Package io.jenetics.ext.rewriting

Class TreeRewriteRule<V>

java.lang.Object

io.jenetics.ext.rewriting.TreeRewriteRule<V>

All Implemented Interfaces:

TreeRewriter<V>, Serializable

public final class TreeRewriteRule<V>
extends Object
implements TreeRewriter<V>, Serializable

Represents a tree rewrite rule. A rewrite rule consists of a match pattern, which must be matched, and a substitution pattern, which is expanded and replaces the variables in the pattern. Some simple arithmetic rewrite rules.

 
     add($x,0) -> $x
     mul($x,1) -> $x
 

The substitution pattern may only use variables, already defined in the match pattern. So, the creation of the following rewrite rule s would lead to an IllegalArgumentException:

 
     add($x,0) -> $y
     mul(0,1) -> mul($x,1)
 

Since:

5.0

Version:

5.0

Author:

Franz Wilhelmstötter

See Also:

Tree rewriting systems, Serialized Form

Constructor Summary

Constructors

Constructor	Description
TreeRewriteRule(TreePattern<V> left, TreePattern<V> right)	Create a new rewrite rule from the given matching (left) and replacement (right) pattern.

Method Summary

Modifier and Type	Method	Description
boolean	equals(Object obj)
int	hashCode()
TreePattern<V>	left()	Return the rule matching pattern.
<B> TreeRewriteRule<B>	map(Function<? super V,? extends B> mapper)	Maps this rewrite rule from type V to type B.
static TreeRewriteRule<String>	parse(String rule)	Compiles the string representation of a rewrite rule:
static <V> TreeRewriteRule<V>	parse(String rule, Function<? super String,? extends V> mapper)	Compiles the string representation of a rewrite rule:
int	rewrite(TreeNode<V> tree, int limit)	Applies the rewriting to the given (mutable) tree.
TreePattern<V>	right()	Return the replacement pattern of the rule.
String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface io.jenetics.ext.rewriting.TreeRewriter

rewrite

Constructor Detail

TreeRewriteRule

public TreeRewriteRule(TreePattern<V> left,
                       TreePattern<V> right)

Create a new rewrite rule from the given matching (left) and replacement (right) pattern.

Parameters:

left - the matching pattern of the rule

right - the substitution pattern

Throws:

NullPointerException - if one of the arguments is null

IllegalArgumentException - if the template pattern uses variables not defined in the matcher pattern

Method Detail

left

public TreePattern<V> left()

Return the rule matching pattern.

Returns:

the rule matching pattern

right

public TreePattern<V> right()

Return the replacement pattern of the rule.

Returns:

the replacement pattern of the rule

map

public <B> TreeRewriteRule<B> map(Function<? super V,? extends B> mapper)

Maps this rewrite rule from type V to type B.

Type Parameters:

B - the target type

Parameters:

mapper - the type mapper

Returns:

a new rewrite rule for the mapped type

Throws:

NullPointerException - if the mapper is null

rewrite

public int rewrite(TreeNode<V> tree,
                   int limit)

Description copied from interface: TreeRewriter

Applies the rewriting to the given (mutable) tree. The tree rewrite is done in place. Via the limit parameter, the termination of the tree-rewrite process can be guaranteed.

Specified by:

rewrite in interface TreeRewriter<V>

Parameters:

tree - the tree to be rewritten

limit - the maximal number this rewrite rule is applied to the given tree. This guarantees the termination of the rewrite method.

Returns:

the number of rewrites applied to the input tree

hashCode

public int hashCode()

Overrides:

hashCode in class Object

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

toString

public String toString()

Overrides:

toString in class Object

parse

public static <V> TreeRewriteRule<V> parse(String rule,
                                           Function<? super String,? extends V> mapper)

Compiles the string representation of a rewrite rule:

 
     add($x,0) -> $x
     mul($x,1) -> $x
 

Type Parameters:

V - the tree node type

Parameters:

rule - the rewrite rule

mapper - the mapper function which converts the node value into the actual type V

Returns:

a new rewrite rule, compiled from the given rule string

Throws:

IllegalArgumentException - if the rewrite rule is invalid

NullPointerException - if on of the arguments is null

parse

public static TreeRewriteRule<String> parse(String rule)

Compiles the string representation of a rewrite rule:

 
     add($x,0) -> $x
     mul($x,1) -> $x
 

Parameters:

rule - the rewrite rule

Returns:

a new rewrite rule, compiled from the given rule string

Throws:

IllegalArgumentException - if the rewrite rule is invalid

NullPointerException - if on of the arguments is null