[lldb] Streamline ConstString -> std::string conversion (NFC)

[JDevlieghere]

Make it easier to go from a ConstString to a std::string without having to go through a C-String or a llvm::StringRef. I made the conversion operator explicit as this is a relatively expensive operations (compared to a StringRef or string_view).

[llvmbot]

@llvm/pr-subscribers-lldb

Author: Jonas Devlieghere (JDevlieghere)

Changes

Make it easier to go from a ConstString to a std::string without having to go through a C-String or a llvm::StringRef. I made the conversion operator explicit as this is a relatively expensive operations (compared to a StringRef or string_view).

---

Full diff: https://github.com/llvm/llvm-project/pull/79649.diff

2 Files Affected:

• (modified) lldb/include/lldb/Utility/ConstString.h (+13-2)
• (modified) lldb/unittests/Utility/ConstStringTest.cpp (+14)

diff --git a/lldb/include/lldb/Utility/ConstString.h b/lldb/include/lldb/Utility/ConstString.h
index cbea4cbf916a430..0ee3f0184b0d08c 100644
--- a/lldb/include/lldb/Utility/ConstString.h
+++ b/lldb/include/lldb/Utility/ConstString.h
@@ -167,8 +167,14 @@ class ConstString {
 
   // Implicitly convert \class ConstString instances to \class StringRef.
   operator llvm::StringRef() const { return GetStringRef(); }
-  // Implicitly convert \class ConstString instances to \calss std::string_view.
-  operator std::string_view() const { return std::string_view(m_string, GetLength()); }
+
+  // Implicitly convert \class ConstString instances to \class std::string_view.
+  operator std::string_view() const {
+    return std::string_view(m_string, GetLength());
+  }
+
+  // Explicitly convert \class ConstString instances to \class std::string.
+  explicit operator std::string() const { return GetString(); }
 
   /// Get the string value as a C string.
   ///
@@ -192,6 +198,11 @@ class ConstString {
     return llvm::StringRef(m_string, GetLength());
   }
 
+  /// Get the string value as a std::string
+  std::string GetString() const {
+    return std::string(m_string, GetLength());
+  }
+
   /// Get the string value as a C string.
   ///
   /// Get the value of the contained string as a NULL terminated C string
diff --git a/lldb/unittests/Utility/ConstStringTest.cpp b/lldb/unittests/Utility/ConstStringTest.cpp
index 9affa927570a5c7..716f2d8d6c80428 100644
--- a/lldb/unittests/Utility/ConstStringTest.cpp
+++ b/lldb/unittests/Utility/ConstStringTest.cpp
@@ -137,3 +137,17 @@ TEST(ConstStringTest, CompareStringRef) {
   EXPECT_TRUE(null == static_cast<const char *>(nullptr));
   EXPECT_TRUE(null != "bar");
 }
+
+TEST(ConstStringTest, StringConversions) {
+  ConstString foo("foo");
+
+  // Member functions.
+  EXPECT_EQ(llvm::StringRef("foo"), foo.GetStringRef());
+  EXPECT_EQ(std::string("foo"), foo.GetString());
+  EXPECT_STREQ("foo", foo.AsCString());
+
+  // Conversion operators.
+  EXPECT_EQ(llvm::StringRef("foo"), llvm::StringRef(foo));
+  EXPECT_EQ(std::string("foo"), std::string_view(foo));
+  EXPECT_EQ(std::string("foo"), std::string(foo));
+}

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[felipepiovezan]

why is this necessary, if we have the explicit operator?

[JDevlieghere]

It's not necessary, it's more for consistency with how we already do things (similar to how StringRef has the explicit operator and the .str() method on the llvm side).