Package org.apache.hadoop.fs.shell.find

Interface Expression

All Known Implementing Classes:

BaseExpression, FilterExpression

public interface Expression

Interface describing an expression to be used in the Find command.

Method Summary

Modifier and Type	Method	Description
void	addArguments(java.util.Deque<java.lang.String> args)	Adds arguments to this expression.
void	addChildren(java.util.Deque<Expression> expressions)	Adds children to this expression.
Result	apply(PathData item, int depth)	Apply the expression to the specified item, called once for each item.
void	finish()	Finishes the expression, called once after processing all items.
java.lang.String[]	getHelp()	Returns a description of the expression for use in help.
int	getPrecedence()	Returns the precedence of this expression (only applicable to operators).
java.lang.String[]	getUsage()	Returns brief usage instructions for this expression.
boolean	isAction()	Indicates whether this expression performs an action, i.e.
boolean	isOperator()	Identifies the expression as an operator rather than a primary.
void	prepare()	Prepares the expression for execution, called once after setting options and before processing any options.
void	setOptions(FindOptions options)	Set the options for this expression, called once before processing any items.

Method Detail

setOptions

void setOptions(FindOptions options)
         throws java.io.IOException

Set the options for this expression, called once before processing any items.

Parameters:

options - options.

Throws:

java.io.IOException - raised on errors performing I/O.

prepare

void prepare()
      throws java.io.IOException

Prepares the expression for execution, called once after setting options and before processing any options.

Throws:

java.io.IOException - raised on errors performing I/O.

apply

Result apply(PathData item,
             int depth)
      throws java.io.IOException

Apply the expression to the specified item, called once for each item.

Parameters:

item - PathData item to be processed

depth - distance of the item from the command line argument

Returns:

Result of applying the expression to the item

Throws:

java.io.IOException - raised on errors performing I/O.

finish

void finish()
     throws java.io.IOException

Finishes the expression, called once after processing all items.

Throws:

java.io.IOException - raised on errors performing I/O.

getUsage

java.lang.String[] getUsage()

Returns brief usage instructions for this expression. Multiple items should be returned if there are multiple ways to use this expression.

Returns:

array of usage instructions

getHelp

java.lang.String[] getHelp()

Returns a description of the expression for use in help. Multiple lines should be returned array items. Lines should be formated to 60 characters or less.

Returns:

array of description lines

isAction

boolean isAction()

Indicates whether this expression performs an action, i.e. provides output back to the user.

Returns:

if is action true, not false.

isOperator

boolean isOperator()

Identifies the expression as an operator rather than a primary.

Returns:

if is operator true, not false.

getPrecedence

int getPrecedence()

Returns the precedence of this expression (only applicable to operators).

Returns:

precedence.

addChildren

void addChildren(java.util.Deque<Expression> expressions)

Adds children to this expression. Children are popped from the head of the deque.

Parameters:

expressions - deque of expressions from which to take the children

addArguments

void addArguments(java.util.Deque<java.lang.String> args)

Adds arguments to this expression. Arguments are popped from the head of the deque and added to the front of the child list, ie last child added is the first evaluated.

Parameters:

args - deque of arguments from which to take expression arguments