feature: ExecExprListOperators

src/main/java/io/github/syst3ms/skriptparser/expressions/ExecExprListOperators.java

@@ -0,0 +1,211 @@
+package io.github.syst3ms.skriptparser.expressions;
+
+import io.github.syst3ms.skriptparser.Parser;
+import io.github.syst3ms.skriptparser.lang.Expression;
+import io.github.syst3ms.skriptparser.lang.TriggerContext;
+import io.github.syst3ms.skriptparser.lang.base.ExecutableExpression;
+import io.github.syst3ms.skriptparser.log.ErrorType;
+import io.github.syst3ms.skriptparser.parsing.ParseContext;
+import io.github.syst3ms.skriptparser.types.changers.ChangeMode;
+import io.github.syst3ms.skriptparser.util.CollectionUtils;
+import org.jetbrains.annotations.Nullable;
+
+import java.math.BigInteger;
+import java.util.ArrayList;
+import java.util.Arrays;
+
+/**
+ * Basic list operators with the following behavior:
+ * <ul>
+ *      <li>{@code pop} removes the last element and returns that removed element.</li>
+ *      <li>{@code shift/poll} removes the first element and returns that removed element.</li>
+ *      <li>{@code extract} removes a specific (or just the first/last element) and returns that removed element</li>
+ *      <li>{@code splice} removes elements in a certain bound and returns those removed elements.</li>
+ * </ul>
+ * These are all changing operators, which mean they apply the operator on the source list
+ * and return other elements accordingly to the operator type. If the list is not changeable,
+ * then these operators will not work.
+ * Note that indices in Skript start at one and that both the lower and upper bounds are inclusive.
+ * The step function can be used in the {@code splice} pattern to skip over certain values. Note that
+ * when a negative step function is used, the list is reversed as well as the lower and upper bounds,
+ * which means the lower bound must be higher than the upper bound.
+ *
+ * @name List Operators
+ * @type EXPRESSION
+ * @pattern pop %objects%
+ * @pattern (shift|poll) %objects%
+ * @pattern splice %objects% (from %integer% to %integer%|starting (at|from) %integer%|up to %integer%) [[with] step %integer%]
+ * @since ALPHA
+ * @author Mwexim
+ * @see ExprElement
+ */
+public class ExecExprListOperators extends ExecutableExpression<Object> {
+	static {
+		Parser.getMainRegistration().addSelfRegisteringElement(
+				ExecExprListOperators.class,
+				Object.class,
+				false,
+				"extract [the] (0:last|1:first|2:%integer%(st|nd|rd|th)) element out [of] %objects%",
+				"pop %objects%",
+				"(shift|poll) %objects%",
+				"splice %objects% (0:from %integer% to %integer%|1:starting (at|from) %integer%|2:up to %integer%) [[with] step %integer%]"
+		);
+	}
+
+	private int type;
+	private Expression<Object> list;
+	private Expression<BigInteger> index;
+	private Expression<BigInteger> lower;
+	private Expression<BigInteger> upper;
+	private Expression<BigInteger> step;
+
+	@SuppressWarnings("unchecked")
+	@Override
+	public boolean init(Expression<?>[] expressions, int matchedPattern, ParseContext parseContext) {
+		switch (matchedPattern) {
+			case 0:
+				type = parseContext.getParseMark();
+				list = (Expression<Object>) (type == 2 ? expressions[1] : expressions[0]);
+				if (type == 2)
+					index = (Expression<BigInteger>) expressions[0];
+				break;
+			case 1:
+			case 2:
+				type = matchedPattern - 1;
+				list = (Expression<Object>) expressions[0];
+				break;
+			case 3:
+				type = 3;
+				list = (Expression<Object>) expressions[0];
+				switch (parseContext.getParseMark()) {
+					case 0:
+						lower = (Expression<BigInteger>) expressions[1];
+						upper = (Expression<BigInteger>) expressions[2];
+						if (expressions.length == 4)
+							step = (Expression<BigInteger>) expressions[3];
+						break;
+					case 1:
+						lower = (Expression<BigInteger>) expressions[1];
+						if (expressions.length == 3)
+							step = (Expression<BigInteger>) expressions[2];
+						break;
+					case 2:
+						upper = (Expression<BigInteger>) expressions[1];
+						if (expressions.length == 3)
+							step = (Expression<BigInteger>) expressions[2];
+						break;
+					default:
+						throw new IllegalStateException();
+				}
+		}
+		var logger = parseContext.getLogger();
+		if (list.acceptsChange(ChangeMode.SET).isEmpty()) {
+			logger.error(
+					list.toString(null, logger.isDebug()) + " is static and cannot be changed",
+					ErrorType.SEMANTIC_ERROR
+			);
+			return false;
+		} else if (list.isSingle()) {
+			logger.error(
+					list.toString(null, logger.isDebug()) + " represents a single value",
+					ErrorType.SEMANTIC_ERROR,
+					"List operators only work on multiple objects at the same time"
+			);
+			return false;
+		}
+		return true;
+	}
+
+	@Override
+	public Object[] getValues(TriggerContext ctx) {
+		var values = list.getValues(ctx);
+		if (values.length == 0)
+			return new Object[0];
+
+		switch (type) {
+			case 0:
+				list.change(ctx, Arrays.copyOfRange(values, 0, values.length - 1), ChangeMode.SET);
+				return new Object[] {values[values.length - 1]};
+			case 1:
+				list.change(ctx, Arrays.copyOfRange(values, 1, values.length), ChangeMode.SET);
+				return new Object[] {values[0]};
+			case 2:
+				int ind = index.getSingle(ctx)
+						.filter(n -> n.signum() > 0 && n.compareTo(BigInteger.valueOf(values.length)) <= 0)
+						.map(n -> n.intValue() - 1)
+						.orElse(-1);
+				if (ind == -1) {
+					return new Object[0];
+				}
+				var skipped = new Object[values.length - 1];
+				for (int i = 0, k = 0; i < values.length; i++) {
+					if (i == ind) {
+						continue;
+					}
+					skipped[k++] = values[i];
+				}
+				list.change(ctx, skipped, ChangeMode.SET);
+				return new Object[] {values[ind]};
+			case 3:
+				var low = lower != null
+						? lower.getSingle(ctx).filter(n -> n.signum() > 0).map(n -> n.intValue() - 1).orElse(-1)
+						: 0;
+				var up = upper != null
+						? upper.getSingle(ctx).filter(n -> n.compareTo(BigInteger.valueOf(values.length)) <= 0).map(BigInteger::intValue).orElse(values.length)
+						: values.length;
+				var st = step != null
+						? step.getSingle(ctx).filter(n -> n.signum() != 0 && n.compareTo(BigInteger.valueOf(-values.length)) >= 0 && n.compareTo(BigInteger.valueOf(values.length)) <= 0).map(BigInteger::intValue).orElse(0)
+						: 1;
+
+				if (st < 0) {
+					CollectionUtils.reverseArray(values);
+					st = -st;
+					int temp = low;
+					low = up - 1;
+					up = temp + 1;
+				}
+				if (low == -1 || up == -1 || up == 0 || st == 0 || low > up) {
+					list.change(ctx, new Object[0], ChangeMode.SET);
+					return new Object[0];
+				} else if (low == up) {
+					// Nothing to change
+					return new Object[0];
+				}
+
+				var spliced = new ArrayList<>();
+				var changed = new ArrayList<>();
+				for (int i = 0; i < values.length; i++) {
+					if (i >= low && i < up && (i - low) % st == 0) {
+						spliced.add(values[i]);
+					} else {
+						changed.add(values[i]);
+					}
+				}
+
+				list.change(ctx, changed.toArray(), ChangeMode.SET);
+				return spliced.toArray(new Object[0]);
+			default:
+				throw new IllegalStateException();
+		}
+	}
+
+	@Override
+	public boolean isSingle() {
+		return type == 0 || type == 1;
+	}
+
+	@Override
+	public String toString(@Nullable TriggerContext ctx, boolean debug) {
+		switch (type) {
+			case 0:
+				return "pop " + list.toString(ctx, debug);
+			case 1:
+				return "poll " + list.toString(ctx, debug);
+			case 2:
+				return "splice " + list.toString(ctx, debug) + " from " + lower.toString(ctx, debug)
+						+ (upper != null ? upper.toString(ctx, debug) : "");
+			default:
+				throw new IllegalStateException();
+		}
+	}
+}

src/main/java/io/github/syst3ms/skriptparser/lang/base/ExecutableExpression.java

@@ -36,7 +36,7 @@ protected void execute(TriggerContext ctx) {
     public void register(SkriptRegistration reg, Object... args) {
         Class<T> type = (Class<T>) args[0];
         boolean isSingle = (boolean) args[1];
-        String[] patterns = (String[]) Arrays.copyOfRange(args, 2, args.length);
+        String[] patterns = Arrays.copyOfRange(args, 2, args.length, String[].class);
 
         // The actual registration
         reg.addExpression(getClass(), type, isSingle, patterns);