/* Definitions for C++ name lookup routines.
   Copyright (C) 2003 Free Software Foundation, Inc.
   Contributed by Gabriel Dos Reis <gdr@integrable-solutions.net>

This file is part of GCC.

GCC is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; either version 2, or (at your option)
any later version.

GCC is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with GCC; see the file COPYING.  If not, write to
the Free Software Foundation, 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.  */

#include "config.h"
#include "system.h"
#include "coretypes.h"
#include "tm.h"
#include "tree.h"
#include "cp-tree.h"
#include "name-lookup.h"
#include "timevar.h"

/* Compute the chain index of a binding_entry given the HASH value of its
   name and the total COUNT of chains.  COUNT is assumed to be a power
   of 2.  */
#define ENTRY_INDEX(HASH, COUNT) (((HASH) >> 3) & ((COUNT) - 1))

/* A free list of "binding_entry"s awaiting for re-use.  */
static GTY((deletable(""))) binding_entry free_binding_entry = NULL;

/* Create a binding_entry object for (NAME, TYPE).  */
static inline binding_entry
binding_entry_make (tree name, tree type)
{
  binding_entry entry;

  if (free_binding_entry)
    {
      entry = free_binding_entry;
      free_binding_entry = entry->chain;
    }
  else
    entry = ggc_alloc (sizeof (struct binding_entry_s));

  entry->name = name;
  entry->type = type;
  entry->chain = NULL;

  return entry;
}

/* Put ENTRY back on the free list.  */
static inline void
binding_entry_free (binding_entry entry)
{
  entry->chain = free_binding_entry;
  free_binding_entry = entry;
}

/* The datatype used to implement the mapping from names to types at
   a given scope.  */
struct binding_table_s GTY(())
{
  /* Array of chains of "binding_entry"s  */
  binding_entry * GTY((length ("%h.chain_count"))) chain;

  /* The number of chains in this table.  This is the length of the
     the member "chain" considered as an array.  */
  size_t chain_count;

  /* Number of "binding_entry"s in this table.  */
  size_t entry_count;
};

/* Construct TABLE with an initial CHAIN_COUNT.  */
static inline void
binding_table_construct (binding_table table, size_t chain_count)
{
  table->chain_count = chain_count;
  table->entry_count = 0;
  table->chain = ggc_alloc_cleared
    (table->chain_count * sizeof (binding_entry));
}

/* Free TABLE by making its entries ready for reuse.  */
void
binding_table_free (binding_table table)
{
  size_t i;
  if (table == NULL)
    return;

  for (i = 0; i < table->chain_count; ++i)
    {
      binding_entry temp = table->chain[i];
      while (temp != NULL)
        {
          binding_entry entry = temp;
          temp = entry->chain;
          entry->chain = NULL; 
          binding_entry_free (entry);
        }
      table->chain[i] = temp;
    }
  table->entry_count = 0;
}

/* Allocate a table with CHAIN_COUNT, assumed to be a power of two.  */
binding_table
binding_table_new (size_t chain_count)
{
  binding_table table = ggc_alloc (sizeof (struct binding_table_s));
  table->chain = NULL;
  binding_table_construct (table, chain_count);
  return table;
}

/* Expand TABLE to twice its current chain_count.  */
static void
binding_table_expand (binding_table table)
{
  const size_t old_chain_count = table->chain_count;
  const size_t old_entry_count = table->entry_count;
  const size_t new_chain_count = 2 * old_chain_count;
  binding_entry *old_chains = table->chain;
  size_t i;

  binding_table_construct (table, new_chain_count);
  for (i = 0; i < old_chain_count; ++i)
    {
      binding_entry entry = old_chains[i];
      for (; entry != NULL; entry = old_chains[i])
        {
          const unsigned int hash = IDENTIFIER_HASH_VALUE (entry->name);
          const size_t j = ENTRY_INDEX (hash, new_chain_count);

          old_chains[i] = entry->chain;
          entry->chain = table->chain[j];
          table->chain[j] = entry;
        }
    }
  table->entry_count = old_entry_count;
}

/* Insert a binding for NAME to TYPe into TABLE.  */
void
binding_table_insert (binding_table table, tree name, tree type)
{
  const unsigned int hash = IDENTIFIER_HASH_VALUE (name);
  const size_t i = ENTRY_INDEX (hash, table->chain_count);
  binding_entry entry = binding_entry_make (name, type);

  entry->chain = table->chain[i];
  table->chain[i] = entry;
  ++table->entry_count;

  if (3 * table->chain_count < 5 * table->entry_count)
    binding_table_expand (table);
}

/* Return the binding_entry, if any, that maps NAME.  */
binding_entry
binding_table_find (binding_table table, tree name)
{
  const unsigned int hash = IDENTIFIER_HASH_VALUE (name);
  binding_entry entry = table->chain[ENTRY_INDEX (hash, table->chain_count)];

  while (entry != NULL && entry->name != name)
    entry = entry->chain;

  return entry;
}

/* Return the binding_entry, if any, that maps name to an anonymous type.  */
tree
binding_table_find_anon_type (binding_table table, tree name)
{
  const unsigned int hash = IDENTIFIER_HASH_VALUE (name);
  binding_entry entry = table->chain[ENTRY_INDEX (hash, table->chain_count)];

  while (entry != NULL && TYPE_IDENTIFIER (entry->type) != name)
    entry = entry->chain;

  return entry ? entry->type : NULL;
}

/* Return the binding_entry, if any, that has TYPE as target.  If NAME
   is non-null, then set the domain and rehash that entry.  */
binding_entry
binding_table_reverse_maybe_remap (binding_table table, tree type, tree name)
{
  const size_t chain_count = table->chain_count;
  binding_entry entry = NULL;
  binding_entry *p = NULL;
  size_t i;

  for (i = 0; i < chain_count && entry == NULL; ++i)
    {
      p = &table->chain[i];
      while (*p != NULL && entry == NULL)
        if ((*p)->type == type)
          entry = *p;
        else
          p = &(*p)->chain;
    }

  if (entry != NULL && name != NULL && entry->name != name)
    {
      /* Remove the bucket from the previous chain.  */
      *p = (*p)->chain;

      /* Remap the name type to type.  */
      i = ENTRY_INDEX (IDENTIFIER_HASH_VALUE (name), chain_count);
      entry->chain = table->chain[i];
      entry->name = name;
      table->chain[i] = entry;
    }

  return entry;
}

/* Remove from TABLE all entries that map to anonymous enums or
   class-types.  */
void
binding_table_remove_anonymous_types (binding_table table)
{
  const size_t chain_count = table->chain_count;
  size_t i;

  for (i = 0; i < chain_count; ++i)
    {
      binding_entry *p = &table->chain[i];

      while (*p != NULL)
        if (ANON_AGGRNAME_P ((*p)->name))
          {
            binding_entry e = *p;
            *p = (*p)->chain;
            --table->entry_count;
            binding_entry_free (e);
          }
        else
          p = &(*p)->chain;
    }
}

/* Apply PROC -- with DATA -- to all entries in TABLE.  */
void
binding_table_foreach (binding_table table, bt_foreach_proc proc, void *data)
{
  const size_t chain_count = table->chain_count;
  size_t i;

  for (i = 0; i < chain_count; ++i)
    {
      binding_entry entry = table->chain[i];
      for (; entry != NULL; entry = entry->chain)
        proc (entry, data);
    }
}


/* A free list of "cxx_binding"s, connected by their PREVIOUS.  */
static GTY((deletable (""))) cxx_binding *free_bindings;

/* (GC)-allocate a binding object with VALUE and TYPE member initialized.  */
cxx_binding *
cxx_binding_make (tree value, tree type)
{
  cxx_binding *binding;
  if (free_bindings)
    {
      binding = free_bindings;
      free_bindings = binding->previous;
    }
  else
    binding = ggc_alloc (sizeof (cxx_binding));

  binding->value = value;
  binding->type = type;
  binding->previous = NULL;

  return binding;
}

/* Put BINDING back on the free list.  */
void
cxx_binding_free (cxx_binding *binding)
{
  binding->previous = free_bindings;
  free_bindings = binding;
}

/* Return (from the stack of) the BINDING, if any, establihsed at SCOPE.  */ 

static inline cxx_binding *
find_binding (cxx_scope *scope, cxx_binding *binding)
{
  timevar_push (TV_NAME_LOOKUP);

  for (; binding != NULL; binding = binding->previous)
    if (BINDING_SCOPE (binding) == scope)
      POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, binding);

  POP_TIMEVAR_AND_RETURN (TV_NAME_LOOKUP, (cxx_binding *)0);
}

/* Return the binding for NAME in SCOPE, if any.  Otherwise, return NULL.  */
cxx_binding *
cxx_scope_find_binding_for_name (cxx_scope *scope, tree name)
{
  cxx_binding *b = IDENTIFIER_NAMESPACE_BINDINGS (name);
  if (b)
    {
      /* Fold-in case where NAME is used only once.  */
      if (scope == BINDING_SCOPE (b) && b->previous == NULL)
        return b;
      return find_binding (scope, b);
    }
  return NULL;
}

/* Always returns a binding for name in scope.  If no binding is
   found, make a new one.  */

cxx_binding *
binding_for_name (cxx_scope *scope, tree name)
{
  cxx_binding *result;

  result = cxx_scope_find_binding_for_name (scope, name);
  if (result)
    return result;
  /* Not found, make a new one.  */
  result = cxx_binding_make (NULL, NULL);
  result->previous = IDENTIFIER_NAMESPACE_BINDINGS (name);
  BINDING_SCOPE (result) = scope;
  result->is_local = false;
  result->value_is_inherited = false;
  IDENTIFIER_NAMESPACE_BINDINGS (name) = result;
  return result;
}

/* Namespace-scope manipulation routines.  */

/* Return the binding value for name in scope.  */

tree
namespace_binding (tree name, tree scope)
{
  cxx_binding *binding;

  if (scope == NULL)
    scope = global_namespace;
  scope = ORIGINAL_NAMESPACE (scope);
  binding = cxx_scope_find_binding_for_name (NAMESPACE_LEVEL (scope), name);

  return binding ? binding->value : NULL_TREE;
}

/* Set the binding value for name in scope.  */

void
set_namespace_binding (tree name, tree scope, tree val)
{
  cxx_binding *b;

  timevar_push (TV_NAME_LOOKUP);
  if (scope == NULL_TREE)
    scope = global_namespace;
  b = binding_for_name (NAMESPACE_LEVEL (scope), name);
  BINDING_VALUE (b) = val;
  timevar_pop (TV_NAME_LOOKUP);
}

#include "gt-cp-name-lookup.h"