Direct Known Subclasses:

InputBuffer
```
public abstract class Input
extends Object
```
Non-blocking token stream reader, with single token lookahead. Input enable incremental, interruptible parsing of network protocols and data formats.
Input tokens

Input tokens are modeled as primitive ints, commonly representing Unicode code points, or raw octets; each Input implementation specifies the semantic type of its tokens. The head() method peeks at the current lookahead token, without consuming it, and the step() method advances the input to the next token.

Input states

Input is always in one of four states: continue, empty, done, or error. The cont state indicates that a lookahead token is immediately available; the empty state indicates that no additional tokens are available at this time, but that the stream may logically resume in the future; the done state indicates that the stream has terminated nominally; and the error state indicates that the stream has terminated abnormally. isCont() returns true when in the cont state; isEmpty() returns true when in the empty state; isDone() returns true when in the done state; and isError() returns true when in the error state.

Non-blocking semantics

Input never blocks. An Input that would otherwise block awaiting additional tokens instead enters the empty state, signaling the input consumer to back off processing the input, but to remain prepared to process additional input in the future. An Input enters the done state when it encounters the final end of its input stream, signaling the input consumer to terminate processing.

isPart() returns true if the Input will enter the empty state after it consumes the last immediately available token; it returns false if the Input will enter the done state after it consumes the last immediately available token.

empty() returns an Input in the empty state. done() returns an Input in the done state.

Position tracking

The logical position of the current lookahead token is made available via the mark() method, with optimized callouts for the byte offset, one-based line number, and one-based column in the current line. The id() method returns a diagnostic identifier for the token stream.

Cloning

An Input may be cloned to provide an indepently mutable position into a shared token stream. Not all Input implementations support cloning.

See Also:

InputSettings, Parser

Constructor Summary

Constructors
Constructor Description

Input()

Method Summary

All Methods Static Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method	Description
`abstract Input`	`clone()`	Returns an independently positioned view into the token stream, initialized with identical state to this `Input`.
`int`	`column()`	Returns the one-based column number of the current lookahead token, relative to the current line in the stream.
`static Input`	`done()`	Returns an `Input` in the done state.
`static Input`	`done(Object id, Mark mark)`	Returns an `Input` in the done state, at the `mark` position of a token stream logically identified by `id`.
`static Input`	`done(Object id, Mark mark, InputSettings settings)`	Returns an `Input` in the done state, at the `mark` position of a token stream logically identified by `id`, with the given `settings`.
`static Input`	`done(InputSettings settings)`	Returns an `Input` in the done state, with the given `settings`.
`static Input`	`empty()`	Returns an `Input` in the empty state.
`static Input`	`empty(Object id, Mark mark)`	Returns an `Input` in the empty state, at the `mark` position of a token stream logically identified by `id`.
`static Input`	`empty(Object id, Mark mark, InputSettings settings)`	Returns an `Input` in the empty state, at the `mark` position of a token stream logically identified by `id`, with the given `settings`.
`static Input`	`empty(InputSettings settings)`	Returns an `Input` in the empty state, with the given `settings`.
`static Input`	`error(Throwable error)`	Returns an `Input` in the error state, with the given input `error`.
`static Input`	`error(Throwable error, Object id, Mark mark)`	Returns an `Input` in the error state, with the given input `error`, at the `mark` position of a token stream logically identified by `id`.
`static Input`	`error(Throwable error, Object id, Mark mark, InputSettings settings)`	Returns an `Input` in the error state, with the given input `error`, at the `mark` position of a token stream logically identified by `id`, with the given `settings`.
`static Input`	`error(Throwable error, InputSettings settings)`	Returns an `Input` in the error state, with the given input `error` and `settings`.
`Input`	`fork(Object condition)`	Returns an `Input` equivalent to this `Input`, but whose behavior may be altered by the given out-of-band `condition`.
`abstract int`	`head()`	Returns the current lookahead token, if this `Input` is in the cont state.
`abstract Object`	`id()`	Returns an object that identifies the token stream, or `null` if the stream is unidentified.
`abstract Input`	`id(Object id)`	Returns an `Input` equivalent to this `Input`, but logically identified by the given–possibly `null`–`id`.
`abstract boolean`	`isCont()`	Returns `true` when a `lookeahead` token is immediately available.
`abstract boolean`	`isDone()`	Returns `true` when no lookahead token is currently available, and no additional input will ever become available.
`abstract boolean`	`isEmpty()`	Returns `true` when no lookahead token is currently available, but additional input may be available in the future.
`abstract boolean`	`isError()`	Returns `true` when no lookahead token is currently available due to an error with the token stream.
`abstract boolean`	`isPart()`	Returns `true` if this is a partial `Input` will that enter the empty state after it consumes the last available input token.
`abstract Input`	`isPart(boolean isPart)`	Returns a partial `Input` equivalent to this `Input`, if `isPart` is `true`; returns a final `Input` equivalent to this `Input` if `isPart` is `false`.
`int`	`line()`	Returns the one-based line number of the current lookahead token, relative to the start of the stream.
`abstract Mark`	`mark()`	Returns the position of the current lookahead token, relative to the start of the stream.
`abstract Input`	`mark(Mark mark)`	Returns an `Input` equivalent to this `Input`, but logically positioned at the given `mark`.
`long`	`offset()`	Returns the byte offset of the current lookahead token, relative to the start of the stream.
`abstract Input`	`seek(Mark mark)`	Returns an `Input` equivalent to this `Input`, but repositioned to the given `mark`.
`abstract InputSettings`	`settings()`	Returns the `InputSettings` used to configure the behavior of input consumers that read from this `Input`.
`abstract Input`	`settings(InputSettings settings)`	Returns an `Input` equivalent to this `Input`, but with the given input `settings`.
`abstract Input`	`step()`	Returns an `Input` equivalent to this `Input`, but advanced to the next token.
`Throwable`	`trap()`	Returns the input error.

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

- Constructor Detail
  - Input
```
public Input()
```
- Method Detail
  - isCont
```
public abstract boolean isCont()
```
    Returns true when a lookeahead token is immediately available. i.e. this Input is in the cont state.
  - isEmpty
```
public abstract boolean isEmpty()
```
    Returns true when no lookahead token is currently available, but additional input may be available in the future. i.e. this Input is in the empty state.
  - isDone
```
public abstract boolean isDone()
```
    Returns true when no lookahead token is currently available, and no additional input will ever become available. i.e. this Input is in the done state.
  - isError
```
public abstract boolean isError()
```
    Returns true when no lookahead token is currently available due to an error with the token stream. i.e. this Input is in the error state. When true, trap() will return the input error.
  - isPart
```
public abstract boolean isPart()
```
    Returns true if this is a partial Input will that enter the empty state after it consumes the last available input token.
  - isPart
```
public abstract Input isPart(boolean isPart)
```
    Returns a partial Input equivalent to this Input, if isPart is true; returns a final Input equivalent to this Input if isPart is false. The caller's reference to this Input should be replaced by the returned Input.
  - head
```
public abstract int head()
```
    Returns the current lookahead token, if this Input is in the cont state.
    
    Throws:
    
    InputException - if this Input is not in the cont state.
  - step
```
public abstract Input step()
```
    Returns an Input equivalent to this Input, but advanced to the next token. Returns an Input in the error state if this Input is not in the cont state. The caller's reference to this Input should be replaced by the returned Input.
  - seek
```
public abstract Input seek(Mark mark)
```
    Returns an Input equivalent to this Input, but repositioned to the given mark. Returns an Input in the error state if this Input does not support seeking, or if this Input is unable to reposition to the given mark. The caller's reference to this Input should be replaced by the returned Input.
  - fork
```
public Input fork(Object condition)
```
    Returns an Input equivalent to this Input, but whose behavior may be altered by the given out-of-band condition. The caller's reference to this Input should be replaced by the returned Input.
  - trap
```
public Throwable trap()
```
    Returns the input error. Only guaranteed to return an error when in the error state.
    
    Throws:
    
    InputException - if this Input is not in the error state.
  - id
```
public abstract Object id()
```
    Returns an object that identifies the token stream, or null if the stream is unidentified.
  - id
```
public abstract Input id(Object id)
```
    Returns an Input equivalent to this Input, but logically identified by the given–possibly null–id. The caller's reference to this Input should be replaced by the returned Input.
  - mark
```
public abstract Mark mark()
```
    Returns the position of the current lookahead token, relative to the start of the stream.
  - mark
```
public abstract Input mark(Mark mark)
```
    Returns an Input equivalent to this Input, but logically positioned at the given mark. The physical position in the input stream is not modified. The caller's reference to this Input should be replaced by the returned Input.
  - offset
```
public long offset()
```
    Returns the byte offset of the current lookahead token, relative to the start of the stream.
  - line
```
public int line()
```
    Returns the one-based line number of the current lookahead token, relative to the start of the stream.
  - column
```
public int column()
```
    Returns the one-based column number of the current lookahead token, relative to the current line in the stream.
  - settings
```
public abstract InputSettings settings()
```
    Returns the InputSettings used to configure the behavior of input consumers that read from this Input.
  - settings
```
public abstract Input settings(InputSettings settings)
```
    Returns an Input equivalent to this Input, but with the given input settings. The caller's reference to this Input should be replaced by the returned Input.
  - clone
```
public abstract Input clone()
```
    Returns an independently positioned view into the token stream, initialized with identical state to this Input.
    
    Overrides:
    
    clone in class Object
    
    Throws:
    
    UnsupportedOperationException - if this Input cannot be cloned.
  - empty
```
public static Input empty()
```
    Returns an Input in the empty state.
  - empty
```
public static Input empty(InputSettings settings)
```
    Returns an Input in the empty state, with the given settings.
  - empty
```
public static Input empty(Object id,
                          Mark mark)
```
    Returns an Input in the empty state, at the mark position of a token stream logically identified by id.
  - empty
```
public static Input empty(Object id,
                          Mark mark,
                          InputSettings settings)
```
    Returns an Input in the empty state, at the mark position of a token stream logically identified by id, with the given settings.
  - done
```
public static Input done()
```
    Returns an Input in the done state.
  - done
```
public static Input done(InputSettings settings)
```
    Returns an Input in the done state, with the given settings.
  - done
```
public static Input done(Object id,
                         Mark mark)
```
    Returns an Input in the done state, at the mark position of a token stream logically identified by id.
  - done
```
public static Input done(Object id,
                         Mark mark,
                         InputSettings settings)
```
    Returns an Input in the done state, at the mark position of a token stream logically identified by id, with the given settings.
  - error
```
public static Input error(Throwable error)
```
    Returns an Input in the error state, with the given input error.
  - error
```
public static Input error(Throwable error,
                          InputSettings settings)
```
    Returns an Input in the error state, with the given input error and settings.
  - error
```
public static Input error(Throwable error,
                          Object id,
                          Mark mark)
```
    Returns an Input in the error state, with the given input error, at the mark position of a token stream logically identified by id.
  - error
```
public static Input error(Throwable error,
                          Object id,
                          Mark mark,
                          InputSettings settings)
```
    Returns an Input in the error state, with the given input error, at the mark position of a token stream logically identified by id, with the given settings.

Class Input

Input tokens

Input states

Non-blocking semantics

Position tracking

Cloning

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

Input

Method Detail

isCont

isEmpty

isDone

isError

isPart

isPart

head

step

seek

fork

trap

id

id

mark

mark

offset

line

column

settings

settings

clone

empty

empty

empty

empty

done

done

done

done

error

error

error

error