From 62e848c28a7083828fd47cbd8a29fbc875cf3ecb Mon Sep 17 00:00:00 2001
From: Ralph Ronnquist <ralph.ronnquist@gmail.com>
Date: Sat, 9 Jul 2022 19:30:55 +1000
Subject: [PATCH] added tostring callback

---
 vector/integeritem.c | 11 ++++++++++-
 vector/itemkeyfun.h  |  8 ++++++++
 vector/stringitem.c  | 14 +++++++++++++-
 vector/tupleitem.c   | 26 ++++++++++++++++++++++++--
 4 files changed, 55 insertions(+), 4 deletions(-)

diff --git a/vector/integeritem.c b/vector/integeritem.c
index 6e6ac04..ae4db92 100644
--- a/vector/integeritem.c
+++ b/vector/integeritem.c
@@ -36,9 +36,18 @@ static void *integeritem_itemkey(void *this,void *item) {
 static void integeritem_releasekey(void *this,void *key) {
 }
 
+/**
+ * This callback function writes a representation of an item into
+ * a character buffer.
+ */
+static int integeritem_tostring(void *this,void *item,char *buffer,int limit) {
+    return snprintf( buffer, limit, "%lld", (long long) item );
+}
+
 itemkeyfun integeritem = {
     .hashcode = integeritem_hashcode,
     .haskey = integeritem_haskey,
     .itemkey = integeritem_itemkey,
-    .releasekey = integeritem_releasekey
+    .releasekey = integeritem_releasekey,
+    .tostring = integeritem_tostring
 };
diff --git a/vector/itemkeyfun.h b/vector/itemkeyfun.h
index 1089a16..7bbe625 100644
--- a/vector/itemkeyfun.h
+++ b/vector/itemkeyfun.h
@@ -1,6 +1,8 @@
 #ifndef itemkeyfun_H
 #define itemkeyfun_H
 
+#include <stdio.h>
+
 /**
  * \struct itemkeyfun
  *
@@ -48,6 +50,12 @@ typedef struct {
      */
     void (*releasekey)(SELF,void *key);
 
+    /**
+     * This callback function writes a representation of an item into
+     * a character buffer.
+     */
+    int (*tostring)(SELF,void *item,char *buffer,int limit);
+
 #undef SELF
 } itemkeyfun;
 
diff --git a/vector/stringitem.c b/vector/stringitem.c
index db400ce..d53576d 100644
--- a/vector/stringitem.c
+++ b/vector/stringitem.c
@@ -38,9 +38,21 @@ static void *stringitem_itemkey(void *this,void *item) {
 static void stringitem_releasekey(void *this,void *key) {
 }
 
+/**
+ * This callback function writes a representation of an item into
+ * a character buffer.
+ */
+static int stringitem_tostring(void *this,void *item,char *buffer,int limit) {
+    if ( item ) {
+	return snprintf( buffer, limit, "\"%s\"", (char*) item );
+    }
+    return snprintf( buffer, limit, "(null)" );
+}
+
 itemkeyfun stringitem = {
     .hashcode = stringitem_hashcode,
     .haskey = stringitem_haskey,
     .itemkey = stringitem_itemkey,
-    .releasekey = stringitem_releasekey
+    .releasekey = stringitem_releasekey,
+    .tostring = stringitem_tostring
 };
diff --git a/vector/tupleitem.c b/vector/tupleitem.c
index 55328c5..f3dfe2c 100644
--- a/vector/tupleitem.c
+++ b/vector/tupleitem.c
@@ -99,6 +99,28 @@ static void tupleitem_releasekey(void *this,void *key) {
     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;
@@ -116,7 +138,8 @@ itemkeyfun tupleschema_callbacks = {
     .hashcode = tupleitem_hashcode,
     .haskey = tupleitem_haskey,
     .itemkey = tupleitem_itemkey,
-    .releasekey = tupleitem_releasekey
+    .releasekey = tupleitem_releasekey,
+    .tostring = tupleitem_tostring
 };
 
 tupleschema *tupleschema_create(int arity,tuple *columns) {
@@ -160,4 +183,3 @@ unsigned long tuple_mask(int arity,tuple *t) {
     }
     return mask;
 }
-
-- 
2.39.2