libk: add its own makefile

1 files changed, 69 insertions, 0 deletions

diff --git a/libk/string.h b/libk/string.h
new file mode 100644
index 0000000..deb6fde
--- /dev/null
+++ b/libk/string.h
@@ -0,0 +1,69 @@
+#pragma once
+#include "types.h"
+
+constexpr size_t strlen(const char *str) {
+  int len = 0;
+  while (str[len])
+    ++len;
+  return len;
+}
+
+/* reverse:  reverse string s in place */
+constexpr void reverse(char s[]) {
+  int i, j;
+  char c;
+
+  for (i = 0, j = strlen(s) - 1; i < j; i++, j--) {
+    c = s[i];
+    s[i] = s[j];
+    s[j] = c;
+  }
+}
+
+/* itoa:  convert n to characters in s */
+template <int base = 10> constexpr void itoa(int n, char s[]) {
+  int i, sign;
+
+  if ((sign = n) < 0) /* record sign */
+    n = -n;           /* make n positive */
+
+  i = 0;
+  do { /* generate digits in reverse order */
+    s[i++] = "0123456789abcdef"[n % base]; /* get next digit */
+  } while ((n /= base) > 0);               /* delete it */
+
+  if (sign < 0)
+    s[i++] = '-';
+
+  s[i] = '\0';
+
+  reverse(s);
+}
+
+class String {
+public:
+  class Iterator {
+    friend class String;
+
+  public:
+    char next() { return p->buffer[pos++]; }
+    operator bool() const { return (pos < p->m_length); }
+
+  private:
+    Iterator(const String *s) : p(s) {}
+
+    size_t pos = 0;
+    const String *p;
+  };
+
+  friend class Iterator;
+
+  String(const char *d) : buffer{d}, m_length{strlen(d)} {}
+  String(const char *d, size_t l) : buffer{d}, m_length{l} {}
+
+  Iterator begin() const { return Iterator(this); }
+
+private:
+  const char *const buffer;
+  const size_t m_length;
+};