RegExpObject.h

/* -*- 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 "mozilla/Attributes.h"
#include "mozilla/MemoryReporting.h"

#include "builtin/SelfHostingDefines.h"
#include "gc/Marking.h"
#include "js/GCHashTable.h"
#include "js/RegExpFlags.h"
#include "proxy/Proxy.h"
#include "vm/ArrayObject.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 {

struct MatchPair;
class MatchPairs;
class RegExpStatics;

namespace frontend {
class TokenStreamAnyChars;
}

// Temporary definitions until irregexp is updated from upstream.
namespace irregexp {
constexpr size_t JS_HOWMANY(size_t x, size_t y) { return (x + y - 1) / y; }

constexpr size_t JS_ROUNDUP(size_t x, size_t y) { return JS_HOWMANY(x, y) * y; }

template <class T>
static constexpr inline T Min(T t1, T t2) {
  return t1 < t2 ? t1 : t2;
}

template <class T>
static constexpr inline T Max(T t1, T t2) {
  return t1 > t2 ? t1 : t2;
}
}  // namespace irregexp

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, HandleAtom source,
                              NewObjectKind newKind);

 public:
  static const unsigned RESERVED_SLOTS = 3;
  static const unsigned PRIVATE_SLOT = 3;

  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, const char16_t* chars,
                                           size_t length, JS::RegExpFlags flags,
                                           NewObjectKind newKind);

  static RegExpObject* createSyntaxChecked(JSContext* cx, HandleAtom source,
                                           JS::RegExpFlags flags,
                                           NewObjectKind newKind);

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

  static RegExpObject* create(JSContext* cx, HandleAtom source,
                              JS::RegExpFlags flags, NewObjectKind newKind);

  static RegExpObject* create(JSContext* cx, HandleAtom source,
                              JS::RegExpFlags flags,
                              frontend::TokenStreamAnyChars& ts,
                              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 Shape* assignInitialShape(JSContext* cx, Handle<RegExpObject*> obj);

  /* Accessors. */

  static unsigned lastIndexSlot() { return LAST_INDEX_SLOT; }

  static bool isInitialShape(RegExpObject* rx) {
    Shape* shape = rx->lastProperty();
    if (shape->isEmptyShape() || !shape->isDataProperty()) {
      return false;
    }
    if (shape->maybeSlot() != LAST_INDEX_SLOT) {
      return false;
    }
    return true;
  }

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

  void setLastIndex(double d) { setSlot(LAST_INDEX_SLOT, NumberValue(d)); }

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

  JSLinearString* toString(JSContext* cx) const;

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

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

  /* Flags. */

  static unsigned flagsSlot() { return FLAGS_SLOT; }

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

  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(); }

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

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

  bool hasShared() { return !!sharedRef(); }

  void setShared(RegExpShared& shared) {
    MOZ_ASSERT(!hasShared());
    sharedRef().init(&shared);
  }

  HeapPtrRegExpShared& sharedRef() {
    auto& ref = NativeObject::privateRef(PRIVATE_SLOT);
    return reinterpret_cast<HeapPtrRegExpShared&>(ref);
  }

  static void trace(JSTracer* trc, JSObject* obj);
  void trace(JSTracer* trc);

  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
  static MOZ_MUST_USE bool dumpBytecode(JSContext* cx,
                                        Handle<RegExpObject*> regexp,
                                        bool match_only,
                                        HandleLinearString 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);
}

template <XDRMode mode>
XDRResult XDRScriptRegExpObject(XDRState<mode>* xdr,
                                MutableHandle<RegExpObject*> objp);

extern JSObject* CloneScriptRegExpObject(JSContext* cx, RegExpObject& re);

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

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

extern bool StringHasRegExpMetaChars(JSLinearString* str);

} /* namespace js */

#endif /* vm_RegExpObject_h */