path: root/guava/src/com/google/common/collect/RegularImmutableTable.java

/*
 * Copyright (C) 2009 The Guava Authors
 *
 * 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 com.google.common.collect;

import static com.google.common.base.Preconditions.checkArgument;
import static com.google.common.base.Preconditions.checkNotNull;

import com.google.common.annotations.GwtCompatible;
import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Objects;

import java.util.Collections;
import java.util.Comparator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

import javax.annotation.Nullable;
import javax.annotation.concurrent.Immutable;

/**
 * An implementation of {@link ImmutableTable} holding an arbitrary number of
 * cells.
 *
 * @author Gregory Kick
 */
@GwtCompatible
abstract class RegularImmutableTable<R, C, V> extends ImmutableTable<R, C, V> {
  private RegularImmutableTable() {}
  
  private transient ImmutableCollection<V> values;

  @Override public final ImmutableCollection<V> values() {
    ImmutableCollection<V> result = values;
    return (result == null) ? values = createValues() : result;
  }
  
  abstract ImmutableCollection<V> createValues();

  @Override public abstract int size();

  @Override public final boolean containsValue(@Nullable Object value) {
    return values().contains(value);
  }
  
  private transient ImmutableSet<Cell<R, C, V>> cellSet;

  @Override
  public final ImmutableSet<Cell<R, C, V>> cellSet() {
    ImmutableSet<Cell<R, C, V>> result = cellSet;
    return (result == null) ? cellSet = createCellSet() : result;
  }
  
  abstract ImmutableSet<Cell<R, C, V>> createCellSet();
  
  abstract class CellSet extends ImmutableSet<Cell<R, C, V>> {
    @Override
    public int size() {
      return RegularImmutableTable.this.size();
    }

    @Override
    public boolean contains(@Nullable Object object) {
      if (object instanceof Cell) {
        Cell<?, ?, ?> cell = (Cell<?, ?, ?>) object;
        Object value = get(cell.getRowKey(), cell.getColumnKey());
        return value != null && value.equals(cell.getValue());
      }
      return false;
    }

    @Override
    boolean isPartialView() {
      return false;
    }
  }

  @Override public final boolean isEmpty() {
    return false;
  }

  static final <R, C, V> RegularImmutableTable<R, C, V> forCells(
      List<Cell<R, C, V>> cells,
      @Nullable final Comparator<? super R> rowComparator,
      @Nullable final Comparator<? super C> columnComparator) {
    checkNotNull(cells);
    if (rowComparator != null || columnComparator != null) {
      /*
       * This sorting logic leads to a cellSet() ordering that may not be
       * expected and that isn't documented in the Javadoc. If a row Comparator
       * is provided, cellSet() iterates across the columns in the first row,
       * the columns in the second row, etc. If a column Comparator is provided
       * but a row Comparator isn't, cellSet() iterates across the rows in the
       * first column, the rows in the second column, etc.
       */
      Comparator<Cell<R, C, V>> comparator = new Comparator<Cell<R, C, V>>() {
        @Override public int compare(Cell<R, C, V> cell1, Cell<R, C, V> cell2) {
          int rowCompare = (rowComparator == null) ? 0
            : rowComparator.compare(cell1.getRowKey(), cell2.getRowKey());
          if (rowCompare != 0) {
            return rowCompare;
          }
          return (columnComparator == null) ? 0
              : columnComparator.compare(
                  cell1.getColumnKey(), cell2.getColumnKey());
        }
      };
      Collections.sort(cells, comparator);
    }
    return forCellsInternal(cells, rowComparator, columnComparator);
  }

  static final <R, C, V> RegularImmutableTable<R, C, V> forCells(
      Iterable<Cell<R, C, V>> cells) {
    return forCellsInternal(cells, null, null);
  }

  /**
   * A factory that chooses the most space-efficient representation of the
   * table.
   */
  private static final <R, C, V> RegularImmutableTable<R, C, V>
      forCellsInternal(Iterable<Cell<R, C, V>> cells,
          @Nullable Comparator<? super R> rowComparator,
          @Nullable Comparator<? super C> columnComparator) {
    ImmutableSet.Builder<R> rowSpaceBuilder = ImmutableSet.builder();
    ImmutableSet.Builder<C> columnSpaceBuilder = ImmutableSet.builder();
    ImmutableList<Cell<R, C, V>> cellList = ImmutableList.copyOf(cells);
    for (Cell<R, C, V> cell : cellList) {
      rowSpaceBuilder.add(cell.getRowKey());
      columnSpaceBuilder.add(cell.getColumnKey());
    }

    ImmutableSet<R> rowSpace = rowSpaceBuilder.build();
    if (rowComparator != null) {
      List<R> rowList = Lists.newArrayList(rowSpace);
      Collections.sort(rowList, rowComparator);
      rowSpace = ImmutableSet.copyOf(rowList);
    }
    ImmutableSet<C> columnSpace = columnSpaceBuilder.build();
    if (columnComparator != null) {
      List<C> columnList = Lists.newArrayList(columnSpace);
      Collections.sort(columnList, columnComparator);
      columnSpace = ImmutableSet.copyOf(columnList);
    }

    // use a dense table if more than half of the cells have values
    // TODO(gak): tune this condition based on empirical evidence
    return (cellList.size() > ((rowSpace.size() * columnSpace.size()) / 2)) ?
        new DenseImmutableTable<R, C, V>(cellList, rowSpace, columnSpace) :
        new SparseImmutableTable<R, C, V>(cellList, rowSpace, columnSpace);
  }

  /**
   * A {@code RegularImmutableTable} optimized for sparse data.
   */
  @Immutable
  @VisibleForTesting
  static final class SparseImmutableTable<R, C, V>
      extends RegularImmutableTable<R, C, V> {

    private final ImmutableMap<R, Map<C, V>> rowMap;
    private final ImmutableMap<C, Map<R, V>> columnMap;
    private final int[] iterationOrderRow;
    private final int[] iterationOrderColumn;

    SparseImmutableTable(ImmutableList<Cell<R, C, V>> cellList,
        ImmutableSet<R> rowSpace, ImmutableSet<C> columnSpace) {
      Map<R, Integer> rowIndex = Maps.newHashMap();
      Map<R, Map<C, V>> rows = Maps.newLinkedHashMap();
      for (R row : rowSpace) {
        rowIndex.put(row, rows.size());
        rows.put(row, new LinkedHashMap<C, V>());
      }
      Map<C, Map<R, V>> columns = Maps.newLinkedHashMap();
      for (C col : columnSpace) {
        columns.put(col, new LinkedHashMap<R, V>());
      }
      int[] iterationOrderRow = new int[cellList.size()];
      int[] iterationOrderColumn = new int[cellList.size()];
      for (int i = 0; i < cellList.size(); i++) {
        Cell<R, C, V> cell = cellList.get(i);
        R rowKey = cell.getRowKey();
        C columnKey = cell.getColumnKey();
        V value = cell.getValue();
        
        iterationOrderRow[i] = rowIndex.get(rowKey);
        Map<C, V> thisRow = rows.get(rowKey);
        iterationOrderColumn[i] = thisRow.size();
        V oldValue = thisRow.put(columnKey, value);
        if (oldValue != null) {
          throw new IllegalArgumentException("Duplicate value for row=" + rowKey + ", column="
              + columnKey + ": " + value + ", " + oldValue);
        }
        columns.get(columnKey).put(rowKey, value);
      }
      this.iterationOrderRow = iterationOrderRow;
      this.iterationOrderColumn = iterationOrderColumn;
      ImmutableMap.Builder<R, Map<C, V>> rowBuilder = ImmutableMap.builder();
      for (Map.Entry<R, Map<C, V>> row : rows.entrySet()) {
        rowBuilder.put(row.getKey(), ImmutableMap.copyOf(row.getValue()));
      }
      this.rowMap = rowBuilder.build();
      
      ImmutableMap.Builder<C, Map<R, V>> columnBuilder = ImmutableMap.builder();
      for (Map.Entry<C, Map<R, V>> col : columns.entrySet()) {
        columnBuilder.put(col.getKey(), ImmutableMap.copyOf(col.getValue()));
      }
      this.columnMap = columnBuilder.build();
    }

    @Override public ImmutableMap<R, V> column(C columnKey) {
      checkNotNull(columnKey);
      // value maps are guaranteed to be immutable maps
      return Objects.firstNonNull((ImmutableMap<R, V>) columnMap.get(columnKey),
          ImmutableMap.<R, V>of());
    }

    @Override public ImmutableSet<C> columnKeySet() {
      return columnMap.keySet();
    }

    @Override public ImmutableMap<C, Map<R, V>> columnMap() {
      return columnMap;
    }

    @Override public ImmutableMap<C, V> row(R rowKey) {
      checkNotNull(rowKey);
      // value maps are guaranteed to be immutable maps
      return Objects.firstNonNull((ImmutableMap<C, V>) rowMap.get(rowKey),
          ImmutableMap.<C, V>of());
    }

    @Override public ImmutableSet<R> rowKeySet() {
      return rowMap.keySet();
    }

    @Override public ImmutableMap<R, Map<C, V>> rowMap() {
      return rowMap;
    }

    @Override public boolean contains(@Nullable Object rowKey,
        @Nullable Object columnKey) {
      Map<C, V> row = rowMap.get(rowKey);
      return (row != null) && row.containsKey(columnKey);
    }

    @Override public boolean containsColumn(@Nullable Object columnKey) {
      return columnMap.containsKey(columnKey);
    }

    @Override public boolean containsRow(@Nullable Object rowKey) {
      return rowMap.containsKey(rowKey);
    }

    @Override public V get(@Nullable Object rowKey,
        @Nullable Object columnKey) {
      Map<C, V> row = rowMap.get(rowKey);
      return (row == null) ? null : row.get(columnKey);
    }

    @Override
    ImmutableCollection<V> createValues() {
      return new ImmutableList<V>() {
        @Override
        public int size() {
          return iterationOrderRow.length;
        }

        @Override
        public V get(int index) {
          int rowIndex = iterationOrderRow[index];
          ImmutableMap<C, V> row = (ImmutableMap<C, V>) rowMap.values().asList().get(rowIndex);
          int columnIndex = iterationOrderColumn[index];
          return row.values().asList().get(columnIndex);
        }

        @Override
        boolean isPartialView() {
          return true;
        }
      };
    }

    @Override
    public int size() {
      return iterationOrderRow.length;
    }

    @Override
    ImmutableSet<Cell<R, C, V>> createCellSet() {
      return new SparseCellSet();
    }
    
    class SparseCellSet extends CellSet {
      @Override
      public UnmodifiableIterator<Cell<R, C, V>> iterator() {
        return asList().iterator();
      }

      @Override
      ImmutableList<Cell<R, C, V>> createAsList() {
        return new ImmutableAsList<Cell<R, C, V>>() {
          @Override
          public Cell<R, C, V> get(int index) {
            int rowIndex = iterationOrderRow[index];
            Map.Entry<R, Map<C, V>> rowEntry = rowMap.entrySet().asList().get(rowIndex);
            ImmutableMap<C, V> row = (ImmutableMap<C, V>) rowEntry.getValue();
            int columnIndex = iterationOrderColumn[index];
            Map.Entry<C, V> colEntry = row.entrySet().asList().get(columnIndex);
            return Tables.immutableCell(rowEntry.getKey(), colEntry.getKey(), colEntry.getValue());
          }

          @Override
          ImmutableCollection<Cell<R, C, V>> delegateCollection() {
            return SparseCellSet.this;
          }
        };
      }
    }
  }

  /**
   * An immutable map implementation backed by an indexed nullable array, used in
   * DenseImmutableTable.
   */
  private abstract static class ImmutableArrayMap<K, V> extends ImmutableMap<K, V> {
    private final int size;

    ImmutableArrayMap(int size) {
      this.size = size;
    }

    abstract ImmutableMap<K, Integer> keyToIndex();

    // True if getValue never returns null.
    private boolean isFull() {
      return size == keyToIndex().size();
    }

    K getKey(int index) {
      return keyToIndex().keySet().asList().get(index);
    }

    @Nullable abstract V getValue(int keyIndex);

    @Override
    ImmutableSet<K> createKeySet() {
      return isFull() ? keyToIndex().keySet() : super.createKeySet();
    }

    @Override
    public int size() {
      return size;
    }

    @Override
    public V get(@Nullable Object key) {
      Integer keyIndex = keyToIndex().get(key);
      return (keyIndex == null) ? null : getValue(keyIndex);
    }

    @Override
    ImmutableSet<Entry<K, V>> createEntrySet() {
      if (isFull()) {
        return new ImmutableMapEntrySet<K, V>() {
          @Override ImmutableMap<K, V> map() {
            return ImmutableArrayMap.this;
          }

          @Override
          public UnmodifiableIterator<Entry<K, V>> iterator() {
            return new AbstractIndexedListIterator<Entry<K, V>>(size()) {
              @Override
              protected Entry<K, V> get(int index) {
                return Maps.immutableEntry(getKey(index), getValue(index));
              }
            };
          }
        };
      } else {
        return new ImmutableMapEntrySet<K, V>() {
          @Override ImmutableMap<K, V> map() {
            return ImmutableArrayMap.this;
          }

          @Override
          public UnmodifiableIterator<Entry<K, V>> iterator() {
            return new AbstractIterator<Entry<K, V>>() {
              private int index = -1;
              private final int maxIndex = keyToIndex().size();

              @Override
              protected Entry<K, V> computeNext() {
                for (index++; index < maxIndex; index++) {
                  V value = getValue(index);
                  if (value != null) {
                    return Maps.immutableEntry(getKey(index), value);
                  }
                }
                return endOfData();
              }
            };
          }
        };
      }
    }
  }

  /**
   * A {@code RegularImmutableTable} optimized for dense data.
   */
  @Immutable @VisibleForTesting
  static final class DenseImmutableTable<R, C, V>
      extends RegularImmutableTable<R, C, V> {

    private final ImmutableMap<R, Integer> rowKeyToIndex;
    private final ImmutableMap<C, Integer> columnKeyToIndex;
    private final ImmutableMap<R, Map<C, V>> rowMap;
    private final ImmutableMap<C, Map<R, V>> columnMap;
    private final int[] rowCounts;
    private final int[] columnCounts;
    private final V[][] values;
    private final int[] iterationOrderRow;
    private final int[] iterationOrderColumn;

    private static <E> ImmutableMap<E, Integer> makeIndex(
        ImmutableSet<E> set) {
      ImmutableMap.Builder<E, Integer> indexBuilder =
          ImmutableMap.builder();
      int i = 0;
      for (E key : set) {
        indexBuilder.put(key, i);
        i++;
      }
      return indexBuilder.build();
    }

    DenseImmutableTable(ImmutableList<Cell<R, C, V>> cellList,
        ImmutableSet<R> rowSpace, ImmutableSet<C> columnSpace) {
      @SuppressWarnings("unchecked")
      V[][] array = (V[][]) new Object[rowSpace.size()][columnSpace.size()];
      this.values = array;
      this.rowKeyToIndex = makeIndex(rowSpace);
      this.columnKeyToIndex = makeIndex(columnSpace);
      rowCounts = new int[rowKeyToIndex.size()];
      columnCounts = new int[columnKeyToIndex.size()];
      int[] iterationOrderRow = new int[cellList.size()];
      int[] iterationOrderColumn = new int[cellList.size()];
      for (int i = 0; i < cellList.size(); i++) {
        Cell<R, C, V> cell = cellList.get(i);
        R rowKey = cell.getRowKey();
        C columnKey = cell.getColumnKey();
        int rowIndex = rowKeyToIndex.get(rowKey);
        int columnIndex = columnKeyToIndex.get(columnKey);
        V existingValue = values[rowIndex][columnIndex];
        checkArgument(existingValue == null, "duplicate key: (%s, %s)", rowKey,
            columnKey);
        values[rowIndex][columnIndex] = cell.getValue();
        rowCounts[rowIndex]++;
        columnCounts[columnIndex]++;
        iterationOrderRow[i] = rowIndex;
        iterationOrderColumn[i] = columnIndex;
      }
      this.iterationOrderRow = iterationOrderRow;
      this.iterationOrderColumn = iterationOrderColumn;
      this.rowMap = new RowMap();
      this.columnMap = new ColumnMap();
    }

    private final class Row extends ImmutableArrayMap<C, V> {
      private final int rowIndex;

      Row(int rowIndex) {
        super(rowCounts[rowIndex]);
        this.rowIndex = rowIndex;
      }

      @Override
      ImmutableMap<C, Integer> keyToIndex() {
        return columnKeyToIndex;
      }

      @Override
      V getValue(int keyIndex) {
        return values[rowIndex][keyIndex];
      }

      @Override
      boolean isPartialView() {
        return true;
      }
    }

    private final class Column extends ImmutableArrayMap<R, V> {
      private final int columnIndex;

      Column(int columnIndex) {
        super(columnCounts[columnIndex]);
        this.columnIndex = columnIndex;
      }

      @Override
      ImmutableMap<R, Integer> keyToIndex() {
        return rowKeyToIndex;
      }

      @Override
      V getValue(int keyIndex) {
        return values[keyIndex][columnIndex];
      }

      @Override
      boolean isPartialView() {
        return true;
      }
    }

    private final class RowMap extends ImmutableArrayMap<R, Map<C, V>> {
      private RowMap() {
        super(rowCounts.length);
      }

      @Override
      ImmutableMap<R, Integer> keyToIndex() {
        return rowKeyToIndex;
      }

      @Override
      Map<C, V> getValue(int keyIndex) {
        return new Row(keyIndex);
      }

      @Override
      boolean isPartialView() {
        return false;
      }
    }

    private final class ColumnMap extends ImmutableArrayMap<C, Map<R, V>> {
      private ColumnMap() {
        super(columnCounts.length);
      }

      @Override
      ImmutableMap<C, Integer> keyToIndex() {
        return columnKeyToIndex;
      }

      @Override
      Map<R, V> getValue(int keyIndex) {
        return new Column(keyIndex);
      }

      @Override
      boolean isPartialView() {
        return false;
      }
    }

    @Override public ImmutableMap<R, V> column(C columnKey) {
      Integer columnIndex = columnKeyToIndex.get(checkNotNull(columnKey));
      if (columnIndex == null) {
        return ImmutableMap.of();
      } else {
        return new Column(columnIndex);
      }
    }

    @Override public ImmutableSet<C> columnKeySet() {
      return columnKeyToIndex.keySet();
    }

    @Override public ImmutableMap<C, Map<R, V>> columnMap() {
      return columnMap;
    }

    @Override public boolean contains(@Nullable Object rowKey,
        @Nullable Object columnKey) {
      return (get(rowKey, columnKey) != null);
    }

    @Override public boolean containsColumn(@Nullable Object columnKey) {
      return columnKeyToIndex.containsKey(columnKey);
    }

    @Override public boolean containsRow(@Nullable Object rowKey) {
      return rowKeyToIndex.containsKey(rowKey);
    }

    @Override public V get(@Nullable Object rowKey,
        @Nullable Object columnKey) {
      Integer rowIndex = rowKeyToIndex.get(rowKey);
      Integer columnIndex = columnKeyToIndex.get(columnKey);
      return ((rowIndex == null) || (columnIndex == null)) ? null
          : values[rowIndex][columnIndex];
    }

    @Override public ImmutableMap<C, V> row(R rowKey) {
      checkNotNull(rowKey);
      Integer rowIndex = rowKeyToIndex.get(rowKey);
      if (rowIndex == null) {
        return ImmutableMap.of();
      } else {
        return new Row(rowIndex);
      }
    }

    @Override public ImmutableSet<R> rowKeySet() {
      return rowKeyToIndex.keySet();
    }

    @Override
    public ImmutableMap<R, Map<C, V>> rowMap() {
      return rowMap;
    }

    @Override
    ImmutableCollection<V> createValues() {
      return new ImmutableList<V>() {
        @Override
        public int size() {
          return iterationOrderRow.length;
        }

        @Override
        public V get(int index) {
          return values[iterationOrderRow[index]][iterationOrderColumn[index]];
        }

        @Override
        boolean isPartialView() {
          return true;
        }
      };
    }

    @Override
    public int size() {
      return iterationOrderRow.length;
    }

    @Override
    ImmutableSet<Cell<R, C, V>> createCellSet() {
      return new DenseCellSet();
    }

    class DenseCellSet extends CellSet {
      @Override
      public UnmodifiableIterator<Cell<R, C, V>> iterator() {
        return asList().iterator();
      }

      @Override
      ImmutableList<Cell<R, C, V>> createAsList() {
        return new ImmutableAsList<Cell<R, C, V>>() {
          @Override
          public Cell<R, C, V> get(int index) {
            int rowIndex = iterationOrderRow[index];
            int columnIndex = iterationOrderColumn[index];
            R rowKey = rowKeySet().asList().get(rowIndex);
            C columnKey = columnKeySet().asList().get(columnIndex);
            V value = values[rowIndex][columnIndex];
            return Tables.immutableCell(rowKey, columnKey, value);
          }
          
          @Override
          ImmutableCollection<Cell<R, C, V>> delegateCollection() {
            return DenseCellSet.this;
          }
        };
      }
    }
  }
}