org.apache.hadoop.fs.shell.find

Class BaseExpression

java.lang.Object

org.apache.hadoop.fs.shell.find.BaseExpression

All Implemented Interfaces:

Configurable, Expression

public abstract class BaseExpression
extends Object
implements Expression, Configurable

Abstract expression for use in the Find command. Provides default behavior for a no-argument primary expression.

Constructor Summary

Constructors

Constructor and Description
BaseExpression()

Method Summary

Methods

Modifier and Type	Method and Description
protected void	addArgument(String arg) Add a single argument to this expression.
void	addArguments(Deque<String> args) Adds arguments to this expression.
protected void	addArguments(Deque<String> args, int count) Add a specific number of arguments to this expression.
void	addChildren(Deque<Expression> exprs) Adds children to this expression.
protected void	addChildren(Deque<Expression> exprs, int count) Add a specific number of children to this expression.
void	finish() Finishes the expression, called once after processing all items.
protected String	getArgument(int position) Returns the argument at the given position (starting from 1).
protected List<String>	getArguments() Returns the arguments of this expression
protected List<Expression>	getChildren() Returns the children of this expression.
Configuration	getConf() Return the configuration used by this object.
protected FileStatus	getFileStatus(org.apache.hadoop.fs.shell.PathData item, int depth) Returns the FileStatus from the PathData item.
protected FileSystem	getFileSystem(org.apache.hadoop.fs.shell.PathData item) Returns the FileSystem associated with the PathData item.
String[]	getHelp() Returns a description of the expression for use in help.
protected FindOptions	getOptions() Return the options to be used by this expression.
protected Path	getPath(org.apache.hadoop.fs.shell.PathData item) Returns the Path from the PathData item.
int	getPrecedence() Returns the precedence of this expression (only applicable to operators).
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	setConf(Configuration conf) Set the configuration to be used by this object.
protected void	setHelp(String[] help) Sets the help text for this Expression
void	setOptions(FindOptions options) Set the options for this expression, called once before processing any items.
protected void	setUsage(String[] usage) Sets the usage text for this Expression
String	toString()

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.fs.shell.find.Expression

apply

Constructor Detail

BaseExpression

public BaseExpression()

Method Detail

setUsage

protected void setUsage(String[] usage)

Sets the usage text for this Expression

setHelp

protected void setHelp(String[] help)

Sets the help text for this Expression

getUsage

public String[] getUsage()

Description copied from interface: Expression

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

Specified by:

getUsage in interface Expression

Returns:

array of usage instructions

getHelp

public String[] getHelp()

Description copied from interface: Expression

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.

Specified by:

getHelp in interface Expression

Returns:

array of description lines

setOptions

public void setOptions(FindOptions options)
                throws IOException

Description copied from interface: Expression

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

Specified by:

setOptions in interface Expression

Throws:

IOException

prepare

public void prepare()
             throws IOException

Description copied from interface: Expression

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

Specified by:

prepare in interface Expression

Throws:

IOException

finish

public void finish()
            throws IOException

Description copied from interface: Expression

Finishes the expression, called once after processing all items.

Specified by:

finish in interface Expression

Throws:

IOException

getOptions

protected FindOptions getOptions()

Return the options to be used by this expression.

setConf

public void setConf(Configuration conf)

Description copied from interface: Configurable

Set the configuration to be used by this object.

Specified by:

setConf in interface Configurable

getConf

public Configuration getConf()

Description copied from interface: Configurable

Return the configuration used by this object.

Specified by:

getConf in interface Configurable

toString

public String toString()

Overrides:

toString in class Object

isAction

public boolean isAction()

Description copied from interface: Expression

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

Specified by:

isAction in interface Expression

isOperator

public boolean isOperator()

Description copied from interface: Expression

Identifies the expression as an operator rather than a primary.

Specified by:

isOperator in interface Expression

getArguments

protected List<String> getArguments()

Returns the arguments of this expression

Returns:

list of argument strings

getArgument

protected String getArgument(int position)
                      throws IOException

Returns the argument at the given position (starting from 1).

Parameters:

position - argument to be returned

Returns:

requested argument

Throws:

IOException - if the argument doesn't exist or is null

getChildren

protected List<Expression> getChildren()

Returns the children of this expression.

Returns:

list of child expressions

getPrecedence

public int getPrecedence()

Description copied from interface: Expression

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

Specified by:

getPrecedence in interface Expression

addChildren

public void addChildren(Deque<Expression> exprs)

Description copied from interface: Expression

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

Specified by:

addChildren in interface Expression

Parameters:

exprs - deque of expressions from which to take the children

addChildren

protected void addChildren(Deque<Expression> exprs,
               int count)

Add a specific number of children to this expression. The children are popped off the head of the expressions.

Parameters:

exprs - deque of expressions from which to take the children

count - number of children to be added

addArguments

public void addArguments(Deque<String> args)

Description copied from interface: Expression

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.

Specified by:

addArguments in interface Expression

Parameters:

args - deque of arguments from which to take expression arguments

addArguments

protected void addArguments(Deque<String> args,
                int count)

Add a specific number of arguments to this expression. The children are popped off the head of the expressions.

Parameters:

args - deque of arguments from which to take the argument

count - number of children to be added

addArgument

protected void addArgument(String arg)

Add a single argument to this expression. The argument is popped off the head of the expressions.

Parameters:

arg - argument to add to the expression

getFileStatus

protected FileStatus getFileStatus(org.apache.hadoop.fs.shell.PathData item,
                       int depth)
                            throws IOException

Returns the FileStatus from the PathData item. If the current options require links to be followed then the returned file status is that of the linked file.

Parameters:

item - PathData

depth - current depth in the process directories

Returns:

FileStatus

Throws:

IOException

getPath

protected Path getPath(org.apache.hadoop.fs.shell.PathData item)
                throws IOException

Returns the Path from the PathData item.

Parameters:

item - PathData

Returns:

Path

Throws:

IOException

getFileSystem

protected FileSystem getFileSystem(org.apache.hadoop.fs.shell.PathData item)
                            throws IOException

Returns the FileSystem associated with the PathData item.

Parameters:

item - PathData

Returns:

FileSystem

Throws:

IOException