Implement Pattern-based Rule
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package it.cavallium.warppi.math.rules.dsl;
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import it.cavallium.warppi.math.Function;
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import it.cavallium.warppi.math.MathContext;
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import it.cavallium.warppi.math.rules.Rule;
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import it.cavallium.warppi.math.rules.RuleType;
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import it.cavallium.warppi.util.Error;
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import it.unimi.dsi.fastutil.objects.ObjectArrayList;
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import java.util.Arrays;
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import java.util.List;
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import java.util.Map;
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import java.util.stream.Collectors;
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/**
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* A <code>Rule</code> which uses <code>Pattern</code>s to match and replace functions.
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*/
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public class PatternRule implements Rule {
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private final String ruleName;
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private final RuleType ruleType;
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private final Pattern target;
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private final List<Pattern> replacements;
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public PatternRule(
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final String ruleName,
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final RuleType ruleType,
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final Pattern target,
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final List<Pattern> replacements
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) {
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this.ruleName = ruleName;
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this.ruleType = ruleType;
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this.target = target;
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this.replacements = replacements;
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}
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public PatternRule(
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final String ruleName,
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final RuleType ruleType,
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final Pattern target,
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final Pattern... replacements
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) {
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this(ruleName, ruleType, target, Arrays.asList(replacements));
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}
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@Override
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public String getRuleName() {
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return ruleName;
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}
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@Override
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public RuleType getRuleType() {
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return ruleType;
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}
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@Override
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public ObjectArrayList<Function> execute(final Function func) throws Error, InterruptedException {
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return target.match(func)
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.map(subFunctions -> applyReplacements(func.getMathContext(), subFunctions))
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.orElse(null);
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}
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private ObjectArrayList<Function> applyReplacements(
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final MathContext mathContext,
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final Map<String, Function> subFunctions
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) {
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return replacements.stream()
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.map(replacement -> replacement.replace(mathContext, subFunctions))
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.collect(Collectors.toCollection(ObjectArrayList::new));
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}
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}
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@ -0,0 +1,127 @@
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package it.cavallium.warppi.math.rules.dsl;
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import it.cavallium.warppi.math.Function;
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import it.cavallium.warppi.math.MathContext;
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import it.cavallium.warppi.math.functions.Number;
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import it.cavallium.warppi.math.functions.Subtraction;
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import it.cavallium.warppi.math.functions.Sum;
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import it.cavallium.warppi.math.functions.SumSubtraction;
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import it.cavallium.warppi.math.rules.RuleType;
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import it.cavallium.warppi.math.rules.dsl.patterns.*;
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import it.cavallium.warppi.util.Error;
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import it.cavallium.warppi.util.Errors;
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import it.unimi.dsi.fastutil.objects.ObjectArrayList;
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import org.junit.Test;
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import java.math.BigDecimal;
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import static org.junit.Assert.*;
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public class PatternRuleTest {
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private final MathContext mathContext = new MathContext();
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private final Pattern x = new SubFunctionPattern("x");
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private final Pattern xPlus0 = new SumPattern(
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x,
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new NumberPattern(new BigDecimal(0))
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);
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@Test
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public void testNonMatching() throws InterruptedException, Error {
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final Function func = new Sum(
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mathContext,
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new Number(mathContext, 1),
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new Number(mathContext, 2)
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);
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final PatternRule rule = new PatternRule("TestRule", RuleType.REDUCTION, xPlus0, xPlus0);
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assertNull(func.simplify(rule));
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}
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@Test
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public void testMatching() throws InterruptedException, Error {
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final Function func = new Sum(
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mathContext,
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new Number(mathContext, 1),
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new Number(mathContext, 0)
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);
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final PatternRule identityRule = new PatternRule("Identity", RuleType.REDUCTION, xPlus0, xPlus0);
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final ObjectArrayList<Function> identityResult = func.simplify(identityRule);
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assertEquals(1, identityResult.size());
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assertEquals(func, identityResult.get(0));
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final PatternRule simplifyRule = new PatternRule("Simplify", RuleType.REDUCTION, xPlus0, x);
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final ObjectArrayList<Function> simplifyResult = func.simplify(simplifyRule);
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assertEquals(1, identityResult.size());
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assertEquals(new Number(mathContext, 1), simplifyResult.get(0));
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}
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@Test
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public void testMatchingRecursive() throws InterruptedException, Error {
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final Function func = new Sum(
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mathContext,
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new Number(mathContext, 3),
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new Sum(
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mathContext,
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new Number(mathContext, 5),
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new Number(mathContext, 0)
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)
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);
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final PatternRule identityRule = new PatternRule("Identity", RuleType.REDUCTION, xPlus0, xPlus0);
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final ObjectArrayList<Function> identityResult = func.simplify(identityRule);
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assertEquals(1, identityResult.size());
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assertEquals(func, identityResult.get(0));
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final PatternRule simplifyRule = new PatternRule("Simplify", RuleType.REDUCTION, xPlus0, x);
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final ObjectArrayList<Function> simplifyResult = func.simplify(simplifyRule);
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assertEquals(1, identityResult.size());
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final Function expected = new Sum(
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mathContext,
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new Number(mathContext, 3),
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new Number(mathContext, 5)
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);
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assertEquals(expected, simplifyResult.get(0));
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}
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@Test
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public void testMultipleReplacements() throws InterruptedException, Error {
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final Number one = new Number(mathContext, 1);
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final Number two = new Number(mathContext, 2);
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final Function func = new SumSubtraction(mathContext, one, two);
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final Pattern x = new SubFunctionPattern("x");
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final Pattern y = new SubFunctionPattern("y");
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final PatternRule rule = new PatternRule(
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"TestRule",
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RuleType.EXPANSION,
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new SumSubtractionPattern(x, y),
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new SumPattern(x, y), new SubtractionPattern(x, y)
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);
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final ObjectArrayList<Function> result = func.simplify(rule);
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final ObjectArrayList<Function> expected = ObjectArrayList.wrap(new Function[]{
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new Sum(mathContext, one, two),
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new Subtraction(mathContext, one, two)
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});
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assertEquals(expected, result);
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}
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@Test
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public void testNoReplacements() throws InterruptedException, Error {
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final Function func = new Sum(
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mathContext,
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new Number(mathContext, 1),
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new Number(mathContext, 2)
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);
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final PatternRule rule = new PatternRule(
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"TestRule",
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RuleType.REDUCTION,
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new SubFunctionPattern("x")
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);
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assertTrue(func.simplify(rule).isEmpty());
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}
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}
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