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 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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 * The Universal Permissive License (UPL), Version 1.0
 *
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 * (b) any piece of software and/or hardware listed in the lrgrwrks.txt file if
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package com.oracle.truffle.regex;

import java.util.Map;

import com.oracle.truffle.api.CompilerDirectives;
import com.oracle.truffle.api.CompilerDirectives.TruffleBoundary;
import com.oracle.truffle.api.dsl.Cached;
import com.oracle.truffle.api.dsl.GenerateUncached;
import com.oracle.truffle.api.dsl.ImportStatic;
import com.oracle.truffle.api.dsl.ReportPolymorphism;
import com.oracle.truffle.api.dsl.Specialization;
import com.oracle.truffle.api.interop.ArityException;
import com.oracle.truffle.api.interop.InteropLibrary;
import com.oracle.truffle.api.interop.TruffleObject;
import com.oracle.truffle.api.interop.UnknownIdentifierException;
import com.oracle.truffle.api.interop.UnsupportedMessageException;
import com.oracle.truffle.api.interop.UnsupportedTypeException;
import com.oracle.truffle.api.library.CachedLibrary;
import com.oracle.truffle.api.library.ExportLibrary;
import com.oracle.truffle.api.library.ExportMessage;
import com.oracle.truffle.api.nodes.DirectCallNode;
import com.oracle.truffle.api.nodes.IndirectCallNode;
import com.oracle.truffle.api.nodes.Node;
import com.oracle.truffle.regex.result.NoMatchResult;
import com.oracle.truffle.regex.result.RegexResult;
import com.oracle.truffle.regex.runtime.nodes.ExpectByteArrayHostObjectNode;
import com.oracle.truffle.regex.runtime.nodes.ExpectStringOrTruffleObjectNode;
import com.oracle.truffle.regex.runtime.nodes.ToLongNode;
import com.oracle.truffle.regex.tregex.parser.flavors.PythonFlags;
import com.oracle.truffle.regex.tregex.parser.flavors.RubyFlags;
import com.oracle.truffle.regex.tregex.util.Exceptions;
import com.oracle.truffle.regex.util.TruffleNull;
import com.oracle.truffle.regex.util.TruffleReadOnlyKeysArray;
import com.oracle.truffle.regex.util.TruffleReadOnlyMap;

RegexObject represents a compiled regular expression that can be used to match against input strings. It is the result of executing a RegexEngine. It exposes the following three properties: 

String pattern: the source of the compiled regular expression
TruffleObject flags: the set of flags passed to the regular expression compiler. The type differs based on the flavor of regular expressions used: 

RegexFlags if the flavor was ECMAScript
PythonFlags if the flavor was PythonStr or PythonBytes
RubyFlags if the flavor was Ruby


int groupCount: number of capture groups present in the regular expression, including group 0.
RegexObjectExecMethod exec: an executable method that matches the compiled regular expression against a string. The method accepts two parameters: 

Object input: the character sequence to search in. This may either be a String or a TruffleObject that responds to InteropLibrary.hasArrayElements(Object) and returns Characters on indexed InteropLibrary.readArrayElement(Object, long) requests.
Number fromIndex: the position to start searching from. This argument will be cast to int, since a String can not be longer than Integer.MAX_VALUE. If fromIndex is greater than Integer.MAX_VALUE, this method will immediately return NO_MATCH.
 The return value is a RegexResult. The contents of the exec can be compiled lazily and so its first invocation might involve a longer delay as the regular expression is compiled on the fly. 

/**
 * {@link RegexObject} represents a compiled regular expression that can be used to match against
 * input strings. It is the result of executing a {@link RegexEngine}. It exposes the following
 * three properties:
 * <ol>
 * <li>{@link String} {@code pattern}: the source of the compiled regular expression</li>
 * <li>{@link TruffleObject} {@code flags}: the set of flags passed to the regular expression
 * compiler. The type differs based on the flavor of regular expressions used:
 * <ul>
 * <li>{@link RegexFlags} if the flavor was {@code ECMAScript}</li>
 * <li>{@link PythonFlags} if the flavor was {@code PythonStr} or {@code PythonBytes}</li>
 * <li>{@link RubyFlags} if the flavor was {@code Ruby}</li>
 * </ul>
 * </li>
 * <li>{@code int groupCount}: number of capture groups present in the regular expression, including
 * group 0.</li>
 * <li>{@link RegexObjectExecMethod} {@code exec}: an executable method that matches the compiled
 * regular expression against a string. The method accepts two parameters:
 * <ol>
 * <li>{@link Object} {@code input}: the character sequence to search in. This may either be a
 * {@link String} or a {@link TruffleObject} that responds to
 * {@link InteropLibrary#hasArrayElements(Object)} and returns {@link Character}s on indexed
 * {@link InteropLibrary#readArrayElement(Object, long)} requests.</li>
 * <li>{@link Number} {@code fromIndex}: the position to start searching from. This argument will be
 * cast to {@code int}, since a {@link String} can not be longer than {@link Integer#MAX_VALUE}. If
 * {@code fromIndex} is greater than {@link Integer#MAX_VALUE}, this method will immediately return
 * NO_MATCH.</li>
 * </ol>
 * The return value is a {@link RegexResult}. The contents of the {@code exec} can be compiled
 * lazily and so its first invocation might involve a longer delay as the regular expression is
 * compiled on the fly.
 * </ol>
 * <p>
 */
@ExportLibrary(InteropLibrary.class)
public final class RegexObject extends AbstractConstantKeysObject {

    static final String PROP_EXEC = "exec";
    static final String PROP_EXEC_BYTES = "execBytes";
    private static final String PROP_PATTERN = "pattern";
    private static final String PROP_FLAGS = "flags";
    private static final String PROP_GROUP_COUNT = "groupCount";
    private static final String PROP_GROUPS = "groups";
    private static final TruffleReadOnlyKeysArray KEYS = new TruffleReadOnlyKeysArray(PROP_EXEC, PROP_PATTERN, PROP_FLAGS, PROP_GROUP_COUNT, PROP_GROUPS);

    private final RegexCompiler compiler;
    private final RegexSource source;
    private final TruffleObject flags;
    private final int numberOfCaptureGroups;
    private final TruffleObject namedCaptureGroups;
    private Object compiledRegexObject;

    public RegexObject(RegexCompiler compiler, RegexSource source, TruffleObject flags, int numberOfCaptureGroups, Map<String, Integer> namedCaptureGroups) {
        this.compiler = compiler;
        this.source = source;
        this.flags = flags;
        this.numberOfCaptureGroups = numberOfCaptureGroups;
        this.namedCaptureGroups = namedCaptureGroups != null ? new TruffleReadOnlyMap(namedCaptureGroups) : TruffleNull.INSTANCE;
    }

    public RegexSource getSource() {
        return source;
    }

    public TruffleObject getFlags() {
        return flags;
    }

    public int getNumberOfCaptureGroups() {
        return numberOfCaptureGroups;
    }

    public TruffleObject getNamedCaptureGroups() {
        return namedCaptureGroups;
    }

    public Object getCompiledRegexObject() {
        if (compiledRegexObject == null) {
            compiledRegexObject = compileRegex(source);
        }
        return compiledRegexObject;
    }

    @TruffleBoundary
    private Object compileRegex(RegexSource src) {
        return compiler.compile(src);
    }

    public void setCompiledRegexObject(TruffleObject compiledRegexObject) {
        this.compiledRegexObject = compiledRegexObject;
    }

    public RegexObjectExecMethod getExecMethod() {
        // this allocation should get virtualized and optimized away by graal
        return new RegexObjectExecMethod(this);
    }

    public RegexObjectExecUTF8Method getExecUTF8Method() {
        // this allocation should get virtualized and optimized away by graal
        return new RegexObjectExecUTF8Method(this);
    }

    @Override
    public TruffleReadOnlyKeysArray getKeys() {
        return KEYS;
    }

    @Override
    public Object readMemberImpl(String symbol) throws UnknownIdentifierException {
        switch (symbol) {
            case PROP_EXEC:
                return getExecMethod();
            case PROP_EXEC_BYTES:
                return getExecUTF8Method();
            case PROP_PATTERN:
                return getSource().getPattern();
            case PROP_FLAGS:
                return getFlags();
            case PROP_GROUP_COUNT:
                return getNumberOfCaptureGroups();
            case PROP_GROUPS:
                return getNamedCaptureGroups();
            default:
                CompilerDirectives.transferToInterpreterAndInvalidate();
                throw UnknownIdentifierException.create(symbol);
        }
    }

    @SuppressWarnings("static-method")
    @ExportMessage
    boolean isMemberInvocable(String member,
                    @Cached IsInvocableCacheNode cache) {
        return cache.execute(member);
    }

    @ExportMessage
    Object invokeMember(String member, Object[] args,
                    @Cached ToLongNode toLongNode,
                    @Cached GetCompiledRegexNode getCompiledRegexNode,
                    @Cached InvokeCacheNode invokeCache)
                    throws UnknownIdentifierException, ArityException, UnsupportedTypeException, UnsupportedMessageException {
        if (args.length != 2) {
            CompilerDirectives.transferToInterpreterAndInvalidate();
            throw ArityException.create(2, args.length);
        }
        Object input = args[0];
        long fromIndex = toLongNode.execute(args[1]);
        if (fromIndex > Integer.MAX_VALUE) {
            return NoMatchResult.getInstance();
        }
        return invokeCache.execute(member, getCompiledRegexNode.execute(this), input, (int) fromIndex);
    }

    private static final String N_METHODS = "2";

    @GenerateUncached
    abstract static class IsInvocableCacheNode extends Node {

        abstract boolean execute(String symbol);

        @SuppressWarnings("unused")
        @Specialization(guards = "symbol == cachedSymbol", limit = N_METHODS)
        static boolean cacheIdentity(String symbol,
                        @Cached("symbol") String cachedSymbol,
                        @Cached("isInvocable(cachedSymbol)") boolean result) {
            return result;
        }

        @SuppressWarnings("unused")
        @Specialization(guards = "symbol.equals(cachedSymbol)", limit = N_METHODS, replaces = "cacheIdentity")
        static boolean cacheEquals(String symbol,
                        @Cached("symbol") String cachedSymbol,
                        @Cached("isInvocable(cachedSymbol)") boolean result) {
            return result;
        }

        @SuppressWarnings("unused")
        @Specialization(replaces = "cacheEquals")
        static boolean isInvocable(String symbol) {
            return PROP_EXEC.equals(symbol) || PROP_EXEC_BYTES.equals(symbol);
        }
    }

    @ImportStatic(RegexObject.class)
    @GenerateUncached
    abstract static class InvokeCacheNode extends Node {

        abstract Object execute(String symbol, Object receiver, Object input, int fromIndex) throws UnsupportedMessageException, ArityException, UnsupportedTypeException, UnknownIdentifierException;

        @SuppressWarnings("unused")
        @Specialization(guards = {"symbol == cachedSymbol", "cachedSymbol.equals(PROP_EXEC)"}, limit = N_METHODS)
        Object getStartIdentity(String symbol, Object receiver, Object input, int fromIndex,
                        @Cached("symbol") String cachedSymbol,
                        @Cached ExpectStringOrTruffleObjectNode expectStringOrTruffleObjectNode,
                        @Cached ExecCompiledRegexNode execNode) throws UnsupportedMessageException, ArityException, UnsupportedTypeException {
            return execNode.execute(receiver, expectStringOrTruffleObjectNode.execute(input), fromIndex);
        }

        @SuppressWarnings("unused")
        @Specialization(guards = {"symbol.equals(cachedSymbol)", "cachedSymbol.equals(PROP_EXEC)"}, limit = N_METHODS, replaces = "getStartIdentity")
        Object getStartEquals(String symbol, Object receiver, Object input, int fromIndex,
                        @Cached("symbol") String cachedSymbol,
                        @Cached ExpectStringOrTruffleObjectNode expectStringOrTruffleObjectNode,
                        @Cached ExecCompiledRegexNode execNode) throws UnsupportedMessageException, ArityException, UnsupportedTypeException {
            return execNode.execute(receiver, expectStringOrTruffleObjectNode.execute(input), fromIndex);
        }

        // EXPERIMENTAL
        @SuppressWarnings("unused")
        @Specialization(guards = {"symbol == cachedSymbol", "cachedSymbol.equals(PROP_EXEC_BYTES)"}, limit = N_METHODS)
        Object getEndIdentity(String symbol, Object receiver, Object input, int fromIndex,
                        @Cached("symbol") String cachedSymbol,
                        @Cached ExpectByteArrayHostObjectNode expectByteArrayHostObjectNode,
                        @Cached ExecCompiledRegexNode execNode) throws UnsupportedMessageException, ArityException, UnsupportedTypeException {
            return execNode.execute(receiver, expectByteArrayHostObjectNode.execute(input), fromIndex);
        }

        // EXPERIMENTAL
        @SuppressWarnings("unused")
        @Specialization(guards = {"symbol.equals(cachedSymbol)", "cachedSymbol.equals(PROP_EXEC_BYTES)"}, limit = N_METHODS, replaces = "getEndIdentity")
        Object getEndEquals(String symbol, Object receiver, Object input, int fromIndex,
                        @Cached("symbol") String cachedSymbol,
                        @Cached ExpectByteArrayHostObjectNode expectByteArrayHostObjectNode,
                        @Cached ExecCompiledRegexNode execNode) throws UnsupportedMessageException, ArityException, UnsupportedTypeException {
            return execNode.execute(receiver, expectByteArrayHostObjectNode.execute(input), fromIndex);
        }

        @ReportPolymorphism.Megamorphic
        @Specialization(replaces = {"getStartEquals", "getEndEquals"})
        static Object invokeGeneric(String symbol, Object receiver, Object input, int fromIndex,
                        @Cached ExpectStringOrTruffleObjectNode expectStringOrTruffleObjectNode,
                        @Cached ExpectByteArrayHostObjectNode expectByteArrayHostObjectNode,
                        @Cached ExecCompiledRegexNode execNode) throws UnsupportedMessageException, ArityException, UnsupportedTypeException, UnknownIdentifierException {
            switch (symbol) {
                case PROP_EXEC:
                    return execNode.execute(receiver, expectStringOrTruffleObjectNode.execute(input), fromIndex);
                case PROP_EXEC_BYTES:
                    return execNode.execute(receiver, expectByteArrayHostObjectNode.execute(input), fromIndex);
                default:
                    CompilerDirectives.transferToInterpreterAndInvalidate();
                    throw UnknownIdentifierException.create(symbol);
            }
        }
    }

    @ExportLibrary(InteropLibrary.class)
    public static final class RegexObjectExecMethod extends AbstractRegexObject {

        private final RegexObject regex;

        public RegexObjectExecMethod(RegexObject regex) {
            this.regex = regex;
        }

        public RegexObject getRegexObject() {
            return regex;
        }

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

        @ExportMessage
        Object execute(Object[] args,
                        @Cached GetCompiledRegexNode getCompiledRegexNode,
                        @Cached ExpectStringOrTruffleObjectNode expectStringOrTruffleObjectNode,
                        @Cached ToLongNode toLongNode,
                        @Cached ExecCompiledRegexNode execNode) throws ArityException, UnsupportedTypeException, UnsupportedMessageException {
            if (args.length != 2) {
                CompilerDirectives.transferToInterpreterAndInvalidate();
                throw ArityException.create(2, args.length);
            }
            Object input = expectStringOrTruffleObjectNode.execute(args[0]);
            long fromIndex = toLongNode.execute(args[1]);
            if (fromIndex > Integer.MAX_VALUE) {
                return NoMatchResult.getInstance();
            }
            return execNode.execute(getCompiledRegexNode.execute(getRegexObject()), input, (int) fromIndex);
        }

    }

    
EXPERIMENTAL. This method is equivalent to RegexObjectExecMethod, except it expects a native byte array as input string. This violation of the interop protocol is probably a bad idea and will be replaced with a Truffle Library soon. /**
     * EXPERIMENTAL. This method is equivalent to {@link RegexObjectExecMethod}, except it expects a
     * native byte array as input string. This violation of the interop protocol is probably a bad
     * idea and will be replaced with a Truffle Library soon.
     */
    @ExportLibrary(InteropLibrary.class)
    public static final class RegexObjectExecUTF8Method extends AbstractRegexObject {

        private final RegexObject regex;

        public RegexObjectExecUTF8Method(RegexObject regex) {
            this.regex = regex;
        }

        public RegexObject getRegexObject() {
            return regex;
        }

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

        @ExportMessage
        Object execute(Object[] args,
                        @Cached GetCompiledRegexNode getCompiledRegexNode,
                        @Cached ExpectByteArrayHostObjectNode expectByteArrayHostObjectNode,
                        @Cached ToLongNode toLongNode,
                        @Cached ExecCompiledRegexNode execNode) throws ArityException, UnsupportedTypeException, UnsupportedMessageException {
            RegexObject regexObj = getRegexObject();
            if (args.length != 2) {
                CompilerDirectives.transferToInterpreterAndInvalidate();
                throw ArityException.create(2, args.length);
            }
            byte[] input = expectByteArrayHostObjectNode.execute(args[0]);
            long fromIndex = toLongNode.execute(args[1]);
            if (fromIndex > Integer.MAX_VALUE) {
                return NoMatchResult.getInstance();
            }
            return execNode.execute(getCompiledRegexNode.execute(regexObj), input, (int) fromIndex);
        }

    }

    @GenerateUncached
    abstract static class GetCompiledRegexNode extends Node {

        abstract Object execute(RegexObject receiver);

        @SuppressWarnings("unused")
        @Specialization(guards = "receiver == cachedReceiver", limit = "4")
        static Object executeFixed(RegexObject receiver,
                        @Cached("receiver") RegexObject cachedReceiver,
                        @Cached("receiver.getCompiledRegexObject()") Object cachedCompiledRegex) {
            return cachedCompiledRegex;
        }

        @ReportPolymorphism.Megamorphic
        @Specialization(replaces = "executeFixed")
        static Object executeVarying(RegexObject receiver) {
            return receiver.getCompiledRegexObject();
        }
    }

    @ImportStatic(RegexObject.class)
    @GenerateUncached
    abstract static class ExecCompiledRegexNode extends Node {

        abstract Object execute(Object receiver, Object input, int fromIndex) throws UnsupportedMessageException, ArityException, UnsupportedTypeException;

        @SuppressWarnings("unused")
        @Specialization(guards = "receiver == cachedReceiver", limit = "4")
        static Object executeTRegexFixed(CompiledRegexObject receiver, Object input, int fromIndex,
                        @Cached("receiver") CompiledRegexObject cachedReceiver,
                        @Cached("create(cachedReceiver.getCallTarget())") DirectCallNode directCallNode) {
            return directCallNode.call(input, fromIndex);
        }

        @ReportPolymorphism.Megamorphic
        @Specialization(replaces = "executeTRegexFixed")
        static Object executeTRegexVarying(CompiledRegexObject receiver, Object input, int fromIndex,
                        @Cached IndirectCallNode indirectCallNode) {
            return indirectCallNode.call(receiver.getCallTarget(), input, fromIndex);
        }

        @SuppressWarnings("unused")
        @Specialization(guards = "receivers.isMemberInvocable(receiver, PROP_EXEC)", limit = "4")
        static Object executeForeign(TruffleObject receiver, Object input, int fromIndex,
                        @CachedLibrary("receiver") InteropLibrary receivers) throws UnsupportedMessageException, ArityException, UnsupportedTypeException {
            try {
                return receivers.invokeMember(receiver, "exec", input, fromIndex);
            } catch (UnknownIdentifierException e) {
                throw Exceptions.shouldNotReachHere("fallback compiled regex does not have an invocable \"exec\" method");
            }
        }
    }
}