Postgres95 1.01 Distribution - Virgin Sources

src/backend/lib/stringinfo.c

@@ -0,0 +1,116 @@
+/*-------------------------------------------------------------------------
+ *
+ * stringinfo.c--
+ *    These are routines that can be used to write informations to a string,
+ *    without having to worry about string lengths, space allocation etc.
+ *    Ideally the interface should look like the file i/o interface,
+ *
+ * Copyright (c) 1994, Regents of the University of California
+ *
+ *
+ * IDENTIFICATION
+ *    $Header: /cvsroot/pgsql/src/backend/lib/stringinfo.c,v 1.1.1.1 1996/07/09 06:21:29 scrappy Exp $
+ *
+ *-------------------------------------------------------------------------
+ */
+#include <string.h>
+#include "postgres.h"
+#include "nodes/pg_list.h"
+#include "lib/stringinfo.h"
+#include "utils/elog.h"
+#include "utils/palloc.h"
+
+/*---------------------------------------------------------------------
+ * makeStringInfo
+ *
+ * Create a StringInfoData & return a pointer to it.
+ *
+ *---------------------------------------------------------------------
+ */
+StringInfo
+makeStringInfo()
+{
+    StringInfo res;
+    long size;
+    
+    res = (StringInfo) palloc(sizeof(StringInfoData));
+    if (res == NULL) {
+	elog(WARN, "makeStringInfo: Out of memory!");
+    }
+    
+    size = 100;
+    res->data = palloc(size);
+    if (res->data == NULL) {
+	elog(WARN,
+	     "makeStringInfo: Out of memory! (%ld bytes requested)", size);
+    }
+    res->maxlen = size;
+    res->len = 0;
+    /*
+     * NOTE: we must initialize `res->data' to the empty string because
+     * we use 'strcat' in 'appendStringInfo', which of course it always
+     * expects a null terminated string.
+     */
+    res->data[0] = '\0';
+    
+    return(res);
+}
+
+/*---------------------------------------------------------------------
+ * appendStringInfo
+ *
+ * append to the current 'StringInfo' a new string.
+ * If there is not enough space in the current 'data', then reallocate
+ * some more...
+ *
+ * NOTE: if we reallocate space, we pfree the old one!
+ *---------------------------------------------------------------------
+ */
+void
+appendStringInfo(StringInfo str, char *buffer)
+{
+    int buflen, newlen;
+    char *s;
+    
+    Assert((str!=NULL));
+    
+    /*
+     * do we have enough space to append the new string?
+     * (don't forget to count the null string terminating char!)
+     * If no, then reallocate some more.
+     */
+    buflen = strlen(buffer);
+    if (buflen + str->len >= str->maxlen-1) {
+	/*
+	 * how much more space to allocate ?
+	 * Let's say double the current space...
+	 * However we must check if this is enough!
+	 */
+	newlen = 2 * str->len;
+	while (buflen + str->len >= newlen-1) {
+	    newlen = 2 * newlen;
+	}
+	/*
+	 * allocate enough space.
+	 */
+	s = palloc(newlen);
+	if (s==NULL) {
+	    elog(WARN,
+		 "appendStringInfo: Out of memory (%d bytes requested)",
+		 newlen);
+	}
+	memmove(s, str->data, str->len+1);
+	pfree(str->data);
+	str->maxlen = newlen;
+	str->data = s;
+    }
+    
+    /*
+     * OK, we have enough space now, append 'buffer' at the
+     * end of the string & update the string length.
+     * NOTE: this is a text string (i.e. printable characters)
+     * so 'strcat' will do the job (no need to use 'bcopy' et all...)
+     */
+    (void) strcat(str->data, buffer);
+    str->len += buflen;
+}