kc3-lang/gnulib/doc/bitset.texi

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• Hash : ac7fd666
  Author :
  Date : 2019-10-21T16:47:00
  

  bitset: let freeing functions accept NULL
  
  * lib/bitset.c (bitset_free, bitset_obstack_free): Do nothing if
  given NULL.
  * lib/bitset.h: Document that.
  * doc/bitset.texi: Fix the example, and demonstrate bitset_free.
  

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• doc/bitset.texi

• @node Bitsets
  @section Bitsets
  
  The module @samp{bitset} provides a common interface to several
  implementations of bitsets.  It also provides routines for vectors of bitsets.
  
  To look at an existing use, see GNU Bison.
  
  Currently it supports five flavours of bitsets:
  @description @code
  @item BITSET_ARRAY
  Array of bits (fixed size, fast for dense bitsets). Memory for bit array
  and bitset structure allocated contiguously.
  @item BITSET_LIST
  Linked list of arrays of bits (variable size, least storage for large
  very sparse sets).
  @item BITSET_TABLE
  Expandable table of pointers to arrays of bits (variable size, less
  storage for large sparse sets).  Faster than @code{BITSET_LIST} for
  random access.
  @item BITSET_VECTOR
  Variable array of bits (variable size, fast for dense bitsets).
  @item BITSET_STATS
  Wrapper bitset for internal use only.  Used for gathering statistics
  and/or better run-time checking.
  @end description
  
  However, the choice of the actual implementation is performed by the
  library, based on the user provided attributes:
  
  @description @code
  @code BITSET_FIXED
  Bitset size fixed.
  @code BITSET_VARIABLE
  Bitset size variable.
  @code BITSET_DENSE
  Bitset dense.
  @code BITSET_SPARSE
  Bitset sparse.
  @code BITSET_FRUGAL
  Prefer most compact.
  @code BITSET_GREEDY
  Prefer fastest at memory expense.
  @end description
  
  
  @smallexample
  enum { nbits = 32 };
  
  bitset bs0 = bitset_create (nbits, BITSET_FIXED);
  bitset_set (bs0, 1);
  bitset_set (bs0, 3);
  bitset_set (bs0, 5);
  
  bitset bs1 = bitset_create (nbits, BITSET_FIXED);
  bitset_set (bs1, 0);
  bitset_set (bs1, 2);
  bitset_set (bs1, 4);
  
  bitset bs = bitset_create (nbits, BITSET_FIXED);
  bitset_or (bs, bs0, bs1);
  ASSERT (bitset_count (bs) == 6);
  
  bitset_free (bs);
  bitset_free (bs1);
  bitset_free (bs0);
  @end smallexample
  

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