org.eclipse.mat.query

Interface IQueryContext

All Known Implementing Classes:

ProviderContextImpl, QueryContextImpl, SnapshotQueryContext

public interface IQueryContext

The context for a query. Hides the snapshot implementation, and is not tied to the snapshot API.

No Implement:

Method Summary

Modifier and Type	Method and Description
boolean	available(Class<?> type, Argument.Advice advice) Is this type of data available from the context?
boolean	converts(Class<?> type, Argument.Advice advice) Does the context have a converter for data of this type?
String	convertToString(Class<?> type, Argument.Advice advice, Object value) Convert the value to a string.
Object	convertToValue(Class<?> type, Argument.Advice advice, String value) Convert the String to the value based on the type and advice.
Object	get(Class<?> type, Argument.Advice advice) Get this type of data from the context.
ContextDerivedData	getContextDerivedData() For example, retained size derived data.
String	getPrefix() The prefix for files generated from snapshot
File	getPrimaryFile() The main file for the snapshot
String	mapToExternalIdentifier(int objectId) Map an id to a readable form.
int	mapToObjectId(String externalIdentifier) Map readable form to internal id.
Object	parse(Class<?> type, Argument.Advice advice, String[] args, ParsePosition pos) Consume the special data.
boolean	parses(Class<?> type, Argument.Advice advice) Is special parsing required to get an object of the required type?

Method Detail

getPrimaryFile

File getPrimaryFile()

The main file for the snapshot

Returns:

the dump

getPrefix

String getPrefix()

The prefix for files generated from snapshot

Returns:

the prefix

Since:

1.3

available

boolean available(Class<?> type,
                  Argument.Advice advice)

Is this type of data available from the context?

Parameters:

type - the type the data should be converted to

advice - advice such as from the query as to how the value should be converted.

Returns:

true if available.

get

Object get(Class<?> type,
           Argument.Advice advice)

Get this type of data from the context.

Parameters:

type - the type the data should be converted to

advice - advice such as from the query as to how the value should be converted.

Returns:

the object of the right type

mapToExternalIdentifier

String mapToExternalIdentifier(int objectId)
                        throws SnapshotException

Map an id to a readable form. For example the hex-address with 0x as a prefix. Reverse of mapToObjectId(java.lang.String)

Parameters:

objectId - The 0-based internal identifier used within MAT.

Returns:

readable external version

Throws:

SnapshotException - if the objectId does not match to a valid object.

See Also:

mapToObjectId(java.lang.String)

mapToObjectId

int mapToObjectId(String externalIdentifier)
           throws SnapshotException

Map readable form to internal id. Reverse of mapToExternalIdentifier(int).

Parameters:

externalIdentifier - as provided by mapToExternalIdentifier(int).

Returns:

the object id

Throws:

SnapshotException - if the external identifier does not match a known object in the snapshot.

converts

boolean converts(Class<?> type,
                 Argument.Advice advice)

Does the context have a converter for data of this type?

Parameters:

type - The Java type of an argument to be supplied with data from this context.

advice - Further details about the argument to be supplied with data.

Returns:

true if available and convertible

convertToString

String convertToString(Class<?> type,
                       Argument.Advice advice,
                       Object value)
                throws SnapshotException

Convert the value to a string. For example the converter might be String.valueOf(Integer)

Parameters:

type - The Java type of the argument.

advice - Further details about the argument.

value - The value of the argument held in the context.

Returns:

the value converted to a String

Throws:

SnapshotException - If there is a problem with the conversion such as the value is not a valid object ID.

convertToValue

Object convertToValue(Class<?> type,
                      Argument.Advice advice,
                      String value)
               throws SnapshotException

Convert the String to the value based on the type and advice.

Parameters:

type - The Java type of the argument

advice - Further details about the argument.

value - The readable string value

Returns:

the String converted to a value suitable to be stored in the argument.

Throws:

SnapshotException - if there is a problem with the conversion, such as an unknown object address.

parses

boolean parses(Class<?> type,
               Argument.Advice advice)

Is special parsing required to get an object of the required type?

Parameters:

type - The Java type of the argument.

advice - Further details about the argument.

Returns:

true if special parsing is needed, for example for a heap object or class object in the heap.

parse

Object parse(Class<?> type,
             Argument.Advice advice,
             String[] args,
             ParsePosition pos)
      throws SnapshotException

Consume the special data. For example using the ArgumentParser for data from a query wizard.

Parameters:

type - The Java type of the destination argument.

advice - Further details about the argument.

args - The source to be converted

pos - Used to index through the array of Strings.

Returns:

the result of parsing the data suitable given the type and advice

Throws:

SnapshotException - If there is a problem in the parsing.

getContextDerivedData

ContextDerivedData getContextDerivedData()

For example, retained size derived data.

Returns:

the derived data