From 84fa20543ae0464a87fde599d1db66bfdbd29198 Mon Sep 17 00:00:00 2001
From: Ralph Ronnquist <ralph.ronnquist@gmail.com>
Date: Tue, 5 Jul 2022 21:53:20 +1000
Subject: [PATCH] updates towards supporting relation.

---
 vector/tupleitem.c | 68 ++++++++++++++++++++++++++++++++++++++--------
 vector/tupleitem.h | 32 +++++++++++++++++++---
 2 files changed, 84 insertions(+), 16 deletions(-)

diff --git a/vector/tupleitem.c b/vector/tupleitem.c
index eff77ce..ce5c713 100644
--- a/vector/tupleitem.c
+++ b/vector/tupleitem.c
@@ -1,9 +1,9 @@
+#include <stdarg.h>
 #include <stdlib.h>
+#include <string.h>
 #include <tupleitem.h>
 
-typedef void *tuple[];
-
-#define COLUMN def->schema[i]
+#define COLUMN def->columns
 
 unsigned long tupleitem_hashcode(itemkeyfun *this,void *key) {
     tupleschema *def = (tupleschema *) this;
@@ -11,9 +11,9 @@ unsigned long tupleitem_hashcode(itemkeyfun *this,void *key) {
     int i = 0;
     unsigned long value = 0;
     for ( ; i < def->arity; i++ ) {
-	if ( COLUMN ) {
+	if ( COLUMN[i] ) {
 	    value <<= 3;
-	    value += COLUMN->hashcode( COLUMN, (*kp)[i] );
+	    value += COLUMN[i]->hashcode( COLUMN[i], (*kp)[i] );
 	}
     }
     return value;
@@ -30,8 +30,8 @@ int tupleitem_haskey(itemkeyfun *this,void *item,void *key) {
     int i = 0;
     int haskey = 1;
     for ( ; i < def->arity; i++ ) {
-	if ( COLUMN ) {
-	    haskey &= COLUMN->haskey( COLUMN, (*tp)[i], (*kp)[i] );
+	if ( COLUMN[i] ) {
+	    haskey &= COLUMN[i]->haskey( COLUMN[i], (*tp)[i], (*kp)[i] );
 	}
     }
     return haskey;
@@ -48,14 +48,14 @@ void *tupleitem_itemkey(itemkeyfun *this,void *item) {
     int i, j;
     int keylen = 0;
     for ( i = 0 ; i < def->arity; i++ ) {
-	if ( COLUMN ) {
+	if ( COLUMN[i] ) {
 	    keylen++;
 	}
     }
     void **parts = calloc( keylen, sizeof( void* ) );
     for ( i = 0, j = 0; i < def->arity; i++ ) {
-	if ( COLUMN ) {
-	    parts[j++] = COLUMN->itemkey( COLUMN, (*tp)[i] );
+	if ( COLUMN[i] ) {
+	    parts[j++] = COLUMN[i]->itemkey( COLUMN[i], (*tp)[i] );
 	}
     }
     return (void*) parts;
@@ -70,10 +70,54 @@ void tupleitem_releasekey(itemkeyfun *this,void *key) {
     tuple *kp = (tuple*) key;
     int i,j;
     for ( i = 0, j = 0; i < def->arity; i++ ) {
-	if ( COLUMN ) {
-	    COLUMN->releasekey( COLUMN, (*kp)[j++] );
+	if ( COLUMN[i] ) {
+	    COLUMN[i]->releasekey( COLUMN[i], (*kp)[j++] );
 	}
     }
     free( key );
 }
 
+// Allocate
+tuple *tuple_create(int arity,...) {
+    va_list ap;
+    int i;
+    tuple *t = (tuple *)malloc( arity * sizeof( void* ) );
+    for ( i = 0; i < arity; i++ ) {
+	(*t)[i] = va_arg( ap, void* );
+    }
+    return t;
+}
+
+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
+	},
+	.arity = arity,
+	.columns = (itemkeyfun**) columns
+    };
+    return ts;
+}
+
+#define COPYA(T,P,N) (T*) memcpy( malloc( N * sizeof(T) ), P, N * sizeof( T ) )
+#define COPY(T,P) COPYA(T,P,1)
+
+// Duplicate a tupleschema with optionally some columns reset.
+tupleschema *tupleschema_mask(tupleschema *schema,...) {
+    tupleschema *masked = COPY(tupleschema,schema);
+    masked->columns = COPYA( itemkeyfun*, schema->columns, schema->arity );
+    va_list ap;
+    int i;
+    for ( ;; ) {
+	i = va_arg( ap, int );
+	if ( i < 0 || i >= schema->arity ) {
+	    break;
+	}
+	masked->columns[i] = 0;
+    };
+    return masked;
+}
diff --git a/vector/tupleitem.h b/vector/tupleitem.h
index baec9e3..37d5e24 100644
--- a/vector/tupleitem.h
+++ b/vector/tupleitem.h
@@ -3,6 +3,11 @@
 
 #include <itemkeyfun.h>
 
+/**
+ * A tuple is an array of void*
+ */
+typedef void *tuple[];
+
 /**
  * A tupleschema record declares the itemkeyfun functions for tuple
  * items together with applicable arity and domain combinations. The
@@ -18,15 +23,17 @@ typedef struct {
      * provide the handling of the tuple columns.
      */
     itemkeyfun functions;
+
     /**
      * This is the number of columns in a tuple.
      */
     int arity;
+
     /**
-     * This is an array of pointers to the tuple item domains as
-     * represented by their associated itemkeyfun records.
+     * This points to an array of pointers to the tuple item domains
+     * as represented by their associated itemkeyfun records.
      */
-    itemkeyfun **schema;
+    itemkeyfun **columns;
 } tupleschema;
 
 /**
@@ -66,13 +73,30 @@ extern void *tupleitem_itemkey(itemkeyfun *this,void *item);
  */
 extern void tupleitem_releasekey(itemkeyfun *this,void *key);
 
+/**
+ * Create a tuples with given values.
+ */
+extern tuple *tuple_create(int arity,...);
+
+/**
+ * Create a tuples with given values.
+ */
+extern tupleschema *tupleschema_create(int arity,tuple *columns);
+
+/**
+ * Copy the given tupleschema into a new tupleschema with some columns
+ * masked. This represents a sub-index type using the unmasked columns
+ * for indexing.
+ */
+extern tupleschema *tupleschema_mask(tupleschema *schema,...);
+
 /**
  * The TUPLEITEMINIT macro is used for initializing a tupleschema
  * record appropriately for a given arity and corresponding sequence
  * of parts itemkeyfun pointers.
  */
 #define TUPLEITEMINIT(arity, ... ) {	\
-	functions = {				\
+	.functions = {				\
 	    .hashcode = tupleitem_hashcode,	\
 	    .haskey = tupleitem_haskey,		\
 	    .itemkey = tupleitem_itemkey,	\
-- 
2.39.2