var->index versus var in linreg code

[Ben Pfaff]

Hi Jason.  While looking over code, I noticed a number of
comparisons in linreg.c, coefficient.c, and design-matrix.c of
the form "var1->index == var2->index".  I think that in each case
this could be replaced by "var1 == var2".

With your permission, I'd like to check in the following change
that takes advantage of this.  It still passes "make check", so
unless you're aware of some kind of subtlety, I think it is
correct:

Index: src/math/coefficient.c
===================================================================
RCS file: /cvsroot/pspp/pspp/src/math/coefficient.c,v
retrieving revision 1.5
diff -u -p -r1.5 coefficient.c
--- src/math/coefficient.c      5 Dec 2006 15:10:21 -0000       1.5
+++ src/math/coefficient.c      6 Dec 2006 03:59:26 -0000
@@ -169,7 +169,7 @@ pspp_coeff_get_value (struct pspp_coeff 
   while (i < c->n_vars)
     {
       candidate = pspp_coeff_get_var (c, i);
-      if (v->index == candidate->index)
+      if (v == candidate)
        {
          return (c->v_info + i)->val;
        }
@@ -201,7 +201,7 @@ pspp_linreg_get_coeff (const pspp_linreg
 
   result = c->coeff[i];
   tmp = pspp_coeff_get_var (result, 0);
-  while (tmp->index != v->index && i < c->n_coeffs)
+  while (tmp != v && i < c->n_coeffs)
     {
       result = c->coeff[i];
       tmp = pspp_coeff_get_var (result, 0);
@@ -221,7 +221,7 @@ pspp_linreg_get_coeff (const pspp_linreg
          If v is categorical, we need to ensure the coefficient
          matches the VAL.
        */
-      while (tmp->index != v->index && i < c->n_coeffs
+      while (tmp != v && i < c->n_coeffs
             && compare_values (pspp_coeff_get_value (result, tmp),
                                val, var_get_width (v)))
        {                       /* FIX THIS */
Index: src/math/design-matrix.c
===================================================================
RCS file: /cvsroot/pspp/pspp/src/math/design-matrix.c,v
retrieving revision 1.4
diff -u -p -r1.4 design-matrix.c
--- src/math/design-matrix.c    5 Dec 2006 15:10:21 -0000       1.4
+++ src/math/design-matrix.c    6 Dec 2006 03:59:26 -0000
@@ -146,8 +146,8 @@ design_matrix_destroy (struct design_mat
   Return the index of the variable for the
   given column.
  */
-static size_t
-design_matrix_col_to_var_index (const struct design_matrix *dm, size_t col)
+struct variable *
+design_matrix_col_to_var (const struct design_matrix *dm, size_t col)
 {
   size_t i;
   struct design_matrix_var v;
@@ -156,42 +156,11 @@ design_matrix_col_to_var_index (const st
     {
       v = dm->vars[i];
       if (v.first_column <= col && col <= v.last_column)
-       return (v.v)->index;
-    }
-  return DM_INDEX_NOT_FOUND;
-}
-
-/*
-  Return a pointer to the variable whose values
-  are stored in column col.
- */
-struct variable *
-design_matrix_col_to_var (const struct design_matrix *dm, size_t col)
-{
-  size_t index;
-  size_t i;
-  struct design_matrix_var dmv;
-
-  index = design_matrix_col_to_var_index (dm, col);
-  for (i = 0; i < dm->n_vars; i++)
-    {
-      dmv = dm->vars[i];
-      if ((dmv.v)->index == index)
-       {
-         return (struct variable *) dmv.v;
-       }
+       return (struct variable *) v.v;
     }
   return NULL;
 }
 
-static size_t
-cmp_dm_var_index (const struct design_matrix_var *dmv, size_t index)
-{
-  if (dmv->v->index == index)
-    return 1;
-  return 0;
-}
-
 /*
   Return the number of the first column which holds the
   values for variable v.
@@ -206,7 +175,7 @@ design_matrix_var_to_column (const struc
   for (i = 0; i < dm->n_vars; i++)
     {
       tmp = dm->vars[i];
-      if (cmp_dm_var_index (&tmp, v->index))
+      if (tmp.v == v)
        {
          return tmp.first_column;
        }
@@ -225,7 +194,7 @@ dm_var_to_last_column (const struct desi
   for (i = 0; i < dm->n_vars; i++)
     {
       tmp = dm->vars[i];
-      if (cmp_dm_var_index (&tmp, v->index))
+      if (tmp.v == v)
        {
          return tmp.last_column;
        }
Index: src/math/linreg/linreg.c
===================================================================
RCS file: /cvsroot/pspp/pspp/src/math/linreg/linreg.c,v
retrieving revision 1.15
diff -u -p -r1.15 linreg.c
--- src/math/linreg/linreg.c    19 May 2006 21:08:20 -0000      1.15
+++ src/math/linreg/linreg.c    6 Dec 2006 03:59:27 -0000
@@ -123,7 +123,7 @@ pspp_linreg_get_vars (const void *c_, st
       /* Repeated variables are likely to bunch together, at the end
          of the array. */
       i = result - 1;
-      while (i >= 0 && (v[i]->index != tmp->index))
+      while (i >= 0 && v[i] != tmp)
        {
          i--;
        }


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