3 files changed, 34 insertions, 1 deletions
diff --git a/src/common/CMakeLists.txt b/src/common/CMakeLists.txt
index 71648589..1056a763 100644
--- a/src/common/CMakeLists.txt
+++ b/src/common/CMakeLists.txt
@@ -12,6 +12,7 @@ target_sources(cru_base PUBLIC
 	${CRU_BASE_INCLUDE_DIR}/Format.hpp
 	${CRU_BASE_INCLUDE_DIR}/Logger.hpp
 	${CRU_BASE_INCLUDE_DIR}/PreConfig.hpp
+	${CRU_BASE_INCLUDE_DIR}/Range.hpp
 	${CRU_BASE_INCLUDE_DIR}/SelfResolvable.hpp
 	${CRU_BASE_INCLUDE_DIR}/String.hpp
 	${CRU_BASE_INCLUDE_DIR}/StringUtil.hpp
diff --git a/src/common/String.cpp b/src/common/String.cpp
index 83dd8aa8..078462c4 100644
--- a/src/common/String.cpp
+++ b/src/common/String.cpp
@@ -148,6 +148,38 @@ std::string String::ToUtf8() const {
   return cru::ToUtf8(std::u16string_view(Char16CStr(), size()));
 }
 
+Index String::IndexFromCodeUnitToCodePoint(Index code_unit_index) const {
+  auto iter = CodePointIterator();
+  Index result = 0;
+  while (iter.GetPosition() <= code_unit_index && !iter.IsPastEnd()) {
+    ++iter;
+    ++result;
+  }
+  return result - 1;
+}
+
+Index String::IndexFromCodePointToCodeUnit(Index code_point_index) const {
+  auto iter = CodePointIterator();
+  Index cpi = 0;
+  while (cpi < code_point_index && !iter.IsPastEnd()) {
+    ++iter;
+    ++cpi;
+  }
+  return iter.GetPosition();
+}
+
+Range String::RangeFromCodeUnitToCodePoint(Range code_unit_range) const {
+  return Range::FromTwoSides(
+      IndexFromCodeUnitToCodePoint(code_unit_range.GetStart()),
+      IndexFromCodeUnitToCodePoint(code_unit_range.GetEnd()));
+}
+
+Range String::RangeFromCodePointToCodeUnit(Range code_point_range) const {
+  return Range::FromTwoSides(
+      IndexFromCodePointToCodeUnit(code_point_range.GetStart()),
+      IndexFromCodePointToCodeUnit(code_point_range.GetEnd()));
+}
+
 namespace {
 inline int Compare(std::uint16_t left, std::uint16_t right) {
   if (left < right) return -1;
diff --git a/src/common/StringUtil.cpp b/src/common/StringUtil.cpp
index 36f4df4e..b1f1ed4b 100644
--- a/src/common/StringUtil.cpp
+++ b/src/common/StringUtil.cpp
@@ -1,6 +1,6 @@
 #include "cru/common/StringUtil.hpp"
 #include "cru/common/Base.hpp"
-#include "gsl/gsl_util"
+#include "cru/common/Exception.hpp"
 
 namespace cru {
 namespace {