ColumnVisibility (Apache Accumulo Project 1.9.3 API)

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 and 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 and 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

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method and Description
`boolean`	`equals(ColumnVisibility otherLe)` Compares two ColumnVisibilities for string equivalence, not as a meaningful comparison of terms and conditions.
`boolean`	`equals(Object obj)` See `equals(ColumnVisibility)`
`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)

Class ColumnVisibility

Nested Class Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

ColumnVisibility

ColumnVisibility

ColumnVisibility

ColumnVisibility

Method Detail

getExpression

normalize

normalize

stringify

flatten

toString

equals

equals

hashCode

getParseTree

quote

quote