ListTag.java

package com.denizenscript.denizencore.objects.core;

import com.denizenscript.denizencore.objects.ArgumentHelper;
import com.denizenscript.denizencore.objects.Fetchable;
import com.denizenscript.denizencore.objects.ObjectFetcher;
import com.denizenscript.denizencore.objects.ObjectTag;
import com.denizenscript.denizencore.tags.TagRunnable;
import com.denizenscript.denizencore.scripts.ScriptEntry;
import com.denizenscript.denizencore.scripts.containers.core.ProcedureScriptContainer;
import com.denizenscript.denizencore.scripts.queues.core.InstantQueue;
import com.denizenscript.denizencore.tags.ObjectTagProcessor;
import com.denizenscript.denizencore.utilities.CoreUtilities;
import com.denizenscript.denizencore.utilities.NaturalOrderComparator;
import com.denizenscript.denizencore.utilities.debugging.Debuggable;
import com.denizenscript.denizencore.utilities.debugging.Debug;
import com.denizenscript.denizencore.DenizenCore;
import com.denizenscript.denizencore.tags.Attribute;
import com.denizenscript.denizencore.tags.TagContext;
import com.denizenscript.denizencore.tags.core.EscapeTagBase;

import java.math.BigDecimal;
import java.util.*;
import java.util.regex.Pattern;

public class ListTag extends ArrayList<String> implements ObjectTag {

    // <--[language]
    // @name ListTag Objects
    // @group Object System
    // @description
    // A ListTag is a list of any data. It can hold any number of objects in any order.
    // The objects can be of any basic Denizen object type, including another list
    // (escaping sub-lists is strongly recommended).
    //
    // For format info, see <@link language li@>
    //
    // -->

    // <--[language]
    // @name li@
    // @group Object Fetcher System
    // @description
    // li@ refers to the 'object identifier' of a ListTag. The 'li@' is notation for Denizen's Object
    // Fetcher. The constructor for a ListTag is the content items of a list separated by a pipe '|' symbol.
    // For example, if I had a list of 'taco', 'potatoes', and 'cheese', I would use
    // 'li@taco|potatoes|cheese'
    //
    // A list with zero items in it is simply 'li@'
    // and a list with one item is just the one item and no pipes.
    //
    // For general info, see <@link language ListTag Objects>
    // -->

    public final ArrayList<ObjectTag> objectForms;

    @Override
    public boolean add(String addMe) {
        objectForms.add(new ElementTag(addMe));
        return super.add(addMe);
    }

    @Override
    public void add(int index, String addMe) {
        objectForms.add(index, new ElementTag(addMe));
        super.add(index, addMe);
    }

    @Override
    public boolean addAll(Collection<? extends String> addMe) {
        for (String str : addMe) {
            add(str);
        }
        return !addMe.isEmpty();
    }

    @Override
    public String remove(int index) {
        objectForms.remove(index);
        return super.remove(index);
    }

    @Override
    public boolean remove(Object key) {
        int ind = super.indexOf(key);
        if (ind < 0 || ind >= size()) {
            return false;
        }
        this.remove(ind);
        return true;
    }

    public boolean addAll(ListTag inp) {
        objectForms.addAll(inp.objectForms);
        return super.addAll(inp);
    }

    public boolean addObject(ObjectTag obj) {
        objectForms.add(obj);
        return super.add(obj.toString());
    }

    public void addObject(int index, ObjectTag obj) {
        objectForms.add(index, obj);
        super.add(index, obj.toString());
    }

    public void setObject(int index, ObjectTag obj) {
        objectForms.set(index, obj);
        super.set(index, obj.toString());
    }

    public ObjectTag getObject(int id) {
        return objectForms.get(id);
    }

    public static ListTag valueOf(String string) {
        return valueOf(string, null);
    }

    @Fetchable("li")
    public static ListTag valueOf(String string, TagContext context) {
        if (string == null) {
            return null;
        }

        ///////
        // Match @object format

        ListTag list = DenizenCore.getImplementation().valueOfFlagListTag(string);

        if (list != null) {
            return list;
        }

        // Use value of string, which will separate values by the use of a pipe '|'
        return new ListTag(string.startsWith("li@") ? string.substring(3) : string, context);
    }

    public static ListTag getListFor(ObjectTag inp, TagContext context) {
        return inp instanceof ListTag ? (ListTag) inp : valueOf(inp.toString(), context);
    }

    public static boolean matches(String arg) {

        boolean flag = DenizenCore.getImplementation().matchesFlagListTag(arg);

        return flag || arg.contains("|") || arg.startsWith("li@");
    }

    /////////////
    //   Constructors
    //////////

    public ListTag(Collection<? extends ObjectTag> objectTagList) {
        objectForms = new ArrayList<>(objectTagList);
        for (ObjectTag obj : objectTagList) {
            super.add(obj.identify());
        }
    }

    public ListTag(ObjectTag... objects) {
        this(Arrays.asList(objects));
    }

    public ListTag() {
        objectForms = new ArrayList<>();
    }

    public ListTag(String items) {
        this(items, null);
    }

    public ListTag(String items, TagContext context) {
        if (items != null && items.length() > 0) {
            // Count brackets
            int brackets = 0;
            // Record start position
            int start = 0;
            // Loop through characters
            for (int i = 0; i < items.length(); i++) {
                char chr = items.charAt(i);
                // Count brackets
                if (chr == '[') {
                    brackets++;
                }
                else if (chr == ']') {
                    if (brackets > 0) {
                        brackets--;
                    }
                }
                // Separate if an un-bracketed pipe is found
                else if (brackets == 0 && chr == '|') {
                    super.add(items.substring(start, i));
                    start = i + 1;
                }
            }
            // If there is an item waiting, add it too
            if (start < items.length()) {
                super.add(items.substring(start));
            }
        }
        objectForms = new ArrayList<>(size());
        for (String str : this) {
            objectForms.add(ObjectFetcher.pickObjectFor(str, context));
        }
    }

    public ListTag(String flag, boolean is_flag, List<String> flag_contents) {
        if (is_flag) {
            this.flag = flag;
        }
        for (String it : flag_contents) {
            super.add(it);
        }
        objectForms = new ArrayList<>(size());
        for (String str : this) {
            objectForms.add(new ElementTag(str));
        }
    }

    public ListTag(ListTag input) {
        objectForms = new ArrayList<>(input.objectForms);
        super.ensureCapacity(input.size());
        for (String str : input) {
            super.add(str);
        }
    }

    // A List<String> of items
    public ListTag(List<String> items) {
        if (items != null) {
            for (String it : items) {
                super.add(it);
            }
        }
        objectForms = new ArrayList<>(size());
        for (String str : this) {
            objectForms.add(new ElementTag(str));
        }
    }

    // A Set<Object> of items
    public ListTag(Set<?> items) {
        objectForms = new ArrayList<>(items.size());
        if (items != null) {
            for (Object o : items) {
                String strd = o.toString();
                super.add(strd);
                if (o instanceof ObjectTag) {
                    objectForms.add((ObjectTag) o);
                }
                else {
                    objectForms.add(new ElementTag(strd));
                }
            }
        }
    }

    // A List<String> of items, with a prefix
    public ListTag(List<String> items, String prefix) {
        for (String element : items) {
            super.add(prefix + element);
        }
        objectForms = new ArrayList<>(size());
        for (String str : this) {
            objectForms.add(new ElementTag(str));
        }
    }

    /////////////
    //   Instance Fields/Methods
    //////////

    public ListTag addObjects(List<ObjectTag> ObjectTags) {
        for (ObjectTag obj : ObjectTags) {
            addObject(obj);
        }

        return this;
    }

    // Returns if the list contains objects from the specified dClass
    // by using the matches() method.
    public boolean containsObjectsFrom(Class<? extends ObjectTag> dClass) {

        // Iterate through elements until one matches() the dClass
        for (ObjectTag testable : objectForms) {
            if (CoreUtilities.canPossiblyBeType(testable, dClass)) {
                return true;
            }
        }

        return false;
    }

    public List<String> filter(Enum[] values) {
        List<String> list = new ArrayList<>(values.length);
        for (String string : this) {
            for (Enum value : values) {
                if (value.name().equalsIgnoreCase(string)) {
                    list.add(string);
                }
            }
        }
        if (!list.isEmpty()) {
            return list;
        }
        return null;
    }

    public <T extends ObjectTag> List<T> filter(Class<T> dClass, ScriptEntry entry) {
        return filter(dClass, (entry == null ? CoreUtilities.basicContext : entry.entryData.getTagContext()), true);
    }

    public <T extends ObjectTag> List<T> filter(Class<T> dClass, Debuggable debugger, boolean showFailure) {
        TagContext context = DenizenCore.getImplementation().getTagContext(null);
        context.debug = debugger.shouldDebug();
        return filter(dClass, context, showFailure);
    }

    public <T extends ObjectTag> List<T> filter(Class<T> dClass, TagContext context) {
        return filter(dClass, context, context == null || context.debug);
    }

    public <T extends ObjectTag> List<T> filter(Class<T> dClass, TagContext context, boolean showFailure) {
        List<T> results = new ArrayList<>(objectForms.size());
        for (ObjectTag obj : objectForms) {
            try {
                if (CoreUtilities.canPossiblyBeType(obj, dClass)) {
                    T object = CoreUtilities.asType(obj, dClass, context);
                    if (object != null) {
                        results.add(object);
                    }
                    else if (showFailure) {
                        Debug.echoError("Cannot process list-entry '" + obj + "' as type '" + dClass.getSimpleName() + "' (conversion returned null).");
                    }
                }
                else if (showFailure) {
                    Debug.echoError("Cannot process list-entry '" + obj + "' as type '" + dClass.getSimpleName() + "' (does not match expected type).");
                }
            }
            catch (Exception e) {
                Debug.echoError(e);
            }
        }
        return results;
    }

    public ListTag deduplicate() {
        ListTag list = new ListTag();
        int size = size();
        for (int i = 0; i < size; i++) {
            String entry = get(i);
            boolean duplicate = false;
            for (int x = 0; x < i; x++) {
                if (get(x).equalsIgnoreCase(entry)) {
                    duplicate = true;
                    break;
                }
            }
            if (!duplicate) {
                list.addObject(objectForms.get(i));
            }
        }
        return list;
    }

    @Override
    public String toString() {
        return identify();
    }

    //////////////////////////////
    //    DSCRIPT ARGUMENT METHODS
    /////////////////////////

    private String prefix = "List";

    @Override
    public String getPrefix() {
        return prefix;
    }

    @Override
    public ListTag setPrefix(String prefix) {
        this.prefix = prefix;
        return this;
    }

    @Override
    public String debuggable() {
        if (isEmpty()) {
            return "li@";
        }
        StringBuilder debugText = new StringBuilder();
        debugText.append("<G>li@<Y> ");
        for (ObjectTag item : objectForms) {
            debugText.append(item.debuggable()).append(" <G>|<Y> ");
        }
        return debugText.substring(0, debugText.length() - " <G>|<Y> ".length());
    }

    public String flag = null;

    @Override
    public boolean isUnique() {
        return flag != null;
    }

    @Override
    public String getObjectType() {
        return "List";
    }

    @Override
    public String identify() {
        if (flag != null && size() == 1) {
            return get(0);
        }
        return identifyList();
    }

    public String identifyList() {
        if (isEmpty()) {
            return "li@";
        }
        StringBuilder output = new StringBuilder();
        output.append("li@");
        for (String item : this) {
            output.append(item).append('|');
        }
        return output.substring(0, output.length() - 1);
    }

    @Override
    public String identifySimple() {
        return identify();
    }

    private static String parseString(ListTag obj, String spacer) {

        StringBuilder dScriptArg = new StringBuilder();
        for (String item : obj) {
            dScriptArg.append(item);
            dScriptArg.append(spacer);
        }
        return dScriptArg.toString().substring(0,
                dScriptArg.length() - spacer.length());
    }

    public static void registerTags() {

        // <--[tag]
        // @attribute <ListTag.combine>
        // @returns ListTag
        // @description
        // returns a list containing the contents of all sublists within this list.
        // -->
        registerTag("combine", (attribute, object) -> {
            ListTag output = new ListTag();
            for (ObjectTag obj : object.objectForms) {
                output.addObjects(ListTag.getListFor(obj, attribute.context).objectForms);
            }
            return output;
        });

        // <--[tag]
        // @attribute <ListTag.space_separated>
        // @returns ElementTag
        // @description
        // returns the list in a cleaner format, separated by spaces.
        // For example: a list of "one|two|three" will return "one two three".
        // -->
        registerTag("space_separated", (attribute, object) -> {
            if (object.isEmpty()) {
                return new ElementTag("");
            }
            return new ElementTag(parseString(object, " "));
        }, "as_string", "asstring");

        // <--[tag]
        // @attribute <ListTag.separated_by[<text>]>
        // @returns ElementTag
        // @description
        // returns the list formatted, with each item separated by the defined text.
        // For example: <list[bob|joe|john].separated_by[ and ]> will return "bob and joe and john".
        // -->
        registerTag("separated_by", (attribute, object) -> {
            if (object.isEmpty()) {
                return new ElementTag("");
            }
            String input = attribute.getContext(1);
            return new ElementTag(parseString(object, input));
        });

        // <--[tag]
        // @attribute <ListTag.comma_separated>
        // @returns ElementTag
        // @description
        // returns the list in a cleaner format, separated by commas.
        // For example: a list of "one|two|three" will return "one, two, three".
        // -->
        registerTag("comma_separated", (attribute, object) -> {
            if (object.isEmpty()) {
                return new ElementTag("");
            }
            return new ElementTag(parseString(object, ", "));
        }, "ascslist", "as_cslist");

        // <--[tag]
        // @attribute <ListTag.unseparated>
        // @returns ElementTag
        // @description
        // returns the list in a less clean format, separated by nothing.
        // For example: a list of "one|two|three" will return "onetwothree".
        // -->
        registerTag("unseparated", (attribute, object) -> {
            if (object.isEmpty()) {
                return new ElementTag("");
            }
            return new ElementTag(parseString(object, ""));
        });

        // <--[tag]
        // @attribute <ListTag.get_sub_items[<#>]>
        // @returns ListTag
        // @description
        // returns a list of the specified sub items in the list, as split by the
        // forward-slash character (/).
        // For example: .get_sub_items[1] on a list of "one/alpha|two/beta" will return "one|two".
        // -->
        registerTag("get_sub_items", (attribute, object) -> {
            int index = -1;
            if (ArgumentHelper.matchesInteger(attribute.getContext(1))) {
                index = attribute.getIntContext(1) - 1;
            }

            // <--[tag]
            // @attribute <ListTag.get_sub_items[<#>].split_by[<element>]>
            // @returns ListTag
            // @description
            // returns a list of the specified sub item in the list, allowing you to specify a
            // character in which to split the sub items by. WARNING: When setting your own split
            // character, make note that it is CASE SENSITIVE.
            // For example: .get_sub_items[1].split_by[-] on a list of "one-alpha|two-beta" will return "one|two".
            // -->

            String split = "/";
            if (attribute.startsWith("split_by", 2)) {
                if (attribute.hasContext(2) && attribute.getContext(2).length() > 0) {
                    split = attribute.getContext(2);
                }
                attribute.fulfill(1);
            }

            if (index < 0) {
                return null;
            }

            ListTag sub_list = new ListTag();

            for (String item : object) {
                String[] strings = item.split(Pattern.quote(split));
                if (strings.length > index) {
                    sub_list.add(strings[index]);
                }
                else {
                    sub_list.add("null");
                }
            }

            return sub_list;
        });

        // <--[tag]
        // @attribute <ListTag.map_get[<element>|...]>
        // @returns ListTag or ElementTag
        // @description
        // Interprets a list of "key/value" pairs as a map, and returns the value for the given key.
        // For example: one/a|two/b.map_get[one] returns a.
        // Optionally, specify a list of keys to get a list back. If any listed keys are not present, will give null.
        // -->
        registerTag("map_get", (attribute, object) -> {
            if (object.isEmpty()) {
                return new ElementTag("");
            }
            ListTag input = getListFor(attribute.getContextObject(1), attribute.context);

            // <--[tag]
            // @attribute <ListTag.map_get[<element>|...].split_by[<element>]>
            // @returns ListTag or ElementTag
            // @description
            // Interprets a list of "key" + "value" pairs split by the input symbol as a map, and returns the value for the given key.
            // For example: one/a|two/b.map_get[one].split_by[/] returns a.
            // Optionally, specify a list of keys to get a list back. If any listed keys are not present, will give null.
            // -->
            String split = "/";
            if (attribute.startsWith("split_by", 2)) {
                if (attribute.hasContext(2) && attribute.getContext(2).length() > 0) {
                    split = attribute.getContext(2);
                }
                attribute.fulfill(1);
            }

            ListTag result = new ListTag();

            for (String key : input) {
                for (String item : object) {
                    String[] strings = item.split(Pattern.quote(split), 2);
                    if (strings.length > 1 && strings[0].equalsIgnoreCase(key)) {
                        result.add(strings[1]);
                    }
                }
            }
            if (input.size() == 1 && result.size() == 1) {
                return new ElementTag(result.get(0));
            }
            else if (input.size() > 1) {
                if (result.size() != input.size()) {
                    return null;
                }
                return result;
            }
            return null;
        });

        // <--[tag]
        // @attribute <ListTag.map_find_key[<element>]>
        // @returns ElementTag
        // @description
        // Interprets a list of "key/value" pairs as a map, and returns the key for the given value.
        // For example: one/a|two/b.map_find_key[a] returns one.
        // -->
        registerTag("map_find_key", (attribute, object) -> {
            String input = attribute.getContext(1);

            // <--[tag]
            // @attribute <ListTag.map_find_key[<element>].split_by[<element>]>
            // @returns ElementTag
            // @description
            // Interprets a list of "key" + "value" pairs split by the input symbol as a map, and returns the value for the given key.
            // For example: one/a|two/b.map_find_key[a].split_by[/] returns one.
            // -->

            String split = "/";
            if (attribute.startsWith("split_by", 2)) {
                if (attribute.hasContext(2) && attribute.getContext(2).length() > 0) {
                    split = attribute.getContext(2);
                }
                attribute.fulfill(1);
            }
            for (String item : object) {
                String[] strings = item.split(Pattern.quote(split), 2);
                if (strings.length > 1 && strings[1].equalsIgnoreCase(input)) {
                    return new ElementTag(strings[0]);
                }
            }
            return null;
        });

        // <--[tag]
        // @attribute <ListTag.size>
        // @returns ElementTag(Number)
        // @description
        // returns the size of the list.
        // For example: a list of "one|two|three" will return "3".
        // -->
        registerTag("size", (attribute, object) -> {
            return new ElementTag(object.size());
        });

        // <--[tag]
        // @attribute <ListTag.is_empty>
        // @returns ElementTag(Boolean)
        // @description
        // returns whether the list is empty.
        // For example: a list of "" returns true, while "one" returns false.
        // -->
        registerTag("is_empty", (attribute, object) -> {
            return new ElementTag(object.isEmpty());
        });

        // <--[tag]
        // @attribute <ListTag.insert[...|...].at[<#>]>
        // @returns ListTag
        // @description
        // returns a new ListTag with the items specified inserted to the specified location.
        // For example: .insert[two|three].at[2] on a list of "one|four" will return "one|two|three|four".
        // -->
        registerTag("insert", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.insert[...] must have a value.");
                return null;
            }
            ListTag items = getListFor(attribute.getContextObject(1), attribute.context);
            if (attribute.startsWith("at", 2) && attribute.hasContext(2)) {
                ListTag result = new ListTag(object);
                int index = attribute.getIntContext(2) - 1;
                if (index < 0) {
                    index = 0;
                }
                if (index > result.size()) {
                    index = result.size();
                }
                for (int i = 0; i < items.size(); i++) {
                    result.addObject(index + i, items.getObject(i));
                }
                attribute.fulfill(1);
                return result;
            }
            else {
                Debug.echoError("The tag ListTag.insert[...] must be followed by .at[#]!");
                return null;
            }
        });

        // <--[tag]
        // @attribute <ListTag.set[...|...].at[<#>]>
        // @returns ListTag
        // @description
        // returns a new ListTag with the items specified inserted to the specified location, replacing the element
        // already at that location.
        // For example: .set[potato].at[2] on a list of "one|two|three" will return "one|potato|three".
        // -->
        registerTag("set", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.set[...] must have a value.");
                return null;
            }
            if (object.isEmpty()) {
                return null;
            }
            ListTag items = getListFor(attribute.getContextObject(1), attribute.context);
            if (attribute.startsWith("at", 2) && attribute.hasContext(2)) {
                ListTag result = new ListTag(object);
                int index = attribute.getIntContext(2) - 1;
                if (index < 0) {
                    index = 0;
                }
                if (index > result.size() - 1) {
                    index = result.size() - 1;
                }
                attribute.fulfill(1);
                result.remove(index);
                for (int i = 0; i < items.size(); i++) {
                    result.addObject(index + i, items.objectForms.get(i));
                }
                return result;
            }
            else {
                Debug.echoError("The tag ListTag.set[...] must be followed by .at[#]!");
                return null;
            }
        });

        // <--[tag]
        // @attribute <ListTag.include[...|...]>
        // @returns ListTag
        // @description
        // returns a new ListTag including the items specified.
        // For example: .include[three|four] on a list of "one|two" will return "one|two|three|four".
        // -->
        registerTag("include", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.include[...] must have a value.");
                return null;
            }
            ListTag copy = new ListTag(object);
            copy.addAll(getListFor(attribute.getContextObject(1), attribute.context));
            return copy;
        });

        // <--[tag]
        // @attribute <ListTag.exclude[...|...]>
        // @returns ListTag
        // @description
        // returns a new ListTag excluding the items specified.
        // For example: .exclude[two|four] on a list of "one|two|three|four" will return "one|three".
        // -->
        registerTag("exclude", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.exclude[...] must have a value.");
                return null;
            }
            ListTag exclusions = getListFor(attribute.getContextObject(1), attribute.context);
            // Create a new ListTag that will contain the exclusions
            ListTag copy = new ListTag(object);
            // Iterate through
            for (String exclusion : exclusions) {
                for (int i = 0; i < copy.size(); i++) {
                    if (copy.get(i).equalsIgnoreCase(exclusion)) {
                        copy.remove(i--);
                    }
                }
            }
            // Return the modified list
            return copy;
        });

        // <--[tag]
        // @attribute <ListTag.remove[<#>|...]>
        // @returns ListTag
        // @description
        // returns a new ListTag excluding the items at the specified index.
        // For example: .remove[2] on a list of "one|two|three|four" will return "one|three|four".
        // Also supports [first] and [last] values.
        // -->
        registerTag("remove", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.remove[#] must have a value.");
                return null;
            }
            ListTag indices = getListFor(attribute.getContextObject(1), attribute.context);
            ListTag copy = new ListTag(object);
            for (String index : indices) {
                int remove;
                if (index.equalsIgnoreCase("last")) {
                    remove = copy.size() - 1;
                }
                else if (index.equalsIgnoreCase("first")) {
                    remove = 0;
                }
                else {
                    remove = new ElementTag(index).asInt() - 1;
                }
                if (remove >= 0 && remove < copy.size()) {
                    copy.set(remove, "\0");
                }
            }
            for (int i = 0; i < copy.size(); i++) {
                if (copy.get(i).equals("\0")) {
                    copy.remove(i--);
                }
            }
            return copy;
        });

        // <--[tag]
        // @attribute <ListTag.replace[(regex:)<element>]>
        // @returns ElementTag
        // @description
        // Returns the list with all instances of an element removed.
        // Specify regex: at the start of the replace element to replace elements that match the Regex.
        // -->

        // <--[tag]
        // @attribute <ListTag.replace[(regex:)<element>].with[<element>]>
        // @returns ListTag
        // @description
        // Returns the list with all instances of an element replaced with another.
        // Specify regex: at the start of the replace element to replace elements that match the Regex.
        // -->
        registerTag("replace", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.replace[...] must have a value.");
                return null;
            }
            String replace = attribute.getContext(1);
            ObjectTag replacement = null;
            if (attribute.startsWith("with", 2)) {
                if (attribute.hasContext(2)) {
                    replacement = attribute.getContextObject(2);
                    attribute.fulfill(1);
                }
            }

            ListTag list = new ListTag();

            if (replace.startsWith("regex:")) {
                String regex = replace.substring("regex:".length());
                Pattern tempPat = Pattern.compile(regex);
                for (int i = 0; i < object.size(); i++) {
                    if (tempPat.matcher(object.get(i)).matches()) {
                        if (replacement != null) {
                            list.addObject(replacement);
                        }
                    }
                    else {
                        list.addObject(object.getObject(i));
                    }
                }
            }
            else {
                String lower = CoreUtilities.toLowerCase(replace);
                for (int i = 0; i < object.size(); i++) {
                    if (CoreUtilities.toLowerCase(object.get(i)).equals(lower)) {
                        if (replacement != null) {
                            list.addObject(replacement);
                        }
                    }
                    else {
                        list.addObject(object.getObject(i));
                    }
                }
            }

            return list;
        });

        // <--[tag]
        // @attribute <ListTag.reverse>
        // @returns ListTag
        // @description
        // returns a copy of the list, with all items placed in opposite order.
        // For example: a list of "one|two|three" will become "three|two|one".
        // -->
        registerTag("reverse", (attribute, object) -> {
            ArrayList<ObjectTag> objs = new ArrayList<>(object.objectForms);
            Collections.reverse(objs);
            return new ListTag(objs);
        });

        // <--[tag]
        // @attribute <ListTag.deduplicate>
        // @returns ListTag
        // @description
        // returns a copy of the list with any duplicate items removed.
        // For example: a list of "one|one|two|three" will become "one|two|three".
        // -->
        registerTag("deduplicate", (attribute, object) -> {
            return object.deduplicate();
        });

        // <--[tag]
        // @attribute <ListTag.get[<#>|...]>
        // @returns ObjectTag
        // @description
        // returns an element of the value specified by the supplied context.
        // For example: .get[1] on a list of "one|two" will return "one", and .get[2] will return "two"
        // Specify more than one index to get a list of results.
        // -->
        TagRunnable.ObjectInterface<ListTag> getRunnable = (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.get[...] must have a value.");
                return null;
            }
            if (object.isEmpty()) {
                if (!attribute.hasAlternative()) {
                    Debug.echoError("Can't get from an empty list.");
                }
                return null;
            }
            ListTag indices = getListFor(attribute.getContextObject(1), attribute.context);
            if (indices.size() > 1) {
                ListTag results = new ListTag();
                for (String index : indices) {
                    int ind = Integer.parseInt(index);
                    if (ind > 0 && ind <= object.size()) {
                        results.add(object.get(ind - 1));
                    }
                }
                return results;
            }
            if (indices.size() > 0) {
                int index = Integer.parseInt(indices.get(0)) - 1;
                if (index >= object.size()) {
                    if (!attribute.hasAlternative()) {
                        Debug.echoError("Invalid list.get index.");
                    }
                    return null;
                }
                if (index < 0) {
                    index = 0;
                }

                // <--[tag]
                // @attribute <ListTag.get[<#>].to[<#>]>
                // @returns ListTag
                // @description
                // returns all elements in the range from the first index to the second.
                // For example: .get[1].to[3] on a list of "one|two|three|four" will return "one|two|three"
                // -->
                if (attribute.startsWith("to", 2) && attribute.hasContext(2)) {
                    int index2 = attribute.getIntContext(2) - 1;
                    if (index2 >= object.size()) {
                        index2 = object.size() - 1;
                    }
                    if (index2 < 0) {
                        index2 = 0;
                    }
                    ListTag newList = new ListTag();
                    for (int i = index; i <= index2; i++) {
                        newList.addObject(object.objectForms.get(i));
                    }
                    attribute.fulfill(1);
                    return newList;
                }
                else {
                    return object.objectForms.get(index);
                }
            }
            return null;
        };
        registerTag("get", getRunnable);
        registerTag("", getRunnable);

        // <--[tag]
        // @attribute <ListTag.find_all_partial[<element>]>
        // @returns ListTag(ElementTag(Number))
        // @description
        // returns all the numbered locations of elements that contain the text within a list,
        // or an empty list if the list does not contain that item.
        // For example: .find_all_partial[tw] on a list of "one|two|three|two" will return "2|4".
        // TODO: Take multiple inputs? Or a regex?
        // -->
        registerTag("find_all_partial", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.find_all_partial[...] must have a value.");
                return null;
            }
            String test = attribute.getContext(1).toUpperCase();
            ListTag positions = new ListTag();
            for (int i = 0; i < object.size(); i++) {
                if (object.get(i).toUpperCase().contains(test)) {// TODO: Efficiency
                    positions.add(String.valueOf(i + 1));
                }
            }
            return positions;
        });

        // <--[tag]
        // @attribute <ListTag.find_all[<element>]>
        // @returns ListTag(ElementTag(Number))
        // @description
        // returns all the numbered locations of elements that match the text within a list,
        // or an empty list if the list does not contain that item.
        // For example: .find_all[two] on a list of "one|two|three|two" will return "2|4".
        // TODO: Take multiple inputs? Or a regex?
        // -->
        registerTag("find_all", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.find_all[...] must have a value.");
                return null;
            }
            ListTag positions = new ListTag();
            for (int i = 0; i < object.size(); i++) {
                if (object.get(i).equalsIgnoreCase(attribute.getContext(1))) {
                    positions.add(String.valueOf(i + 1));
                }
            }
            return positions;
        });

        // <--[tag]
        // @attribute <ListTag.find_partial[<element>]>
        // @returns ElementTag(Number)
        // @description
        // returns the numbered location of the first partially matching element within a list,
        // or -1 if the list does not contain that item.
        // For example: .find_partial[tw] on a list of "one|two|three" will return "2".
        // TODO: Take multiple inputs? Or a regex?
        // -->
        registerTag("find_partial", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.find_partial[...] must have a value.");
                return null;
            }
            String test = attribute.getContext(1).toUpperCase();
            for (int i = 0; i < object.size(); i++) {
                if (object.get(i).toUpperCase().contains(test)) { // TODO: Efficiency
                    return new ElementTag(i + 1);
                }
            }
            return new ElementTag(-1);
        });

        // <--[tag]
        // @attribute <ListTag.find[<element>]>
        // @returns ElementTag(Number)
        // @description
        // returns the numbered location of an element within a list,
        // or -1 if the list does not contain that item.
        // For example: .find[two] on a list of "one|two|three" will return "2".
        // TODO: Take multiple inputs? Or a regex?
        // -->
        registerTag("find", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.find[...] must have a value.");
                return null;
            }
            for (int i = 0; i < object.size(); i++) {
                if (object.get(i).equalsIgnoreCase(attribute.getContext(1))) {
                    return new ElementTag(i + 1);
                }
            }
            // TODO: This should be find_partial or something
            /*
            for (int i = 0; i < size(); i++) {
                if (get(i).toUpperCase().contains(attribute.getContext(1).toUpperCase()))
                    return new Element(i + 1);
            }
            */
            return new ElementTag(-1);
        });

        // <--[tag]
        // @attribute <ListTag.count[<element>]>
        // @returns ElementTag(Number)
        // @description
        // returns how many times in the sub-list occurs.
        // For example: a list of "one|two|two|three" .count[two] returns 2.
        // -->
        registerTag("count", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.count[...] must have a value.");
                return null;
            }
            String element = attribute.getContext(1);
            int count = 0;
            for (int i = 0; i < object.size(); i++) {
                if (object.get(i).equalsIgnoreCase(element)) {
                    count++;
                }
            }
            return new ElementTag(count);
        });

        // <--[tag]
        // @attribute <ListTag.sum>
        // @returns ElementTag(Number)
        // @description
        // returns the sum of all numbers in the list. Ignores non-numerical values.
        // -->
        registerTag("sum", (attribute, object) -> {
            double sum = 0;
            for (String entry : object) {
                if (ArgumentHelper.matchesDouble(entry)) {
                    sum += Double.parseDouble(entry);
                }
            }
            return new ElementTag(sum);
        });

        // <--[tag]
        // @attribute <ListTag.average>
        // @returns ElementTag(Number)
        // @description
        // returns the average of all numbers in the list. Ignores non-numerical values.
        // -->
        registerTag("average", (attribute, object) -> {
            if (object.isEmpty()) {
                return new ElementTag(0);
            }
            double sum = 0;
            for (String entry : object) {
                if (ArgumentHelper.matchesDouble(entry)) {
                    sum += Double.parseDouble(entry);
                }
            }
            return new ElementTag(sum / object.size());
        });

        // <--[tag]
        // @attribute <ListTag.first>
        // @returns ObjectTag
        // @description
        // returns the first element in the list.
        // If the list is empty, returns null instead.
        // For example: a list of "one|two|three" will return "one".
        // Effectively equivalent to .get[1]
        // -->
        registerTag("first", (attribute, object) -> {
            if (object.isEmpty()) {
                return null;
            }
            else {
                return object.objectForms.get(0);
            }
        });

        // <--[tag]
        // @attribute <ListTag.last>
        // @returns ObjectTag
        // @description
        // returns the last element in the list.
        // If the list is empty, returns null instead.
        // For example: a list of "one|two|three" will return "three".
        // Effectively equivalent to .get[<list.size>]
        // -->
        registerTag("last", (attribute, object) -> {
            if (object.isEmpty()) {
                return null;
            }
            else {
                return object.objectForms.get(object.size() - 1);
            }
        });

        // <--[tag]
        // @attribute <ListTag.lowest>
        // @returns ElementTag(Decimal)
        // @description
        // returns the smallest value in a list of decimal numbers.
        // For example: a list of "3|2|1|10" will return "1".
        // -->
        registerTag("lowest", (attribute, object) -> {
            BigDecimal lowest = null;
            for (String str : object) {
                if (ArgumentHelper.matchesDouble(str)) {
                    BigDecimal val = new ElementTag(str).asBigDecimal();
                    if (lowest == null || lowest.compareTo(val) > 0) {
                        lowest = val;
                    }
                }
            }
            if (lowest == null) {
                return null;
            }
            return new ElementTag(lowest);
        });

        // <--[tag]
        // @attribute <ListTag.highest>
        // @returns ElementTag(Decimal)
        // @description
        // returns the highest value in a list of decimal numbers.
        // For example: a list of "3|2|1|10" will return "10".
        // -->
        registerTag("highest", (attribute, object) -> {
            BigDecimal highest = null;
            for (String str : object) {
                if (ArgumentHelper.matchesDouble(str)) {
                    BigDecimal val = new ElementTag(str).asBigDecimal();
                    if (highest == null || highest.compareTo(val) < 0) {
                        highest = val;
                    }
                }
            }
            if (highest == null) {
                return null;
            }
            return new ElementTag(highest);
        });

        // <--[tag]
        // @attribute <ListTag.numerical>
        // @returns ListTag
        // @description
        // returns the list sorted to be in numerical order.
        // For example: a list of "3|2|1|10" will return "1|2|3|10".
        // -->
        registerTag("numerical", (attribute, object) -> {
            ArrayList<String> sortable = new ArrayList<>(object);
            Collections.sort(sortable, new Comparator<String>() {
                @Override
                public int compare(String o1, String o2) {
                    double value = new ElementTag(o1).asDouble() - new ElementTag(o2).asDouble();
                    if (value == 0) {
                        return 0;
                    }
                    else if (value > 0) {
                        return 1;
                    }
                    else {
                        return -1;
                    }
                }
            });
            return new ListTag(sortable);
        });

        // <--[tag]
        // @attribute <ListTag.alphanumeric>
        // @returns ElementTag
        // @description
        // returns the list sorted to be in alphabetical/numerical order.
        // For example: a list of "b|c|a10|a1" will return "a1|a10|b|c".
        // -->
        registerTag("alphanumeric", (attribute, object) -> {
            ArrayList<String> sortable = new ArrayList<>(object);
            Collections.sort(sortable, new NaturalOrderComparator());
            return new ListTag(sortable);
        });

        // <--[tag]
        // @attribute <ListTag.alphabetical>
        // @returns ElementTag
        // @description
        // returns the list sorted to be in alphabetical order.
        // For example: a list of "c|d|q|a|g" will return "a|c|d|g|q".
        // -->
        registerTag("alphabetical", (attribute, object) -> {
            ArrayList<String> sortable = new ArrayList<>(object);
            Collections.sort(sortable, new Comparator<String>() {
                @Override
                public int compare(String o1, String o2) {
                    return o1.compareToIgnoreCase(o2);
                }
            });
            return new ListTag(sortable);
        });

        // <--[tag]
        // @attribute <ListTag.sort_by_value[<tag>]>
        // @returns ListTag
        // @description
        // returns a copy of the list, sorted alphanumerically.
        // Rather than sorting based on the item itself, it sorts based on a tag attribute read from within the object being read.
        // For example, you might sort a list of players based on their names, via .sort_by_value[name] on the list of valid players.
        // -->
        registerTag("sort_by_value", (attribute, object) -> {
            ListTag newlist = new ListTag(object);
            final NaturalOrderComparator comparator = new NaturalOrderComparator();
            try {
                Collections.sort(newlist.objectForms, new Comparator<ObjectTag>() {
                    @Override
                    public int compare(ObjectTag o1, ObjectTag o2) {
                        ObjectTag or1 = CoreUtilities.autoAttribTyped(o1, new Attribute(attribute.getContext(1), attribute.getScriptEntry(), attribute.context));
                        ObjectTag or2 = CoreUtilities.autoAttribTyped(o2, new Attribute(attribute.getContext(1), attribute.getScriptEntry(), attribute.context));
                        return comparator.compare(or1, or2);
                    }
                });
                return new ListTag(newlist.objectForms);
            }
            catch (Exception ex) {
                Debug.echoError(ex);
            }
            return newlist;
        });

        // <--[tag]
        // @attribute <ListTag.sort_by_number[<tag>]>
        // @returns ListTag
        // @description
        // returns a copy of the list, sorted such that the lower numbers appear first, and the higher numbers appear last.
        // Rather than sorting based on the item itself, it sorts based on a tag attribute read from within the object being read.
        // For example, you might sort a list of players based on the amount of money they have, via .sort_by_number[money] on the list of valid players.
        // Non-numerical input is considered an error, and the result is not guaranteed.
        // -->
        registerTag("sort_by_number", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                attribute.echoError("Sort_By_Number must have an input value.");
                return null;
            }
            ListTag newlist = new ListTag(object);
            try {
                Collections.sort(newlist.objectForms, new Comparator<ObjectTag>() {
                    @Override
                    public int compare(ObjectTag o1, ObjectTag o2) {
                        ObjectTag or1 = CoreUtilities.autoAttribTyped(o1, new Attribute(attribute.getContext(1), attribute.getScriptEntry(), attribute.context));
                        ObjectTag or2 = CoreUtilities.autoAttribTyped(o2, new Attribute(attribute.getContext(1), attribute.getScriptEntry(), attribute.context));
                        try {
                            double r1 = Double.parseDouble(or1.toString());
                            double r2 = Double.parseDouble(or2.toString());
                            double value = r1 - r2;
                            if (value == 0) {
                                return 0;
                            }
                            else if (value > 0) {
                                return 1;
                            }
                            else {
                                return -1;
                            }
                        }
                        catch (NumberFormatException ex) {
                            attribute.echoError("Invalid non-numerical input to sort_by_number tag: " + or1.toString() + ", " + or2.toString());
                            return 0;
                        }
                    }
                });
                return new ListTag(newlist.objectForms);
            }
            catch (Exception ex) {
                Debug.echoError(ex);
            }
            return newlist;
        });

        // <--[tag]
        // @attribute <ListTag.sort[<procedure>]>
        // @returns ListTag
        // @description
        // returns a list sorted according to the return values of a procedure.
        // The <procedure> should link a procedure script that takes two definitions each of which will be an item
        // in the list, and returns -1, 0, or 1 based on whether the second item should be added. EG, if a procedure
        // with definitions "one" and "two" returned -1, it would place "two" after "one". Note that this
        // uses some complex internal sorting code that could potentially throw errors if the procedure does not return
        // consistently - EG, if "one" and "two" returned 1, but "two" and "one" returned 1 as well - obviously,
        // "two" can not be both before AND after "one"!
        // Note that the script should ALWAYS return -1, 0, or 1, or glitches could happen!
        // Note that if two inputs are exactly equal, the procedure should always return 0.
        // -->
        registerTag("sort", (attribute, object) -> {
            ListTag obj = new ListTag(object);
            final ProcedureScriptContainer script = (ProcedureScriptContainer) ScriptTag.valueOf(attribute.getContext(1)).getContainer();
            if (script == null) {
                Debug.echoError("'" + attribute.getContext(1) + "' is not a valid procedure script!");
                return obj;
            }
            final ScriptEntry entry = attribute.getScriptEntry();
            // <--[tag]
            // @attribute <ListTag.sort[<procedure>].context[<context>]>
            // @returns ElementTag
            // @description
            // Sort a list, with context. See <@link tag ListTag.sort[<procedure>]> for general sort details.
            // -->
            ListTag context = new ListTag();
            if (attribute.startsWith("context", 2)) {
                context = getListFor(attribute.getContextObject(2), attribute.context);
                attribute.fulfill(1);
            }
            final ListTag context_send = context;
            List<String> list = new ArrayList<>(obj);
            try {
                Collections.sort(list, new Comparator<String>() {
                    @Override
                    public int compare(String o1, String o2) {
                        List<ScriptEntry> entries = script.getBaseEntries(entry == null ?
                                DenizenCore.getImplementation().getEmptyScriptEntryData() : entry.entryData.clone());
                        if (entries.isEmpty()) {
                            return 0;
                        }
                        InstantQueue queue = new InstantQueue("LISTTAG_SORT");
                        queue.addEntries(entries);
                        int x = 1;
                        ListTag definitions = new ListTag();
                        definitions.add(o1);
                        definitions.add(o2);
                        definitions.addAll(context_send);
                        String[] definition_names = null;
                        try {
                            definition_names = script.getString("definitions").split("\\|");
                        }
                        catch (Exception e) { /* IGNORE */ }
                        for (String definition : definitions) {
                            String name = definition_names != null && definition_names.length >= x ?
                                    definition_names[x - 1].trim() : String.valueOf(x);
                            queue.addDefinition(name, definition);
                            Debug.echoDebug(entries.get(0), "Adding definition '" + name + "' as " + definition);
                            x++;
                        }
                        queue.start();
                        int res = 0;
                        if (queue.determinations != null && queue.determinations.size() > 0) {
                            res = new ElementTag(queue.determinations.get(0)).asInt();
                        }
                        if (res < 0) {
                            return -1;
                        }
                        else if (res > 0) {
                            return 1;
                        }
                        else {
                            return 0;
                        }
                    }
                });
            }
            catch (Exception e) {
                Debug.echoError("list.sort[...] tag failed - procedure returned unreasonable response - internal error: " + e.getMessage());
            }
            return new ListTag(list);
        });

        // <--[tag]
        // @attribute <ListTag.filter[<tag>]>
        // @returns ListTag
        // @description
        // returns a copy of the list with all its contents parsed through the given tag and only including ones that returned 'true'.
        // For example: a list of '1|2|3|4|5' .filter[is[or_more].than[3]] returns a list of '3|4|5'.
        // -->
        registerTag("filter", (attribute, object) -> {
            String tag = attribute.getContext(1);
            boolean defaultValue = tag.endsWith("||true");
            if (defaultValue) {
                tag = tag.substring(0, tag.length() - "||true".length());
            }
            ListTag newlist = new ListTag();
            try {
                for (ObjectTag obj : object.objectForms) {
                    Attribute tempAttrib = new Attribute(tag,
                            attribute.getScriptEntry(), attribute.context);
                    tempAttrib.setHadAlternative(true);
                    ObjectTag objs = CoreUtilities.autoAttribTyped(obj, tempAttrib);
                    if ((objs == null) ? defaultValue : CoreUtilities.toLowerCase(objs.toString()).equals("true")) {
                        newlist.addObject(obj);
                    }
                }
            }
            catch (Exception ex) {
                Debug.echoError(ex);
            }
            return newlist;
        });

        // <--[tag]
        // @attribute <ListTag.parse[<tag>]>
        // @returns ListTag
        // @description
        // returns a copy of the list with all its contents parsed through the given tag.
        // For example: a list of 'one|two' .parse[to_uppercase] returns a list of 'ONE|TWO'.
        // -->
        registerTag("parse", (attribute, object) -> {
            ListTag newlist = new ListTag();
            String tag = attribute.getContext(1);
            String defaultValue = "null";
            boolean fallback = false;
            if (tag.contains("||")) {
                int marks = 0;
                int lengthLimit = tag.length() - 1;
                for (int i = 0; i < lengthLimit; i++) {
                    char c = tag.charAt(i);
                    if (c == '<') {
                        marks++;
                    }
                    else if (c == '>') {
                        marks--;
                    }
                    else if (marks == 0 && c == '|' && tag.charAt(i + 1) == '|') {
                        fallback = true;
                        defaultValue = tag.substring(i + 2);
                        tag = tag.substring(0, i);
                        break;
                    }
                }
            }
            try {
                for (ObjectTag obj : object.objectForms) {
                    Attribute tempAttrib = new Attribute(tag,
                            attribute.getScriptEntry(), attribute.context);
                    tempAttrib.setHadAlternative(attribute.hasAlternative() || fallback);
                    ObjectTag objs = CoreUtilities.autoAttribTyped(obj, tempAttrib);
                    if (objs == null) {
                        objs = new ElementTag(defaultValue);
                    }
                    newlist.addObject(objs);
                }
            }
            catch (Exception ex) {
                Debug.echoError(ex);
            }
            return newlist;
        });

        // <--[tag]
        // @attribute <ListTag.pad_left[<#>]>
        // @returns ListTag
        // @description
        // Returns a ListTag extended to reach a minimum specified length
        // by adding entries to the left side.
        // -->
        registerTag("pad_left", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.pad_left[...] must have a value.");
                return null;
            }
            ObjectTag with = new ElementTag("");
            int length = attribute.getIntContext(1);

            // <--[tag]
            // @attribute <ListTag.pad_left[<#>].with[<element>]>
            // @returns ListTag
            // @description
            // Returns a ListTag extended to reach a minimum specified length
            // by adding a specific entry to the left side.
            // -->
            if (attribute.startsWith("with", 2) && attribute.hasContext(2)) {
                with = attribute.getContextObject(2);
                attribute.fulfill(1);
            }

            ListTag newList = new ListTag(object);
            while (newList.size() < length) {
                newList.addObject(with);
            }

            return newList;
        });

        // <--[tag]
        // @attribute <ListTag.pad_right[<#>]>
        // @returns ListTag
        // @description
        // Returns a ListTag extended to reach a minimum specified length
        // by adding entries to the right side.
        // -->
        registerTag("pad_right", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.pad_right[...] must have a value.");
                return null;
            }
            ObjectTag with = new ElementTag("");
            int length = attribute.getIntContext(1);

            // <--[tag]
            // @attribute <ListTag.pad_right[<#>].with[<element>]>
            // @returns ListTag
            // @description
            // Returns a ListTag extended to reach a minimum specified length
            // by adding a specific entry to the right side.
            // -->
            if (attribute.startsWith("with", 2) && attribute.hasContext(2)) {
                with = attribute.getContextObject(2);
                attribute.fulfill(1);
            }

            ListTag newList = new ListTag(object);
            while (newList.size() < length) {
                newList.addObject(with);
            }

            return newList;
        });

        // <--[tag]
        // @attribute <ListTag.escape_contents>
        // @returns ListTag
        // @description
        // returns a copy of the list with all its contents escaped.
        // Inverts <@link tag ListTag.unescape_contents>.
        // See <@link language property escaping>.
        // -->
        registerTag("escape_contents", (attribute, object) -> {
            ListTag escaped = new ListTag();
            for (String entry : object) {
                escaped.add(EscapeTagBase.escape(entry));
            }
            return escaped;
        });

        // <--[tag]
        // @attribute <ListTag.unescape_contents>
        // @returns ListTag
        // @description
        // returns a copy of the list with all its contents unescaped.
        // Inverts <@link tag ListTag.escape_contents>.
        // See <@link language property escaping>.
        // -->
        registerTag("unescape_contents", (attribute, object) -> {
            ListTag escaped = new ListTag();
            for (String entry : object) {
                escaped.add(EscapeTagBase.unEscape(entry));
            }
            return escaped;
        });

        // <--[tag]
        // @attribute <ListTag.contains_any_case_sensitive[<element>|...]>
        // @returns ElementTag(Boolean)
        // @description
        // returns whether the list contains any of a list of given elements, case-sensitive.
        // -->
        registerTag("contains_any_case_sensitive", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.contains_any_case_sensitive[...] must have a value.");
                return null;
            }
            ListTag list = getListFor(attribute.getContextObject(1), attribute.context);
            boolean state = false;

            full_set:
            for (String element : object) {
                for (String sub_element : list) {
                    if (element.equals(sub_element)) {
                        state = true;
                        break full_set;
                    }
                }
            }

            return new ElementTag(state);
        });

        // <--[tag]
        // @attribute <ListTag.contains_any[<element>|...]>
        // @returns ElementTag(Boolean)
        // @description
        // returns whether the list contains any of a list of given elements.
        // -->
        registerTag("contains_any", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.contains_any[...] must have a value.");
                return null;
            }
            ListTag list = getListFor(attribute.getContextObject(1), attribute.context);
            boolean state = false;

            full_set:
            for (String element : object) {
                for (String sub_element : list) {
                    if (element.equalsIgnoreCase(sub_element)) {
                        state = true;
                        break full_set;
                    }
                }
            }

            return new ElementTag(state);
        });

        // <--[tag]
        // @attribute <ListTag.contains_case_sensitive[<element>]>
        // @returns ElementTag(Boolean)
        // @description
        // returns whether the list contains a given element, case-sensitive.
        // -->
        registerTag("contains_case_sensitive", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.contains_case_sensitive[...] must have a value.");
                return null;
            }
            boolean state = false;

            for (String element : object) {
                if (element.equals(attribute.getContext(1))) {
                    state = true;
                    break;
                }
            }

            return new ElementTag(state);
        });

        // <--[tag]
        // @attribute <ListTag.contains[<element>|...]>
        // @returns ElementTag(Boolean)
        // @description
        // returns whether the list contains all of the given elements.
        // -->
        registerTag("contains", (attribute, object) -> {
            if (!attribute.hasContext(1)) {
                Debug.echoError("The tag ListTag.contains[...] must have a value.");
                return null;
            }
            ListTag needed = getListFor(attribute.getContextObject(1), attribute.context);
            int gotten = 0;

            for (String check : needed) {
                for (String element : object) {
                    if (element.equalsIgnoreCase(check)) {
                        gotten++;
                        break;
                    }
                }
            }

            return new ElementTag(gotten == needed.size() && gotten > 0);
        });

        // <--[tag]
        // @attribute <ListTag.random[(<#>)]>
        // @returns ObjectTag
        // @description
        // Gets a random item in the list and returns it as an Element.
        // Optionally, add [<#>] to get a list of multiple randomly chosen elements.
        // For example: .random on a list of "one|two" could return EITHER "one" or "two" - different each time!
        // For example: .random[2] on a list of "one|two|three" could return "one|two", "two|three", OR "one|three" - different each time!
        // For example: .random[9999] on a list of "one|two|three" could return "one|two|three", "one|three|two", "two|one|three",
        // "two|three|one", "three|two|one", OR "three|one|two" - different each time!
        // -->
        registerTag("random", (attribute, object) -> {
            if (object.isEmpty()) {
                return null;
            }
            if (attribute.hasContext(1)) {
                int count = Integer.valueOf(attribute.getContext(1));
                int times = 0;
                ArrayList<ObjectTag> available = new ArrayList<>(object.objectForms);
                ListTag toReturn = new ListTag();
                while (!available.isEmpty() && times < count) {
                    int random = CoreUtilities.getRandom().nextInt(available.size());
                    toReturn.addObject(available.get(random));
                    available.remove(random);
                    times++;
                }
                return toReturn;
            }
            else {
                return object.objectForms.get(CoreUtilities.getRandom().nextInt(object.size()));
            }
        });

        // <--[tag]
        // @attribute <ListTag.closest_to[<text>]>
        // @returns ElementTag
        // @description
        // Returns the item in the list that seems closest to the given value.
        // Particularly useful for command handlers, "<list[c1|c2|c3|...].closest_to[<argument>]>" to get the best option as  "did you mean" suggestion.
        // For example, "<list[dance|quit|spawn].closest_to[spwn]>" returns "spawn".
        // Be warned that this will always return /something/, excluding the case of an empty list, which will return an empty element.
        // Uses the logic of tag "ElementTag.difference"!
        // You can use that tag to add an upper limit on how different the strings can be.
        // -->
        registerTag("closest_to", (attribute, object) -> {
            return new ElementTag(CoreUtilities.getClosestOption(object, attribute.getContext(1)));
        });

        registerTag("as_list", (attribute, object) -> {
            // Special handler for flag lists.
            return new ListTag(object);
        }, "aslist");

        // <--[tag]
        // @attribute <ListTag.type>
        // @returns ElementTag
        // @description
        // Always returns 'List' for ListTag objects. All objects fetchable by the Object Fetcher will return the
        // type of object that is fulfilling this attribute.
        // -->
        registerTag("type", (attribute, object) -> {
            return new ElementTag("List");
        });
    }

    public static ObjectTagProcessor<ListTag> tagProcessor = new ObjectTagProcessor<>();

    public static void registerTag(String name, TagRunnable.ObjectInterface<ListTag> runnable, String... variants) {
        tagProcessor.registerTag(name, runnable, variants);
    }

    @Override
    public ObjectTag getObjectAttribute(Attribute attribute) {
        return tagProcessor.getObjectAttribute(this, attribute);
    }

    @Override
    public ObjectTag getNextObjectTypeDown() {
        return (flag != null && size() == 1) ? getObject(0) : new ElementTag(identifyList());
    }

    @Override
    public ObjectTag specialTagProcessing(Attribute attribute) {
        String attrLow = attribute.getAttributeWithoutContext(1);
        if (Debug.verbose) {
            Debug.log("ListTag alternate attribute " + attrLow);
        }
        if (ArgumentHelper.matchesInteger(attrLow)) {
            int index = Integer.parseInt(attrLow);
            if (index != 0) {
                attribute.fulfill(1);
                if (index < 1 || index > size()) {
                    if (!attribute.hasAlternative()) {
                        Debug.echoError("ListTag index " + index + " is out of range");
                    }
                    return null;
                }
                return getObject(index - 1);
            }
        }
        return null;
    }
}