldMap() {
      return null;
    }
  
    private static void getFieldRecurse(List<Slot> slots, RelDataType type,
        int depth, String fieldName, boolean caseSensitive) {
      while (slots.size() <= depth) {
        slots.add(new Slot());
      }
      final Slot slot = slots.get(depth);
      for (RelDataTypeField field : type.getFieldList()) {
        if (Util.matches(caseSensitive, field.getName(), fieldName)) {
          slot.count++;
          slot.field = field;
        }
      }
      // No point looking to depth + 1 if there is a hit at depth.
      if (slot.count == 0) {
        for (RelDataTypeField field : type.getFieldList()) {
          if (field.getType().isStruct()) {
            getFieldRecurse(slots, field.getType(), depth + 1,
                fieldName, caseSensitive);
          }
        }
      }
    }
  
    @Override public List<RelDataTypeField> getFieldList() {
      if (fieldList == null) {
        throw new AssertionError("fieldList must not be null, type = " + this);
      }
      return fieldList;
    }
  
    @Override public List<String> getFieldNames() {
      if (fieldList == null) {
        throw new AssertionError("fieldList must not be null, type = " + this);
      }
      return Pair.left(fieldList);
    }
  
    @Override public int getFieldCount() {
      if (fieldList == null) {
        throw new AssertionError("fieldList must not be null, type = " + this);
      }
      return fieldList.size();
    }
  
    @Override public StructKind getStructKind() {
      return isStruct() ? StructKind.FULLY_QUALIFIED : StructKind.NONE;
    }
  
    @Override public @Nullable RelDataType getComponentType() {
      // this is not a collection type
      return null;
    }
  
    @Override public @Nullable RelDataType getKeyType() {
      // this is not a map type
      return null;
    }
  
    @Override public @Nullable RelDataType getValueType() {
      // this is not a map type
      return null;
    }
  
    @Override public boolean isStruct() {
      return fieldList != null;
    }
  
    @Override public boolean equals(@Nullable Object obj) {
      return this == obj
          || obj instanceof RelDataTypeImpl
          && Objects.equals(this.digest, ((RelDataTypeImpl) obj).digest);
    }
  
    @Override public int hashCode() {
      return Objects.hashCode(digest);
    }
  
    @Override public String getFullTypeString() {
      return requireNonNull(digest, "digest");
    }
  
    @Override public boolean isNullable() {
      return false;
    }
  
    @Override public @Nullable Charset getCharset() {
      return null;
    }
  
    @Override public @Nullable SqlCollation getCollation() {
      return null;
    }
  
    @Override public @Nullable SqlIntervalQualifier getIntervalQualifier() {
      return null;
    }
  
    @Override public int getPrecision() {
      return PRECISION_NOT_SPECIFIED;
    }
  
    @Override public int getScale() {
      return SCALE_NOT_SPECIFIED;
    }
  
    /**
     * Gets the {@link SqlTypeName} of this type.
     * Sub-classes must override the method to ensure the resulting value is non-nullable.
     *
     * @return SqlTypeName, never null
     */
    @Override public SqlTypeName getSqlTypeName() {
      // The implementations must provide non-null value, however, we keep this for compatibility
      return castNonNull(null);
    }
  
    @Override public @Nullable SqlIdentifier getSqlIdentifier() {
      SqlTypeName typeName = getSqlTypeName();
      if (typeName == null) {
        return null;
      }
      return new SqlIdentifier(
          typeName.name(),
          SqlParserPos.ZERO);
    }
  
    @Override public RelDataTypeFamily getFamily() {
      // by default, put each type into its own family
      return this;
    }
  
    /**
     * Generates a string representation of this type.
     *
     * @param sb         StringBuilder into which to generate the string
     * @param withDetail when true, all detail information needed to compute a
     *                   unique digest (and return from getFullTypeString) should
     *                   be included;
     */
    protected abstract void generateTypeString(
        StringBuilder sb,
        boolean withDetail);
  
    /**
     * Computes the digest field. This should be called in every non-abstract
     * subclass constructor once the type is fully defined.
     */
    @SuppressWarnings("method.invocation.invalid")
    protected void computeDigest(@UnknownInitialization RelDataTypeImpl this) {
      StringBuilder sb = new StringBuilder();
      generateTypeString(sb, true);
      if (!isNullable()) {
        sb.append(NON_NULLABLE_SUFFIX);
      }
      digest = sb.toString();
    }
  
    @Override public String toString() {
      StringBuilder sb = new StringBuilder();
      generateTypeString(sb, false);
      return sb.toString();
    }
  
    @Override public RelDataTypePrecedenceList getPrecedenceList() {
      // by default, make each type have a precedence list containing
      // only other types in the same family
      return new RelDataTypePrecedenceList() {
        @Override public boolean containsType(RelDataType type) {
          return getFamily() == type.getFamily();
        }
  
        @Override public int compareTypePrecedence(
            RelDataType type1,
            RelDataType type2) {
          assert containsType(type1);
          assert containsType(type2);
          return 0;
        }
      };
    }
  
    @Override public RelDataTypeComparability getComparability() {
      return RelDataTypeComparability.ALL;
    }
  
    /**
     * Returns an implementation of
     * {@link RelProtoDataType}
     * that copies a given type using the given type factory.
     */
    public static RelProtoDataType proto(final RelDataType protoType) {
      requireNonNull(protoType, "protoType");
      return typeFactory -> typeFactory.copyType(protoType);
    }
  
    /** Returns a {@link org.apache.calcite.rel.type.RelProtoDataType}
     * that will create a type {@code typeName}.
     *
     * <p>For example, {@code proto(SqlTypeName.DATE), false}
     * will create {@code DATE NOT NULL}.
     *
     * @param typeName Type name
     * @param nullable Whether nullable
     * @return Proto data type
     */
    public static RelProtoDataType proto(final SqlTypeName typeName,
        final boolean nullable) {
      requireNonNull(typeName, "typeName");
      return typeFactory -> {
        final RelDataType type = typeFactory.createSqlType(typeName);
        return typeFactory.createTypeWithNullability(type, nullable);
      };
    }
  
    /** Returns a {@link org.apache.calcite.rel.type.RelProtoDataType}
     * that will create a type {@code typeName(precision)}.
     *
     * <p>For example, {@code proto(SqlTypeName.VARCHAR, 100, false)}
     * will create {@code VARCHAR(100) NOT NULL}.
     *
     * @param typeName Type name
     * @param precision Precision
     * @param nullable Whether nullable
     * @return Proto data type
     */
    public static RelProtoDataType proto(final SqlTypeName typeName,
        final int precision, final boolean nullable) {
      requireNonNull(typeName, "typeName");
      return typeFactory -> {
        final RelDataType type = typeFactory.createSqlType(typeName, precision);
        return typeFactory.createTypeWithNullability(type, nullable);
      };
    }
  
    /** Returns a {@link org.apache.calcite.rel.type.RelProtoDataType}
     * that will create a type {@code typeName(precision, scale)}.
     *
     * <p>For example, {@code proto(SqlTypeName.DECIMAL, 7, 2, false)}
     * will create {@code DECIMAL(7, 2) NOT NULL}.
     *
     * @param typeName Type name
     * @param precision Precision
     * @param scale Scale
     * @param nullable Whether nullable
     * @return Proto data type
     */
    public static RelProtoDataType proto(final SqlTypeName typeName,
        final int precision, final int scale, final boolean nullable) {
      return typeFactory -> {
        final RelDataType type =
            typeFactory.createSqlType(typeName, precision, scale);
        return typeFactory.createTypeWithNullability(type, nullable);
      };
    }
  
    /**
     * Returns the "extra" field in a row type whose presence signals that
     * fields will come into existence just by asking for them.
     *
     * @param rowType Row type
     * @return The "extra" field, or null
     */
    public static @Nullable RelDataTypeField extra(RelDataType rowType) {
      // Even in a case-insensitive connection, the name must be precisely
      // "_extra".
      return rowType.getField("_extra", true, false);
    }
  
    @Override public boolean isDynamicStruct() {
      return false;
    }
  
    /** Work space for {@link RelDataTypeImpl#getFieldRecurse}. */
    private static class Slot {
      int count;
      @Nullable RelDataTypeField field;
    }
  }
  