/* -*- 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/. */

#ifndef frontend_EmitterScope_h
#define frontend_EmitterScope_h

#include "mozilla/Attributes.h"
#include "mozilla/Maybe.h"

#include <stdint.h>

#include "ds/Nestable.h"
#include "frontend/AbstractScopePtr.h"
#include "frontend/NameAnalysisTypes.h"
#include "frontend/NameCollections.h"
#include "frontend/ParseContext.h"
#include "frontend/SharedContext.h"
#include "js/TypeDecls.h"
#include "vm/BytecodeUtil.h"   // JSOp
#include "vm/SharedStencil.h"  // GCThingIndex

namespace js {

class Scope;

namespace frontend {

struct BytecodeEmitter;

// A scope that introduces bindings.
class EmitterScope : public Nestable<EmitterScope> {
  // The cache of bound names that may be looked up in the
  // scope. Initially populated as the set of names this scope binds. As
  // names are looked up in enclosing scopes, they are cached on the
  // current scope.
  PooledMapPtr<NameLocationMap> nameCache_;

  // If this scope's cache does not include free names, such as the
  // global scope, the NameLocation to return.
  mozilla::Maybe<NameLocation> fallbackFreeNameLocation_;

  // True if there is a corresponding EnvironmentObject on the environment
  // chain, false if all bindings are stored in frame slots on the stack.
  bool hasEnvironment_;

  // The number of enclosing environments. Used for error checking.
  uint8_t environmentChainLength_;

  // The next usable slot on the frame for not-closed over bindings.
  //
  // The initial frame slot when assigning slots to bindings is the
  // enclosing scope's nextFrameSlot. For the first scope in a frame,
  // the initial frame slot is 0.
  uint32_t nextFrameSlot_;

  // The index in the BytecodeEmitter's interned scope vector, otherwise
  // ScopeNote::NoScopeIndex.
  GCThingIndex scopeIndex_;

  // If kind is Lexical, Catch, or With, the index in the BytecodeEmitter's
  // block scope note list. Otherwise ScopeNote::NoScopeNote.
  uint32_t noteIndex_;

  MOZ_MUST_USE bool ensureCache(BytecodeEmitter* bce);

  MOZ_MUST_USE bool checkSlotLimits(BytecodeEmitter* bce,
                                    const ParserBindingIter& bi);

  MOZ_MUST_USE bool checkEnvironmentChainLength(BytecodeEmitter* bce);

  void updateFrameFixedSlots(BytecodeEmitter* bce, const ParserBindingIter& bi);

  MOZ_MUST_USE bool putNameInCache(BytecodeEmitter* bce, const ParserAtom* name,
                                   NameLocation loc);

  mozilla::Maybe<NameLocation> lookupInCache(BytecodeEmitter* bce,
                                             const ParserAtom* name);

  EmitterScope* enclosing(BytecodeEmitter** bce) const;

  mozilla::Maybe<ScopeIndex> enclosingScopeIndex(BytecodeEmitter* bce) const;

  static bool nameCanBeFree(BytecodeEmitter* bce, const ParserAtom* name);

  static NameLocation searchInEnclosingScope(JSAtom* name, Scope* scope,
                                             uint8_t hops);
  NameLocation searchAndCache(BytecodeEmitter* bce, const ParserAtom* name);

  MOZ_MUST_USE bool internEmptyGlobalScopeAsBody(BytecodeEmitter* bce);

  template <typename ScopeCreator>
  MOZ_MUST_USE bool internScopeCreationData(BytecodeEmitter* bce,
                                            ScopeCreator createScope);

  template <typename ScopeCreator>
  MOZ_MUST_USE bool internBodyScopeCreationData(BytecodeEmitter* bce,
                                                ScopeCreator createScope);
  MOZ_MUST_USE bool appendScopeNote(BytecodeEmitter* bce);

  MOZ_MUST_USE bool clearFrameSlotRange(BytecodeEmitter* bce, JSOp opcode,
                                        uint32_t slotStart,
                                        uint32_t slotEnd) const;

  MOZ_MUST_USE bool deadZoneFrameSlotRange(BytecodeEmitter* bce,
                                           uint32_t slotStart,
                                           uint32_t slotEnd) const {
    return clearFrameSlotRange(bce, JSOp::Uninitialized, slotStart, slotEnd);
  }

 public:
  explicit EmitterScope(BytecodeEmitter* bce);

  void dump(BytecodeEmitter* bce);

  MOZ_MUST_USE bool enterLexical(BytecodeEmitter* bce, ScopeKind kind,
                                 LexicalScope::ParserData* bindings);
  MOZ_MUST_USE bool enterNamedLambda(BytecodeEmitter* bce, FunctionBox* funbox);
  MOZ_MUST_USE bool enterFunction(BytecodeEmitter* bce, FunctionBox* funbox);
  MOZ_MUST_USE bool enterFunctionExtraBodyVar(BytecodeEmitter* bce,
                                              FunctionBox* funbox);
  MOZ_MUST_USE bool enterGlobal(BytecodeEmitter* bce,
                                GlobalSharedContext* globalsc);
  MOZ_MUST_USE bool enterEval(BytecodeEmitter* bce, EvalSharedContext* evalsc);
  MOZ_MUST_USE bool enterModule(BytecodeEmitter* module,
                                ModuleSharedContext* modulesc);
  MOZ_MUST_USE bool enterWith(BytecodeEmitter* bce);
  MOZ_MUST_USE bool deadZoneFrameSlots(BytecodeEmitter* bce) const;

  MOZ_MUST_USE bool leave(BytecodeEmitter* bce, bool nonLocal = false);

  GCThingIndex index() const {
    MOZ_ASSERT(scopeIndex_ != ScopeNote::NoScopeIndex,
               "Did you forget to intern a Scope?");
    return scopeIndex_;
  }

  uint32_t noteIndex() const { return noteIndex_; }

  AbstractScopePtr scope(const BytecodeEmitter* bce) const;
  mozilla::Maybe<ScopeIndex> scopeIndex(const BytecodeEmitter* bce) const;

  bool hasEnvironment() const { return hasEnvironment_; }

  // The first frame slot used.
  uint32_t frameSlotStart() const {
    if (EmitterScope* inFrame = enclosingInFrame()) {
      return inFrame->nextFrameSlot_;
    }
    return 0;
  }

  // The last frame slot used + 1.
  uint32_t frameSlotEnd() const { return nextFrameSlot_; }

  EmitterScope* enclosingInFrame() const {
    return Nestable<EmitterScope>::enclosing();
  }

  NameLocation lookup(BytecodeEmitter* bce, const ParserAtom* name);

  mozilla::Maybe<NameLocation> locationBoundInScope(const ParserAtom* name,
                                                    EmitterScope* target);
};

} /* namespace frontend */
} /* namespace js */

#endif /* frontend_EmitterScope_h */