//===-- llvm/SymbolTable.h - Implement a type plane'd symtab ----*- C++ -*-===//
// 
//                     The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and re-written by Reid
// Spencer. It is distributed under the University of Illinois Open Source 
// License. See LICENSE.TXT for details.
// 
//===----------------------------------------------------------------------===//
//
// This file implements the main symbol table for LLVM.
//
//===----------------------------------------------------------------------===//

#ifndef LLVM_SYMBOL_TABLE_H
#define LLVM_SYMBOL_TABLE_H

#include "llvm/Value.h"
#include <map>

namespace llvm {

/// This class provides a symbol table of name/value pairs that is broken
/// up by type. For each Type* there is a "plane" of name/value pairs in 
/// the symbol table.  Identical types may have overlapping symbol names as 
/// long as they are distinct. The SymbolTable also tracks,  separately, a 
/// map of name/type pairs. This allows types to be named. Types are treated 
/// distinctly from Values.
/// 
/// The SymbolTable provides several utility functions for answering common
/// questions about its contents as well as an iterator interface for
/// directly iterating over the contents. To reduce confusion, the terms 
/// "type", "value", and "plane" are used consistently. For example,
/// There is a TypeMap typedef that is the mapping of names to Types. 
/// Similarly there is a ValueMap typedef that is the mapping of 
/// names to Values. Finally, there is a PlaneMap typedef that is the
/// mapping of types to planes of ValueMap. THis is the basic structure
/// of the symbol table. When you call type_begin() you're asking
/// for an iterator at the start of the TypeMap. When you call
/// plane_begin(), you're asking for an iterator at the start of 
/// the PlaneMap. Finally, when you call value_begin(), you're asking
/// for an iterator at the start of a ValueMap for a specific type
/// plane.
class SymbolTable : public AbstractTypeUser {

/// @name Types
/// @{
public:

  /// @brief A mapping of names to types.
  typedef std::map<const std::string, Type*> TypeMap;

  /// @brief An iterator over the TypeMap.
  typedef TypeMap::iterator type_iterator;

  /// @brief A const_iterator over the TypeMap.
  typedef TypeMap::const_iterator type_const_iterator;

  /// @brief A mapping of names to values.
  typedef std::map<const std::string, Value *> ValueMap;

  /// @brief An iterator over a ValueMap.
  typedef ValueMap::iterator value_iterator;

  /// @brief A const_iterator over a ValueMap.
  typedef ValueMap::const_iterator value_const_iterator;

  /// @brief A mapping of types to names to values (type planes).
  typedef std::map<const Type *, ValueMap> PlaneMap;

  /// @brief An iterator over the type planes.
  typedef PlaneMap::iterator plane_iterator;

  /// @brief A const_iterator over the type planes
  typedef PlaneMap::const_iterator plane_const_iterator;

/// @}
/// @name Constructors
/// @{
public:

  inline SymbolTable() 
    : pmap(), tmap(), InternallyInconsistent(false), LastUnique(0) {}
  ~SymbolTable();

/// @}
/// @name Accessors
/// @{
public:

  /// This method finds the value with the given \p name in the
  /// type plane \p Ty and returns it. This method will not find any
  /// Types, only Values. Use lookupType to find Types by name.
  /// @returns null on failure, otherwise the Value associated with
  /// the \p name in type plane \p Ty.
  /// @brief Lookup a named, typed value.
  Value *lookup(const Type *Ty, const std::string &name) const;

  /// This method finds the type with the given \p name in the
  /// type  map and returns it.
  /// @returns null if the name is not found, otherwise the Type
  /// associated with the \p name.
  /// @brief Lookup a type by name.
  Type* lookupType( const std::string& name ) const;

  /// @returns true iff the type map is not empty.
  /// @brief Determine if there are types in the symbol table
  inline bool hasTypes() const { return ! tmap.empty(); }

  /// @returns true iff the type map and the type plane are both not 
  /// empty.
  /// @brief Determine if the symbol table is empty
  inline bool isEmpty() const { return pmap.empty() && tmap.empty(); }

  /// The plane associated with the \p TypeID parameter is found
  /// and the number of entries in the plane is returned.
  /// @returns Number of entries in the specified type plane or 0.
  /// @brief Get the size of a type plane.
  unsigned type_size(const Type *TypeID) const;

  /// @brief The number of name/type pairs is returned.
  inline unsigned num_types() const { return tmap.size(); }

  /// Finds the value \p val in the symbol table and returns its
  /// name. Only the type plane associated with the type of \p val
  /// is searched.
  /// @brief Return the name of a value
  std::string get_name( const Value* Val ) const;

  /// Finds the type \p Ty in the symbol table and returns its name.
  /// @brief Return the name of a type
  std::string get_name( const Type* Ty ) const;

  /// Given a base name, return a string that is either equal to it or 
  /// derived from it that does not already occur in the symbol table 
  /// for the specified type.
  /// @brief Get a name unique to this symbol table
  std::string getUniqueName(const Type *Ty, 
    const std::string &BaseName) const;

  /// This function can be used from the debugger to display the
  /// content of the symbol table while debugging.
  /// @brief Print out symbol table on stderr
  void dump() const;  

/// @}
/// @name Mutators
/// @{
public:

  /// This method adds the provided value \p N to the symbol table. 
  /// The Value must have both a name and a type which are extracted 
  /// and used to place the value in the correct type plane under 
  /// the value's name.
  /// @brief Add a named value to the symbol table
  inline void insert(Value *Val) {
    assert(Val && "Can't insert null type into symbol table!");
    assert(Val->hasName() && "Value must be named to go into symbol table!");
    insertEntry(Val->getName(), Val->getType(), Val);
  }

  /// Inserts a constant or type into the symbol table with the specified
  /// name. There can be a many to one mapping between names and constants
  /// or types.
  /// @brief Insert a constant or type.
  inline void insert(const std::string &Name, Value *Val) {
    assert(Val && "Can't insert null type into symbol table!");
    assert((isa<Type>(Val) || isa<Constant>(Val)) &&
           "Can only insert types and constants into a symbol table!");
    insertEntry(Name, Val->getType(), Val);
  }

  /// Inserts a type into the symbol table with the specified name. There
  /// can be a many-to-one mapping between names and types. This method
  /// allows a type with an existing entry in the symbol table to get
  /// a new name.
  /// @brief Insert a type under a new name.
  inline void insert(const std::string &Name, Type *Typ) {
    assert(Typ && "Can't insert null type into symbol table!");
    insertEntry(Name, Typ );
  }

  /// This method removes a named value from the symbol table. The
  /// type and name of the Value are extracted from \p N and used to
  /// lookup the Value in the correct type plane. If the Value is
  /// not in the symbol table, this method silently ignores the
  /// request.
  /// @brief Remove a named value from the symbol table.
  void remove(Value* Val);

  /// This method removes a named type from the symbol table. The
  /// name of the type is extracted from \P T and used to look up
  /// the Type in the type map. If the Type is not in the symbol
  /// table, this method silently ignores the request.
  /// @brief Remove a named type from the symbol table.
  void remove(Type* Typ );

  /// Remove a constant or type with the specified name from the 
  /// symbol table.
  /// @returns the removed Value.
  /// @brief Remove a constant or type from the symbol table.
  inline Value* remove(const std::string &Name, Value *Val) {
    assert(Val && "Can't remove null value from symbol table!");
    plane_iterator PI = pmap.find(Val->getType());
    return removeEntry(PI, PI->second.find(Name));
  }

  /// Remove a type with the specified name from the symbol table.
  /// @returns the removed Type.
  /// @brief Remove a named tyep from the symbol table.
  inline Type* remove(const std::string& Name, Type* T ) {
    return removeEntry( tmap.find(Name) );
  }

  /// Removes a specific value from the symbol table. 
  /// @returns the removed value.
  /// @brief Remove a specific value given by an iterator
  inline Value *value_remove(const value_iterator &It) {
    return this->removeEntry(pmap.find(It->second->getType()), It);
  }

  /// This method will strip the symbol table of its names leaving
  /// the type and values. 
  /// @brief Strip the symbol table. 
  bool strip();

  /// @brief Empty the symbol table completely.
  inline void clear() { pmap.clear(); tmap.clear(); }

/// @}
/// @name Iteration
/// @{
public:

  /// Get an iterator that starts at the beginning of the type planes.
  /// The iterator will iterate over the Type/ValueMap pairs in the
  /// type planes. 
  inline plane_iterator plane_begin() { return pmap.begin(); }

  /// Get a const_iterator that starts at the beginning of the type 
  /// planes.  The iterator will iterate over the Type/ValueMap pairs 
  /// in the type planes. 
  inline plane_const_iterator plane_begin() const { return pmap.begin(); }

  /// Get an iterator at the end of the type planes. This serves as
  /// the marker for end of iteration over the type planes.
  inline plane_iterator plane_end() { return pmap.end(); }

  /// Get a const_iterator at the end of the type planes. This serves as
  /// the marker for end of iteration over the type planes.
  inline plane_const_iterator plane_end() const { return pmap.end(); }

  /// Get an iterator that starts at the beginning of a type plane.
  /// The iterator will iterate over the name/value pairs in the type plane.
  /// @note The type plane must already exist before using this.
  inline value_iterator value_begin(const Type *Typ) { 
    assert(Typ && "Can't get value iterator with null type!");
    return pmap.find(Typ)->second.begin(); 
  }

  /// Get a const_iterator that starts at the beginning of a type plane.
  /// The iterator will iterate over the name/value pairs in the type plane.
  /// @note The type plane must already exist before using this.
  inline value_const_iterator value_begin(const Type *Typ) const {
    assert(Typ && "Can't get value iterator with null type!");
    return pmap.find(Typ)->second.begin(); 
  }

  /// Get an iterator to the end of a type plane. This serves as the marker
  /// for end of iteration of the type plane.
  /// @note The type plane must already exist before using this.
  inline value_iterator value_end(const Type *Typ) { 
    assert(Typ && "Can't get value iterator with null type!");
    return pmap.find(Typ)->second.end(); 
  }

  /// Get a const_iterator to the end of a type plane. This serves as the
  /// marker for end of iteration of the type plane.
  /// @note The type plane must already exist before using this.
  inline value_const_iterator value_end(const Type *Typ) const { 
    assert(Typ && "Can't get value iterator with null type!");
    return pmap.find(Typ)->second.end(); 
  }

  /// Get an iterator to the start of the name/Type map.
  inline type_iterator type_begin() { return tmap.begin(); }

  /// @brief Get a const_iterator to the start of the name/Type map.
  inline type_const_iterator type_begin() const { return tmap.begin(); }

  /// Get an iterator to the end of the name/Type map. This serves as the
  /// marker for end of iteration of the types.
  inline type_iterator type_end() { return tmap.end(); }

  /// Get a const-iterator to the end of the name/Type map. This serves 
  /// as the marker for end of iteration of the types.
  inline type_const_iterator type_end() const { return tmap.end(); }

  /// This method returns a plane_const_iterator for iteration over
  /// the type planes starting at a specific plane, given by \p Ty.
  /// @brief Find a type plane.
  inline plane_const_iterator find(const Type* Typ ) const {
    assert(Typ && "Can't find type plane with null type!");
    return pmap.find( Typ );
  }

  /// This method returns a plane_iterator for iteration over the
  /// type planes starting at a specific plane, given by \p Ty.
  /// @brief Find a type plane.
  inline plane_iterator find( const Type* Typ ) { 
    assert(Typ && "Can't find type plane with null type!");
    return pmap.find(Typ); 
  }

  /// This method returns a ValueMap* for a specific type plane. This
  /// interface is deprecated and may go away in the future.
  /// @deprecated
  /// @brief Find a type plane
  inline const ValueMap* findPlane( const Type* Typ ) const {
    assert(Typ && "Can't find type plane with null type!");
    plane_const_iterator I = pmap.find( Typ );
    if ( I == pmap.end() ) return 0;
    return &I->second;
  }

/// @}
/// @name Internal Methods
/// @{
private:
  /// @brief Insert a value into the symbol table with the specified name.
  void insertEntry(const std::string &Name, const Type *Ty, Value *V);

  /// @brief Insert a type into the symbol table with the specified name.
  void insertEntry(const std::string &Name, Type *T);

  /// Remove a specific value from a specific plane in the SymbolTable.
  /// @returns the removed Value.
  Value* removeEntry(plane_iterator Plane, value_iterator Entry);

  /// Remove a specific type from the SymbolTable.
  /// @returns the removed Type.
  Type*  removeEntry(type_iterator Entry);

  /// This function is called when one of the types in the type plane 
  /// is refined.
  virtual void refineAbstractType(const DerivedType *OldTy, const Type *NewTy);

  /// This function markes a type as being concrete (defined).
  virtual void typeBecameConcrete(const DerivedType *AbsTy);

/// @}
/// @name Internal Data 
/// @{
private:

  /// This is the main content of the symbol table. It provides
  /// separate type planes for named values. That is, each named
  /// value is organized into a separate dictionary based on 
  /// Type. This means that the same name can be used for different
  /// types without conflict. Note that the Type::TypeTy plane is
  /// not stored in this map but is in tmap.
  /// @brief The mapping of types to names to values.
  PlaneMap pmap;

  /// This is the Type::TypeTy plane. It is separated from the pmap
  /// because the elements of the map are name/Type pairs not 
  /// name/Value pairs and Type is not a Value.
  TypeMap tmap;

  /// There are times when the symbol table is internally inconsistent with 
  /// the rest of the program.  In this one case, a value exists with a Name, 
  /// and it's not in the symbol table.  When we call V->setName(""), it 
  /// tries to remove itself from the symbol table and dies.  We know this 
  /// is happening, and so if the flag InternallyInconsistent is set, 
  /// removal from the symbol table is a noop.
  /// @brief Indicator of symbol table internal inconsistency.
  bool InternallyInconsistent;

  /// This value is used to retain the last unique value used
  /// by getUniqueName to generate unique names.
  mutable unsigned long LastUnique;

/// @}

};

} // End llvm namespace

// vim: sw=2

#endif