ExpressionLanguage (pvmanager 2.9.1-SNAPSHOT API)

java.lang.Object
- org.epics.pvmanager.ExpressionLanguage

```
public class ExpressionLanguage
extends Object
```
Operators to constructs expression of PVs that the PVManager will be able to monitor.

Author:

carcassi

Nested Class Summary

Nested Classes
Modifier and Type	Class and Description
`static class`	`ExpressionLanguage.Filter<T>` Filters a data stream, removing updates that match the given function.
`static interface`	`ExpressionLanguage.OneArgFunction<R,A>` A user provided single argument function.
`static interface`	`ExpressionLanguage.TwoArgFunction<R,A1,A2>` A user provided double argument function.

Method Summary

Methods
Modifier and Type	Method and Description
`static <R> Cache<R>`	`cacheOf(Class<R> clazz)` A cache of objects of the given class.
`static ChannelExpression<Object,Object>`	`channel(String name)` A channel with the given name of any type.
`static <R,W> ChannelExpression<R,W>`	`channel(String name, Class<R> readType, Class<W> writeType)` A channel with the given name and type.
`static ChannelExpressionList<Object,Object>`	`channels(Collection<String> names)` A list of channels with the given names of any type.
`static <R,W> ChannelExpressionList<R,W>`	`channels(Collection<String> names, Class<R> readType, Class<W> writeType)` A list of channels with the given names and type.
`static ChannelExpressionList<Object,Object>`	`channels(String... names)` A list of channels with the given names of any type.
`static <T> DesiredRateExpression<T>`	`constant(T value)` Creates a constant expression that always return that object.
`static <T> DesiredRateExpression<T>`	`constant(T value, String name)` Creates a constant expression that always return that object, with the given name for the expression.
`static <T> DesiredRateExpression<List<T>>`	`filterBy(ExpressionLanguage.Filter<?> filter, DesiredRateExpression<List<T>> expression)` Filters a stream of updates with the given filter.
`static <T> DesiredRateExpression<T>`	`latestValueOf(SourceRateExpression<T> expression)` Expression that returns (only) the latest value computed from a `SourceRateExpression`.
`static <T> DesiredRateExpressionList<T>`	`latestValueOf(SourceRateExpressionList<T> expressions)` Expression that returns (only) the latest value computed from a `SourceRateExpression`.
`static <R,W> DesiredRateReadWriteExpression<R,W>`	`latestValueOf(SourceRateReadWriteExpression<R,W> expression)` For reads, returns (only) the latest value computed from a `SourceRateReadWriteExpression`; for writes, same as the given expression.
`static <R,W> DesiredRateReadWriteExpressionList<R,W>`	`latestValueOf(SourceRateReadWriteExpressionList<R,W> expressions)` For reads, returns (only) the latest value computed from a `SourceRateReadWriteExpression`; for writes, same as the given expression.
`static <T> DesiredRateExpression<List<T>>`	`listOf(DesiredRateExpressionList<T> expressions)` Converts a list of expressions to an expression that returns the list of results.
`static <R,W> ReadWriteMap<R,W>`	`mapOf(Class<R> readClass, Class<W> writeClass)` An empty map that can read/write expressions of the given type.
`static <R> ReadMap<R>`	`mapOf(DesiredRateExpressionList<R> expressions)` An expression that returns a key/value map where the key is the expression name and the value is the expression value.
`static <R,W> ReadWriteMap<R,W>`	`mapOf(DesiredRateReadWriteExpressionList<R,W> expressions)` An expression that works on a key/value map where the key is the expression name and the value is the expression value.
`static <W> WriteMap<W>`	`mapOf(WriteExpressionList<W> expressions)` An expression that expects a key/value map where the key is the expression name and the value is the expression value.
`static <T> DesiredRateExpression<List<T>>`	`newValuesOf(SourceRateExpression<T> expression)` Returns up to 1,000 new values generated by the expression source rate.
`static <T> DesiredRateExpression<List<T>>`	`newValuesOf(SourceRateExpression<T> expression, int maxValues)` Returns up to maxValues new values generated by the expression source rate.
`static <T> DesiredRateExpressionList<List<T>>`	`newValuesOf(SourceRateExpressionList<T> expressions)` Returns all the new values generated by the expression source rate.
`static <R> Queue<R>`	`queueOf(Class<R> clazz)` A queue of objects of the given class.
`static <R> ReadMap<R>`	`readMapOf(Class<R> clazz)` An empty map that can manage expressions of the given type.
`static <R,A> DesiredRateExpression<R>`	`resultOf(ExpressionLanguage.OneArgFunction<R,A> function, DesiredRateExpression<? extends A> argExpression)` An expression that represents the result of a user provided function.
`static <R,A> DesiredRateExpression<R>`	`resultOf(ExpressionLanguage.OneArgFunction<R,A> function, DesiredRateExpression<? extends A> argExpression, String name)` An expression that represents the result of a user provided function.
`static <R,A1,A2> DesiredRateExpression<R>`	`resultOf(ExpressionLanguage.TwoArgFunction<R,A1,A2> function, DesiredRateExpression<? extends A1> arg1Expression, DesiredRateExpression<? extends A2> arg2Expression)` An expression that represents the result of a user provided function.
`static <R,A1,A2> DesiredRateExpression<R>`	`resultOf(ExpressionLanguage.TwoArgFunction<R,A1,A2> function, DesiredRateExpression<? extends A1> arg1Expression, DesiredRateExpression<? extends A2> arg2Expression, String name)` An expression that represents the result of a user provided function.
`static <W> WriteMap<W>`	`writeMapOf(Class<W> clazz)` An empty map that can write expressions of the given type.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Method Detail
  - constant
```
public static <T> DesiredRateExpression<T> constant(T value)
```
    Creates a constant expression that always return that object. This is useful to test expressions or to introduce data that is available at connection time at that will not change.
    
    Type Parameters:
    T - type of the value
    Parameters:
    value - the actual value
    
    Returns:
    an expression that is always going to return the given value
  - constant
```
public static <T> DesiredRateExpression<T> constant(T value,
                                    String name)
```
    Creates a constant expression that always return that object, with the given name for the expression. This is useful to test expressions or to introduce data that is available at connection time at that will not change.
    
    Type Parameters:
    T - type of the value
    Parameters:
    value - the actual value
    name - the name of the expression
    
    Returns:
    an expression that is always going to return the given value
  - channel
```
public static ChannelExpression<Object,Object> channel(String name)
```
    A channel with the given name of any type. This expression can be used both in a read and a write expression.
    
    Parameters:
    name - the channel name
    
    Returns:
    an expression representing the channel
  - channel
```
public static <R,W> ChannelExpression<R,W> channel(String name,
                                   Class<R> readType,
                                   Class<W> writeType)
```
    A channel with the given name and type. This expression can be used both in a read and a write expression.
    
    Type Parameters:
    R - read payload
    W - write payload
    Parameters:
    name - the channel name
    readType - type being read
    writeType - type being written
    
    Returns:
    an expression representing the channel
  - channels
```
public static ChannelExpressionList<Object,Object> channels(String... names)
```
    A list of channels with the given names of any type. This expression can be used both in a read and a write expression.
    
    Parameters:
    names - the channel names; can't be null
    
    Returns:
    an list of expressions representing the channels
  - channels
```
public static <R,W> ChannelExpressionList<R,W> channels(Collection<String> names,
                                        Class<R> readType,
                                        Class<W> writeType)
```
    A list of channels with the given names and type. This expression can be used both in a read and a write expression.
    
    Type Parameters:
    R - read payload
    W - write payload
    Parameters:
    readType - type being read
    writeType - type being written
    names - the channel names; can't be null
    
    Returns:
    an list of expressions representing the channels
  - channels
```
public static ChannelExpressionList<Object,Object> channels(Collection<String> names)
```
    A list of channels with the given names of any type. This expression can be used both in a read and a write expression.
    
    Parameters:
    names - the channel names; can't be null
    
    Returns:
    an list of expressions representing the channels
  - newValuesOf
```
public static <T> DesiredRateExpressionList<List<T>> newValuesOf(SourceRateExpressionList<T> expressions)
```
    Returns all the new values generated by the expression source rate.
    
    Type Parameters:
    T - type being read
    Parameters:
    expressions - source rate expressions
    
    Returns:
    a new expression
  - newValuesOf
```
public static <T> DesiredRateExpression<List<T>> newValuesOf(SourceRateExpression<T> expression)
```
    Returns up to 1,000 new values generated by the expression source rate.
    You are strongly encouraged to use newValuesOf(org.epics.pvmanager.expression.SourceRateExpression, int) to set a limit that is appropriate for your application.
    
    Type Parameters:
    T - type being read
    Parameters:
    expression - source rate expression
    
    Returns:
    a new expression
  - newValuesOf
```
public static <T> DesiredRateExpression<List<T>> newValuesOf(SourceRateExpression<T> expression,
                                             int maxValues)
```
    Returns up to maxValues new values generated by the expression source rate.
    
    Type Parameters:
    T - type being read
    Parameters:
    expression - source rate expression
    maxValues - maximum number of values to send with each notification
    
    Returns:
    a new expression
  - latestValueOf
```
public static <T> DesiredRateExpression<T> latestValueOf(SourceRateExpression<T> expression)
```
    Expression that returns (only) the latest value computed from a SourceRateExpression.
    
    Type Parameters:
    T - type being read
    Parameters:
    expression - expression read at the source rate
    
    Returns:
    a new expression
  - latestValueOf
```
public static <T> DesiredRateExpressionList<T> latestValueOf(SourceRateExpressionList<T> expressions)
```
    Expression that returns (only) the latest value computed from a SourceRateExpression.
    
    Type Parameters:
    T - type being read
    Parameters:
    expressions - expressions read at the source rate
    
    Returns:
    an expression list
  - latestValueOf
```
public static <R,W> DesiredRateReadWriteExpression<R,W> latestValueOf(SourceRateReadWriteExpression<R,W> expression)
```
    For reads, returns (only) the latest value computed from a SourceRateReadWriteExpression; for writes, same as the given expression.
    
    Type Parameters:
    R - read payload
    W - write payload
    Parameters:
    expression - expression read at the source rate
    
    Returns:
    a new expression
  - latestValueOf
```
public static <R,W> DesiredRateReadWriteExpressionList<R,W> latestValueOf(SourceRateReadWriteExpressionList<R,W> expressions)
```
    For reads, returns (only) the latest value computed from a SourceRateReadWriteExpression; for writes, same as the given expression.
    
    Type Parameters:
    R - read payload
    W - write payload
    Parameters:
    expressions - expressions read at the source rate
    
    Returns:
    a new expression
  - resultOf
```
public static <R,A> DesiredRateExpression<R> resultOf(ExpressionLanguage.OneArgFunction<R,A> function,
                                      DesiredRateExpression<? extends A> argExpression)
```
    An expression that represents the result of a user provided function.
    
    Type Parameters:
    R - result type
    A - argument type
    Parameters:
    function - the user provided function
    argExpression - expression for the function argument
    
    Returns:
    a new expression
  - resultOf
```
public static <R,A> DesiredRateExpression<R> resultOf(ExpressionLanguage.OneArgFunction<R,A> function,
                                      DesiredRateExpression<? extends A> argExpression,
                                      String name)
```
    An expression that represents the result of a user provided function.
    
    Type Parameters:
    R - result type
    A - argument type
    Parameters:
    function - the user provided function
    argExpression - expression for the function argument
    name - expression name
    
    Returns:
    a new expression
  - resultOf
```
public static <R,A1,A2> DesiredRateExpression<R> resultOf(ExpressionLanguage.TwoArgFunction<R,A1,A2> function,
                                          DesiredRateExpression<? extends A1> arg1Expression,
                                          DesiredRateExpression<? extends A2> arg2Expression)
```
    An expression that represents the result of a user provided function.
    
    Type Parameters:
    R - result type
    A1 - first argument type
    A2 - second argument type
    Parameters:
    function - the user provided function
    arg1Expression - expression for the first argument
    arg2Expression - expression for the second argument
    
    Returns:
    a new expression
  - resultOf
```
public static <R,A1,A2> DesiredRateExpression<R> resultOf(ExpressionLanguage.TwoArgFunction<R,A1,A2> function,
                                          DesiredRateExpression<? extends A1> arg1Expression,
                                          DesiredRateExpression<? extends A2> arg2Expression,
                                          String name)
```
    An expression that represents the result of a user provided function.
    
    Type Parameters:
    R - result type
    A1 - first argument type
    A2 - second argument type
    Parameters:
    function - the user provided function
    arg1Expression - expression for the first argument
    arg2Expression - expression for the second argument
    name - expression name
    
    Returns:
    a new expression
  - filterBy
```
public static <T> DesiredRateExpression<List<T>> filterBy(ExpressionLanguage.Filter<?> filter,
                                          DesiredRateExpression<List<T>> expression)
```
    Filters a stream of updates with the given filter.
    
    Type Parameters:
    T - the type of data streaming in and out
    Parameters:
    filter - the filtering function
    expression - the argument expression
    
    Returns:
    a new expression for the filtering result
  - listOf
```
public static <T> DesiredRateExpression<List<T>> listOf(DesiredRateExpressionList<T> expressions)
```
    Converts a list of expressions to an expression that returns the list of results.
    
    Type Parameters:
    T - type being read
    Parameters:
    expressions - a list of expressions
    
    Returns:
    an expression representing the list of results
  - readMapOf
```
public static <R> ReadMap<R> readMapOf(Class<R> clazz)
```
    An empty map that can manage expressions of the given type.
    The returned expression is dynamic, which means child expressions can be added or removed from the map.
    
    Type Parameters:
    R - the type of the values
    Parameters:
    clazz - the type of the values
    
    Returns:
    an expression representing a map from name to results
  - writeMapOf
```
public static <W> WriteMap<W> writeMapOf(Class<W> clazz)
```
    An empty map that can write expressions of the given type.
    The returned expression is dynamic, which means child expressions can be added or removed from the map.
    
    Type Parameters:
    W - the type of the values
    Parameters:
    clazz - the type of the values
    
    Returns:
    an expression representing a map from name to results
  - mapOf
```
public static <R,W> ReadWriteMap<R,W> mapOf(Class<R> readClass,
                            Class<W> writeClass)
```
    An empty map that can read/write expressions of the given type.
    The returned expression is dynamic, which means child expressions can be added or removed from the map.
    
    Type Parameters:
    R - the type of the values to read
    W - the type of the values to write
    Parameters:
    readClass - the type of the values to read
    writeClass - the type of the values to write
    
    Returns:
    an expression representing a map from name to results
  - mapOf
```
public static <R> ReadMap<R> mapOf(DesiredRateExpressionList<R> expressions)
```
    An expression that returns a key/value map where the key is the expression name and the value is the expression value.
    The returned expression is dynamic, which means child expressions can be added or removed from the map.
    
    Type Parameters:
    R - the type of the values
    Parameters:
    expressions - a list of expressions
    
    Returns:
    an expression representing a map from name to results
  - mapOf
```
public static <W> WriteMap<W> mapOf(WriteExpressionList<W> expressions)
```
    An expression that expects a key/value map where the key is the expression name and the value is the expression value.
    The returned expression is dynamic, which means child expressions can be added or removed from the map.
    
    Type Parameters:
    W - the type of the values
    Parameters:
    expressions - a list of expressions
    
    Returns:
    an expression representing a map from name to results
  - mapOf
```
public static <R,W> ReadWriteMap<R,W> mapOf(DesiredRateReadWriteExpressionList<R,W> expressions)
```
    An expression that works on a key/value map where the key is the expression name and the value is the expression value.
    The returned expression is dynamic, which means child expressions can be added or removed from the map.
    
    Type Parameters:
    R - the type for the read values
    W - the type for the write values
    Parameters:
    expressions - a list of expressions
    
    Returns:
    an expression representing a map from name to results
  - queueOf
```
public static <R> Queue<R> queueOf(Class<R> clazz)
```
    A queue of objects of the given class. By default, it holds at maximum 10 elements.
    This can be used to create expressions where the source of the data is not just pvmanager data sources. One can add new values to a queue from any thread, and in response to any event, such as user input, updates from time consuming tasks or responses from services.
    
    Type Parameters:
    R - the type to be kept in the queue
    Parameters:
    clazz - the type for the values to be kept in the queue
    
    Returns:
    a new queue
  - cacheOf
```
public static <R> Cache<R> cacheOf(Class<R> clazz)
```
    A cache of objects of the given class. By default, it holds at maximum 10 elements.
    This can be used to create expressions where the source of the data is not just pvmanager data sources. One can add new values to the cache from any thread, and in response to any event, such as user input, updates from time consuming tasks or responses from services.
    
    Type Parameters:
    R - the type to be kept in the queue
    Parameters:
    clazz - the type for the values to be kept in the queue
    
    Returns:
    a new queue

Class ExpressionLanguage

Nested Class Summary

Method Summary

Methods inherited from class java.lang.Object

Method Detail

constant

constant

channel

channel

channels

channels

channels

newValuesOf

newValuesOf

newValuesOf

latestValueOf

latestValueOf

latestValueOf

latestValueOf

resultOf

resultOf

resultOf

resultOf

filterBy

listOf

readMapOf

writeMapOf

mapOf

mapOf

mapOf

mapOf

queueOf

cacheOf