io.cdap.wrangler.api.parser

Class UsageDefinition

java.lang.Object

io.cdap.wrangler.api.parser.UsageDefinition

All Implemented Interfaces:

Serializable

public final class UsageDefinition
extends Object
implements Serializable

This class UsageDefinition provides a way for users to registers the argument for UDDs. UsageDefinition is a collection of TokenDefinition and the name of the directive itself. Each token specification has an associated ordinal that can be used to position the argument within the directive. Following is a example of how this class can be used. UsageDefinition.Builder builder = UsageDefinition.builder(); builder.add("col1", TypeToken.COLUMN_NAME); // By default, this field is required. builder.add("col2", TypeToken.COLUMN_NAME, false); // This is a optional field. builder.add("expression", TypeToken.EXPRESSION); UsageDefinition definition = builder.build(); NOTE: No constraints checks are included in this implementation.

See Also:

TokenDefinition, Serialized Form

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	UsageDefinition.Builder This inner builder class provides a way to create UsageDefinition object.

Method Summary

Modifier and Type	Method and Description
static UsageDefinition.Builder	builder(String directive) This is a static method for creating a builder for the UsageDefinition object.
String	getDirectiveName() Returns the name of the directive for which the this UsageDefinition object is created.
int	getOptionalTokensCount() Returns the count of TokenDefinition that have been specified as optional in the UsageDefinition.
List<TokenDefinition>	getTokens() This method returns the list of TokenDefinition that should be used for parsing the directive into Arguments.
String	toString() This method converts the UsageDefinition into a usage string for this directive.

Methods inherited from class java.lang.Object

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

Method Detail

getDirectiveName

public String getDirectiveName()

Returns the name of the directive for which the this UsageDefinition object is created.

Returns:

name of the directive.

getTokens

public List<TokenDefinition> getTokens()

This method returns the list of TokenDefinition that should be used for parsing the directive into Arguments.

Returns:

List of TokenDefinition.

getOptionalTokensCount

public int getOptionalTokensCount()

Returns the count of TokenDefinition that have been specified as optional in the UsageDefinition.

Returns:

number of tokens in the usage that are optional.

toString

public String toString()

This method converts the UsageDefinition into a usage string for this directive. It inspects all the tokens to generate a standard syntax for the usage of the directive.

Overrides:

toString in class Object

Returns:

a usage representation of this object.

builder

public static UsageDefinition.Builder builder(String directive)

This is a static method for creating a builder for the UsageDefinition object. In order to create a UsageDefinition, a builder has to created.

This builder is provided as user API for constructing the usage specification for a directive.

Parameters:

directive - name of the directive for which the builder is created for.

Returns:

A UsageDefinition.Builder object that can be used to construct UsageDefinition object.