1 files changed, 214 insertions, 0 deletions
diff --git a/Source/cmValue.h b/Source/cmValue.h
new file mode 100644
index 0000000..43a5e0d
--- /dev/null
+++ b/Source/cmValue.h
@@ -0,0 +1,214 @@
+/* Distributed under the OSI-approved BSD 3-Clause License.  See accompanying
+   file Copyright.txt or https://cmake.org/licensing for details.  */
+#pragma once
+
+#include "cmConfigure.h" // IWYU pragma: keep
+
+#include <cstddef>
+#include <iosfwd>
+#include <string>
+
+#include <cm/string_view>
+
+class cmValue
+{
+public:
+  cmValue() noexcept = default;
+  cmValue(std::nullptr_t) noexcept {}
+  explicit cmValue(const std::string* value) noexcept
+    : Value(value)
+  {
+  }
+  explicit cmValue(const std::string& value) noexcept
+    : Value(&value)
+  {
+  }
+  cmValue(const cmValue& other) noexcept = default;
+
+  cmValue& operator=(const cmValue& other) noexcept = default;
+  cmValue& operator=(std::nullptr_t) noexcept
+  {
+    this->Value = nullptr;
+    return *this;
+  }
+
+  const std::string* Get() const noexcept { return this->Value; }
+  const char* GetCStr() const noexcept
+  {
+    return this->Value == nullptr ? nullptr : this->Value->c_str();
+  }
+
+  const std::string* operator->() const noexcept
+  {
+    return this->Value == nullptr ? &cmValue::Empty : this->Value;
+  }
+  const std::string& operator*() const noexcept
+  {
+    return this->Value == nullptr ? cmValue::Empty : *this->Value;
+  }
+
+  explicit operator bool() const noexcept { return this->Value != nullptr; }
+  operator const std::string&() const noexcept { return this->operator*(); }
+  explicit operator cm::string_view() const noexcept
+  {
+    return this->operator*();
+  }
+
+  /**
+   * Does the value indicate a true or ON value?
+   */
+  bool IsOn() const noexcept
+  {
+    return this->Value != nullptr &&
+      cmValue::IsOn(cm::string_view(*this->Value));
+  }
+  /**
+   * Does the value indicate a false or off value ? Note that this is
+   * not the same as !IsOn(...) because there are a number of
+   * ambiguous values such as "/usr/local/bin" a path will result in
+   * IsOn and IsOff both returning false. Note that the special path
+   * NOTFOUND, *-NOTFOUND or IGNORE will cause IsOff to return true.
+   */
+  bool IsOff() const noexcept
+  {
+    return this->Value == nullptr ||
+      cmValue::IsOff(cm::string_view(*this->Value));
+  }
+  /** Return true if value is NOTFOUND or ends in -NOTFOUND.  */
+  bool IsNOTFOUND() const noexcept
+  {
+    return this->Value != nullptr &&
+      cmValue::IsNOTFOUND(cm::string_view(*this->Value));
+  }
+  bool IsEmpty() const noexcept
+  {
+    return this->Value == nullptr || this->Value->empty();
+  }
+
+  bool IsSet() const noexcept
+  {
+    return !this->IsEmpty() && !this->IsNOTFOUND();
+  }
+
+  /**
+   * Does a string indicate a true or ON value?
+   */
+  static bool IsOn(const char* value) noexcept
+  {
+    return value != nullptr && IsOn(cm::string_view(value));
+  }
+  static bool IsOn(cm::string_view) noexcept;
+
+  /**
+   * Compare method has same semantic as std::optional::compare
+   */
+  int Compare(cmValue value) const noexcept;
+  int Compare(cm::string_view value) const noexcept;
+
+  /**
+   * Does a string indicate a false or off value ? Note that this is
+   * not the same as !IsOn(...) because there are a number of
+   * ambiguous values such as "/usr/local/bin" a path will result in
+   * IsOn and IsOff both returning false. Note that the special path
+   * NOTFOUND, *-NOTFOUND or IGNORE will cause IsOff to return true.
+   */
+  static bool IsOff(const char* value) noexcept
+  {
+    return value == nullptr || IsOff(cm::string_view(value));
+  }
+  static bool IsOff(cm::string_view) noexcept;
+
+  /** Return true if value is NOTFOUND or ends in -NOTFOUND.  */
+  static bool IsNOTFOUND(const char* value) noexcept
+  {
+    return value == nullptr || IsNOTFOUND(cm::string_view(value));
+  }
+  static bool IsNOTFOUND(cm::string_view) noexcept;
+
+  static bool IsEmpty(const char* value) noexcept
+  {
+    return value == nullptr || *value == '\0';
+  }
+  static bool IsEmpty(cm::string_view value) noexcept { return value.empty(); }
+
+private:
+  static std::string Empty;
+  const std::string* Value = nullptr;
+};
+
+std::ostream& operator<<(std::ostream& o, cmValue v);
+
+inline bool operator==(cmValue l, cmValue r) noexcept
+{
+  return l.Compare(r) == 0;
+}
+inline bool operator!=(cmValue l, cmValue r) noexcept
+{
+  return l.Compare(r) != 0;
+}
+inline bool operator<(cmValue l, cmValue r) noexcept
+{
+  return l.Compare(r) < 0;
+}
+inline bool operator<=(cmValue l, cmValue r) noexcept
+{
+  return l.Compare(r) <= 0;
+}
+inline bool operator>(cmValue l, cmValue r) noexcept
+{
+  return l.Compare(r) > 0;
+}
+inline bool operator>=(cmValue l, cmValue r) noexcept
+{
+  return l.Compare(r) >= 0;
+}
+
+inline bool operator==(cmValue l, cm::string_view r) noexcept
+{
+  return l.Compare(r) == 0;
+}
+inline bool operator!=(cmValue l, cm::string_view r) noexcept
+{
+  return l.Compare(r) != 0;
+}
+inline bool operator<(cmValue l, cm::string_view r) noexcept
+{
+  return l.Compare(r) < 0;
+}
+inline bool operator<=(cmValue l, cm::string_view r) noexcept
+{
+  return l.Compare(r) <= 0;
+}
+inline bool operator>(cmValue l, cm::string_view r) noexcept
+{
+  return l.Compare(r) > 0;
+}
+inline bool operator>=(cmValue l, cm::string_view r) noexcept
+{
+  return l.Compare(r) >= 0;
+}
+
+inline bool operator==(cmValue l, std::nullptr_t) noexcept
+{
+  return l.Compare(cmValue{}) == 0;
+}
+inline bool operator!=(cmValue l, std::nullptr_t) noexcept
+{
+  return l.Compare(cmValue{}) != 0;
+}
+inline bool operator<(cmValue l, std::nullptr_t) noexcept
+{
+  return l.Compare(cmValue{}) < 0;
+}
+inline bool operator<=(cmValue l, std::nullptr_t) noexcept
+{
+  return l.Compare(cmValue{}) <= 0;
+}
+inline bool operator>(cmValue l, std::nullptr_t) noexcept
+{
+  return l.Compare(cmValue{}) > 0;
+}
+inline bool operator>=(cmValue l, std::nullptr_t) noexcept
+{
+  return l.Compare(cmValue{}) >= 0;
+}