/*

 * Copyright (c) 1997, 2017, Oracle and/or its affiliates. All rights reserved.

 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code 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

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

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 *

 */

#include "precompiled.hpp"

#include "libadt/dict.hpp"

// Dictionaries - An Abstract Data Type

// %%%%% includes not needed with AVM framework - Ungar

#include <assert.h>

//------------------------------data-----------------------------------------

// String hash tables

#define MAXID 20

static uint8_t initflag = 0;       // True after 1st initialization

static const char shft[MAXID] = {1,2,3,4,5,6,7,1,2,3,4,5,6,7,1,2,3,4,5,6};

static short xsum[MAXID];

//------------------------------bucket---------------------------------------

class bucket : public ResourceObj {

public:

  uint _cnt, _max;              // Size of bucket

  void **_keyvals;              // Array of keys and values

};

//------------------------------Dict-----------------------------------------

// The dictionary is kept has a hash table.  The hash table is a even power

// of two, for nice modulo operations.  Each bucket in the hash table points

// to a linear list of key-value pairs; each key & value is just a (void *).

// The list starts with a count.  A hash lookup finds the list head, then a

// simple linear scan finds the key.  If the table gets too full, it's

// doubled in size; the total amount of EXTRA times all hash functions are

// computed for the doubling is no more than the current size - thus the

// doubling in size costs no more than a constant factor in speed.

  int i;

  // Precompute table of null character hashes

  if( !initflag ) {             // Not initializated yet?

    xsum[0] = (1<<shft[0])+1;   // Initialize

    for(i=1; i<MAXID; i++) {

      xsum[i] = (1<<shft[i])+1+xsum[i-1];

    }

    initflag = 1;               // Never again

  }

  _size = 16;                   // Size is a power of 2

  _cnt = 0;                     // Dictionary is empty

  _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);

  memset((void*)_bin,0,sizeof(bucket)*_size);

}

Dict::Dict(CmpKey initcmp, Hash inithash, Arena *arena, int size)

  int i;

  // Precompute table of null character hashes

  if( !initflag ) {             // Not initializated yet?

    xsum[0] = (1<<shft[0])+1;   // Initialize

    for(i=1; i<MAXID; i++) {

      xsum[i] = (1<<shft[i])+1+xsum[i-1];

    }

    initflag = 1;               // Never again

  }

  i=16;

  while( i < size ) i <<= 1;

  _size = i;                    // Size is a power of 2

  _cnt = 0;                     // Dictionary is empty

  _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);

  memset((void*)_bin,0,sizeof(bucket)*_size);

}

//------------------------------~Dict------------------------------------------

// Delete an existing dictionary.

Dict::~Dict() {

  /*

  tty->print("~Dict %d/%d: ",_cnt,_size);

  for( uint i=0; i < _size; i++) // For complete new table do

    tty->print("%d ",_bin[i]._cnt);

  tty->print("\n");*/

  /*for( uint i=0; i<_size; i++ ) {

    FREE_FAST( _bin[i]._keyvals );

    } */

}

//------------------------------Clear----------------------------------------

// Zap to empty; ready for re-use

void Dict::Clear() {

  _cnt = 0;                     // Empty contents

  for( uint i=0; i<_size; i++ )

    _bin[i]._cnt = 0;           // Empty buckets, but leave allocated

  // Leave _size & _bin alone, under the assumption that dictionary will

  // grow to this size again.

}

//------------------------------doubhash---------------------------------------

// Double hash table size.  If can't do so, just suffer.  If can, then run

// thru old hash table, moving things to new table.  Note that since hash

// table doubled, exactly 1 new bit is exposed in the mask - so everything

// in the old table ends up on 1 of two lists in the new table; a hi and a

// lo list depending on the value of the bit.

void Dict::doubhash(void) {

  uint oldsize = _size;

  _size <<= 1;                  // Double in size

  _bin = (bucket*)_arena->Arealloc(_bin, sizeof(bucket) * oldsize, sizeof(bucket) * _size);

  memset((void*)(&_bin[oldsize]), 0, oldsize * sizeof(bucket));

  // Rehash things to spread into new table

  for (uint i = 0; i < oldsize; i++) { // For complete OLD table do

    bucket *b = &_bin[i];              // Handy shortcut for _bin[i]

    if (!b->_keyvals) continue;        // Skip empties fast

    bucket *nb = &_bin[i+oldsize];     // New bucket shortcut

    uint j = b->_max;                  // Trim new bucket to nearest power of 2

    while (j > b->_cnt) { j >>= 1; }   // above old bucket _cnt

    if (!j) { j = 1; }                 // Handle zero-sized buckets

    nb->_max = j << 1;

    // Allocate worst case space for key-value pairs

    nb->_keyvals = (void**)_arena->Amalloc_4(sizeof(void *) * nb->_max * 2);

    uint nbcnt = 0;

    for (j = 0; j < b->_cnt; ) {           // Rehash all keys in this bucket

      void *key = b->_keyvals[j + j];

      if ((_hash(key) & (_size-1)) != i) { // Moving to hi bucket?

        nb->_keyvals[nbcnt + nbcnt] = key;

        nb->_keyvals[nbcnt + nbcnt + 1] = b->_keyvals[j + j + 1];

        nb->_cnt = nbcnt = nbcnt + 1;

        b->_cnt--;                         // Remove key/value from lo bucket

        b->_keyvals[j + j] = b->_keyvals[b->_cnt + b->_cnt];

        b->_keyvals[j + j + 1] = b->_keyvals[b->_cnt + b->_cnt + 1];

        // Don't increment j, hash compacted element also.

      } else {

        j++; // Iterate.

      }

    } // End of for all key-value pairs in bucket

  } // End of for all buckets

}

//------------------------------Dict-----------------------------------------

// Deep copy a dictionary.

  _bin = (bucket*)_arena->Amalloc_4(sizeof(bucket)*_size);

  memcpy( (void*)_bin, (void*)d._bin, sizeof(bucket)*_size );

  for( uint i=0; i<_size; i++ ) {

    if( !_bin[i]._keyvals ) continue;

    _bin[i]._keyvals=(void**)_arena->Amalloc_4( sizeof(void *)*_bin[i]._max*2);

    memcpy( _bin[i]._keyvals, d._bin[i]._keyvals,_bin[i]._cnt*2*sizeof(void*));

  }

}

//------------------------------Dict-----------------------------------------

// Deep copy a dictionary.

Dict &Dict::operator =( const Dict &d ) {

  if( _size < d._size ) {       // If must have more buckets

    _arena = d._arena;

    _bin = (bucket*)_arena->Arealloc( _bin, sizeof(bucket)*_size, sizeof(bucket)*d._size );

    memset( (void*)(&_bin[_size]), 0, (d._size-_size)*sizeof(bucket) );

    _size = d._size;

  }

  uint i;

  for( i=0; i<_size; i++ ) // All buckets are empty

    _bin[i]._cnt = 0;           // But leave bucket allocations alone

  _cnt = d._cnt;

  *(Hash*)(&_hash) = d._hash;

  *(CmpKey*)(&_cmp) = d._cmp;

  for( i=0; i<_size; i++ ) {

    bucket *b = &d._bin[i];     // Shortcut to source bucket

    for( uint j=0; j<b->_cnt; j++ )

      Insert( b->_keyvals[j+j], b->_keyvals[j+j+1] );

  }

  return *this;

}

//------------------------------Insert----------------------------------------

// Insert or replace a key/value pair in the given dictionary.  If the

// dictionary is too full, it's size is doubled.  The prior value being

// replaced is returned (NULL if this is a 1st insertion of that key).  If

// an old value is found, it's swapped with the prior key-value pair on the

// list.  This moves a commonly searched-for value towards the list head.

void *Dict::Insert(void *key, void *val, bool replace) {

  uint hash = _hash( key );     // Get hash key

  uint i = hash & (_size-1);    // Get hash key, corrected for size

  bucket *b = &_bin[i];         // Handy shortcut

  for( uint j=0; j<b->_cnt; j++ ) {

    if( !_cmp(key,b->_keyvals[j+j]) ) {

      if (!replace) {

        return b->_keyvals[j+j+1];

      } else {

        void *prior = b->_keyvals[j+j+1];

        b->_keyvals[j+j  ] = key;       // Insert current key-value

        b->_keyvals[j+j+1] = val;

        return prior;           // Return prior

      }

    }

  }

  if( ++_cnt > _size ) {        // Hash table is full

    doubhash();                 // Grow whole table if too full

    i = hash & (_size-1);       // Rehash

    b = &_bin[i];               // Handy shortcut

  }

  if( b->_cnt == b->_max ) {    // Must grow bucket?

    if( !b->_keyvals ) {

      b->_max = 2;              // Initial bucket size

      b->_keyvals = (void**)_arena->Amalloc_4(sizeof(void*) * b->_max * 2);

    } else {

      b->_keyvals = (void**)_arena->Arealloc(b->_keyvals, sizeof(void*) * b->_max * 2, sizeof(void*) * b->_max * 4);

      b->_max <<= 1;            // Double bucket

    }

  }

  b->_keyvals[b->_cnt+b->_cnt  ] = key;

  b->_keyvals[b->_cnt+b->_cnt+1] = val;

  b->_cnt++;

  return NULL;                  // Nothing found prior

}

//------------------------------Delete---------------------------------------

// Find & remove a value from dictionary. Return old value.

void *Dict::Delete(void *key) {

  uint i = _hash( key ) & (_size-1);    // Get hash key, corrected for size

  bucket *b = &_bin[i];         // Handy shortcut

  for( uint j=0; j<b->_cnt; j++ )

    if( !_cmp(key,b->_keyvals[j+j]) ) {

      void *prior = b->_keyvals[j+j+1];

      b->_cnt--;                // Remove key/value from lo bucket

      b->_keyvals[j+j  ] = b->_keyvals[b->_cnt+b->_cnt  ];

      b->_keyvals[j+j+1] = b->_keyvals[b->_cnt+b->_cnt+1];

      _cnt--;                   // One less thing in table

      return prior;

    }

  return NULL;

}

//------------------------------FindDict-------------------------------------

// Find a key-value pair in the given dictionary.  If not found, return NULL.

// If found, move key-value pair towards head of list.

void *Dict::operator [](const void *key) const {

  uint i = _hash( key ) & (_size-1);    // Get hash key, corrected for size

  bucket *b = &_bin[i];         // Handy shortcut

  for( uint j=0; j<b->_cnt; j++ )

    if( !_cmp(key,b->_keyvals[j+j]) )

      return b->_keyvals[j+j+1];

  return NULL;

}

//------------------------------CmpDict--------------------------------------

// CmpDict compares two dictionaries; they must have the same keys (their

// keys must match using CmpKey) and they must have the same values (pointer

// comparison).  If so 1 is returned, if not 0 is returned.

int32_t Dict::operator ==(const Dict &d2) const {

  if( _cnt != d2._cnt ) return 0;

  if( _hash != d2._hash ) return 0;

  if( _cmp != d2._cmp ) return 0;

  for( uint i=0; i < _size; i++) {      // For complete hash table do

    bucket *b = &_bin[i];       // Handy shortcut

    if( b->_cnt != d2._bin[i]._cnt ) return 0;

    if( memcmp(b->_keyvals, d2._bin[i]._keyvals, b->_cnt*2*sizeof(void*) ) )

      return 0;                 // Key-value pairs must match

  }

  return 1;                     // All match, is OK

}

//------------------------------print------------------------------------------

// Handier print routine

void Dict::print() {

  DictI i(this); // Moved definition in iterator here because of g++.

  tty->print("Dict@" INTPTR_FORMAT "[%d] = {", p2i(this), _cnt);

  for( ; i.test(); ++i ) {

    tty->print("(" INTPTR_FORMAT "," INTPTR_FORMAT "),", p2i(i._key), p2i(i._value));

  }

  tty->print_cr("}");

}

//------------------------------Hashing Functions----------------------------

// Convert string to hash key.  This algorithm implements a universal hash

// function with the multipliers frozen (ok, so it's not universal).  The

// multipliers (and allowable characters) are all odd, so the resultant sum

// is odd - guaranteed not divisible by any power of two, so the hash tables

// can be any power of two with good results.  Also, I choose multipliers

// that have only 2 bits set (the low is always set to be odd) so

// multiplication requires only shifts and adds.  Characters are required to

// be in the range 0-127 (I double & add 1 to force oddness).  Keys are

// limited to MAXID characters in length.  Experimental evidence on 150K of

// C text shows excellent spreading of values for any size hash table.

int hashstr(const void *t) {

  char c, k = 0;

  int32_t sum = 0;

  const char *s = (const char *)t;

  while( ((c = *s++) != '\0') && (k < MAXID-1) ) { // Get characters till null or MAXID-1

    c = (c<<1)+1;               // Characters are always odd!

    sum += c + (c<<shft[k++]);  // Universal hash function

  }

  return (int)((sum+xsum[k]) >> 1); // Hash key, un-modulo'd table size

}

//------------------------------hashptr--------------------------------------

// Slimey cheap hash function; no guaranteed performance.  Better than the

// default for pointers, especially on MS-DOS machines.

int hashptr(const void *key) {

  return ((intptr_t)key >> 2);

}

// Slimey cheap hash function; no guaranteed performance.

int hashkey(const void *key) {

  return (intptr_t)key;

}

//------------------------------Key Comparator Functions---------------------

int32_t cmpstr(const void *k1, const void *k2) {

  return strcmp((const char *)k1,(const char *)k2);

}

// Cheap key comparator.

int32_t cmpkey(const void *key1, const void *key2) {

  if (key1 == key2) return 0;

  intptr_t delta = (intptr_t)key1 - (intptr_t)key2;

  if (delta > 0) return 1;

  return -1;

}

//=============================================================================

//------------------------------reset------------------------------------------

// Create an iterator and initialize the first variables.

void DictI::reset( const Dict *dict ) {

  _d = dict;                    // The dictionary

  _i = (uint)-1;                // Before the first bin

  _j = 0;                       // Nothing left in the current bin

  ++(*this);                    // Step to first real value

}

//------------------------------next-------------------------------------------

// Find the next key-value pair in the dictionary, or return a NULL key and

// value.

void DictI::operator ++(void) {

  if( _j-- ) {                  // Still working in current bin?

    _key   = _d->_bin[_i]._keyvals[_j+_j];

    _value = _d->_bin[_i]._keyvals[_j+_j+1];

    return;

  }

  while( ++_i < _d->_size ) {   // Else scan for non-zero bucket

    _j = _d->_bin[_i]._cnt;

    if( !_j ) continue;

    _j--;

    _key   = _d->_bin[_i]._keyvals[_j+_j];

    _value = _d->_bin[_i]._keyvals[_j+_j+1];

    return;

  }

  _key = _value = NULL;

}