org.eigenbase.sql
Class SqlWindowOperator

java.lang.Object
  org.eigenbase.sql.SqlOperator
      org.eigenbase.sql.SqlWindowOperator

public class SqlWindowOperator
extends SqlOperator

An operator describing a window specification.

Operands are as follows:

• 0: name of referenced window (SqlIdentifier)
• 1: partition clause (SqlNodeList)
• 2: order clause (SqlNodeList)
• 3: isRows (SqlLiteral)
• 4: lowerBound (SqlNode)
• 5: upperBound (SqlNode)

All operands are optional.

Since:

Oct 19, 2004

Version:

$Id: //open/dev/farrago/src/org/eigenbase/sql/SqlWindowOperator.java#23 $

Author:

jhyde

Nested Class Summary

(package private) static class	SqlWindowOperator.Bound An enumeration of types of bounds in a window: CURRENT ROW, UNBOUNDED PRECEDING, and UNBOUNDED FOLLOWING.
static class	SqlWindowOperator.OffsetRange
private static class	SqlWindowOperator.ValSign

Field Summary

(package private) static SqlPostfixOperator	followingOperator The FOLLOWING operator used exclusively in a window specification.
(package private) static SqlPostfixOperator	precedingOperator The PRECEDING operator used exclusively in a window specification.

Fields inherited from class org.eigenbase.sql.SqlOperator

MaxPrec, NL

Constructor Summary

SqlWindowOperator()

Method Summary

<R> void	acceptCall(SqlVisitor<R> visitor, SqlCall call, boolean onlyExpressions, SqlBasicVisitor.ArgHandler<R> argHandler) Accepts a SqlVisitor, directing an SqlBasicVisitor.ArgHandler to visit operand of a call.
private static void	checkSpecialLiterals(SqlWindow window, SqlValidator validator)
static SqlNode	createBound(SqlLiteral range)
SqlWindow	createCall(SqlIdentifier declName, SqlIdentifier refName, SqlNodeList partitionList, SqlNodeList orderList, SqlLiteral isRows, SqlNode lowerBound, SqlNode upperBound, SqlLiteral allowPartial, SqlParserPos pos)
SqlCall	createCall(SqlLiteral functionQualifier, SqlParserPos pos, SqlNode... operands) Creates a call to this operand with an array of operands.
static SqlNode	createCurrentRow(SqlParserPos pos)
SqlWindow	createCurrentRowWindow(String columnName) Creates a window (RANGE columnName CURRENT ROW).
static SqlNode	createFollowing(SqlLiteral literal, SqlParserPos pos)
static SqlNode	createPreceding(SqlLiteral literal, SqlParserPos pos)
static SqlNode	createUnboundedFollowing(SqlParserPos pos)
static SqlNode	createUnboundedPreceding(SqlParserPos pos)
SqlWindow	createUnboundedPrecedingWindow(String columnName) Creates a window (RANGE columnName UNBOUNDED PRECEDING).
static SqlWindowOperator.OffsetRange	getOffsetAndRange(SqlNode lowerBound, SqlNode upperBound, boolean physical) Converts a pair of bounds into a (range, offset) pair.
private static SqlWindowOperator.ValSign	getRangeOffset(SqlNode node, SqlPostfixOperator op) Decodes a node, representing an upper or lower bound to a window, into a range offset.
SqlSyntax	getSyntax() Returns the syntactic type of this operator.
static boolean	isCurrentRow(SqlNode node) Returns whether an expression represents the "CURRENT ROW" bound.
private static boolean	isTableSorted(SqlValidatorScope scope) This method retrieves the list of columns for the current table then walks through the list looking for a column that is monotonic (sorted)
static boolean	isUnboundedFollowing(SqlNode node) Returns whether an expression represents the "UNBOUNDED FOLLOWING" bound.
static boolean	isUnboundedPreceding(SqlNode node) Returns whether an expression represents the "UNBOUNDED PRECEDING" bound.
void	unparse(SqlWriter writer, SqlNode[] operands, int leftPrec, int rightPrec) Writes a SQL representation of a call to this operator to a writer, including parentheses if the operators on either side are of greater precedence.
void	validateCall(SqlCall call, SqlValidator validator, SqlValidatorScope scope, SqlValidatorScope operandScope) Validates a call to this operator.
private void	validateFrameBoundary(SqlNode bound, boolean isRows, SqlTypeFamily orderTypeFam, SqlValidator validator, SqlValidatorScope scope)

Methods inherited from class org.eigenbase.sql.SqlOperator

acceptCall, adjustType, argumentMustBeScalar, checkOperandCount, checkOperandTypes, createCall, createCall, createCall, deriveType, equals, getAllowedSignatures, getAllowedSignatures, getKind, getLeftPrec, getMonotonicity, getName, getOperandCountRange, getOperandTypeChecker, getOperandTypeInference, getReturnTypeInference, getRightPrec, getSignatureTemplate, hashCode, inferReturnType, inferReturnType, isAggregator, isDeterministic, isDynamicFunction, isName, leftPrec, preValidateCall, requiresDecimalExpansion, rewriteCall, rightPrec, toString, unparseListClause, unparseListClause, validateOperands

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

followingOperator

static final SqlPostfixOperator followingOperator

The FOLLOWING operator used exclusively in a window specification.

precedingOperator

static final SqlPostfixOperator precedingOperator

The PRECEDING operator used exclusively in a window specification.

Constructor Detail

SqlWindowOperator

public SqlWindowOperator()

Method Detail

getSyntax

public SqlSyntax getSyntax()

Description copied from class: SqlOperator

Returns the syntactic type of this operator.

Specified by:

getSyntax in class SqlOperator

createCall

public SqlCall createCall(SqlLiteral functionQualifier,
                          SqlParserPos pos,
                          SqlNode... operands)

Description copied from class: SqlOperator

Creates a call to this operand with an array of operands.

The position of the resulting call is the union of the pos and the positions of all of the operands.

Overrides:

createCall in class SqlOperator

Parameters:

functionQualifier - function qualifier (e.g. "DISTINCT"), may be

pos - parser position of the identifier of the call

operands - array of operands

createCall

public SqlWindow createCall(SqlIdentifier declName,
                            SqlIdentifier refName,
                            SqlNodeList partitionList,
                            SqlNodeList orderList,
                            SqlLiteral isRows,
                            SqlNode lowerBound,
                            SqlNode upperBound,
                            SqlLiteral allowPartial,
                            SqlParserPos pos)

acceptCall

public <R> void acceptCall(SqlVisitor<R> visitor,
                           SqlCall call,
                           boolean onlyExpressions,
                           SqlBasicVisitor.ArgHandler<R> argHandler)

Description copied from class: SqlOperator

Accepts a SqlVisitor, directing an SqlBasicVisitor.ArgHandler to visit operand of a call. The argument handler allows fine control about how the operands are visited, and how the results are combined.

Overrides:

acceptCall in class SqlOperator

Parameters:

visitor - Visitor

call - Call to visit

onlyExpressions - If true, ignores operands which are not expressions. For example, in the call to the AS operator

argHandler - Called for each operand

unparse

public void unparse(SqlWriter writer,
                    SqlNode[] operands,
                    int leftPrec,
                    int rightPrec)

Description copied from class: SqlOperator

Writes a SQL representation of a call to this operator to a writer, including parentheses if the operators on either side are of greater precedence.

The default implementation of this method delegates to SqlSyntax.unparse(org.eigenbase.sql.SqlWriter, org.eigenbase.sql.SqlOperator, org.eigenbase.sql.SqlNode[], int, int).

Overrides:

unparse in class SqlOperator

validateCall

public void validateCall(SqlCall call,
                         SqlValidator validator,
                         SqlValidatorScope scope,
                         SqlValidatorScope operandScope)

Description copied from class: SqlOperator

Validates a call to this operator.

This method should not perform type-derivation or perform validation related related to types. That is done later, by SqlOperator.deriveType(SqlValidator, SqlValidatorScope, SqlCall). This method should focus on structural validation.

A typical implementation of this method first validates the operands, then performs some operator-specific logic. The default implementation just validates the operands.

This method is the default implementation of SqlCall.validate(org.eigenbase.sql.validate.SqlValidator, org.eigenbase.sql.validate.SqlValidatorScope); but note that some sub-classes of SqlCall never call this method.

Overrides:

validateCall in class SqlOperator

Parameters:

call - the call to this operator

validator - the active validator

scope - validator scope

operandScope - validator scope in which to validate operands to this call; usually equal to scope, but not always because some operators introduce new scopes

See Also:

SqlNode.validateExpr(SqlValidator, SqlValidatorScope), SqlOperator.deriveType(SqlValidator, SqlValidatorScope, SqlCall)

validateFrameBoundary

private void validateFrameBoundary(SqlNode bound,
                                   boolean isRows,
                                   SqlTypeFamily orderTypeFam,
                                   SqlValidator validator,
                                   SqlValidatorScope scope)

checkSpecialLiterals

private static void checkSpecialLiterals(SqlWindow window,
                                         SqlValidator validator)

isTableSorted

private static boolean isTableSorted(SqlValidatorScope scope)

This method retrieves the list of columns for the current table then walks through the list looking for a column that is monotonic (sorted)

createCurrentRowWindow

public SqlWindow createCurrentRowWindow(String columnName)

Creates a window (RANGE columnName CURRENT ROW).

Parameters:

columnName - Order column

createUnboundedPrecedingWindow

public SqlWindow createUnboundedPrecedingWindow(String columnName)

Creates a window (RANGE columnName UNBOUNDED PRECEDING).

Parameters:

columnName - Order column

createCurrentRow

public static SqlNode createCurrentRow(SqlParserPos pos)

createUnboundedFollowing

public static SqlNode createUnboundedFollowing(SqlParserPos pos)

createUnboundedPreceding

public static SqlNode createUnboundedPreceding(SqlParserPos pos)

createFollowing

public static SqlNode createFollowing(SqlLiteral literal,
                                      SqlParserPos pos)

createPreceding

public static SqlNode createPreceding(SqlLiteral literal,
                                      SqlParserPos pos)

createBound

public static SqlNode createBound(SqlLiteral range)

isCurrentRow

public static boolean isCurrentRow(SqlNode node)

Returns whether an expression represents the "CURRENT ROW" bound.

isUnboundedPreceding

public static boolean isUnboundedPreceding(SqlNode node)

Returns whether an expression represents the "UNBOUNDED PRECEDING" bound.

isUnboundedFollowing

public static boolean isUnboundedFollowing(SqlNode node)

Returns whether an expression represents the "UNBOUNDED FOLLOWING" bound.

getOffsetAndRange

public static SqlWindowOperator.OffsetRange getOffsetAndRange(SqlNode lowerBound,
                                                              SqlNode upperBound,
                                                              boolean physical)

Converts a pair of bounds into a (range, offset) pair.

If the upper bound is unbounded, returns null, since that cannot be represented as a (range, offset) pair. (The offset would be +infinity, but what would the range be?)

Parameters:

lowerBound - Lower bound

upperBound - Upper bound

physical - Whether interval is physical (rows), as opposed to logical (values)

Returns:

range-offset pair, or null

getRangeOffset

private static SqlWindowOperator.ValSign getRangeOffset(SqlNode node,
                                                        SqlPostfixOperator op)

Decodes a node, representing an upper or lower bound to a window, into a range offset. For example, '3 FOLLOWING' is 3, '3 PRECEDING' is -3, and 'UNBOUNDED PRECEDING' or 'UNBOUNDED FOLLOWING' is null.

Parameters:

node - Node representing window bound

op - Either precedingOperator or followingOperator

Returns:

range