X-Git-Url: https://pintos-os.org/cgi-bin/gitweb.cgi?a=blobdiff_plain;f=src%2Fdata%2Fcase.c;h=4432579e5d2e1284102a9ab7854d79db3b10d197;hb=37329c68f3f4c77ee2baa88a70e9ba6701e4008f;hp=cec6f21e1be8ae94ccd7dcbc2284841e91ec9cab;hpb=9f087e7aa4cdff1d5d46d5e188c0017a9d2d0029;p=pspp-builds.git

diff --git a/src/data/case.c b/src/data/case.c
index cec6f21e..4432579e 100644
--- a/src/data/case.c
+++ b/src/data/case.c
@@ -1,5 +1,5 @@
 /* PSPP - a program for statistical analysis.
-   Copyright (C) 2004, 2007 Free Software Foundation, Inc.
+   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
@@ -20,6 +20,7 @@
 
 #include <assert.h>
 #include <limits.h>
+#include <stddef.h>
 #include <stdlib.h>
 
 #include <data/value.h>
@@ -29,212 +30,127 @@
 #include "minmax.h"
 #include "xalloc.h"
 
-/* Reference-counted case implementation. */
-struct case_data
-  {
-    size_t value_cnt;                   /* Number of values. */
-    unsigned ref_cnt;                   /* Reference count. */
-    union value values[1];              /* Values. */
-  };
-
-/* Ensures that C does not share data with any other case. */
-static void
-case_unshare (struct ccase *c)
-{
-  if (c->case_data->ref_cnt > 1)
-    {
-      struct case_data *cd = c->case_data;
-      cd->ref_cnt--;
-      case_create (c, cd->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
+/* Returns the number of bytes needed by a case with N_VALUES
    values. */
 static size_t
-case_size (size_t value_cnt)
+case_size (size_t n_values)
 {
-  return (offsetof (struct case_data, values)
-          + value_cnt * sizeof (union value));
+  return offsetof (struct ccase, values) + n_values * sizeof (union value);
 }
 
-/* Initializes C as a null case. */
-void
-case_nullify (struct ccase *c)
+/* Returns true if case C contains COUNT cases starting at index
+   OFS, false if any of those values are out of range for case
+   C. */
+static inline bool UNUSED
+range_is_valid (const struct ccase *c, size_t ofs, size_t count)
 {
-  c->case_data = NULL;
+  return (count <= c->n_values
+          && ofs <= c->n_values
+          && ofs + count <= c->n_values);
 }
 
-/* Returns true iff C is a null case. */
-bool
-case_is_null (const struct ccase *c)
-{
-  return c->case_data == NULL;
-}
-
-/* Initializes C as a new case that can store VALUE_CNT values.
+/* Creates and returns a new case that can store N_VALUES values.
    The values have indeterminate contents until explicitly
    written. */
-void
-case_create (struct ccase *c, size_t value_cnt)
+struct ccase *
+case_create (size_t n_values)
 {
-  if (!case_try_create (c, value_cnt))
+  struct ccase *c = case_try_create (n_values);
+  if (c == NULL)
     xalloc_die ();
+  return c;
 }
 
-/* Initializes CLONE as a copy of ORIG. */
-void
-case_clone (struct ccase *clone, const struct ccase *orig)
+/* Like case_create, but returns a null pointer if not enough
+   memory is available. */
+struct ccase *
+case_try_create (size_t n_values)
 {
-  assert (orig->case_data->ref_cnt > 0);
-
-  if (clone != orig)
-    *clone = *orig;
-  orig->case_data->ref_cnt++;
-#ifdef DEBUGGING
-  case_unshare (clone);
-#endif
-}
-
-/* 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->case_data->ref_cnt > 0);
-
-  if (dst != src)
+  struct ccase *c = malloc (case_size (n_values));
+  if (c)
     {
-      *dst = *src;
-      case_nullify (src);
+      c->n_values = n_values;
+      c->ref_cnt = 1;
     }
+  return c;
 }
 
-/* Destroys case C. */
-void
-case_destroy (struct ccase *c)
+/* Resizes case C, which must not be shared, to N_VALUES union
+   values.  If N_VALUES is greater than the current size of case
+   C, then the newly added values have indeterminate content that
+   the caller is responsible for initializing.  Returns the new
+   case. */
+struct ccase *
+case_resize (struct ccase *c, size_t n_values)
 {
-  struct case_data *cd;
-
-  cd = c->case_data;
-  if (cd != NULL && --cd->ref_cnt == 0)
+  assert (!case_is_shared (c));
+  if (n_values != c->n_values)
     {
-      memset (cd->values, 0xcc, sizeof *cd->values * cd->value_cnt);
-      cd->value_cnt = 0xdeadbeef;
-      free (cd);
+      c->n_values = n_values;
+      return xrealloc (c, case_size (n_values));
     }
+  else
+    return c;
 }
 
-/* Returns the number of union values in C. */
-size_t
-case_get_value_cnt (const struct ccase *c)
-{
-  return c->case_data->value_cnt;
-}
+/* case_unshare_and_resize(C, N) is equivalent to
+   case_resize(case_unshare(C), N), but it is faster if case C is
+   shared.
 
-/* Resizes case C to NEW_CNT union values. */
-void
-case_resize (struct ccase *c, size_t new_cnt)
+   Returns the new case.*/
+struct ccase *
+case_unshare_and_resize (struct ccase *c, size_t n_values)
 {
-  size_t old_cnt = case_get_value_cnt (c);
-  if (old_cnt != new_cnt)
+  if (!case_is_shared (c))
+    return case_resize (c, n_values);
+  else
     {
-      struct ccase new;
-
-      case_create (&new, new_cnt);
-      case_copy (&new, 0, c, 0, MIN (old_cnt, new_cnt));
-      case_swap (&new, c);
-      case_destroy (&new);
+      struct ccase *new = case_create (n_values);
+      case_copy (new, 0, c, 0, MIN (n_values, c->n_values));
+      c->ref_cnt--;
+      return new;
     }
 }
 
-/* Swaps cases A and B. */
-void
-case_swap (struct ccase *a, struct ccase *b)
-{
-  struct case_data *t = a->case_data;
-  a->case_data = b->case_data;
-  b->case_data = t;
-}
+/* Copies N_VALUES values from SRC (starting at SRC_IDX) to DST
+   (starting at DST_IDX).
 
-/* Attempts to create C as a new case that holds VALUE_CNT
-   values.  Returns true if successful, false if memory
-   allocation failed. */
-bool
-case_try_create (struct ccase *c, size_t value_cnt)
-{
-  c->case_data = malloc (case_size (value_cnt));
-  if (c->case_data != NULL)
-    {
-      c->case_data->value_cnt = value_cnt;
-      c->case_data->ref_cnt = 1;
-      return true;
-    }
-
-  return false;
-}
-
-/* Tries to initialize CLONE as a copy of ORIG.
-   Returns true if successful, false if memory allocation
-   failed. */
-bool
-case_try_clone (struct ccase *clone, const struct ccase *orig)
-{
-  case_clone (clone, orig);
-  return true;
-}
-
-/* Copies VALUE_CNT values from SRC (starting at SRC_IDX) to DST
-   (starting at DST_IDX). */
+   DST 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)
+           size_t n_values)
 {
-  assert (dst->case_data->ref_cnt > 0);
-  assert (dst_idx + value_cnt <= dst->case_data->value_cnt);
+  assert (!case_is_shared (dst));
+  assert (range_is_valid (dst, dst_idx, n_values));
+  assert (range_is_valid (src, src_idx, n_values));
 
-  assert (src->case_data->ref_cnt > 0);
-  assert (src_idx + value_cnt <= src->case_data->value_cnt);
-
-  if (dst->case_data != src->case_data || dst_idx != src_idx)
-    {
-      case_unshare (dst);
-      memmove (dst->case_data->values + dst_idx,
-               src->case_data->values + src_idx,
-               sizeof *dst->case_data->values * value_cnt);
-    }
+  if (dst != src || dst_idx != src_idx)
+    memmove (dst->values + dst_idx, src->values + src_idx,
+             sizeof *dst->values * n_values);
 }
 
-/* Copies VALUE_CNT values out of case C to VALUES, starting at
+/* 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 value_cnt)
+               size_t start_idx, union value *values, size_t n_values)
 {
-  assert (c->case_data->ref_cnt > 0);
-  assert (value_cnt <= c->case_data->value_cnt);
-  assert (start_idx + value_cnt <= c->case_data->value_cnt);
-
-  memcpy (values, c->case_data->values + start_idx,
-          value_cnt * sizeof *values);
+  assert (range_is_valid (c, start_idx, n_values));
+  memcpy (values, c->values + start_idx, n_values * sizeof *values);
 }
 
-/* Copies VALUE_CNT values from VALUES into case C, staring at
-   the given START_IDX. */
+/* Copies N_VALUES values from VALUES into case C, starting at
+   the given START_IDX.
+
+   C must not be shared. */
 void
 case_copy_in (struct ccase *c,
-              size_t start_idx, const union value *values, size_t value_cnt)
+              size_t start_idx, const union value *values, size_t n_values)
 {
-  assert (c->case_data->ref_cnt > 0);
-  assert (value_cnt <= c->case_data->value_cnt);
-  assert (start_idx + value_cnt <= c->case_data->value_cnt);
-
-  case_unshare (c);
-  memcpy (c->case_data->values + start_idx, values,
-          value_cnt * sizeof *values);
+  assert (!case_is_shared (c));
+  assert (range_is_valid (c, start_idx, n_values));
+  memcpy (c->values + start_idx, values, n_values * sizeof *values);
 }
 
 /* Returns a pointer to the `union value' used for the
@@ -247,30 +163,21 @@ case_data (const struct ccase *c, const struct variable *v)
   return case_data_idx (c, var_get_case_index (v));
 }
 
-/* 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)
+/* 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)
 {
-  return case_num_idx (c, var_get_case_index (v));
+  assert (idx < c->n_values);
+  return &c->values[idx];
 }
 
-/* Returns the string value of the `union value' in C for
-   variable V.
-   Case C must be drawn from V's dictionary.
-   (Note that the value is not null-terminated.)
-   The caller must not modify the return value. */
-const char *
-case_str (const struct ccase *c, const struct variable *v)
-{
-  return case_str_idx (c, var_get_case_index (v));
-}
+/* 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.
 
-/* 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)
 {
@@ -279,14 +186,24 @@ case_data_rw (struct ccase *c, const struct variable *v)
 
 /* 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)
+   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->case_data->ref_cnt > 0);
-  assert (idx < c->case_data->value_cnt);
+  assert (!case_is_shared (c));
+  assert (idx < c->n_values);
+  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)
+{
+  return case_num_idx (c, var_get_case_index (v));
 }
 
 /* Returns the numeric value of the `union value' in C numbered
@@ -294,57 +211,53 @@ case_data_idx (const struct ccase *c, size_t idx)
 double
 case_num_idx (const struct ccase *c, size_t idx)
 {
-  assert (c->case_data->ref_cnt > 0);
-  assert (idx < c->case_data->value_cnt);
-
-  return c->case_data->values[idx].f;
+  assert (idx < c->n_values);
+  return c->values[idx].f;
 }
 
-/* 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. */
+/* 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.
+
+   Like all "union value"s, the return value is not
+   null-terminated. */
 const char *
-case_str_idx (const struct ccase *c, size_t idx)
+case_str (const struct ccase *c, const struct variable *v)
 {
-  assert (c->case_data->ref_cnt > 0);
-  assert (idx < c->case_data->value_cnt);
-
-  return c->case_data->values[idx].s;
+  return case_str_idx (c, var_get_case_index (v));
 }
 
-/* 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_idx (struct ccase *c, size_t idx)
-{
-  assert (c->case_data->ref_cnt > 0);
-  assert (idx < c->case_data->value_cnt);
+/* Returns the string value of the `union value' in C numbered
+   IDX.  The caller must not modify the return value.
 
-  case_unshare (c);
-  return &c->case_data->values[idx];
+   Like all "union value"s, the return value is not
+   null-terminated. */
+const char *
+case_str_idx (const struct ccase *c, size_t idx)
+{
+  assert (idx < c->n_values);
+  return c->values[idx].s;
 }
 
-/* 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,
-              const 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,
                     const struct variable *const *vap,
-		const struct variable *const *vbp,
-                    size_t var_cnt)
+                    const struct variable *const *vbp,
+                    size_t n_vars)
 {
-  for (; var_cnt-- > 0; vap++, vbp++)
+  for (; n_vars-- > 0; vap++, vbp++)
     {
       const struct variable *va = *vap;
       const struct variable *vb = *vbp;
@@ -375,26 +288,34 @@ case_compare_2dict (const struct ccase *ca, const struct ccase *cb,
 /* 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)
 {
-  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)
 {
-  assert (c->case_data->ref_cnt > 0);
+  assert (!case_is_shared (c));
+  return c->values;
+}
 
-  case_unshare (c);
-  return c->case_data->values;
+/* Internal helper function for case_unshare. */
+struct ccase *
+case_unshare__ (struct ccase *old)
+{
+  struct ccase *new = case_create (old->n_values);
+  memcpy (new->values, old->values, old->n_values * sizeof old->values[0]);
+  --old->ref_cnt;
+  return new;
 }