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Make possible to rewrite discrete expressions with rules #983

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Make possible to rewrite discrete expressions with rules #983

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abf7232
Making it possible to rewrite expressions
cprudhom Nov 30, 2022
2302115
Merge branch 'master' into dev_rewrite
cprudhom Dec 1, 2022
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101 changes: 69 additions & 32 deletions solver/src/main/java/org/chocosolver/solver/expression/discrete/arithmetic/ArExpression.java
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Original file line number Diff line number Diff line change
Expand Up @@ -17,13 +17,9 @@
import org.chocosolver.solver.variables.IntVar;
import org.chocosolver.util.tools.MathUtils;

import java.util.Arrays;
import java.util.HashSet;
import java.util.Map;
import java.util.OptionalInt;
import java.util.*;

/**
*
* arithmetic expression
* <p>
* Project: choco-solver.
Expand All @@ -36,7 +32,7 @@ public interface ArExpression {
/**
* List of available operator for arithmetic expression
*/
enum Operator {
enum Operator implements ExpOperator {
/**
* negation operator
*/
Expand Down Expand Up @@ -143,13 +139,13 @@ int eval(int i1) {

@Override
int eval(int i1, int i2) {
if(i2 == 0){
if(i1>0) {
if (i2 == 0) {
if (i1 > 0) {
return Integer.MAX_VALUE;
}else{
} else {
return Integer.MIN_VALUE;
}
}else {
} else {
return i1 / i2;
}
}
Expand All @@ -170,13 +166,13 @@ int eval(int i1) {

@Override
int eval(int i1, int i2) {
if(i2 == 0){
if(i1>0) {
if (i2 == 0) {
if (i1 > 0) {
return Integer.MAX_VALUE;
}else{
} else {
return Integer.MIN_VALUE;
}
}else {
} else {
return i1 % i2;
}
}
Expand Down Expand Up @@ -262,7 +258,7 @@ int identity() {
return Integer.MIN_VALUE;
}
},
NOP{
NOP {
@Override
int eval(int i1) {
return 0;
Expand Down Expand Up @@ -307,19 +303,20 @@ int identity() {
/**
* @return an {@link OptionalInt} which contains an {@code int} this expression is a primitive.
*/
default OptionalInt primitive(){
default OptionalInt primitive() {
return OptionalInt.empty();
}

/**
* @return <tt>true</tt> if this expression is a leaf, ie a variable, <tt>false</tt> otherwise
*/
default boolean isExpressionLeaf(){
default boolean isExpressionLeaf() {
return false;
}

/**
* Extract the variables from this expression
*
* @param variables set of variables
*/
default void extractVar(HashSet<IntVar> variables) {
Expand All @@ -334,29 +331,69 @@ default void extractVar(HashSet<IntVar> variables) {

/**
* @param values int values to evaluate
* @param map mapping between variables of the topmost expression and position in <i>values</i>
* @param map mapping between variables of the topmost expression and position in <i>values</i>
* @return an evaluation of this expression with a tuple
*/
@SuppressWarnings("SuspiciousMethodCalls")
default int ieval(int[] values, Map<IntVar, Integer> map){
default int ieval(int[] values, Map<IntVar, Integer> map) {
assert this instanceof IntVar;
return values[map.get(this)];
}

/**
* @return the child of this expression, or null if thid
*/
default int getNoChild(){
default int getNoChild() {
return 0;
}

/**
* @return the child of this expression, or null if thid
*/
default ArExpression[] getExpressionChild(){
default ArExpression[] getExpressionChild() {
return NO_CHILD;
}

/**
* @return the operator of this expression
*/
default ExpOperator getOperator() {
return Operator.NOP;
}

/**
* Replace the sub-expression at position <i>idx</i> in the expression by <i>e</i>.
*
* @param idx index of the expression to replace
* @param e the new expression
* @implSpec This method is only supposed to be used by {{@link #rewrite(List)}
*/
default void set(int idx, ArExpression e) {
}

/**
* Rewrite the current expression by applying the rewriting rules in parameters.
* @param rules list of rules to applied sequentially
* @return the rewritten expression
* @implNote The rules are applied sequentially according to the order defined by the list.
* A rule is first applied to each sub-expressions, recursively, before being applied to the top expression.
* For a given rule to be applied twice, put it twice in the list.
* If a rule rewrite an expression, the replacement is made in place ({@link #set(int, ArExpression)}.
*/
@SuppressWarnings("unchecked")
default <E extends ArExpression> E rewrite(List<Rule<ArExpression>> rules) {
E rewritten = (E) this;
for (Rule<ArExpression> rule : rules) {
ArExpression[] children = this.getExpressionChild();
for (int i = 0; i < children.length; i++) {
rewritten.set(i, children[i].rewrite(Collections.singletonList(rule)));
}
if (rule.predicate.test(rewritten)) {
rewritten = (E) rule.rewriter.apply(rewritten);
}
}
return rewritten;
}

/**
* @return return the expression "-x" where this is "x"
*/
Expand Down Expand Up @@ -384,7 +421,7 @@ default ArExpression add(int y) {
* @return return the expression "x + y" where this is "x"
*/
default ArExpression add(ArExpression y) {
if(y.primitive().isPresent()){
if (y.primitive().isPresent()) {
return add(y.primitive().getAsInt());
}
return new BiArExpression(ArExpression.Operator.ADD, this, y);
Expand Down Expand Up @@ -431,7 +468,7 @@ default ArExpression mul(int y) {
* @return return the expression "x * y" where this is "x"
*/
default ArExpression mul(ArExpression y) {
if(y.primitive().isPresent()) {
if (y.primitive().isPresent()) {
return mul(y.primitive().getAsInt());
}
return new BiArExpression(ArExpression.Operator.MUL, this, y);
Expand All @@ -458,7 +495,7 @@ default ArExpression div(int y) {
* @return return the expression "x / y" where this is "x"
*/
default ArExpression div(ArExpression y) {
if(y.primitive().isPresent()) {
if (y.primitive().isPresent()) {
return div(y.primitive().getAsInt());
}
return new BiArExpression(ArExpression.Operator.DIV, this, y);
Expand All @@ -477,7 +514,7 @@ default ArExpression mod(int y) {
* @return return the expression "x % y" where this is "x"
*/
default ArExpression mod(ArExpression y) {
if(y.primitive().isPresent()) {
if (y.primitive().isPresent()) {
return mod(y.primitive().getAsInt());
}
return new BiArExpression(ArExpression.Operator.MOD, this, y);
Expand All @@ -503,7 +540,7 @@ default ArExpression pow(int y) {
* @return return the expression "x + y" where this is "x"
*/
default ArExpression pow(ArExpression y) {
if(y.primitive().isPresent()) {
if (y.primitive().isPresent()) {
return pow(y.primitive().getAsInt());
}
return new BiArExpression(ArExpression.Operator.POW, this, y);
Expand All @@ -522,7 +559,7 @@ default ArExpression min(int y) {
* @return return the expression "min(x, y)" where this is "x"
*/
default ArExpression min(ArExpression y) {
if(y.primitive().isPresent()) {
if (y.primitive().isPresent()) {
return min(y.primitive().getAsInt());
}
return new BiArExpression(ArExpression.Operator.MIN, this, y);
Expand All @@ -549,7 +586,7 @@ default ArExpression max(int y) {
* @return return the expression "max(x, y)" where this is "x"
*/
default ArExpression max(ArExpression y) {
if(y.primitive().isPresent()) {
if (y.primitive().isPresent()) {
return max(y.primitive().getAsInt());
}
return new BiArExpression(ArExpression.Operator.MAX, this, y);
Expand Down Expand Up @@ -592,7 +629,7 @@ default ReExpression lt(int y) {
* @return return the expression "x < y" where this is "x"
*/
default ReExpression lt(ArExpression y) {
if(y.primitive().isPresent()) {
if (y.primitive().isPresent()) {
return lt(y.primitive().getAsInt());
}
return new BiReExpression(ReExpression.Operator.LT, this, y);
Expand Down Expand Up @@ -630,7 +667,7 @@ default ReExpression gt(int y) {
* @return return the expression "x > y" where this is "x"
*/
default ReExpression gt(ArExpression y) {
if(y.primitive().isPresent()) {
if (y.primitive().isPresent()) {
return gt(y.primitive().getAsInt());
}
return new BiReExpression(ReExpression.Operator.GT, this, y);
Expand Down Expand Up @@ -668,7 +705,7 @@ default ReExpression ne(int y) {
* @return return the expression "x =/= y" where this is "x"
*/
default ReExpression ne(ArExpression y) {
if(y.primitive().isPresent()) {
if (y.primitive().isPresent()) {
return ne(y.primitive().getAsInt());
}
return new BiReExpression(ReExpression.Operator.NE, this, y);
Expand Down
23 changes: 17 additions & 6 deletions ...r/src/main/java/org/chocosolver/solver/expression/discrete/arithmetic/BiArExpression.java
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Original file line number Diff line number Diff line change
Expand Up @@ -44,11 +44,11 @@ public class BiArExpression implements ArExpression {
/**
* The first expression this expression relies on
*/
private final ArExpression e1;
private ArExpression e1;
/**
* The second expression this expression relies on
*/
private final ArExpression e2;
private ArExpression e2;

/**
* Builds a binary expression
Expand Down Expand Up @@ -110,10 +110,10 @@ public IntVar intVar() {
bounds = VariableUtils.boundsForPow(v1, v2);
me = model.intVar(model.generateName("pow_exp_"), bounds[0], bounds[1]);
Tuples tuples = new Tuples(true);
for(int val1 : v1){
for(int val2 : v2){
int res = (int)Math.pow(val1, val2);
if(me.contains(res)) {
for (int val1 : v1) {
for (int val2 : v2) {
int res = (int) Math.pow(val1, val2);
if (me.contains(res)) {
tuples.add(val1, val2, res);
}
}
Expand Down Expand Up @@ -152,6 +152,17 @@ public ArExpression[] getExpressionChild() {
return new ArExpression[]{e1, e2};
}

@Override
public ExpOperator getOperator() {
return op;
}

@Override
public void set(int idx, ArExpression e) {
if (idx == 0) this.e1 = e;
if (idx == 1) this.e2 = e;
}

@Override
public String toString() {
return op.name() + "(" + e1.toString() + "," + e2.toString() + ")";
Expand Down
21 changes: 21 additions & 0 deletions solver/src/main/java/org/chocosolver/solver/expression/discrete/arithmetic/ExpOperator.java
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@@ -0,0 +1,21 @@
/*
* This file is part of choco-solver, http://choco-solver.org/
*
* Copyright (c) 2022, IMT Atlantique. All rights reserved.
*
* Licensed under the BSD 4-clause license.
*
* See LICENSE file in the project root for full license information.
*/
package org.chocosolver.solver.expression.discrete.arithmetic;

/**
* An interface that is implemented by expressions to defined specific operators.
* This interface is only required to ease rewriting expressions.
* <br/>
*
* @author Charles Prud'homme
* @since 30/11/2022
*/
public interface ExpOperator {
}
12 changes: 12 additions & 0 deletions ...r/src/main/java/org/chocosolver/solver/expression/discrete/arithmetic/NaArExpression.java
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Expand Up @@ -135,6 +135,18 @@ public ArExpression[] getExpressionChild() {
return es;
}

@Override
public ExpOperator getOperator() {
return op;
}

@Override
public void set(int idx, ArExpression e) {
if (idx >= 0 && idx < es.length) {
this.es[idx] = e;
}
}

@Override
public String toString() {
return op.name() + "(" + es[0].toString() + ",... ," + es[es.length - 1].toString() + ")";
Expand Down
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