org.eigenbase.sql.validate
Class DelegatingScope

java.lang.Object
  org.eigenbase.sql.validate.DelegatingScope

All Implemented Interfaces:

SqlValidatorScope

Direct Known Subclasses:

AggregatingSelectScope, ListScope, OrderByScope

public abstract class DelegatingScope
extends Object
implements SqlValidatorScope

A scope which delegates all requests to its parent scope. Use this as a base class for defining nested scopes.

Since:

Mar 25, 2003

Version:

$Id: //open/dev/farrago/src/org/eigenbase/sql/validate/DelegatingScope.java#19 $

Author:

jhyde

Field Summary

protected SqlValidatorScope	parent Parent scope.
protected SqlValidatorImpl	validator

Constructor Summary

DelegatingScope(SqlValidatorScope parent)
Creates a DelegatingScope.

Method Summary

void	addChild(SqlValidatorNamespace ns, String alias) Registers a relation in this scope.
protected void	addColumnNames(SqlValidatorNamespace ns, List<SqlMoniker> colNames)
void	findAliases(List<SqlMoniker> result) Collects the SqlMonikers of all table aliases (uses of tables in query FROM clauses) available in this scope.
void	findAllColumnNames(List<SqlMoniker> result) Collects the SqlMonikers of all possible columns in this scope.
String	findQualifyingTableName(String columnName, SqlNode ctx) Finds the table alias which is implicitly qualifying an unqualified column name.
SqlIdentifier	fullyQualify(SqlIdentifier identifier) Converts an identifier into a fully-qualified identifier.
SqlMonotonicity	getMonotonicity(SqlNode expr) Returns whether an expression is monotonic in this scope.
SqlValidatorScope	getOperandScope(SqlCall call) Returns the scope within which operands to a call are to be validated.
SqlNodeList	getOrderList() Returns the expressions by which the rows in this scope are sorted.
SqlValidatorScope	getParent() Returns the parent scope of this DelegatingScope.
SqlValidator	getValidator() Returns the validator which created this scope.
SqlWindow	lookupWindow(String name) Finds a window with a given name.
SqlValidatorNamespace	resolve(String name, SqlValidatorScope[] ancestorOut, int[] offsetOut) Looks up a node with a given name.
RelDataType	resolveColumn(String name, SqlNode ctx) Resolves a single identifier to a column, and returns the datatype of that column.
void	validateExpr(SqlNode expr) Performs any scope-specific validation of an expression.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface org.eigenbase.sql.validate.SqlValidatorScope

getNode

Field Detail

parent

protected final SqlValidatorScope parent

Parent scope. This is where to look next to resolve an identifier; it is not always the parent object in the parse tree.

This is never null: at the top of the tree, it is an EmptyScope.

validator

protected final SqlValidatorImpl validator

Constructor Detail

DelegatingScope

DelegatingScope(SqlValidatorScope parent)

Creates a DelegatingScope.

Parameters:

parent - Parent scope

Method Detail

addChild

public void addChild(SqlValidatorNamespace ns,
                     String alias)

Description copied from interface: SqlValidatorScope

Registers a relation in this scope.

Specified by:

addChild in interface SqlValidatorScope

Parameters:

ns - Namespace representing the result-columns of the relation

alias - Alias with which to reference the relation, must not be null

resolve

public SqlValidatorNamespace resolve(String name,
                                     SqlValidatorScope[] ancestorOut,
                                     int[] offsetOut)

Description copied from interface: SqlValidatorScope

Looks up a node with a given name. Returns null if none is found.

Specified by:

resolve in interface SqlValidatorScope

Parameters:

name - Name of node to find

ancestorOut - If not null, writes the ancestor scope here

offsetOut - If not null, writes the offset within the ancestor here

addColumnNames

protected void addColumnNames(SqlValidatorNamespace ns,
                              List<SqlMoniker> colNames)

findAllColumnNames

public void findAllColumnNames(List<SqlMoniker> result)

Description copied from interface: SqlValidatorScope

Collects the SqlMonikers of all possible columns in this scope.

Specified by:

findAllColumnNames in interface SqlValidatorScope

Parameters:

result - an array list of strings to add the result to

findAliases

public void findAliases(List<SqlMoniker> result)

Description copied from interface: SqlValidatorScope

Collects the SqlMonikers of all table aliases (uses of tables in query FROM clauses) available in this scope.

Specified by:

findAliases in interface SqlValidatorScope

Parameters:

result - a list of monikers to add the result to

findQualifyingTableName

public String findQualifyingTableName(String columnName,
                                      SqlNode ctx)

Description copied from interface: SqlValidatorScope

Finds the table alias which is implicitly qualifying an unqualified column name. Throws an error if there is not exactly one table.

This method is only implemented in scopes (such as SelectScope) which can be the context for name-resolution. In scopes such as IdentifierNamespace, it throws UnsupportedOperationException.

Specified by:

findQualifyingTableName in interface SqlValidatorScope

Parameters:

columnName - Column name

ctx - Validation context, to appear in any error thrown

Returns:

Table alias

resolveColumn

public RelDataType resolveColumn(String name,
                                 SqlNode ctx)

Description copied from interface: SqlValidatorScope

Resolves a single identifier to a column, and returns the datatype of that column.

If it cannot find the column, returns null. If the column is ambiguous, throws an error with context ctx.

Specified by:

resolveColumn in interface SqlValidatorScope

Parameters:

name - Name of column

ctx - Context for exception

Returns:

Type of column, if found and unambiguous; null if not found

getOperandScope

public SqlValidatorScope getOperandScope(SqlCall call)

Description copied from interface: SqlValidatorScope

Returns the scope within which operands to a call are to be validated. Usually it is this scope, but when the call is to an aggregate function and this is an aggregating scope, it will be a a different scope.

Specified by:

getOperandScope in interface SqlValidatorScope

Parameters:

call - Call

Returns:

Scope within which to validate arguments to call.

getValidator

public SqlValidator getValidator()

Description copied from interface: SqlValidatorScope

Returns the validator which created this scope.

Specified by:

getValidator in interface SqlValidatorScope

fullyQualify

public SqlIdentifier fullyQualify(SqlIdentifier identifier)

Converts an identifier into a fully-qualified identifier. For example, the "empno" in "select empno from emp natural join dept" becomes "emp.empno".

If the identifier cannot be resolved, throws. Never returns null.

Specified by:

fullyQualify in interface SqlValidatorScope

validateExpr

public void validateExpr(SqlNode expr)

Description copied from interface: SqlValidatorScope

Performs any scope-specific validation of an expression. For example, an aggregating scope requires that expressions are valid aggregations. The expression has already been validated.

Specified by:

validateExpr in interface SqlValidatorScope

lookupWindow

public SqlWindow lookupWindow(String name)

Description copied from interface: SqlValidatorScope

Finds a window with a given name. Returns null if not found.

Specified by:

lookupWindow in interface SqlValidatorScope

getMonotonicity

public SqlMonotonicity getMonotonicity(SqlNode expr)

Description copied from interface: SqlValidatorScope

Returns whether an expression is monotonic in this scope. For example, if the scope has previously been sorted by columns X, Y, then X is monotonic in this scope, but Y is not.

Specified by:

getMonotonicity in interface SqlValidatorScope

getOrderList

public SqlNodeList getOrderList()

Description copied from interface: SqlValidatorScope

Returns the expressions by which the rows in this scope are sorted. If the rows are unsorted, returns null.

Specified by:

getOrderList in interface SqlValidatorScope

getParent

public SqlValidatorScope getParent()

Returns the parent scope of this DelegatingScope.