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 * (a) the Software, and
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
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 * Software and the Larger Work(s), and to sublicense the foregoing rights on
 * either these or other terms.
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package com.oracle.truffle.js.runtime;

import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.TruffleLanguage;
import com.oracle.truffle.api.dsl.Fallback;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.interop.InteropLibrary;
import com.oracle.truffle.api.interop.TruffleObject;
import com.oracle.truffle.api.library.ExportLibrary;
import com.oracle.truffle.api.library.ExportMessage;
import com.oracle.truffle.api.utilities.TriState;
import com.oracle.truffle.js.lang.JavaScriptLanguage;
import com.oracle.truffle.js.runtime.builtins.JSSymbol;
import com.oracle.truffle.js.runtime.interop.JSMetaType;
import com.oracle.truffle.js.runtime.objects.Undefined;

See Also:
JSSymbol/**
 * @see JSSymbol
 */
@ExportLibrary(InteropLibrary.class)
public final class Symbol implements TruffleObject {
    // Predefined symbols, as per ES6 6.1.5.1 Well-Known Symbols (in alphabetical order)
    
A method that determines if a constructor object recognizes an object as one of the
constructor's instances. Called by the semantics of the instanceof operator.
/**
     * A method that determines if a constructor object recognizes an object as one of the
     * constructor's instances. Called by the semantics of the instanceof operator.
     */
    public static final Symbol SYMBOL_HAS_INSTANCE = Symbol.create("Symbol.hasInstance");
    
A Boolean valued property that if true indicates that an object should be flatten to its
array elements by Array.prototype.concat.
/**
     * A Boolean valued property that if true indicates that an object should be flatten to its
     * array elements by Array.prototype.concat.
     */
    public static final Symbol SYMBOL_IS_CONCAT_SPREADABLE = Symbol.create("Symbol.isConcatSpreadable");
    
A method that returns the default iterator for an object. Called by the semantics of the
for-of statement.
/**
     * A method that returns the default iterator for an object. Called by the semantics of the
     * for-of statement.
     */
    public static final Symbol SYMBOL_ITERATOR = Symbol.create("Symbol.iterator");
    
A method that returns the default asynchronous iterator for an object. Called by the
semantics of the for-await-of statement.
/**
     * A method that returns the default asynchronous iterator for an object. Called by the
     * semantics of the for-await-of statement.
     */
    public static final Symbol SYMBOL_ASYNC_ITERATOR = Symbol.create("Symbol.asyncIterator");
    
A regular expression method that matches the regular expression against a string. Called by
the String.prototype.match method.
/**
     * A regular expression method that matches the regular expression against a string. Called by
     * the String.prototype.match method.
     */
    public static final Symbol SYMBOL_MATCH = Symbol.create("Symbol.match");
    
A regular expression method that returns an iterator, that yields matches of the regular
expression against a string. Called by the String.prototype.matchAll method.
/**
     * A regular expression method that returns an iterator, that yields matches of the regular
     * expression against a string. Called by the String.prototype.matchAll method.
     */
    public static final Symbol SYMBOL_MATCH_ALL = Symbol.create("Symbol.matchAll");
    
A regular expression method that replaces matched substrings of a string. Called by the
String.prototype.replace method.
/**
     * A regular expression method that replaces matched substrings of a string. Called by the
     * String.prototype.replace method.
     */
    public static final Symbol SYMBOL_REPLACE = Symbol.create("Symbol.replace");
    
A regular expression method that returns the index within a string that matches the regular
expression. Called by the String.prototype.search method.
/**
     * A regular expression method that returns the index within a string that matches the regular
     * expression. Called by the String.prototype.search method.
     */
    public static final Symbol SYMBOL_SEARCH = Symbol.create("Symbol.search");
    
A function valued property that is the constructor function that is used to create derived
objects.
/**
     * A function valued property that is the constructor function that is used to create derived
     * objects.
     */
    public static final Symbol SYMBOL_SPECIES = Symbol.create("Symbol.species");
    
A regular expression method that splits a string at the indices that match the regular
expression. Called by the String.prototype.split method.
/**
     * A regular expression method that splits a string at the indices that match the regular
     * expression. Called by the String.prototype.split method.
     */
    public static final Symbol SYMBOL_SPLIT = Symbol.create("Symbol.split");
    
A method that converts an object to a corresponding primitive value. Called by the
ToPrimitive abstract operation.
/**
     * A method that converts an object to a corresponding primitive value. Called by the
     * ToPrimitive abstract operation.
     */
    public static final Symbol SYMBOL_TO_PRIMITIVE = Symbol.create("Symbol.toPrimitive");
    
A property whose String value that is used in the creation of the default string description
of an object. Called by the built-in method Object.prototype.toString.
/**
     * A property whose String value that is used in the creation of the default string description
     * of an object. Called by the built-in method Object.prototype.toString.
     */
    public static final Symbol SYMBOL_TO_STRING_TAG = Symbol.create("Symbol.toStringTag");
    
A property whose value is an Object whose own property names are property names that are
excluded from the with environment bindings of the associated object.
/**
     * A property whose value is an Object whose own property names are property names that are
     * excluded from the with environment bindings of the associated object.
     */
    public static final Symbol SYMBOL_UNSCOPABLES = Symbol.create("Symbol.unscopables");

    
[[Description]] of Symbol if it is a String value, null otherwise ([[Description]] is undefined). /**
     * [[Description]] of Symbol if it is a String value, {@code null} otherwise ([[Description]] is
     * undefined).
     */
    private final String description;

    private Symbol(String description) {
        this.description = description;
    }

    public static Symbol create(String description) {
        return new Symbol(description);
    }

    public Object getDescription() {
        return (description == null) ? Undefined.instance : description;
    }

    public String getName() {
        return description == null ? "" : description;
    }

    @Override
    @TruffleBoundary
    public String toString() {
        return "Symbol(" + getName() + ")";
    }

    @TruffleBoundary
    public String toFunctionNameString() {
        return (description == null) ? "" : '[' + description + ']';
    }

    @Override
    public boolean equals(Object obj) {
        return (this == obj);
    }

    @Override
    public int hashCode() {
        return super.hashCode();
    }

    @SuppressWarnings("static-method")
    @ExportMessage
    boolean hasLanguage() {
        return true;
    }

    @SuppressWarnings("static-method")
    @ExportMessage
    Class<? extends TruffleLanguage<?>> getLanguage() {
        return JavaScriptLanguage.class;
    }

    @ExportMessage
    Object toDisplayString(@SuppressWarnings("unused") boolean allowSideEffects) {
        return toString();
    }

    @SuppressWarnings("static-method")
    @ExportMessage
    boolean hasMetaObject() {
        return true;
    }

    @SuppressWarnings("static-method")
    @ExportMessage
    Object getMetaObject() {
        return JSMetaType.JS_SYMBOL;
    }

    @ExportMessage
    static final class IsIdenticalOrUndefined {
        @Specialization
        static TriState doHostObject(Symbol receiver, Symbol other) {
            return TriState.valueOf(receiver == other);
        }

        @SuppressWarnings("unused")
        @Fallback
        static TriState doOther(Symbol receiver, Object other) {
            return TriState.UNDEFINED;
        }
    }

    @TruffleBoundary
    @ExportMessage
    int identityHashCode() {
        return super.hashCode();
    }
}