/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: set ts=8 sts=2 et sw=2 tw=80:
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

/* JavaScript RegExp objects. */

#ifndef vm_RegExpObject_h
#define vm_RegExpObject_h

#include "builtin/SelfHostingDefines.h"
#include "js/RegExpFlags.h"
#include "proxy/Proxy.h"
#include "vm/JSAtomState.h"
#include "vm/JSContext.h"
#include "vm/RegExpShared.h"
#include "vm/Shape.h"

/*
 * JavaScript Regular Expressions
 *
 * There are several engine concepts associated with a single logical regexp:
 *
 *   RegExpObject:
 *     The JS-visible object whose .[[Class]] equals "RegExp".
 *   RegExpShared:
 *     The compiled representation of the regexp (lazily created, cleared
 *     during some forms of GC).
 *   RegExpZone:
 *     Owns all RegExpShared instances in a zone.
 */
namespace js {

extern RegExpObject* RegExpAlloc(JSContext* cx, NewObjectKind newKind,
                                 HandleObject proto = nullptr);

extern JSObject* CloneRegExpObject(JSContext* cx, Handle<RegExpObject*> regex);

class RegExpObject : public NativeObject {
  static const unsigned LAST_INDEX_SLOT = 0;
  static const unsigned SOURCE_SLOT = 1;
  static const unsigned FLAGS_SLOT = 2;

  static_assert(RegExpObject::FLAGS_SLOT == REGEXP_FLAGS_SLOT,
                "FLAGS_SLOT values should be in sync with self-hosted JS");

  static RegExpObject* create(JSContext* cx, Handle<JSAtom*> source,
                              NewObjectKind newKind);

 public:
  static const unsigned SHARED_SLOT = 3;
  static const unsigned RESERVED_SLOTS = 4;

  static const JSClass class_;
  static const JSClass protoClass_;

  // The maximum number of pairs a MatchResult can have, without having to
  // allocate a bigger MatchResult.
  static const size_t MaxPairCount = 14;

  template <typename CharT>
  static RegExpObject* create(JSContext* cx, const CharT* chars, size_t length,
                              JS::RegExpFlags flags, NewObjectKind newKind);

  // This variant assumes that the characters have already previously been
  // syntax checked.
  static RegExpObject* createSyntaxChecked(JSContext* cx,
                                           Handle<JSAtom*> source,
                                           JS::RegExpFlags flags,
                                           NewObjectKind newKind);

  static RegExpObject* create(JSContext* cx, Handle<JSAtom*> source,
                              JS::RegExpFlags flags, NewObjectKind newKind);

  /*
   * Compute the initial shape to associate with fresh RegExp objects,
   * encoding their initial properties. Return the shape after
   * changing |obj|'s last property to it.
   */
  static SharedShape* assignInitialShape(JSContext* cx,
                                         Handle<RegExpObject*> obj);

  /* Accessors. */

  static constexpr size_t lastIndexSlot() { return LAST_INDEX_SLOT; }

  static constexpr size_t offsetOfLastIndex() {
    return getFixedSlotOffset(lastIndexSlot());
  }

  static bool isInitialShape(RegExpObject* rx) {
    // RegExpObject has a non-configurable lastIndex property, so there must be
    // at least one property. Even though lastIndex is non-configurable, it can
    // be made non-writable, so we have to check if it's still writable.
    MOZ_ASSERT(!rx->empty());
    PropertyInfoWithKey prop = rx->getLastProperty();
    return prop.isDataProperty() && prop.slot() == LAST_INDEX_SLOT &&
           prop.writable();
  }

  const Value& getLastIndex() const { return getReservedSlot(LAST_INDEX_SLOT); }

  void setLastIndex(JSContext* cx, int32_t lastIndex) {
    MOZ_ASSERT(lastIndex >= 0);
    MOZ_ASSERT(lookupPure(cx->names().lastIndex)->writable(),
               "can't infallibly set a non-writable lastIndex on a "
               "RegExp that's been exposed to script");
    setReservedSlot(LAST_INDEX_SLOT, Int32Value(lastIndex));
  }
  void zeroLastIndex(JSContext* cx) { setLastIndex(cx, 0); }

  static JSLinearString* toString(JSContext* cx, Handle<RegExpObject*> obj);

  JSAtom* getSource() const {
    return &getReservedSlot(SOURCE_SLOT).toString()->asAtom();
  }

  void setSource(JSAtom* source) {
    setReservedSlot(SOURCE_SLOT, StringValue(source));
  }

  /* Flags. */

  static constexpr size_t flagsSlot() { return FLAGS_SLOT; }

  static constexpr size_t offsetOfFlags() {
    return getFixedSlotOffset(flagsSlot());
  }

  JS::RegExpFlags getFlags() const {
    return JS::RegExpFlags(getFixedSlot(FLAGS_SLOT).toInt32());
  }
  void setFlags(JS::RegExpFlags flags) {
    setFixedSlot(FLAGS_SLOT, Int32Value(flags.value()));
  }

  bool hasIndices() const { return getFlags().hasIndices(); }
  bool global() const { return getFlags().global(); }
  bool ignoreCase() const { return getFlags().ignoreCase(); }
  bool multiline() const { return getFlags().multiline(); }
  bool dotAll() const { return getFlags().dotAll(); }
  bool unicode() const { return getFlags().unicode(); }
  bool sticky() const { return getFlags().sticky(); }

  bool isGlobalOrSticky() const {
    JS::RegExpFlags flags = getFlags();
    return flags.global() || flags.sticky();
  }

  static bool isOriginalFlagGetter(JSNative native, JS::RegExpFlags* mask);

  static RegExpShared* getShared(JSContext* cx, Handle<RegExpObject*> regexp);

  bool hasShared() const { return !getFixedSlot(SHARED_SLOT).isUndefined(); }

  RegExpShared* getShared() const {
    return static_cast<RegExpShared*>(getFixedSlot(SHARED_SLOT).toGCThing());
  }

  void setShared(RegExpShared* shared) {
    MOZ_ASSERT(shared);
    setFixedSlot(SHARED_SLOT, PrivateGCThingValue(shared));
  }

  void clearShared() { setFixedSlot(SHARED_SLOT, UndefinedValue()); }

  void initIgnoringLastIndex(JSAtom* source, JS::RegExpFlags flags);

  // NOTE: This method is *only* safe to call on RegExps that haven't been
  //       exposed to script, because it requires that the "lastIndex"
  //       property be writable.
  void initAndZeroLastIndex(JSAtom* source, JS::RegExpFlags flags,
                            JSContext* cx);

#ifdef DEBUG
  [[nodiscard]] static bool dumpBytecode(JSContext* cx,
                                         Handle<RegExpObject*> regexp,
                                         Handle<JSLinearString*> input);
#endif

 private:
  /*
   * Precondition: the syntax for |source| has already been validated.
   * Side effect: sets the private field.
   */
  static RegExpShared* createShared(JSContext* cx,
                                    Handle<RegExpObject*> regexp);

  /* Call setShared in preference to setPrivate. */
  void setPrivate(void* priv) = delete;
};

/*
 * Parse regexp flags. Report an error and return false if an invalid
 * sequence of flags is encountered (repeat/invalid flag).
 *
 * N.B. flagStr must be rooted.
 */
bool ParseRegExpFlags(JSContext* cx, JSString* flagStr,
                      JS::RegExpFlags* flagsOut);

// Assuming GetBuiltinClass(obj) is ESClass::RegExp, return a RegExpShared for
// obj.
inline RegExpShared* RegExpToShared(JSContext* cx, HandleObject obj) {
  if (obj->is<RegExpObject>()) {
    return RegExpObject::getShared(cx, obj.as<RegExpObject>());
  }

  return Proxy::regexp_toShared(cx, obj);
}

/* Escape all slashes and newlines in the given string. */
extern JSLinearString* EscapeRegExpPattern(JSContext* cx, Handle<JSAtom*> src);

template <typename CharT>
extern bool HasRegExpMetaChars(const CharT* chars, size_t length);

extern bool StringHasRegExpMetaChars(JSLinearString* str);

} /* namespace js */

#endif /* vm_RegExpObject_h */