org.exolab.castor.jdo.oql
Class ParseTreeWalker

java.lang.Object
  org.exolab.castor.jdo.oql.ParseTreeWalker

public class ParseTreeWalker
extends Object

A class which walks the parse tree created by the parser to check for errors and translate to SQL.

Version:

$Revision: 8459 $ $Date: 2006-04-25 15:08:23 -0600 (Tue, 25 Apr 2006) $

Author:

Nissim Karpenstein

Field Summary

static int	AGGREGATE
static int	DEPENDANT_OBJECT
static int	DEPENDANT_OBJECT_VALUE
static int	DEPENDANT_VALUE
static int	FUNCTION
static int	MAX_TABLE_LENGTH
static int	PARENT_OBJECT

Constructor Summary

ParseTreeWalker(LockEngine dbEngine, ParseTreeNode parseTree, ClassLoader classLoader, DbMetaInfo dbInfo)
Creates a new parse tree walker.

Method Summary

String	buildTableAlias(String tableName, Vector<String> path, int tableIndex) Builds the alias name for a table from the path info.
ClassDescriptor	getClassDescriptor() Accessor method for _clsDesc.
Class<?>	getObjClass() Accessor method for _objClass.
Hashtable<Integer,ParamInfo>	getParamInfo() Accessor method for _paramInfo.
Vector<String>	getProjectionInfo() Method to get path info for the selected object.
int	getProjectionType() Accessor method for _projectionType.
QueryExpression	getQueryExpression() Accessor method for private _queryExpr member.

Methods inherited from class java.lang.Object

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

Field Detail

AGGREGATE

public static final int AGGREGATE

See Also:

Constant Field Values

FUNCTION

public static final int FUNCTION

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Constant Field Values

PARENT_OBJECT

public static final int PARENT_OBJECT

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Constant Field Values

DEPENDANT_OBJECT

public static final int DEPENDANT_OBJECT

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Constant Field Values

DEPENDANT_OBJECT_VALUE

public static final int DEPENDANT_OBJECT_VALUE

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Constant Field Values

DEPENDANT_VALUE

public static final int DEPENDANT_VALUE

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Constant Field Values

MAX_TABLE_LENGTH

public static final int MAX_TABLE_LENGTH

See Also:

Constant Field Values

Constructor Detail

ParseTreeWalker

public ParseTreeWalker(LockEngine dbEngine,
                       ParseTreeNode parseTree,
                       ClassLoader classLoader,
                       DbMetaInfo dbInfo)
                throws QueryException

Creates a new parse tree walker. Which checks the tree for errors, and generates a QueryExpression containing the SQL translation.

Parameters:

dbEngine - The Persistence Engine

parseTree - The parse tree to walk

classLoader - A ClassLoader instance to load classes.

Throws:

QueryException - Thrown by checkErrors.

Method Detail

getObjClass

public Class<?> getObjClass()

Accessor method for _objClass.

Returns:

The _objClass member.

getProjectionType

public int getProjectionType()

Accessor method for _projectionType.

Returns:

The _projectionType member.

getQueryExpression

public QueryExpression getQueryExpression()

Accessor method for private _queryExpr member.

Returns:

private _queryExpr member

getParamInfo

public Hashtable<Integer,ParamInfo> getParamInfo()

Accessor method for _paramInfo.

Returns:

The _paramInfo member.

getClassDescriptor

public ClassDescriptor getClassDescriptor()

Accessor method for _clsDesc.

Returns:

The _clsDesc member.

getProjectionInfo

public Vector<String> getProjectionInfo()

Method to get path info for the selected object. This is the path which will be used by the QueryResults to follow the path if the object selected is a DEPENDANT_OBJECT or DEPENDANT_OBJECT_VALUE. Any other projectionTypes do not need this, so null will be returned.

Returns:

Path info for the selected element, null otherwise.

buildTableAlias

public String buildTableAlias(String tableName,
                              Vector<String> path,
                              int tableIndex)

Builds the alias name for a table from the path info.

Parameters:

tableName - The name of the table to add to the select clause

path - The path info vector to build the alias with

tableIndex - Field index in the path info

Returns:

Alias name for a given table.