opendap.dap
Class Alias

java.lang.Object
  opendap.dap.Attribute
      opendap.dap.Alias

All Implemented Interfaces:

java.io.Serializable, java.lang.Cloneable

public class Alias
extends Attribute
implements java.lang.Cloneable

The Alias type is a special attribute. It is simply a reference (like a "soft link" in a UNIX file system) to another attribute.

The rules for the definiton and interpretation an Alias are as follows:

In the persistent representation of the DDS (XML, or old DAS & DDS syntax) Alias definitions will contain 2 fields: name, attribute. Example from a DDS:

 Alias CalDate  .profiler.cast.conductivity.calibration.date
 

Or a DDX:

 <Alias name="CalDate" attribute=".profiler.cast.conductivity.calibration.date"/>
 

The rules for the interpretation of these fields are as follows:

• Then Alias defintion begins with the word Alias
• The name field is consumed in it's entirety (unparsed) and used as the name of the Alias.

• There a number of rules specific to the representation and interpretation of the attribute field in the Alias declaration.
• The " (double quote) and the \ (backslash aka escape) characters MUST be escaped (using \ character) in the value of the attribute field.
• Each variable and attribute name in the attribute field must be enclosed in double quotes if their values contain the dot (.) character. For example: .sometimes."names.contain".dots would be three names sometimes, names.contain, and dots.
• Fully qualified attribute names always begin with the dot (.) character.
• All attribute names always MUST be fully qualified (begin with a dot). The leading dot represents a fully qualifed path attribute reference, starting at top level of DDX, or the DAS.
• If the attribute field contains only the dot (.) character, then it is referencing the collection of attributes associated with the highest level of the Dataset (global attributes) This collection always exists, but may be empty.
• The attribute field MUST NOT be empty.
• The attribute field MUST NOT point to another Alias.
• After the parser has completely parsed the DDX (or DAS) it will attempt to reslove each alias to a specific attribute. If an alias cannot be resolved to some attribute, and exception will be thrown by the parser.

Warning: DAS and DDS objects built using methods other than DDS.parse(), DDS.parseXML, DDS.getDAS(), or DAS.parse() must call DDS.resolveAliases() or DAS.resolveAliases() prior to allowing client software access to these objects. Since an Alias essentially represents a "pointer" to some (other) Attribute, that Attribute object must be found. Once this has been done (by calling the correct resolveAliases() method) the Aliases will act transparently as references to their target Attributes.

Version:

$Revision: 23881 $

Author:

ndp

See Also:

AttributeTable, DDS, DDS.parse(java.io.InputStream), DDS.parseXML(java.io.InputStream, boolean), DDS.getDAS(), DAS, DAS.resolveAliases(), Serialized Form

Field Summary

Fields inherited from class opendap.dap.Attribute

ALIAS, BYTE, CONTAINER, FLOAT32, FLOAT64, INT16, INT32, STRING, UINT16, UINT32, UNKNOWN, URL

Constructor Summary

Alias(java.lang.String aName, java.lang.String attributeName)
Construct an Alias.

Method Summary

void	appendValue(java.lang.String value) Append a value to this attribute.
void	appendValue(java.lang.String value, boolean check) Append a value to this attribute.
java.lang.Object	clone() Returns a clone of this Attribute.
void	deleteValueAt(int index) Remove the i'th String from this attribute.
java.lang.String	getAliasedTo() Returns the name of the attribute aliased to.
java.lang.String	getAliasedToAttributeField() Returns the name of the attribute aliased to.
java.lang.String	getAliasedToAttributeFieldAsClearString() Returns the name of the attribute aliased to.
AttributeTable	getContainer() Returns the AttributeTable container.
int	getType() Returns the attribute type constant.
java.lang.String	getValueAt(int index) Returns the attribute value at index.
java.util.Enumeration	getValues() Returns the values of this attribute as an Enumeration of String.
boolean	isAlias() Returns true if the attribute is an alias.
boolean	isContainer() Returns true if the attribute is a container.
void	print(java.io.PrintWriter os, java.lang.String pad)
void	printXML(java.io.PrintWriter pw, java.lang.String pad, boolean constrained)
void	setMyAttribute(Attribute a)
void	setMyVariable(BaseType v)

Methods inherited from class opendap.dap.Attribute

getClearName, getContainerN, getName, getNumVal, getTypeString, getTypeVal, getValueAtN, getValuesIterator, print, print, print, printXML, printXML, printXML, printXML, setClearName, setName

Methods inherited from class java.lang.Object

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

Constructor Detail

Alias

public Alias(java.lang.String aName,
             java.lang.String attributeName)

Construct an Alias. This constructor is used by the DDSXMLParser to and the DAS parser build Aliases for the DDX.

Parameters:

aName - a String containing the name of the alias.

attributeName - the String containing the normalized name of the variable and attribute that this Alias references.

Method Detail

clone

public java.lang.Object clone()

Returns a clone of this Attribute. A deep copy is performed on all attribute values.

Overrides:

clone in class Attribute

Returns:

a clone of this Attribute.

setMyAttribute

public void setMyAttribute(Attribute a)

setMyVariable

public void setMyVariable(BaseType v)

getType

public int getType()

Returns the attribute type constant.

Overrides:

getType in class Attribute

Returns:

the attribute type constant.

isContainer

public boolean isContainer()

Returns true if the attribute is a container.

Overrides:

isContainer in class Attribute

Returns:

true if the attribute is a container.

isAlias

public boolean isAlias()

Returns true if the attribute is an alias.

Overrides:

isAlias in class Attribute

Returns:

true if the attribute is an alias.

getAliasedTo

public java.lang.String getAliasedTo()

Returns the name of the attribute aliased to.

Returns:

the name of the attribute aliased to.

getAliasedToAttributeFieldAsClearString

public java.lang.String getAliasedToAttributeFieldAsClearString()

Returns the name of the attribute aliased to.

Returns:

the name of the attribute aliased to.

getAliasedToAttributeField

public java.lang.String getAliasedToAttributeField()

Returns the name of the attribute aliased to.

Returns:

the name of the attribute aliased to.

getContainer

public AttributeTable getContainer()
                            throws NoSuchAttributeException

Returns the AttributeTable container.

Overrides:

getContainer in class Attribute

Returns:

the AttributeTable container.

Throws:

NoSuchAttributeException - If the instance of Attribute on which it is called is not a container.

getValues

public java.util.Enumeration getValues()
                                throws NoSuchAttributeException

Returns the values of this attribute as an Enumeration of String.

Overrides:

getValues in class Attribute

Returns:

an Enumeration of String.

Throws:

NoSuchAttributeException

getValueAt

public java.lang.String getValueAt(int index)
                            throws NoSuchAttributeException

Returns the attribute value at index.

Overrides:

getValueAt in class Attribute

Parameters:

index - the index of the attribute value to return.

Returns:

the attribute String at index.

Throws:

NoSuchAttributeException

appendValue

public void appendValue(java.lang.String value)
                 throws AttributeBadValueException

Append a value to this attribute. Always checks the validity of the attribute's value.

Overrides:

appendValue in class Attribute

Parameters:

value - the attribute String to add.

Throws:

AttributeBadValueException - thrown if the value is not a legal member of type

appendValue

public void appendValue(java.lang.String value,
                        boolean check)
                 throws AttributeBadValueException

Append a value to this attribute.

Overrides:

appendValue in class Attribute

Parameters:

value - the attribute String to add.

check - if true, check the validity of he attribute's value, if false don't.

Throws:

AttributeBadValueException - thrown if the value is not a legal member of type

deleteValueAt

public void deleteValueAt(int index)
                   throws AttributeBadValueException

Remove the i'th String from this attribute.

Overrides:

deleteValueAt in class Attribute

Parameters:

index - the index of the value to remove.

Throws:

AttributeBadValueException

print

public void print(java.io.PrintWriter os,
                  java.lang.String pad)

Overrides:

print in class Attribute

printXML

public void printXML(java.io.PrintWriter pw,
                     java.lang.String pad,
                     boolean constrained)

Overrides:

printXML in class Attribute