add strspn functions

Signed-off-by: Mattias Andrée <maandree@operamail.com>

1 files changed, 96 insertions, 0 deletions

diff --git a/src/string/strspn.c b/src/string/strspn.c
new file mode 100644
index 0000000..cf82529
--- /dev/null
+++ b/src/string/strspn.c
@@ -0,0 +1,96 @@
+/**
+ * slibc — Yet another C library
+ * Copyright © 2015  Mattias Andrée (maandree@member.fsf.org)
+ * 
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ * 
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ * 
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+#include <string.h>
+#include <stddef.h>
+
+
+
+/**
+ * Returns length of the initial substring
+ * that consists entirely of a set of specified
+ * bytes.
+ * 
+ * @param   string   The string.
+ * @param   skipset  Bytes allowed in the substring.
+ * @return           The length of the substring.
+ */
+size_t strspn(const char* string, const char* skipset)
+{
+  char set[256];
+  char c;
+  const char* s = string;
+  memset(set, 0, 256);
+  while ((c = *skipset++))
+    set[(size_t)c] = 1;
+  while ((c = *s++))
+    if (set[(size_t)c])
+      break;
+  return (size_t)(s - 1 - string);
+}
+
+
+/**
+ * Returns length of the initial substring
+ * that consists entirely of the complement
+ * of a set of specified bytes.
+ * 
+ * @param   string   The string.
+ * @param   stopset  Bytes disallowed in the substring.
+ * @return           The length of the substring.
+ */
+size_t strcspn(const char* string, const char* stopset)
+{
+  char set[256];
+  char c;
+  const char* s = string;
+  memset(set, 0, 256);
+  while ((c = *skipset++))
+    set[(size_t)c] = 1;
+  while ((c = *s++))
+    if (!set[(size_t)c])
+      break;
+  return (size_t)(s - 1 - string);
+}
+
+
+/**
+ * This function works like `strcspn`,
+ * except it returns the pointer to the
+ * location of the first found non-matching
+ * byte.
+ * 
+ * @param   string   The string.
+ * @param   stopset  Bytes disallowed in the substring.
+ * @return           A pointer to the first occurrence in
+ *                   `string` of a byte found in `stopset`.
+ *                   `NULL` is returned if none is found.
+ */
+char* stpbrk(const char* string, const char* stopset)
+{
+  char set[256];
+  char c;
+  const char* s = string;
+  memset(set, 0, 256);
+  while ((c = *skipset++))
+    set[(size_t)c] = 1;
+  while ((c = *s++))
+    if (!set[(size_t)c])
+      break;
+  return c ? (s - 1) : NULL;
+}
+