[Glacier] Add a StringView class and StrSplit method.

lib/glacier/string/string_view.h

@@ -0,0 +1,35 @@
+#pragma once
+
+#include <stdint.h>
+
+namespace glcr {
+
+class StringView {
+ public:
+  static const uint64_t npos = -1;
+
+  StringView();
+  StringView(const StringView& other) = default;
+  StringView(const char* str);
+  StringView(const char* str, uint64_t count);
+
+  const char* data() const;
+  uint64_t size() const;
+
+  bool empty() const;
+
+  char at(uint64_t pos) const;
+
+  uint64_t find(char c, uint64_t pos = 0) const;
+
+  StringView substr(uint64_t start, uint64_t count) const;
+
+ private:
+  const char* value_ = nullptr;
+  uint64_t size_ = 0;
+};
+
+bool operator==(const StringView& str1, const StringView& str2);
+bool operator!=(const StringView& str1, const StringView& str2);
+
+}  // namespace glcr