org.apache.openjpa.kernel.exps
Class AbstractExpressionBuilder

java.lang.Object
  org.apache.openjpa.kernel.exps.AbstractExpressionBuilder

public abstract class AbstractExpressionBuilder
extends Object

Abstract base class to help build expressions. Provides generic language-independent support for variable resolution, path traversal, and error messages.

Author:

Marc Prud'hommeaux

Field Summary

protected static int	CONTAINS_TYPE_ELEMENT
protected static int	CONTAINS_TYPE_KEY
protected static int	CONTAINS_TYPE_VALUE
protected static int	EX_FATAL
protected static int	EX_UNSUPPORTED
protected static int	EX_USER
protected ExpressionFactory	factory
protected Resolver	resolver
protected static Class	TYPE_CHAR_OBJ
protected static Class	TYPE_COLLECTION
protected static Class	TYPE_MAP
protected static Class	TYPE_NUMBER
protected static Class	TYPE_OBJECT
protected static Class	TYPE_STRING

Constructor Summary

AbstractExpressionBuilder(ExpressionFactory factory, Resolver resolver)
Constructor.

Method Summary

protected ClassMetaData	addAccessPath(ClassMetaData meta) Register the specified metadata as being in the query's access path.
protected void	assertUnboundVariablesValid() Validate that all unbound variables are of a PC type.
protected void	bind(Value var) Record that the given variable is bound.
protected abstract String	currentQuery() Returns the current string being parsed; used for error messages.
protected ClassMetaData[]	getAccessPath() Return the recorded query access path.
protected abstract ClassLoader	getClassLoader() Returns the class loader that should be used for resolving class names (in addition to the resolver in the query).
protected abstract Class	getDeclaredVariableType(String name) Returns the type of the named variabe if it has been declared.
protected abstract Localizer	getLocalizer() Used for obtaining the Localizer to use for translating error messages.
protected ClassMetaData	getMetaData(Class c, boolean required) Convenience method to get metadata for the given type.
protected ClassMetaData	getMetaData(Class c, boolean required, ClassLoader loader) Convenience method to get metadata for the given type.
protected Value	getVariable(String id, boolean bind) Returns a value for the given id.
protected boolean	isBound(Value var) Return true if the given variable has been bound.
protected abstract boolean	isDeclaredVariable(String id) Returns whether the specified variable name has been explicitly declared.
protected boolean	isSeenVariable(String id) Return whether the given id has been used as a variable.
protected OpenJPAException	parseException(int e, String token, Object[] args, Exception nest) Create a proper parse exception for the given reason.
protected void	setImplicitContainsTypes(Value val1, Value val2, int op) Set the implicit types of the given values based on the fact that the first is supposed to contain the second.
protected static void	setImplicitType(Value val, Class expected) Set the implicit type of the given value to the given class.
protected void	setImplicitTypes(Value val1, Value val2, Class expected) Set the implicit types of the given values based on the fact that they're used together, and based on the operator type.
protected Value	traversePath(Path path, String field) Traverse the given field in the given path.
protected Value	traversePath(Path path, String field, boolean pcOnly, boolean allowNull) Traverse the given field in the given path.
protected Object	traverseStaticField(Class cls, String field) Return a constant containing the value of the given static field.

Methods inherited from class java.lang.Object

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

Field Detail

EX_USER

protected static final int EX_USER

See Also:

Constant Field Values

EX_FATAL

protected static final int EX_FATAL

See Also:

Constant Field Values

EX_UNSUPPORTED

protected static final int EX_UNSUPPORTED

See Also:

Constant Field Values

TYPE_OBJECT

protected static final Class TYPE_OBJECT

TYPE_STRING

protected static final Class TYPE_STRING

TYPE_CHAR_OBJ

protected static final Class TYPE_CHAR_OBJ

TYPE_NUMBER

protected static final Class TYPE_NUMBER

TYPE_COLLECTION

protected static final Class TYPE_COLLECTION

TYPE_MAP

protected static final Class TYPE_MAP

CONTAINS_TYPE_ELEMENT

protected static final int CONTAINS_TYPE_ELEMENT

See Also:

Constant Field Values

CONTAINS_TYPE_KEY

protected static final int CONTAINS_TYPE_KEY

See Also:

Constant Field Values

CONTAINS_TYPE_VALUE

protected static final int CONTAINS_TYPE_VALUE

See Also:

Constant Field Values

resolver

protected final Resolver resolver

factory

protected ExpressionFactory factory

Constructor Detail

AbstractExpressionBuilder

public AbstractExpressionBuilder(ExpressionFactory factory,
                                 Resolver resolver)

Constructor.

Parameters:

factory - the expression factory to use

resolver - used to resolve variables, parameters, and class names used in the query

Method Detail

getClassLoader

protected abstract ClassLoader getClassLoader()

Returns the class loader that should be used for resolving class names (in addition to the resolver in the query).

parseException

protected OpenJPAException parseException(int e,
                                          String token,
                                          Object[] args,
                                          Exception nest)

Create a proper parse exception for the given reason.

addAccessPath

protected ClassMetaData addAccessPath(ClassMetaData meta)

Register the specified metadata as being in the query's access path.

getAccessPath

protected ClassMetaData[] getAccessPath()

Return the recorded query access path.

isBound

protected boolean isBound(Value var)

Return true if the given variable has been bound.

bind

protected void bind(Value var)

Record that the given variable is bound.

getVariable

protected Value getVariable(String id,
                            boolean bind)

Returns a value for the given id.

assertUnboundVariablesValid

protected void assertUnboundVariablesValid()

Validate that all unbound variables are of a PC type. If not, assume that the user actually made a typo that we took for an implicit unbound variable.

isDeclaredVariable

protected abstract boolean isDeclaredVariable(String id)

Returns whether the specified variable name has been explicitly declared. Note all query languages necessarily support declaring variables.

Parameters:

id - the variable to check

Returns:

true if the variabe has been explicitely declared

isSeenVariable

protected boolean isSeenVariable(String id)

Return whether the given id has been used as a variable.

getMetaData

protected ClassMetaData getMetaData(Class c,
                                    boolean required)

Convenience method to get metadata for the given type.

getMetaData

protected ClassMetaData getMetaData(Class c,
                                    boolean required,
                                    ClassLoader loader)

Convenience method to get metadata for the given type.

traversePath

protected Value traversePath(Path path,
                             String field)

Traverse the given field in the given path.

traversePath

protected Value traversePath(Path path,
                             String field,
                             boolean pcOnly,
                             boolean allowNull)

Traverse the given field in the given path.

traverseStaticField

protected Object traverseStaticField(Class cls,
                                     String field)

Return a constant containing the value of the given static field.

getDeclaredVariableType

protected abstract Class getDeclaredVariableType(String name)

Returns the type of the named variabe if it has been declared.

setImplicitTypes

protected void setImplicitTypes(Value val1,
                                Value val2,
                                Class expected)

Set the implicit types of the given values based on the fact that they're used together, and based on the operator type.

setImplicitContainsTypes

protected void setImplicitContainsTypes(Value val1,
                                        Value val2,
                                        int op)

Set the implicit types of the given values based on the fact that the first is supposed to contain the second.

setImplicitType

protected static void setImplicitType(Value val,
                                      Class expected)

Set the implicit type of the given value to the given class.

getLocalizer

protected abstract Localizer getLocalizer()

Used for obtaining the Localizer to use for translating error messages.

currentQuery

protected abstract String currentQuery()

Returns the current string being parsed; used for error messages.