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https://github.com/aNNiMON/Own-Programming-Language-Tutorial.git
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Pattern matching по значениям списка
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Victor
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b957569759
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726e96488a
@ -38,3 +38,28 @@ def printArrayRecursive(arr) = match arr {
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case []: "[]"
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case last: "[" + last + ", []]"
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}
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println "\nPattern matching on arrays by value"
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def tupleMatch(x) = match x {
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case (0, 0): "00"
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case (1, 0): "10"
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case (0, 1): "01"
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case (1, 1): "11"
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case (2, _): "2?"
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case _: "unknown"
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}
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println tupleMatch([0, 1])
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println tupleMatch([1, 1])
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println tupleMatch([2, 1])
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println tupleMatch([3, 9])
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println "\nFizzBuzz with pattern matching"
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for i = 1, i <= 100, i++ {
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println match [i % 3 == 0, i % 5 == 0] {
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case (true, false): "Fizz"
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case (false, true): "Buzz"
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case (true, true): "FizzBuzz"
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case _: i
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}
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}
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@ -368,6 +368,19 @@ public final class Parser {
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match(TokenType.COLONCOLON);
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}
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pattern = listPattern;
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} else if (match(TokenType.LPAREN)) {
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// case (1, 2):
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final MatchExpression.TuplePattern tuplePattern = new MatchExpression.TuplePattern();
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while (!match(TokenType.RPAREN)) {
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if ("_".equals(get(0).getText())) {
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tuplePattern.addAny();
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consume(TokenType.WORD);
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} else {
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tuplePattern.add(expression());
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}
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match(TokenType.COMMA);
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}
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pattern = tuplePattern;
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}
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if (pattern == null) {
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@ -7,6 +7,7 @@ import com.annimon.ownlang.lib.Types;
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import com.annimon.ownlang.lib.Value;
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import com.annimon.ownlang.lib.Variables;
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import java.util.ArrayList;
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import java.util.Iterator;
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import java.util.List;
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/**
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@ -14,7 +15,7 @@ import java.util.List;
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* @author aNNiMON
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*/
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public final class MatchExpression implements Expression, Statement {
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public final Expression expression;
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public final List<Pattern> patterns;
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@ -22,12 +23,12 @@ public final class MatchExpression implements Expression, Statement {
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this.expression = expression;
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this.patterns = patterns;
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}
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@Override
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public void execute() {
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eval();
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}
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@Override
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public Value eval() {
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final Value value = expression.eval();
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@ -41,7 +42,7 @@ public final class MatchExpression implements Expression, Statement {
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if (p instanceof VariablePattern) {
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final VariablePattern pattern = (VariablePattern) p;
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if (pattern.variable.equals("_")) return evalResult(p.result);
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if (Variables.isExists(pattern.variable)) {
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if (match(value, Variables.get(pattern.variable)) && optMatches(p)) {
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return evalResult(p.result);
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@ -49,7 +50,7 @@ public final class MatchExpression implements Expression, Statement {
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} else {
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Variables.define(pattern.variable, value);
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if (optMatches(p)) {
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final Value result = evalResult(p.result);;
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final Value result = evalResult(p.result);
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Variables.remove(pattern.variable);
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return result;
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}
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@ -67,10 +68,29 @@ public final class MatchExpression implements Expression, Statement {
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return result;
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}
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}
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if ((value.type() == Types.ARRAY) && (p instanceof TuplePattern)) {
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final TuplePattern pattern = (TuplePattern) p;
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if (matchTuplePattern((ArrayValue) value, pattern) && optMatches(p)) {
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return evalResult(p.result);
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}
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}
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}
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throw new PatternMatchingException("No pattern were matched");
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}
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private boolean matchTuplePattern(ArrayValue array, TuplePattern p) {
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if (p.values.size() != array.size()) return false;
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final int size = array.size();
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for (int i = 0; i < size; i++) {
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final Expression expr = p.values.get(i);
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if ( (expr != TuplePattern.ANY) && (expr.eval().compareTo(array.get(i)) != 0) ) {
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return false;
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}
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}
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return true;
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}
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private boolean matchListPattern(ArrayValue array, ListPattern p) {
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final List<String> parts = p.parts;
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final int partsSize = parts.size();
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@ -90,7 +110,7 @@ public final class MatchExpression implements Expression, Statement {
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}
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Variables.remove(variable);
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return false;
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default: { // match arr { case [...]: .. }
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if (partsSize == arraySize) {
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// match [0, 1, 2] { case [a::b::c]: a=0, b=1, c=2 ... }
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@ -102,7 +122,7 @@ public final class MatchExpression implements Expression, Statement {
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return false;
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}
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}
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}
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}
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private boolean matchListPatternEqualsSize(ListPattern p, List<String> parts, int partsSize, ArrayValue array) {
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// Set variables
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@ -119,7 +139,7 @@ public final class MatchExpression implements Expression, Statement {
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}
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return false;
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}
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private boolean matchListPatternWithTail(ListPattern p, List<String> parts, int partsSize, ArrayValue array, int arraySize) {
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// Set element variables
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final int lastPart = partsSize - 1;
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@ -143,17 +163,17 @@ public final class MatchExpression implements Expression, Statement {
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}
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return false;
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}
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private boolean match(Value value, Value constant) {
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if (value.type() != constant.type()) return false;
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return value.equals(constant);
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}
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private boolean optMatches(Pattern pattern) {
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if (pattern.optCondition == null) return true;
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return pattern.optCondition.eval() != NumberValue.ZERO;
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}
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private Value evalResult(Statement s) {
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try {
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s.execute();
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@ -162,7 +182,7 @@ public final class MatchExpression implements Expression, Statement {
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}
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return NumberValue.ZERO;
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}
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@Override
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public void accept(Visitor visitor) {
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visitor.visit(this);
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@ -183,15 +203,15 @@ public final class MatchExpression implements Expression, Statement {
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sb.append("\n}");
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return sb.toString();
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}
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public static abstract class Pattern {
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public Statement result;
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public Expression optCondition;
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}
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public static class ConstantPattern extends Pattern {
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public Value constant;
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public ConstantPattern(Value pattern) {
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this.constant = pattern;
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}
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@ -201,10 +221,10 @@ public final class MatchExpression implements Expression, Statement {
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return constant + ": " + result;
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}
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}
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public static class VariablePattern extends Pattern {
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public String variable;
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public VariablePattern(String pattern) {
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this.variable = pattern;
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}
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@ -214,14 +234,14 @@ public final class MatchExpression implements Expression, Statement {
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return variable + ": " + result;
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}
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}
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public static class ListPattern extends Pattern {
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public List<String> parts;
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public ListPattern() {
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this(new ArrayList<String>());
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}
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public ListPattern(List<String> parts) {
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this.parts = parts;
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}
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@ -232,7 +252,73 @@ public final class MatchExpression implements Expression, Statement {
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@Override
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public String toString() {
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return parts + ": " + result;
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final Iterator<String> it = parts.iterator();
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if (it.hasNext()) {
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final StringBuilder sb = new StringBuilder();
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sb.append("[").append(it.next());
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while (it.hasNext()) {
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sb.append(" :: ").append(it.next());
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}
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sb.append("]: ").append(result);
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return sb.toString();
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}
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return "[]: " + result;
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}
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}
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public static class TuplePattern extends Pattern {
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public List<Expression> values;
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public TuplePattern() {
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this(new ArrayList<Expression>());
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}
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public TuplePattern(List<Expression> parts) {
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this.values = parts;
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}
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public void addAny() {
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values.add(ANY);
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}
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public void add(Expression value) {
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values.add(value);
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}
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@Override
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public String toString() {
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final Iterator<Expression> it = values.iterator();
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if (it.hasNext()) {
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final StringBuilder sb = new StringBuilder();
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sb.append("(").append(it.next());
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while (it.hasNext()) {
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sb.append(", ").append(it.next());
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}
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sb.append("): ").append(result);
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return sb.toString();
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}
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return "(): " + result;
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}
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private static final Expression ANY = new Expression() {
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@Override
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public Value eval() {
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return NumberValue.ONE;
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}
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@Override
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public void accept(Visitor visitor) {
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}
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@Override
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public <R, T> R accept(ResultVisitor<R, T> visitor, T input) {
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return null;
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}
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@Override
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public String toString() {
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return "_";
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}
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};
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}
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}
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