Reworked settings so as to use one large struct instead of lots of static

[pspp-builds.git] / src / data / casereader.c

diff --git a/src/data/casereader.c b/src/data/casereader.c
index 3be1042d8224f2e4b97d6beb66e4dcc71adb56ee..ee7facb769dbf9a26dc96d717f1249a7fe44879b 100644 (file)
--- a/src/data/casereader.c
+++ b/src/data/casereader.c
@@ -56,19 +56,30 @@ static void insert_shim (struct casereader *);
 bool
 casereader_read (struct casereader *reader, struct ccase *c)
 {
-  if (reader->case_cnt != 0 && reader->class->read (reader, reader->aux, c))
+  if (reader->case_cnt != 0)
     {
-      assert (case_get_value_cnt (c) >= reader->value_cnt);
+      /* ->read may use casereader_swap to replace itself by
+         another reader and then delegate to that reader by
+         recursively calling casereader_read.  Currently only
+         lazy_casereader does this and, with luck, nothing else
+         ever will.
+
+         To allow this to work, however, we must decrement
+         case_cnt before calling ->read.  If we decremented
+         case_cnt after calling ->read, then this would actually
+         drop two cases from case_cnt instead of one, and we'd
+         lose the last case in the casereader. */
       if (reader->case_cnt != CASENUMBER_MAX)
         reader->case_cnt--;
-      return true;
-    }
-  else
-    {
-      reader->case_cnt = 0;
-      case_nullify (c);
-      return false;
+      if (reader->class->read (reader, reader->aux, c))
+        {
+          assert (case_get_value_cnt (c) >= reader->value_cnt);
+          return true;
+        }
     }
+  reader->case_cnt = 0;
+  case_nullify (c);
+  return false;
 }
 
 /* Destroys READER.
@@ -172,6 +183,24 @@ casereader_peek (struct casereader *reader, casenumber idx, struct ccase *c)
   return false;
 }
 
+/* Returns true if no cases remain to be read from READER, or if
+   an error has occurred on READER.  (A return value of false
+   does *not* mean that the next call to casereader_peek or
+   casereader_read will return true, because an error can occur
+   in the meantime.) */
+bool
+casereader_is_empty (struct casereader *reader)
+{
+  struct ccase c;
+  if (reader->case_cnt == 0 || !casereader_peek (reader, 0, &c))
+    return true;
+  else
+    {
+      case_destroy (&c);
+      return false;
+    }
+}
+
 /* Returns true if an I/O error or another hard error has
    occurred on READER, a clone of READER, or on some object on
    which READER's data has a dependency, false otherwise. */
@@ -311,6 +340,26 @@ casereader_create_sequential (const struct taint *taint,
   reader->aux = aux;
   return reader;
 }
+
+/* If READER is a casereader of the given CLASS, returns its
+   associated auxiliary data; otherwise, returns a null pointer.
+
+   This function is intended for use from casereader
+   implementations, not by casereader users.  Even within
+   casereader implementations, its usefulness is quite limited,
+   for at least two reasons.  First, every casereader member
+   function already receives a pointer to the casereader's
+   auxiliary data.  Second, a casereader's class can change
+   (through a call to casereader_swap) and this is in practice
+   quite common (e.g. any call to casereader_clone on a
+   casereader that does not directly support clone will cause the
+   casereader to be replaced by a shim caseader). */
+void *
+casereader_dynamic_cast (struct casereader *reader,
+                         const struct casereader_class *class)
+{
+  return reader->class == class ? reader->aux : NULL;
+}
 \f
 /* Random-access casereader implementation.
 
@@ -344,7 +393,7 @@ struct random_reader_shared
     void *aux;
   };
 
-static struct casereader_class random_reader_casereader_class;
+static const struct casereader_class random_reader_casereader_class;
 
 /* Creates and returns a new random_reader with the given SHARED
    data and OFFSET.  Inserts the new random reader into the
@@ -492,7 +541,7 @@ random_reader_peek (struct casereader *reader, void *br_,
 }
 
 /* Casereader class for random reader. */
-static struct casereader_class random_reader_casereader_class =
+static const struct casereader_class random_reader_casereader_class =
   {
     random_reader_read,
     random_reader_destroy,
@@ -531,7 +580,7 @@ struct shim
     struct casereader *subreader;       /* Subordinate casereader. */
   };
 
-static struct casereader_random_class shim_class;
+static const struct casereader_random_class shim_class;
 
 /* Interposes a buffering shim atop READER. */
 static void
@@ -540,7 +589,7 @@ insert_shim (struct casereader *reader)
   size_t value_cnt = casereader_get_value_cnt (reader);
   casenumber case_cnt = casereader_get_case_cnt (reader);
   struct shim *b = xmalloc (sizeof *b);
-  b->window = casewindow_create (value_cnt, get_workspace_cases (value_cnt));
+  b->window = casewindow_create (value_cnt, settings_get_workspace_cases (value_cnt));
   b->subreader = casereader_create_random (value_cnt, case_cnt,
                                            &shim_class, b);
   casereader_swap (reader, b->subreader);
@@ -597,7 +646,7 @@ shim_advance (struct casereader *reader UNUSED, void *b_, casenumber case_cnt)
 }
 
 /* Class for the buffered reader. */
-static struct casereader_random_class shim_class =
+static const struct casereader_random_class shim_class =
   {
     shim_read,
     shim_destroy,