X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fdata%2Fcase.c;h=dc4029268ebf981bc10d96ecccf7c88eb53dd71a;hb=8830c95bb9e8d72621787866141a27fc22e8c786;hp=8613eca6f1b9944da0ffd2269f4dd8bf0691f429;hpb=5fd22ca7771c8175ef05e91e1194c3c4096337f4;p=pspp-builds.git

diff --git a/src/data/case.c b/src/data/case.c
index 8613eca6..dc402926 100644
--- a/src/data/case.c
+++ b/src/data/case.c
@@ -1,431 +1,483 @@
-/* PSPP - computes sample statistics.
-   Copyright (C) 2004 Free Software Foundation, Inc.
-   Written by Ben Pfaff <blp@gnu.org>.
+/* PSPP - a program for statistical analysis.
+   Copyright (C) 2004, 2007, 2009 Free Software Foundation, Inc.
 
-   This program 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 of the
-   License, or (at your option) any later version.
+   This program 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 3 of the License, or
+   (at your option) any later version.
 
-   This program 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.
+   This program 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 this program; if not, write to the Free Software
-   Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
-   02110-1301, USA. */
+   along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #include <config.h>
-#include "case.h"
+
+#include <data/case.h>
+
 #include <limits.h>
+#include <stddef.h>
 #include <stdlib.h>
-#include "value.h"
-#include "alloc.h"
-#include "str.h"
-#include "variable.h"
-
-#ifdef DEBUGGING
-#undef NDEBUG
-#else
-#ifndef NDEBUG
-#define NDEBUG
-#endif
-#endif
-#include <assert.h>
-
-/* Changes C not to share data with any other case.
-   C must be a case with a reference count greater than 1.
-   There should be no reason for external code to call this
-   function explicitly.  It will be called automatically when
-   needed. */
-void
-case_unshare (struct ccase *c) 
-{
-  struct case_data *cd;
-  
-  assert (c != NULL);
-  assert (c->this == c);
-  assert (c->case_data != NULL);
-  assert (c->case_data->ref_cnt > 1);
-
-  cd = c->case_data;
-  cd->ref_cnt--;
-  case_create (c, c->case_data->value_cnt);
-  memcpy (c->case_data->values, cd->values,
-          sizeof *cd->values * cd->value_cnt); 
-}
 
-/* Returns the number of bytes needed by a case with VALUE_CNT
-   values. */
-static inline size_t
-case_size (size_t value_cnt) 
+#include <data/value.h>
+#include <data/variable.h>
+#include <libpspp/assertion.h>
+#include <libpspp/str.h>
+
+#include "minmax.h"
+#include "xalloc.h"
+
+static size_t case_size (const struct caseproto *);
+static bool variable_matches_case (const struct ccase *,
+                                   const struct variable *);
+static void copy_forward (struct ccase *dst, size_t dst_idx,
+                          const struct ccase *src, size_t src_idx,
+                          size_t n_values);
+static void copy_backward (struct ccase *dst, size_t dst_idx,
+                           const struct ccase *src, size_t src_idx,
+                           size_t n_values);
+
+/* Creates and returns a new case that stores data of the form
+   specified by PROTO.  The data in the case have indeterminate
+   contents until explicitly written.
+
+   The caller retains ownership of PROTO. */
+struct ccase *
+case_create (const struct caseproto *proto)
 {
-  return (offsetof (struct case_data, values)
-          + value_cnt * sizeof (union value));
+  struct ccase *c = case_try_create (proto);
+  if (c == NULL)
+    xalloc_die ();
+  return c;
 }
 
-#ifdef DEBUGGING
-/* Initializes C as a null case. */
-void
-case_nullify (struct ccase *c) 
+/* Like case_create, but returns a null pointer if not enough
+   memory is available. */
+struct ccase *
+case_try_create (const struct caseproto *proto)
 {
-  c->case_data = NULL;
-  c->this = c;
+  struct ccase *c = malloc (case_size (proto));
+  if (c != NULL)
+    {
+      if (caseproto_try_init_values (proto, c->values))
+        {
+          c->proto = caseproto_ref (proto);
+          c->ref_cnt = 1;
+          return c;
+        }
+      free (c);
+    }
+  return NULL;
 }
-#endif /* DEBUGGING */
 
-#ifdef DEBUGGING
-/* Returns true iff C is a null case. */
-int
-case_is_null (const struct ccase *c) 
+/* Creates and returns an unshared copy of case C. */
+struct ccase *
+case_clone (const struct ccase *c)
 {
-  return c->case_data == NULL;
+  return case_unshare (case_ref (c));
 }
-#endif /* DEBUGGING */
 
-/* Initializes C as a new case that can store VALUE_CNT values.
-   The values have indeterminate contents until explicitly
-   written. */
-void
-case_create (struct ccase *c, size_t value_cnt) 
+/* Returns an estimate of the number of bytes of memory that
+   would be consumed in creating a case based on PROTO.  The
+   estimate includes typical overhead from malloc() in addition
+   to the actual size of data. */
+size_t
+case_get_cost (const struct caseproto *proto)
 {
-  if (!case_try_create (c, value_cnt))
-    xalloc_die ();
+  /* FIXME: improve approximation? */
+  return (1 + caseproto_get_n_widths (proto)
+          + 3 * caseproto_get_n_long_strings (proto)) * sizeof (union value);
 }
 
-#ifdef DEBUGGING
-/* Initializes CLONE as a copy of ORIG. */
-void
-case_clone (struct ccase *clone, const struct ccase *orig)
+/* Changes the prototype for case C, which must not be shared.
+   The new PROTO must be conformable with C's current prototype
+   (as defined by caseproto_is_conformable).
+
+   Any new values created by this function have indeterminate
+   content that the caller is responsible for initializing.
+
+   The caller retains ownership of PROTO.
+
+   Returns a new case that replaces C, which is freed. */
+struct ccase *
+case_resize (struct ccase *c, const struct caseproto *new_proto)
 {
-  assert (orig != NULL);
-  assert (orig->this == orig);
-  assert (orig->case_data != NULL);
-  assert (orig->case_data->ref_cnt > 0);
-  assert (clone != NULL);
+  struct caseproto *old_proto = c->proto;
+  size_t old_n_widths = caseproto_get_n_widths (old_proto);
+  size_t new_n_widths = caseproto_get_n_widths (new_proto);
 
-  if (clone != orig) 
+  assert (!case_is_shared (c));
+  expensive_assert (caseproto_is_conformable (old_proto, new_proto));
+
+  if (old_n_widths != new_n_widths)
     {
-      *clone = *orig;
-      clone->this = clone;
+      if (new_n_widths < old_n_widths)
+        caseproto_reinit_values (old_proto, new_proto, c->values);
+      c = xrealloc (c, case_size (new_proto));
+      if (new_n_widths > old_n_widths)
+        caseproto_reinit_values (old_proto, new_proto, c->values);
+
+      caseproto_unref (old_proto);
+      c->proto = caseproto_ref (new_proto);
     }
-  orig->case_data->ref_cnt++;
-}
-#endif /* DEBUGGING */
 
-#ifdef DEBUGGING
-/* Replaces DST by SRC and nullifies SRC.
-   DST and SRC must be initialized cases at entry. */
-void
-case_move (struct ccase *dst, struct ccase *src) 
-{
-  assert (src != NULL);
-  assert (src->this == src);
-  assert (src->case_data != NULL);
-  assert (src->case_data->ref_cnt > 0);
-  assert (dst != NULL);
-
-  *dst = *src;
-  dst->this = dst;
-  case_nullify (src);
+  return c;
 }
-#endif /* DEBUGGING */
 
-#ifdef DEBUGGING
-/* Destroys case C. */
-void
-case_destroy (struct ccase *c) 
-{
-  struct case_data *cd;
-  
-  assert (c != NULL);
-  assert (c->this == c);
+/* case_unshare_and_resize(C, PROTO) is equivalent to
+   case_resize(case_unshare(C), PROTO), but it is faster if case
+   C is shared.
 
-  cd = c->case_data;
-  if (cd != NULL && --cd->ref_cnt == 0) 
+   Any new values created by this function have indeterminate
+   content that the caller is responsible for initializing.
+
+   The caller retains ownership of PROTO.
+
+   Returns the new case that replaces C, which is freed. */
+struct ccase *
+case_unshare_and_resize (struct ccase *c, const struct caseproto *proto)
+{
+  if (!case_is_shared (c))
+    return case_resize (c, proto);
+  else
     {
-      memset (cd->values, 0xcc, sizeof *cd->values * cd->value_cnt);
-      cd->value_cnt = 0xdeadbeef;
-      free (cd); 
+      struct ccase *new = case_create (proto);
+      size_t old_n_values = caseproto_get_n_widths (c->proto);
+      size_t new_n_values = caseproto_get_n_widths (proto);
+      case_copy (new, 0, c, 0, MIN (old_n_values, new_n_values));
+      c->ref_cnt--;
+      return new;
     }
 }
-#endif /* DEBUGGING */
 
-/* Resizes case C from OLD_CNT to NEW_CNT values. */
+/* Sets all of the numeric values in case C to the system-missing
+   value, and all of the string values to spaces. */
 void
-case_resize (struct ccase *c, size_t old_cnt, size_t new_cnt) 
+case_set_missing (struct ccase *c)
 {
-  struct ccase new;
+  size_t i;
 
-  case_create (&new, new_cnt);
-  case_copy (&new, 0, c, 0, old_cnt < new_cnt ? old_cnt : new_cnt);
-  case_swap (&new, c);
-  case_destroy (&new);
+  assert (!case_is_shared (c));
+  for (i = 0; i < caseproto_get_n_widths (c->proto); i++)
+    value_set_missing (&c->values[i], caseproto_get_width (c->proto, i));
 }
 
-/* Swaps cases A and B. */
+/* Copies N_VALUES values from SRC (starting at SRC_IDX) to DST
+   (starting at DST_IDX).  Each value that is copied into must
+   have the same width as the value that it is copied from.
+
+   Properly handles overlapping ranges when DST == SRC.
+
+   DST must not be shared. */
 void
-case_swap (struct ccase *a, struct ccase *b) 
+case_copy (struct ccase *dst, size_t dst_idx,
+           const struct ccase *src, size_t src_idx,
+           size_t n_values)
 {
-  struct case_data *t = a->case_data;
-  a->case_data = b->case_data;
-  b->case_data = t;
-}
+  assert (!case_is_shared (dst));
+  assert (caseproto_range_is_valid (dst->proto, dst_idx, n_values));
+  assert (caseproto_range_is_valid (src->proto, src_idx, n_values));
+  assert (caseproto_equal (dst->proto, dst_idx, src->proto, src_idx,
+                           n_values));
 
-/* Attempts to create C as a new case that holds VALUE_CNT
-   values.  Returns nonzero if successful, zero if memory
-   allocation failed. */
-int
-case_try_create (struct ccase *c, size_t value_cnt) 
-{
-  c->case_data = malloc (case_size (value_cnt));
-  if (c->case_data != NULL) 
+  if (dst != src)
     {
-#ifdef DEBUGGING
-      c->this = c;
-#endif
-      c->case_data->value_cnt = value_cnt;
-      c->case_data->ref_cnt = 1;
-      return 1;
+      if (!dst->proto->n_long_strings || !src->proto->n_long_strings)
+        memcpy (&dst->values[dst_idx], &src->values[src_idx],
+                sizeof dst->values[0] * n_values);
+      else
+        copy_forward (dst, dst_idx, src, src_idx, n_values);
     }
-  else 
+  else if (dst_idx != src_idx)
     {
-#ifdef DEBUGGING
-      c->this = c;
-#endif
-      return 0;
+      if (!dst->proto->n_long_strings)
+        memmove (&dst->values[dst_idx], &src->values[src_idx],
+                 sizeof dst->values[0] * n_values);
+      else if (dst_idx < src_idx)
+        copy_forward (dst, dst_idx, src, src_idx, n_values);
+      else /* dst_idx > src_idx */
+        copy_backward (dst, dst_idx, src, src_idx, n_values);
     }
 }
 
-/* Tries to initialize CLONE as a copy of ORIG.
-   Returns nonzero if successful, zero if memory allocation
-   failed. */
-int
-case_try_clone (struct ccase *clone, const struct ccase *orig) 
+/* Copies N_VALUES values out of case C to VALUES, starting at
+   the given START_IDX. */
+void
+case_copy_out (const struct ccase *c,
+               size_t start_idx, union value *values, size_t n_values)
 {
-  case_clone (clone, orig);
-  return 1;
+  size_t i;
+
+  assert (caseproto_range_is_valid (c->proto, start_idx, n_values));
+
+  for (i = 0; i < n_values; i++)
+    value_copy (&values[i], &c->values[start_idx + i],
+                caseproto_get_width (c->proto, start_idx + i));
 }
 
-#ifdef DEBUGGING
-/* Copies VALUE_CNT values from SRC (starting at SRC_IDX) to DST
-   (starting at DST_IDX). */
+/* Copies N_VALUES values from VALUES into case C, starting at
+   the given START_IDX.
+
+   C must not be shared. */
 void
-case_copy (struct ccase *dst, size_t dst_idx,
-           const struct ccase *src, size_t src_idx,
-           size_t value_cnt)
+case_copy_in (struct ccase *c,
+              size_t start_idx, const union value *values, size_t n_values)
 {
-  assert (dst != NULL);
-  assert (dst->this == dst);
-  assert (dst->case_data != NULL);
-  assert (dst->case_data->ref_cnt > 0);
-  assert (dst_idx + value_cnt <= dst->case_data->value_cnt);
-
-  assert (src != NULL);
-  assert (src->this == src);
-  assert (src->case_data != NULL);
-  assert (src->case_data->ref_cnt > 0);
-  assert (src_idx + value_cnt <= dst->case_data->value_cnt);
-
-  if (dst->case_data->ref_cnt > 1)
-    case_unshare (dst);
-  if (dst->case_data != src->case_data || dst_idx != src_idx) 
-    memmove (dst->case_data->values + dst_idx,
-             src->case_data->values + src_idx,
-             sizeof *dst->case_data->values * value_cnt); 
+  size_t i;
+
+  assert (!case_is_shared (c));
+  assert (caseproto_range_is_valid (c->proto, start_idx, n_values));
+
+  for (i = 0; i < n_values; i++)
+    value_copy (&c->values[start_idx + i], &values[i],
+                caseproto_get_width (c->proto, start_idx + i));
 }
-#endif /* DEBUGGING */
 
-#ifdef DEBUGGING
-/* Copies case C to OUTPUT.
-   OUTPUT_SIZE is the number of `union values' in OUTPUT,
-   which must match the number of `union values' in C. */
-void
-case_to_values (const struct ccase *c, union value *output,
-                size_t output_size UNUSED) 
+/* Returns a pointer to the `union value' used for the
+   element of C for variable V.
+   Case C must be drawn from V's dictionary.
+   The caller must not modify the returned data. */
+const union value *
+case_data (const struct ccase *c, const struct variable *v)
 {
-  assert (c != NULL);
-  assert (c->this == c);
-  assert (c->case_data != NULL);
-  assert (c->case_data->ref_cnt > 0);
-  assert (output_size == c->case_data->value_cnt);
-  assert (output != NULL || output_size == 0);
-
-  memcpy (output, c->case_data->values,
-          c->case_data->value_cnt * sizeof *output);
+  assert (variable_matches_case (c, v));
+  return &c->values[var_get_case_index (v)];
 }
-#endif /* DEBUGGING */
 
-#ifdef DEBUGGING
-/* Copies INPUT into case C.
-   INPUT_SIZE is the number of `union values' in INPUT,
-   which must match the number of `union values' in C. */
-void
-case_from_values (struct ccase *c, const union value *input,
-                  size_t input_size UNUSED) 
+/* Returns a pointer to the `union value' used for the element of
+   C numbered IDX.  The caller must not modify the returned
+   data. */
+const union value *
+case_data_idx (const struct ccase *c, size_t idx)
+{
+  assert (idx < c->proto->n_widths);
+  return &c->values[idx];
+}
+
+/* Returns a pointer to the `union value' used for the element of
+   C for variable V.  Case C must be drawn from V's dictionary.
+   The caller is allowed to modify the returned data.
+
+   Case C must not be shared. */
+union value *
+case_data_rw (struct ccase *c, const struct variable *v)
 {
-  assert (c != NULL);
-  assert (c->this == c);
-  assert (c->case_data != NULL);
-  assert (c->case_data->ref_cnt > 0);
-  assert (input_size == c->case_data->value_cnt);
-  assert (input != NULL || input_size == 0);
-
-  if (c->case_data->ref_cnt > 1)
-    case_unshare (c);
-  memcpy (c->case_data->values, input,
-          c->case_data->value_cnt * sizeof *input);
+  assert (variable_matches_case (c, v));
+  assert (!case_is_shared (c));
+  return &c->values[var_get_case_index (v)];
 }
-#endif /* DEBUGGING */
 
-#ifdef DEBUGGING
 /* Returns a pointer to the `union value' used for the
    element of C numbered IDX.
-   The caller must not modify the returned data. */
-const union value *
-case_data (const struct ccase *c, size_t idx) 
+   The caller is allowed to modify the returned data.
+
+   Case C must not be shared. */
+union value *
+case_data_rw_idx (struct ccase *c, size_t idx)
 {
-  assert (c != NULL);
-  assert (c->this == c);
-  assert (c->case_data != NULL);
-  assert (c->case_data->ref_cnt > 0);
-  assert (idx < c->case_data->value_cnt);
+  assert (idx < c->proto->n_widths);
+  assert (!case_is_shared (c));
+  return &c->values[idx];
+}
 
-  return &c->case_data->values[idx];
+/* Returns the numeric value of the `union value' in C for
+   variable V.
+   Case C must be drawn from V's dictionary. */
+double
+case_num (const struct ccase *c, const struct variable *v)
+{
+  assert (variable_matches_case (c, v));
+  return c->values[var_get_case_index (v)].f;
 }
-#endif /* DEBUGGING */
 
-#ifdef DEBUGGING
 /* Returns the numeric value of the `union value' in C numbered
    IDX. */
 double
-case_num (const struct ccase *c, size_t idx) 
+case_num_idx (const struct ccase *c, size_t idx)
 {
-  assert (c != NULL);
-  assert (c->this == c);
-  assert (c->case_data != NULL);
-  assert (c->case_data->ref_cnt > 0);
-  assert (idx < c->case_data->value_cnt);
+  assert (idx < c->proto->n_widths);
+  return c->values[idx].f;
+}
+
+/* Returns the string value of the `union value' in C for
+   variable V.  Case C must be drawn from V's dictionary.  The
+   caller must not modify the return value.
 
-  return c->case_data->values[idx].f;
+   Like the strings embedded in all "union value"s, the return
+   value is not null-terminated. */
+const uint8_t *
+case_str (const struct ccase *c, const struct variable *v)
+{
+  size_t idx = var_get_case_index (v);
+  assert (variable_matches_case (c, v));
+  return value_str (&c->values[idx], caseproto_get_width (c->proto, idx));
 }
-#endif /* DEBUGGING */
 
-#ifdef DEBUGGING
 /* Returns the string value of the `union value' in C numbered
-   IDX.
-   (Note that the value is not null-terminated.)
-   The caller must not modify the return value. */
-const char *
-case_str (const struct ccase *c, size_t idx) 
+   IDX.  The caller must not modify the return value.
+
+   Like the strings embedded in all "union value"s, the return
+   value is not null-terminated. */
+const uint8_t *
+case_str_idx (const struct ccase *c, size_t idx)
 {
-  assert (c != NULL);
-  assert (c->this == c);
-  assert (c->case_data != NULL);
-  assert (c->case_data->ref_cnt > 0);
-  assert (idx < c->case_data->value_cnt);
+  assert (idx < c->proto->n_widths);
+  return value_str (&c->values[idx], caseproto_get_width (c->proto, idx));
+}
 
-  return c->case_data->values[idx].s;
+/* Returns the string value of the `union value' in C for
+   variable V.  Case C must be drawn from V's dictionary.  The
+   caller may modify the return value.
+
+   Case C must not be shared.
+
+   Like the strings embedded in all "union value"s, the return
+   value is not null-terminated. */
+uint8_t *
+case_str_rw (struct ccase *c, const struct variable *v)
+{
+  size_t idx = var_get_case_index (v);
+  assert (variable_matches_case (c, v));
+  assert (!case_is_shared (c));
+  return value_str_rw (&c->values[idx], caseproto_get_width (c->proto, idx));
 }
-#endif /* DEBUGGING */
 
-#ifdef DEBUGGING
-/* Returns a pointer to the `union value' used for the
-   element of C numbered IDX.
-   The caller is allowed to modify the returned data. */
-union value *
-case_data_rw (struct ccase *c, size_t idx) 
+/* Returns the string value of the `union value' in C numbered
+   IDX.  The caller may modify the return value.
+
+   Case C must not be shared.
+
+   Like the strings embedded in all "union value"s, the return
+   value is not null-terminated. */
+uint8_t *
+case_str_rw_idx (struct ccase *c, size_t idx)
 {
-  assert (c != NULL);
-  assert (c->this == c);
-  assert (c->case_data != NULL);
-  assert (c->case_data->ref_cnt > 0);
-  assert (idx < c->case_data->value_cnt);
-
-  if (c->case_data->ref_cnt > 1)
-    case_unshare (c);
-  return &c->case_data->values[idx];
+  assert (idx < c->proto->n_widths);
+  assert (!case_is_shared (c));
+  return value_str_rw (&c->values[idx], caseproto_get_width (c->proto, idx));
 }
-#endif /* DEBUGGING */
 
-/* Compares the values of the VAR_CNT variables in VP
+/* Compares the values of the N_VARS variables in VP
    in cases A and B and returns a strcmp()-type result. */
 int
 case_compare (const struct ccase *a, const struct ccase *b,
-              struct variable *const *vp, size_t var_cnt)
+              const struct variable *const *vp, size_t n_vars)
 {
-  return case_compare_2dict (a, b, vp, vp, var_cnt);
+  return case_compare_2dict (a, b, vp, vp, n_vars);
 }
 
-/* Compares the values of the VAR_CNT variables in VAP in case CA
-   to the values of the VAR_CNT variables in VBP in CB
+/* Compares the values of the N_VARS variables in VAP in case CA
+   to the values of the N_VARS variables in VBP in CB
    and returns a strcmp()-type result. */
 int
 case_compare_2dict (const struct ccase *ca, const struct ccase *cb,
-                    struct variable *const *vap, struct variable *const *vbp,
-                    size_t var_cnt) 
+                    const struct variable *const *vap,
+                    const struct variable *const *vbp,
+                    size_t n_vars)
 {
-  for (; var_cnt-- > 0; vap++, vbp++) 
+  int cmp = 0;
+  for (; !cmp && n_vars-- > 0; vap++, vbp++)
     {
-      const struct variable *va = *vap;
-      const struct variable *vb = *vbp;
-
-      assert (va->type == vb->type);
-      assert (va->width == vb->width);
-      
-      if (va->width == 0) 
-        {
-          double af = case_num (ca, va->fv);
-          double bf = case_num (cb, vb->fv);
-
-          if (af != bf) 
-            return af > bf ? 1 : -1;
-        }
-      else 
-        {
-          const char *as = case_str (ca, va->fv);
-          const char *bs = case_str (cb, vb->fv);
-          int cmp = memcmp (as, bs, va->width);
-
-          if (cmp != 0)
-            return cmp;
-        }
+      const union value *va = case_data (ca, *vap);
+      const union value *vb = case_data (cb, *vbp);
+      assert (var_get_width (*vap) == var_get_width (*vbp));
+      cmp = value_compare_3way (va, vb, var_get_width (*vap)); 
     }
-  return 0;
+  return cmp;
 }
 
 /* Returns a pointer to the array of `union value's used for C.
    The caller must *not* modify the returned data.
 
-   NOTE: This function breaks the case abstraction.  It should
-   *not* be used often.  Prefer the other case functions. */
+   This function breaks the case abstraction.  It should *not* be
+   commonly used.  Prefer the other case functions. */
 const union value *
-case_data_all (const struct ccase *c) 
+case_data_all (const struct ccase *c)
 {
-  assert (c != NULL);
-  assert (c->this == c);
-  assert (c->case_data != NULL);
-  assert (c->case_data->ref_cnt > 0);
-
-  return c->case_data->values;
+  return c->values;
 }
 
 /* Returns a pointer to the array of `union value's used for C.
    The caller is allowed to modify the returned data.
 
-   NOTE: This function breaks the case abstraction.  It should
-   *not* be used often.  Prefer the other case functions. */
+   Case C must not be shared.
+
+   This function breaks the case abstraction.  It should *not* be
+   commonly used.  Prefer the other case functions. */
 union value *
-case_data_all_rw (struct ccase *c) 
+case_data_all_rw (struct ccase *c)
+{
+  assert (!case_is_shared (c));
+  return c->values;
+}
+
+/* Internal helper function for case_unshare. */
+struct ccase *
+case_unshare__ (struct ccase *old)
+{
+  struct ccase *new = case_create (old->proto);
+  case_copy (new, 0, old, 0, caseproto_get_n_widths (new->proto));
+  --old->ref_cnt;
+  return new;
+}
+
+/* Internal helper function for case_unref. */
+void
+case_unref__ (struct ccase *c)
+{
+  caseproto_destroy_values (c->proto, c->values);
+  caseproto_unref (c->proto);
+  free (c);
+}
+
+/* Returns the number of bytes needed by a case for case
+   prototype PROTO. */
+static size_t
+case_size (const struct caseproto *proto)
 {
-  assert (c != NULL);
-  assert (c->this == c);
-  assert (c->case_data != NULL);
-  assert (c->case_data->ref_cnt > 0);
-
-  if (c->case_data->ref_cnt > 1)
-    case_unshare (c);
-  return c->case_data->values;
+  return (offsetof (struct ccase, values)
+          + caseproto_get_n_widths (proto) * sizeof (union value));
 }
+
+/* Returns true if C contains a value at V's case index with the
+   same width as V; that is, if V may plausibly be used to read
+   or write data in C.
+
+   Useful in assertions. */
+static bool UNUSED
+variable_matches_case (const struct ccase *c, const struct variable *v)
+{
+  size_t case_idx = var_get_case_index (v);
+  return (case_idx < caseproto_get_n_widths (c->proto)
+          && caseproto_get_width (c->proto, case_idx) == var_get_width (v));
+}
+
+/* Internal helper function for case_copy(). */
+static void
+copy_forward (struct ccase *dst, size_t dst_idx,
+              const struct ccase *src, size_t src_idx,
+              size_t n_values)
+{
+  size_t i;
+
+  for (i = 0; i < n_values; i++)
+    value_copy (&dst->values[dst_idx + i], &src->values[src_idx + i],
+                caseproto_get_width (dst->proto, dst_idx + i));
+}
+
+/* Internal helper function for case_copy(). */
+static void
+copy_backward (struct ccase *dst, size_t dst_idx,
+               const struct ccase *src, size_t src_idx,
+               size_t n_values)
+{
+  size_t i;
+
+  for (i = n_values; i-- != 0; )
+    value_copy (&dst->values[dst_idx + i], &src->values[src_idx + i],
+                caseproto_get_width (dst->proto, dst_idx + i));
+}
+