示例#1
0
文件: RexUtil.java 项目: kunlqt/optiq
 /**
  * Returns whether a node represents the NULL value.
  *
  * <p>Examples:
  *
  * <ul>
  *   <li>For {@link org.eigenbase.rex.RexLiteral} Unknown, returns false.
  *   <li>For <code>CAST(NULL AS <i>type</i>)</code>, returns true if <code>
  * allowCast</code> is true, false otherwise.
  *   <li>For <code>CAST(CAST(NULL AS <i>type</i>) AS <i>type</i>))</code>, returns false.
  * </ul>
  */
 public static boolean isNullLiteral(RexNode node, boolean allowCast) {
   if (node instanceof RexLiteral) {
     RexLiteral literal = (RexLiteral) node;
     if (literal.getTypeName() == SqlTypeName.NULL) {
       assert (null == literal.getValue());
       return true;
     } else {
       // We don't regard UNKNOWN -- SqlLiteral(null,Boolean) -- as
       // NULL.
       return false;
     }
   }
   if (allowCast) {
     if (node.isA(RexKind.Cast)) {
       RexCall call = (RexCall) node;
       if (isNullLiteral(call.operands[0], false)) {
         // node is "CAST(NULL as type)"
         return true;
       }
     }
   }
   return false;
 }
示例#2
0
 /** Converts an expression from {@link RexNode} to {@link SqlNode} format. */
 SqlNode toSql(RexProgram program, RexNode rex) {
   if (rex instanceof RexLocalRef) {
     final int index = ((RexLocalRef) rex).getIndex();
     return toSql(program, program.getExprList().get(index));
   } else if (rex instanceof RexInputRef) {
     return field(((RexInputRef) rex).getIndex());
   } else if (rex instanceof RexLiteral) {
     final RexLiteral literal = (RexLiteral) rex;
     switch (literal.getTypeName().getFamily()) {
       case CHARACTER:
         return SqlLiteral.createCharString((String) literal.getValue2(), POS);
       case NUMERIC:
       case EXACT_NUMERIC:
         return SqlLiteral.createExactNumeric(literal.getValue().toString(), POS);
       case APPROXIMATE_NUMERIC:
         return SqlLiteral.createApproxNumeric(literal.getValue().toString(), POS);
       case BOOLEAN:
         return SqlLiteral.createBoolean((Boolean) literal.getValue(), POS);
       case DATE:
         return SqlLiteral.createDate((Calendar) literal.getValue(), POS);
       case TIME:
         return SqlLiteral.createTime(
             (Calendar) literal.getValue(), literal.getType().getPrecision(), POS);
       case TIMESTAMP:
         return SqlLiteral.createTimestamp(
             (Calendar) literal.getValue(), literal.getType().getPrecision(), POS);
       case ANY:
         switch (literal.getTypeName()) {
           case NULL:
             return SqlLiteral.createNull(POS);
             // fall through
         }
       default:
         throw new AssertionError(literal + ": " + literal.getTypeName());
     }
   } else if (rex instanceof RexCall) {
     final RexCall call = (RexCall) rex;
     final SqlOperator op = call.getOperator();
     final List<SqlNode> nodeList = toSql(program, call.getOperands());
     if (op == SqlStdOperatorTable.CAST) {
       RelDataType type = call.getType();
       if (type.getSqlTypeName() == SqlTypeName.VARCHAR
           && dialect.getDatabaseProduct() == SqlDialect.DatabaseProduct.MYSQL) {
         // MySQL doesn't have a VARCHAR type, only CHAR.
         nodeList.add(
             new SqlDataTypeSpec(
                 new SqlIdentifier("CHAR", POS), type.getPrecision(), -1, null, null, POS));
       } else {
         nodeList.add(toSql(type));
       }
     }
     if (op == SqlStdOperatorTable.CASE) {
       final SqlNode valueNode;
       final List<SqlNode> whenList = Expressions.list();
       final List<SqlNode> thenList = Expressions.list();
       final SqlNode elseNode;
       if (nodeList.size() % 2 == 0) {
         // switched:
         //   "case x when v1 then t1 when v2 then t2 ... else e end"
         valueNode = nodeList.get(0);
         for (int i = 1; i < nodeList.size() - 1; i += 2) {
           whenList.add(nodeList.get(i));
           thenList.add(nodeList.get(i + 1));
         }
       } else {
         // other: "case when w1 then t1 when w2 then t2 ... else e end"
         valueNode = null;
         for (int i = 0; i < nodeList.size() - 1; i += 2) {
           whenList.add(nodeList.get(i));
           thenList.add(nodeList.get(i + 1));
         }
       }
       elseNode = nodeList.get(nodeList.size() - 1);
       return op.createCall(
           POS,
           valueNode,
           new SqlNodeList(whenList, POS),
           new SqlNodeList(thenList, POS),
           elseNode);
     }
     if (op instanceof SqlBinaryOperator && nodeList.size() > 2) {
       // In RexNode trees, OR and AND have any number of children;
       // SqlCall requires exactly 2. So, convert to a left-deep binary tree.
       return createLeftCall(op, nodeList);
     }
     return op.createCall(new SqlNodeList(nodeList, POS));
   } else {
     throw new AssertionError(rex);
   }
 }