com.github.fge.grappa.parsers

Class BaseActions<V>

java.lang.Object

com.github.fge.grappa.parsers.BaseActions<V>

Type Parameters:

V - the type of the parser values

All Implemented Interfaces:

ContextAware<V>

Direct Known Subclasses:

BaseParser

public abstract class BaseActions<V>
extends Object
implements ContextAware<V>

Convenience context aware base class defining a number of useful helper methods.

Constructor Summary

Constructors

Constructor and Description
BaseActions()

Method Summary

Methods

Modifier and Type	Method and Description
Character	currentChar() Returns the next input character about to be matched.
int	currentIndex() Returns the current index in the input buffer.
boolean	drop() Removes the value at the top of the value stack.
boolean	drop(int down) Removes the value the given number of elements below the top of the value stack.
boolean	dup() Duplicates the top value of the value stack.
Context<V>	getContext() The current context for use with action methods.
boolean	hasError() Determines whether the current rule or a sub rule has recorded a parse error.
boolean	inPredicate() Returns true if the current rule is running somewhere underneath a Test/TestNot rule.
String	match() Returns the input text matched by the rule immediately preceding the action expression that is currently being evaluated.
char	matchedChar() Returns the first character of the input text matched by the rule immediately preceding the action expression that is currently being evaluated.
int	matchEnd() Returns the end location of the rule immediately preceding the action expression that is currently being evaluated.
int	matchLength() Returns the number of characters matched by the rule immediately preceding the action expression that is currently being evaluated.
String	matchOrDefault(String defaultString) Returns the input text matched by the rule immediately preceding the action expression that is currently being evaluated.
IndexRange	matchRange() Creates a new IndexRange instance covering the input text matched by the rule immediately preceding the action expression that is currently being evaluated.
int	matchStart() Returns the start index of the rule immediately preceding the action expression that is currently being evaluated.
V	peek() Returns the value at the top of the value stack without removing it.
V	peek(int down) Returns the value the given number of elements below the top of the value stack without removing it.
<E extends V> E	peekAs(Class<E> c) Returns and casts the value at the top of the value stack without removing it.
<E extends V> E	peekAs(Class<E> c, int down) Returns and casts the value the given number of elements below the top of the value stack without removing it.
boolean	poke(int down, V value) Replaces the element the given number of elements below the current top of the value stack.
boolean	poke(V value) Replaces the current top value of the value stack with the given value.
V	pop() Removes the value at the top of the value stack and returns it.
V	pop(int down) Removes the value the given number of elements below the top of the value stack and returns it
<E extends V> E	popAs(Class<E> c) Removes the value at the top of the value stack and casts it before returning it
<E extends V> E	popAs(Class<E> c, int down) Removes the value the given number of elements below the top of the value stack and casts it before returning it
Position	position() Returns the current position in the underlying InputBuffer as a Position instance.
boolean	push(int down, V value) Inserts the given value a given number of elements below the current top of the value stack.
boolean	push(V value) Pushes the given value onto the value stack.
void	setContext(Context<V> context) ContextAware interface implementation.
boolean	swap() Swaps the top two elements of the value stack.
boolean	swap(int n) Reverse the order of the top n elements of this context's value stack

Methods inherited from class java.lang.Object

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

Constructor Detail

BaseActions

public BaseActions()

Method Detail

getContext

public final Context<V> getContext()

The current context for use with action methods. Updated immediately before action calls.

Returns:

the current context

setContext

public final void setContext(Context<V> context)

ContextAware interface implementation.

Specified by:

setContext in interface ContextAware<V>

Parameters:

context - the context

currentIndex

public final int currentIndex()

Returns the current index in the input buffer.

Returns:

the current index

match

public String match()

Returns the input text matched by the rule immediately preceding the action expression that is currently being evaluated. This call can only be used in actions that are part of a Sequence rule and are not at first position in this Sequence.

Returns:

the input text matched by the immediately preceding subrule

matchRange

public IndexRange matchRange()

Creates a new IndexRange instance covering the input text matched by the rule immediately preceding the action expression that is currently being evaluated. This call can only be used in actions that are part of a Sequence rule and are not at first position in this Sequence.

Returns:

a new IndexRange instance

matchOrDefault

public String matchOrDefault(String defaultString)

Returns the input text matched by the rule immediately preceding the action expression that is currently being evaluated. If the matched input text is empty the given default string is returned. This call can only be used in actions that are part of a Sequence rule and are not at first position in this Sequence.

Parameters:

defaultString - the default string to return if the matched input text is empty

Returns:

the input text matched by the immediately preceding subrule or the default string

matchedChar

public char matchedChar()

Returns the first character of the input text matched by the rule immediately preceding the action expression that is currently being evaluated. This call can only be used in actions that are part of a Sequence rule and are not at first position in this Sequence.

If the immediately preceding rule did not match anything this method throws a GrammarException. If you need to be able to handle that case use the getMatch() method.

Returns:

the first input char of the input text matched by the immediately preceding subrule or null, if the previous rule matched nothing

matchStart

public int matchStart()

Returns the start index of the rule immediately preceding the action expression that is currently being evaluated. This call can only be used in actions that are part of a Sequence rule and are not at first position in this Sequence.

Returns:

the start index of the context immediately preceding current action

matchEnd

public int matchEnd()

Returns the end location of the rule immediately preceding the action expression that is currently being evaluated. This call can only be used in actions that are part of a Sequence rule and are not at first position in this Sequence.

Returns:

the end index of the context immediately preceding current action, i.e. the index of the character immediately following the last matched character

matchLength

public int matchLength()

Returns the number of characters matched by the rule immediately preceding the action expression that is currently being evaluated. This call can only be used in actions that are part of a Sequence rule and are not at first position in this Sequence.

Returns:

the number of characters matched

position

public Position position()

Returns the current position in the underlying InputBuffer as a Position instance.

Returns:

the current position in the underlying inputbuffer

push

public boolean push(V value)

Pushes the given value onto the value stack. Equivalent to push(0, value).

Parameters:

value - the value to push

Returns:

true

push

public boolean push(int down,
           V value)

Inserts the given value a given number of elements below the current top of the value stack.

Parameters:

down - the number of elements to skip before inserting the value (0 being equivalent to push(value))

value - the value

Returns:

true

Throws:

IllegalArgumentException - if the stack does not contain enough elements to perform this operation

pop

public V pop()

Removes the value at the top of the value stack and returns it.

Returns:

the current top value

Throws:

IllegalArgumentException - if the stack is empty

popAs

public <E extends V> E popAs(@Nonnull
                    Class<E> c)

Removes the value at the top of the value stack and casts it before returning it

Type Parameters:

E - type of the class

Parameters:

c - the class to cast to

Returns:

the current top value

Throws:

IllegalArgumentException - if the stack is empty

See Also:

pop()

pop

public V pop(int down)

Removes the value the given number of elements below the top of the value stack and returns it

Parameters:

down - the number of elements to skip before removing the value (0 being equivalent to pop())

Returns:

the value

Throws:

IllegalArgumentException - if the stack does not contain enough elements to perform this operation

popAs

public <E extends V> E popAs(Class<E> c,
                    int down)

Removes the value the given number of elements below the top of the value stack and casts it before returning it

Type Parameters:

E - type of the class

Parameters:

c - the class to cast to

down - the number of elements to skip before removing the value (0 being equivalent to pop())

Returns:

the value

Throws:

IllegalArgumentException - if the stack does not contain enough elements to perform this operation

See Also:

pop(int)

drop

public boolean drop()

Removes the value at the top of the value stack.

Returns:

true

Throws:

IllegalArgumentException - if the stack is empty

drop

public boolean drop(int down)

Removes the value the given number of elements below the top of the value stack.

Parameters:

down - the number of elements to skip before removing the value (0 being equivalent to drop())

Returns:

true

Throws:

IllegalArgumentException - if the stack does not contain enough elements to perform this operation

peek

public V peek()

Returns the value at the top of the value stack without removing it.

Returns:

the current top value

Throws:

IllegalArgumentException - if the stack is empty

peekAs

public <E extends V> E peekAs(Class<E> c)

Returns and casts the value at the top of the value stack without removing it.

Type Parameters:

E - type of the class

Parameters:

c - the class to cast to

Returns:

the value

See Also:

peek()

peek

public V peek(int down)

Returns the value the given number of elements below the top of the value stack without removing it.

Parameters:

down - the number of elements to skip (0 being equivalent to peek())

Returns:

the value

Throws:

IllegalArgumentException - if the stack does not contain enough elements to perform this operation

peekAs

public <E extends V> E peekAs(Class<E> c,
                     int down)

Returns and casts the value the given number of elements below the top of the value stack without removing it.

Type Parameters:

E - type of the class

Parameters:

c - the class to cast to

down - the number of elements to skip (0 being equivalent to peek())

Returns:

the value

See Also:

peek(int)

poke

public boolean poke(V value)

Replaces the current top value of the value stack with the given value. Equivalent to poke(0, value).

Parameters:

value - the value

Returns:

true

Throws:

IllegalArgumentException - if the stack is empty

poke

public boolean poke(int down,
           V value)

Replaces the element the given number of elements below the current top of the value stack.

Parameters:

down - the number of elements to skip before replacing the value (0 being equivalent to poke(value))

value - the value to replace with

Returns:

true

Throws:

IllegalArgumentException - if the stack does not contain enough elements to perform this operation

dup

public boolean dup()

Duplicates the top value of the value stack. Equivalent to push(peek()).

Returns:

true

Throws:

IllegalArgumentException - if the stack is empty

swap

public boolean swap()

Swaps the top two elements of the value stack.

Returns:

true

Throws:

IllegalArgumentException - if the stack does not contain at least two elements

swap

public boolean swap(int n)

Reverse the order of the top n elements of this context's value stack

Parameters:

n - the number of elements to swap

Returns:

always true

Throws:

IllegalArgumentException - stack does not contain enough elements

See Also:

ValueStack.swap(int)

currentChar

public Character currentChar()

Returns the next input character about to be matched.

Returns:

the next input character about to be matched

inPredicate

public boolean inPredicate()

Returns true if the current rule is running somewhere underneath a Test/TestNot rule. Useful for example for making sure actions are not run inside of a predicate evaluation: return Sequence( ..., inPredicate() || actions.doSomething() );

Returns:

true if in a predicate

hasError

public boolean hasError()

Determines whether the current rule or a sub rule has recorded a parse error. Useful for example for making sure actions are not run on erroneous input: return Sequence( ..., !hasError() && actions.doSomething() );

Returns:

true if either the current rule or a sub rule has recorded a parse error