Java Linq4j类代码示例

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
@Override
public Queryable<Integer> asQueryable(QueryProvider queryProvider, SchemaPlus schemaPlus, String tableName) {
    return new AbstractTableQueryable<Integer>(queryProvider, schemaPlus, this, tableName) {
        @Override
        public Enumerator<Integer> enumerator() {
            FluentIterable<Integer> it = FluentIterable
                    .from(classesList.getClasses())
                    .transformAndConcat(
                            new Function<IClass, Iterable<Integer>>() {
                                @Override
                                public Iterable<Integer> apply(IClass input) {
                                    try {
                                        return Ints.asList(input
                                                .getObjectIds());
                                    } catch (SnapshotException e) {
                                        e.printStackTrace();
                                        return Collections.emptyList();
                                    }
                                }
                            });

            return Linq4j.iterableEnumerator(it);
        }
    };
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
protected MetaResultSet createResultSet(
        Map<String, Object> internalParameters, List<ColumnMetaData> columns,
        CursorFactory cursorFactory, final Frame firstFrame) {
    try {
        final CalciteConnectionImpl connection = getConnection();
        final AvaticaStatement statement = connection.createStatement();
        final CalcitePrepare.CalciteSignature<Object> signature =
                new CalcitePrepare.CalciteSignature<Object>("",
                        ImmutableList.<AvaticaParameter>of(), internalParameters, null,
                        columns, cursorFactory, ImmutableList.<RelCollation>of(), -1,
                        null, Meta.StatementType.SELECT) {
                    @Override
                    public Enumerable<Object> enumerable(
                            DataContext dataContext) {
                        return Linq4j.asEnumerable(firstFrame.rows);
                    }
                };
        return MetaResultSet.create(connection.id, statement.getId(), true,
                signature, firstFrame);
    } catch (SQLException e) {
        throw new RuntimeException(e);
    }
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
Enumerable<MetaSchema> schemas(String catalog) {
    return Linq4j.asEnumerable(
            getConnection().getCalciteRootSchema().getSubSchemaMap().values())
            .select(
                    new Function1<CalciteSchema, MetaSchema>() {
                        public MetaSchema apply(CalciteSchema calciteSchema) {
                            return new CalciteMetaSchema(
                                    calciteSchema,
                                    connection.getCatalog(),
                                    calciteSchema.getName());
                        }
                    })
            .orderBy(
                    new Function1<MetaSchema, Comparable>() {
                        public Comparable apply(MetaSchema metaSchema) {
                            return (Comparable) FlatLists.of(
                                    Util.first(metaSchema.tableCatalog, ""),
                                    metaSchema.tableSchem);
                        }
                    });
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
protected MetaResultSet createResultSet(
    Map<String, Object> internalParameters, List<ColumnMetaData> columns,
    CursorFactory cursorFactory, final Frame firstFrame) {
  try {
    final QuarkConnectionImpl connection = getConnection();
    final AvaticaStatement statement = connection.createStatement();
    final CalcitePrepare.CalciteSignature<Object> signature =
        new CalcitePrepare.CalciteSignature<Object>("",
            ImmutableList.<AvaticaParameter>of(), internalParameters, null,
            columns, cursorFactory, null, ImmutableList.<RelCollation>of(), -1,
            null, Meta.StatementType.SELECT) {
          @Override public Enumerable<Object> enumerable(
              DataContext dataContext) {
            return Linq4j.asEnumerable(firstFrame.rows);
          }
        };
    return MetaResultSet.create(connection.id, statement.getId(), true,
        signature, firstFrame);
  } catch (SQLException e) {
    throw new RuntimeException(e);
  }
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
@Override
public Frame fetch(StatementHandle h, long offset, int fetchMaxRowCount) {
  final QuarkConnectionImpl calciteConnection = getConnection();
  QuarkJdbcStatement stmt = calciteConnection.server.getStatement(h);
  final Signature signature = stmt.getSignature();
  final Iterator<Object> iterator;
  if (stmt.getResultSet() == null) {
    final Iterable<Object> iterable =
        Linq4j.emptyEnumerable();
    iterator = iterable.iterator();
    stmt.setResultSet(iterator);
  } else {
    iterator = stmt.getResultSet();
  }
  final List<List<Object>> list = new ArrayList<>();
  List<List<Object>> rows =
      MetaImpl.collect(signature.cursorFactory,
          LimitIterator.of(iterator, fetchMaxRowCount), list);
  boolean done = fetchMaxRowCount == 0 || list.size() < fetchMaxRowCount;
  return new Meta.Frame(offset, done, (List<Object>) (List) rows);
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
@Test public void testUnnestItemsInMapWithNoAliasAndAdditionalArgument()
    throws SQLException {
  Connection connection = DriverManager.getConnection("jdbc:calcite:");
  final String sql =
      "select * from unnest(MAP['a', 1, 'b', 2], array[5, 6, 7])";
  ResultSet resultSet = connection.createStatement().executeQuery(sql);

  List<String> map = FlatLists.of("KEY=a; VALUE=1", "KEY=b; VALUE=2");
  List<String> array = FlatLists.of(" EXPR$1=5", " EXPR$1=6", " EXPR$1=7");

  final StringBuilder b = new StringBuilder();
  for (List<String> row : Linq4j.product(FlatLists.of(map, array))) {
    b.append(row.get(0)).append(";").append(row.get(1)).append("\n");
  }
  final String expected = b.toString();

  assertThat(CalciteAssert.toString(resultSet), is(expected));
  connection.close();
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
@Override
public Queryable<Object[]> asQueryable(QueryProvider queryProvider, SchemaPlus schemaPlus, String tableName) {
    return new AbstractTableQueryable<Object[]>(queryProvider, schemaPlus, this, tableName) {
        @Override
        public Enumerator<Object[]> enumerator() {
            FluentIterable<Object[]> it = FluentIterable
                    .from(references)
                    .transform(new Function<NamedReference, Object[]>() {
                        @Nullable
                        @Override
                        public Object[] apply(@Nullable NamedReference namedReference) {
                            HeapReference ref = null;
                            try {
                                ref = HeapReference.valueOf(namedReference.getObject());
                            } catch (SnapshotException e) {
                                e.printStackTrace();
                            }
                            return new Object[]{namedReference.getName(), ref};
                        }
                    });

            return Linq4j.iterableEnumerator(it);
        }
    };
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
public Enumerable<Object[]> scan(DataContext root) {
  final Random random = seed >= 0 ? new Random(seed) : new Random();
  final Maze maze = new Maze(width, height);
  final PrintWriter pw = Util.printWriter(System.out);
  maze.layout(random, pw);
  if (Maze.DEBUG) {
    maze.print(pw, true);
  }
  return new AbstractEnumerable<Object[]>() {
    public Enumerator<Object[]> enumerator() {
      final Set<Integer> solutionSet;
      if (solution) {
        solutionSet = maze.solve(0, 0);
      } else {
        solutionSet = null;
      }
      return Linq4j.transform(maze.enumerator(solutionSet),
          new Function1<String, Object[]>() {
            public Object[] apply(String s) {
              return new Object[] {s};
            }
          });
    }
  };
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
@Test public void testZip() {
  final Enumerable<String> e1 = Linq4j.asEnumerable(Arrays.asList("a", "b", "c"));
  final Enumerable<String> e2 = Linq4j.asEnumerable(Arrays.asList("1", "2", "3"));

  final Enumerable<String> zipped = e1.zip(e2,
      new Function2<String, String, String>() {
        public String apply(String v0, String v1) {
          return v0 + v1;
        }
      });
  assertEquals(3, zipped.count());
  zipped.enumerator().reset();
  for (int i = 0; i < 3; i++) {
    assertEquals("" + (char) ('a' + i) + (char) ('1' + i), zipped.elementAt(i));
  }
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
@Test public void testFlatListProduct() {
  final List<Enumerator<List<String>>> list = new ArrayList<>();
  list.add(Linq4j.enumerator(l2(l1("a"), l1("b"))));
  list.add(Linq4j.enumerator(l3(l2("x", "p"), l2("y", "q"), l2("z", "r"))));
  final Enumerable<FlatLists.ComparableList<String>> product =
      SqlFunctions.product(list, 3, false);
  int n = 0;
  FlatLists.ComparableList<String> previous = FlatLists.of();
  for (FlatLists.ComparableList<String> strings : product) {
    if (n++ == 1) {
      assertThat(strings.size(), is(3));
      assertThat(strings.get(0), is("a"));
      assertThat(strings.get(1), is("y"));
      assertThat(strings.get(2), is("q"));
    }
    if (previous != null) {
      assertTrue(previous.compareTo(strings) < 0);
    }
    previous = strings;
  }
  assertThat(n, is(6));
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
@Test public void testToMapWithComparer() {
  final Map<String, String> map =
      Linq4j.asEnumerable(Arrays.asList("foo", "bar", "far"))
          .toMap(Functions.<String>identitySelector(), new EqualityComparer<String>() {
            public boolean equal(String v1, String v2) {
              return String.CASE_INSENSITIVE_ORDER.compare(v1, v2) == 0;
            }
            public int hashCode(String s) {
              return s == null ? Objects.hashCode(null)
                  : s.toLowerCase(Locale.ROOT).hashCode();
            }
          });
  assertEquals(3, map.size());
  assertTrue(map.get("foo").equals("foo"));
  assertTrue(map.get("Foo").equals("foo"));
  assertTrue(map.get("FOO").equals("foo"));
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
public <T> Queryable<T> asQueryable(final QueryProvider queryProvider,
    SchemaPlus schema, String tableName) {
  return new AbstractQueryable<T>() {
    public Type getElementType() {
      return elementType;
    }

    public Expression getExpression() {
      return expression;
    }

    public QueryProvider getProvider() {
      return queryProvider;
    }

    public Iterator<T> iterator() {
      //noinspection unchecked
      return list.iterator();
    }

    public Enumerator<T> enumerator() {
      //noinspection unchecked
      return Linq4j.enumerator(list);
    }
  };
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
@Test public void testContainsWithEqualityComparer() {
  EqualityComparer<Employee> compareByEmpno =
      new EqualityComparer<Employee>() {
        public boolean equal(Employee e1, Employee e2) {
          return e1 != null && e2 != null
              && e1.empno == e2.empno;
        }

        public int hashCode(Employee t) {
          return t == null ? 0x789d : t.hashCode();
        }
      };

  Employee e = emps[1];
  Employee employeeClone = new Employee(e.empno, e.name, e.deptno);
  Employee employeeOther = badEmps[0];

  assertEquals(e, employeeClone);
  assertTrue(Linq4j.asEnumerable(emps)
      .contains(e, compareByEmpno));
  assertTrue(Linq4j.asEnumerable(emps)
      .contains(employeeClone, compareByEmpno));
  assertFalse(Linq4j.asEnumerable(emps)
      .contains(employeeOther, compareByEmpno));

}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
/**
 * Tests the version of
 * {@link ExtendedEnumerable#aggregate}
 * that has a result selector. Note how similar it is to
 * {@link #testGroupBy()}.
 */
@Test public void testAggregate2() {
  String s =
      Linq4j.asEnumerable(emps)
          .aggregate(
              new Function0<String>() {
                public String apply() {
                  return null;
                }
              }.apply(), //CHECKSTYLE: IGNORE 0
              new Function2<String, Employee, String>() {
                public String apply(String v1, Employee e0) {
                  return v1 == null ? e0.name : (v1 + "+" + e0.name);
                }
              },
              new Function1<String, String>() {
                public String apply(String v2) {
                  return "<no key>: " + v2;
                }
              });
  assertEquals(
      "<no key>: Fred+Bill+Eric+Janet",
      s);
}
 

import org.apache.calcite.linq4j.Linq4j; //导入依赖的package包/类
@Test public void testGroupByWithKeySelectorAndElementSelectorAndResultSelector() {
  String s =
      Linq4j.asEnumerable(emps)
          .groupBy(EMP_DEPTNO_SELECTOR, EMP_NAME_SELECTOR,
              new Function2<Integer, Enumerable<String>, String>() {
                public String apply(Integer key, Enumerable<String> group) {
                  return String.format(Locale.ROOT, "%s: %s", key,
                      stringJoin("+", group));
                }
              })
          .toList()
          .toString();
  assertEquals(
      "[10: Fred+Eric+Janet, 30: Bill]",
      s);
}