change tupleitem key to be column matched with null items.

[rrq/rrqmisc.git] / vector / tupleitem.c

diff --git a/vector/tupleitem.c b/vector/tupleitem.c
index ce5c71386476be7ed1449ef96a6c9f9b27240e2c..2a4a01a7dc6cc96efde2a08a2af3d92bdaf45ee0 100644 (file)
--- a/vector/tupleitem.c
+++ b/vector/tupleitem.c
@@ -5,16 +5,36 @@
 
 #define COLUMN def->columns
 
-unsigned long tupleitem_hashcode(itemkeyfun *this,void *key) {
+/**
+ * This callback function returns the hashcode of a key.
+ *
+ * \param this is a pointer to the itemkeyfun record from where this
+ * callback got invoked
+ *
+ * \param key is the key to produce a hascode for
+ *
+ * \returns the hashcode which is a vector_index (i.e. unsigned long)
+ *
+ * The hashcode is used for indexing into the backing vector for
+ * finding the an item via its key. The same key must map consistently
+ * to the same hashcode while the hashtable contains an item with that
+ * key. Different keys map map to the same hashcode, in which case the
+ * vector placement is made at the first empty or hole slot following
+ * the hashcode index.
+ */
+static unsigned long tupleitem_hashcode(void *this,void *key) {
     tupleschema *def = (tupleschema *) this;
     tuple *kp = (tuple*) key;
     int i = 0;
-    unsigned long value = 0;
+    unsigned long value = 5381;
     for ( ; i < def->arity; i++ ) {
        if ( COLUMN[i] ) {
            value <<= 3;
-           value += COLUMN[i]->hashcode( COLUMN[i], (*kp)[i] );
+           if ( (*kp)[i] ) {
+               value += COLUMN[i]->hashcode( COLUMN[i], (*kp)[i] );
+           }
        }
+       value += 17;
     }
     return value;
 }
@@ -23,18 +43,19 @@ unsigned long tupleitem_hashcode(itemkeyfun *this,void *key) {
  * This callback function determines whether an item has a
  * given key or not.
  */
-int tupleitem_haskey(itemkeyfun *this,void *item,void *key) {
+static int tupleitem_haskey(void *this,void *item,void *key) {
     tupleschema *def = (tupleschema *) this;
     tuple *kp = (tuple*) key;
     tuple *tp = (tuple*) item;
     int i = 0;
-    int haskey = 1;
     for ( ; i < def->arity; i++ ) {
-       if ( COLUMN[i] ) {
-           haskey &= COLUMN[i]->haskey( COLUMN[i], (*tp)[i], (*kp)[i] );
+       if ( COLUMN[i] && (*kp)[i] ) {
+           if ( COLUMN[i]->haskey( COLUMN[i], (*tp)[i], (*kp)[i] ) == 0 ) {
+               return 0;
+           }
        }
     }
-    return haskey;
+    return 1;
 }
 
 
@@ -42,20 +63,15 @@ int tupleitem_haskey(itemkeyfun *this,void *item,void *key) {
  * This callback function returns the key of an item by considering
  * the arity and mask.
  */
-void *tupleitem_itemkey(itemkeyfun *this,void *item) {
+static void *tupleitem_itemkey(void *this,void *item) {
     tupleschema *def = (tupleschema *) this;
     tuple *tp = (tuple*) item;
-    int i, j;
-    int keylen = 0;
-    for ( i = 0 ; i < def->arity; i++ ) {
-       if ( COLUMN[i] ) {
-           keylen++;
-       }
-    }
+    int i;
+    int keylen = def->arity;
     void **parts = calloc( keylen, sizeof( void* ) );
-    for ( i = 0, j = 0; i < def->arity; i++ ) {
+    for ( i = 0; i < def->arity; i++ ) {
        if ( COLUMN[i] ) {
-           parts[j++] = COLUMN[i]->itemkey( COLUMN[i], (*tp)[i] );
+           parts[i] = COLUMN[i]->itemkey( COLUMN[i], (*tp)[i] );
        }
     }
     return (void*) parts;
@@ -65,38 +81,65 @@ void *tupleitem_itemkey(itemkeyfun *this,void *item) {
  * This callback function handles a key obtained from the itemkey
  * callback function to reclaim temporary allocation.
  */
-void tupleitem_releasekey(itemkeyfun *this,void *key) {
+static void tupleitem_releasekey(void *this,void *key) {
     tupleschema *def = (tupleschema *) this;
     tuple *kp = (tuple*) key;
-    int i,j;
-    for ( i = 0, j = 0; i < def->arity; i++ ) {
+    int i;
+    for ( i = 0; i < def->arity; i++ ) {
        if ( COLUMN[i] ) {
-           COLUMN[i]->releasekey( COLUMN[i], (*kp)[j++] );
+           COLUMN[i]->releasekey( COLUMN[i], (*kp)[i] );
        }
     }
     free( key );
 }
 
+#define OUT(X) a = X; if ( a > limit ) return 0; buffer += a; limit -= a
+
+/**
+ * This callback function writes a representation of an item into
+ * a character buffer.
+ */
+static int tupleitem_tostring(void *this,void *item,char *buffer,int limit) {
+    tupleschema *def = (tupleschema *) this;
+    tuple *t = (tuple*) item;
+    char *x = "<";
+    int a, i;
+    for ( i = 0; i < def->arity; i++ ) {
+       OUT( snprintf( buffer, limit, x ) );
+       x = ",";
+       OUT( def->columns[i]->tostring(
+                def->columns[i], (*t)[i], buffer, limit ) );
+    }
+    OUT( snprintf( buffer, limit, ">" ) );
+    return a;
+}
+
+
 // Allocate
 tuple *tuple_create(int arity,...) {
     va_list ap;
     int i;
     tuple *t = (tuple *)malloc( arity * sizeof( void* ) );
+    va_start( ap, arity );
     for ( i = 0; i < arity; i++ ) {
        (*t)[i] = va_arg( ap, void* );
     }
+    va_end( ap );
     return t;
 }
 
+itemkeyfun tupleschema_callbacks = {
+    .hashcode = tupleitem_hashcode,
+    .haskey = tupleitem_haskey,
+    .itemkey = tupleitem_itemkey,
+    .releasekey = tupleitem_releasekey,
+    .tostring = tupleitem_tostring
+};
+
 tupleschema *tupleschema_create(int arity,tuple *columns) {
     tupleschema *ts = (tupleschema*) malloc( sizeof( tupleschema ) );
     (*ts) = (tupleschema) {
-       .functions = {
-           .hashcode = tupleitem_hashcode,
-           .haskey = tupleitem_haskey,
-           .itemkey = tupleitem_itemkey,
-           .releasekey = tupleitem_releasekey
-       },
+       .base = tupleschema_callbacks,
        .arity = arity,
        .columns = (itemkeyfun**) columns
     };
@@ -112,6 +155,7 @@ tupleschema *tupleschema_mask(tupleschema *schema,...) {
     masked->columns = COPYA( itemkeyfun*, schema->columns, schema->arity );
     va_list ap;
     int i;
+    va_start( ap, schema );
     for ( ;; ) {
        i = va_arg( ap, int );
        if ( i < 0 || i >= schema->arity ) {
@@ -119,5 +163,17 @@ tupleschema *tupleschema_mask(tupleschema *schema,...) {
        }
        masked->columns[i] = 0;
     };
+    va_end( ap );
     return masked;
 }
+
+unsigned long tuple_mask(int arity,tuple *t) {
+    unsigned long mask = 0;
+    while ( arity-- > 0 ) {
+       mask <<= 1;
+       if ( (*t)[ arity ] ) {
+           mask++;
+       }
+    }
+    return mask;
+}