Package org.apache.accumulo.core.security

Class ColumnVisibility

java.lang.Object

org.apache.accumulo.core.security.ColumnVisibility

public class ColumnVisibility
extends Object

Validate the column visibility is a valid expression and set the visibility for a Mutation. See ColumnVisibility(byte[]) for the definition of an expression.

The expression is a sequence of characters from the set [A-Za-z0-9_-.] along with the binary operators "&" and "|" indicating that both operands are necessary, or the either is necessary. The following are valid expressions for visibility:

 A
 A|B
 (A|B)&(C|D)
 orange|(red&yellow)
 

The following are not valid expressions for visibility:

 A|B&C
 A=B
 A|B|
 A&|B
 ()
 )
 dog|!cat
 

In addition to the base set of visibilities, any character can be used in the expression if it is quoted. If the quoted term contains '"' or '\', then escape the character with '\'. The quote(String) method can be used to properly quote and escape terms automatically. The following is an example of a quoted term:

 "A#C" & B
 

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static class	ColumnVisibility.Node	A node in the parse tree for a visibility expression.
static class	ColumnVisibility.NodeComparator	A node comparator.
static class	ColumnVisibility.NodeType	The node types in a parse tree for a visibility expression.

Constructor Summary

Constructors

Constructor	Description
ColumnVisibility()	Creates an empty visibility.
ColumnVisibility(byte[] expression)	Creates a column visibility for a Mutation from a string already encoded in UTF-8 bytes.
ColumnVisibility(String expression)	Creates a column visibility for a Mutation.
ColumnVisibility(org.apache.hadoop.io.Text expression)	Creates a column visibility for a Mutation.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object obj)	See equals(ColumnVisibility)
boolean	equals(ColumnVisibility otherLe)	Compares two ColumnVisibilities for string equivalence, not as a meaningful comparison of terms and conditions.
byte[]	flatten()	Generates a byte[] that represents a normalized, but logically equivalent, form of this evaluator's expression.
byte[]	getExpression()	Accessor for the underlying byte string.
ColumnVisibility.Node	getParseTree()	Gets the parse tree for this column visibility.
int	hashCode()
static ColumnVisibility.Node	normalize(ColumnVisibility.Node root, byte[] expression)
static ColumnVisibility.Node	normalize(ColumnVisibility.Node root, byte[] expression, ColumnVisibility.NodeComparator comparator)
static byte[]	quote(byte[] term)	Properly quotes terms in a column visibility expression.
static String	quote(String term)	Properly quotes terms in a column visibility expression.
static void	stringify(ColumnVisibility.Node root, byte[] expression, StringBuilder out)
String	toString()

Methods inherited from class java.lang.Object

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

Constructor Detail

ColumnVisibility

public ColumnVisibility()

Creates an empty visibility. Normally, elements with empty visibility can be seen by everyone. Though, one could change this behavior with filters.

See Also:

ColumnVisibility(String)

ColumnVisibility

public ColumnVisibility(String expression)

Creates a column visibility for a Mutation.

Parameters:

expression - An expression of the rights needed to see this mutation. The expression syntax is defined at the class-level documentation

ColumnVisibility

public ColumnVisibility(org.apache.hadoop.io.Text expression)

Creates a column visibility for a Mutation.

Parameters:

expression - visibility expression

See Also:

ColumnVisibility(String)

ColumnVisibility

public ColumnVisibility(byte[] expression)

Creates a column visibility for a Mutation from a string already encoded in UTF-8 bytes.

Parameters:

expression - visibility expression, encoded as UTF-8 bytes

See Also:

ColumnVisibility(String)

Method Detail

getExpression

public byte[] getExpression()

Accessor for the underlying byte string.

Returns:

byte array representation of a visibility expression

normalize

public static ColumnVisibility.Node normalize(ColumnVisibility.Node root,
                                              byte[] expression)

normalize

public static ColumnVisibility.Node normalize(ColumnVisibility.Node root,
                                              byte[] expression,
                                              ColumnVisibility.NodeComparator comparator)

stringify

public static void stringify(ColumnVisibility.Node root,
                             byte[] expression,
                             StringBuilder out)

flatten

public byte[] flatten()

Generates a byte[] that represents a normalized, but logically equivalent, form of this evaluator's expression.

Returns:

normalized expression in byte[] form

toString

public String toString()

Overrides:

toString in class Object

equals

public boolean equals(Object obj)

See equals(ColumnVisibility)

Overrides:

equals in class Object

equals

public boolean equals(ColumnVisibility otherLe)

Compares two ColumnVisibilities for string equivalence, not as a meaningful comparison of terms and conditions.

Parameters:

otherLe - other column visibility

Returns:

true if this visibility equals the other via string comparison

hashCode

public int hashCode()

Overrides:

hashCode in class Object

getParseTree

public ColumnVisibility.Node getParseTree()

Gets the parse tree for this column visibility.

Returns:

parse tree node

quote

public static String quote(String term)

Properly quotes terms in a column visibility expression. If no quoting is needed, then nothing is done.

Examples of using quote :

 import static org.apache.accumulo.core.security.ColumnVisibility.quote;
   .
   .
   .
 String s = quote("A#C") + "&" + quote("FOO");
 ColumnVisibility cv = new ColumnVisibility(s);
 

Parameters:

term - term to quote

Returns:

quoted term (unquoted if unnecessary)

quote

public static byte[] quote(byte[] term)

Properly quotes terms in a column visibility expression. If no quoting is needed, then nothing is done.

Parameters:

term - term to quote, encoded as UTF-8 bytes

Returns:

quoted term (unquoted if unnecessary), encoded as UTF-8 bytes

See Also:

quote(String)