From ef01f187c3f7f33ba9527df2dad960426990122a Mon Sep 17 00:00:00 2001
From: apio <blobs.trading@gmail.com>
Date: Wed, 29 Mar 2023 17:43:10 +0200
Subject: [PATCH] libluna: Add StringView

---
 libluna/CMakeLists.txt            |  1 +
 libluna/include/luna/String.h     |  6 +++++
 libluna/include/luna/StringView.h | 39 ++++++++++++++++++++++++++++
 libluna/src/StringView.cpp        | 42 +++++++++++++++++++++++++++++++
 4 files changed, 88 insertions(+)
 create mode 100644 libluna/include/luna/StringView.h
 create mode 100644 libluna/src/StringView.cpp

diff --git a/libluna/CMakeLists.txt b/libluna/CMakeLists.txt
index eb99bd36..0a5cc9de 100644
--- a/libluna/CMakeLists.txt
+++ b/libluna/CMakeLists.txt
@@ -14,6 +14,7 @@ set(FREESTANDING_SOURCES
     src/Buffer.cpp
     src/Stack.cpp
     src/String.cpp
+    src/StringView.cpp
     src/Utf8.cpp
     src/TarStream.cpp
     src/DebugLog.cpp
diff --git a/libluna/include/luna/String.h b/libluna/include/luna/String.h
index f9202d7c..219e4e2f 100644
--- a/libluna/include/luna/String.h
+++ b/libluna/include/luna/String.h
@@ -1,5 +1,6 @@
 #pragma once
 #include <luna/Result.h>
+#include <luna/StringView.h>
 
 class String
 {
@@ -35,6 +36,11 @@ class String
         return m_length == 0;
     }
 
+    StringView view() const
+    {
+        return { chars(), m_length };
+    }
+
     const char& operator[](usize) const;
 
   private:
diff --git a/libluna/include/luna/StringView.h b/libluna/include/luna/StringView.h
new file mode 100644
index 00000000..68c4885b
--- /dev/null
+++ b/libluna/include/luna/StringView.h
@@ -0,0 +1,39 @@
+#pragma once
+#include <luna/Result.h>
+
+class String;
+
+class StringView
+{
+  public:
+    StringView(const char* c_str);
+    StringView(const char* c_str, usize length);
+
+    StringView();
+
+    StringView(const StringView&);
+
+    Result<String> to_string();
+
+    const char* chars() const
+    {
+        return m_string;
+    }
+
+    usize length() const
+    {
+        return m_length;
+    }
+
+    bool is_empty() const
+    {
+        return m_length == 0;
+    }
+
+    const char& operator[](usize) const;
+
+  private:
+    const char* m_string { nullptr };
+
+    usize m_length { 0 };
+};
diff --git a/libluna/src/StringView.cpp b/libluna/src/StringView.cpp
new file mode 100644
index 00000000..40161b7a
--- /dev/null
+++ b/libluna/src/StringView.cpp
@@ -0,0 +1,42 @@
+#include <luna/CString.h>
+#include <luna/String.h>
+#include <luna/StringView.h>
+
+static const char* empty = "";
+
+StringView::StringView()
+{
+    m_string = empty;
+    m_length = 0;
+}
+
+StringView::StringView(const StringView& other)
+{
+    m_string = other.m_string;
+    m_length = other.m_length;
+}
+
+StringView::StringView(const char* c_str)
+{
+    check(c_str);
+    m_string = c_str;
+    m_length = strlen(m_string);
+}
+
+StringView::StringView(const char* c_str, usize length)
+{
+    check(c_str);
+    m_string = c_str;
+    m_length = length;
+}
+
+const char& StringView::operator[](usize index) const
+{
+    expect(index < m_length, "index out of range");
+    return m_string[index];
+}
+
+Result<String> StringView::to_string()
+{
+    return String::from_cstring(m_string);
+}