3 files changed, 89 insertions, 1 deletions

diff --git a/include/cru/common/StringUtil.hpp b/include/cru/common/StringUtil.hpp
index 276048f5..62999d53 100644
--- a/include/cru/common/StringUtil.hpp
+++ b/include/cru/common/StringUtil.hpp
@@ -1,7 +1,10 @@
 #pragma once
-#include <string>
 #include "Base.hpp"
 
+#include <functional>
+#include <string>
+#include <string_view>
+
 namespace cru {
 using CodePoint = std::int32_t;
 constexpr CodePoint k_invalid_code_point = -1;
@@ -128,4 +131,18 @@ std::u16string ToUtf16(std::string_view s);
 
 // If given s is not a valid utf16 string, return value is UD.
 bool Utf16IsValidInsertPosition(std::u16string_view s, gsl::index position);
+
+// Return position after the character making predicate returns true or 0 if no
+// character doing so.
+gsl::index Utf16BackwardUntil(std::u16string_view str, gsl::index position,
+                              const std::function<bool(CodePoint)>& predicate);
+// Return position before the character making predicate returns true or
+// str.size() if no character doing so.
+gsl::index Utf16ForwardUntil(std::u16string_view str, gsl::index position,
+                             const std::function<bool(CodePoint)>& predicate);
+
+gsl::index Utf16PreviousWord(std::u16string_view str, gsl::index position,
+                             bool* is_space = nullptr);
+gsl::index Utf16NextWord(std::u16string_view str, gsl::index position,
+                         bool* is_space = nullptr);
 }  // namespace cru
diff --git a/src/common/StringUtil.cpp b/src/common/StringUtil.cpp
index 3c312d49..b13c0193 100644
--- a/src/common/StringUtil.cpp
+++ b/src/common/StringUtil.cpp
@@ -1,4 +1,5 @@
 #include "cru/common/StringUtil.hpp"
+#include "cru/common/Base.hpp"
 #include "gsl/gsl_util"
 
 namespace cru {
@@ -229,4 +230,58 @@ bool Utf16IsValidInsertPosition(std::u16string_view s, gsl::index position) {
   if (position == static_cast<gsl::index>(s.size())) return true;
   return !IsUtf16SurrogatePairTrailing(s[position]);
 }
+
+gsl::index Utf16BackwardUntil(std::u16string_view str, gsl::index position,
+                              const std::function<bool(CodePoint)>& predicate) {
+  if (position <= 0) return position;
+  while (true) {
+    gsl::index p = position;
+    auto c = Utf16PreviousCodePoint(str, p, &position);
+    if (predicate(c)) return p;
+    if (c == k_invalid_code_point) return p;
+  }
+  UnreachableCode();
+}
+
+gsl::index Utf16ForwardUntil(std::u16string_view str, gsl::index position,
+                             const std::function<bool(CodePoint)>& predicate) {
+  if (position >= static_cast<gsl::index>(str.size())) return position;
+  while (true) {
+    gsl::index p = position;
+    auto c = Utf16NextCodePoint(str, p, &position);
+    if (predicate(c)) return p;
+    if (c == k_invalid_code_point) return p;
+  }
+  UnreachableCode();
+}
+
+inline bool IsSpace(CodePoint c) { return c == 0x20; }
+
+gsl::index Utf16PreviousWord(std::u16string_view str, gsl::index position,
+                             bool* is_space) {
+  if (position <= 0) return position;
+  auto c = Utf16PreviousCodePoint(str, position, nullptr);
+  if (IsSpace(c)) {  // TODO: Currently only test against 0x20(space).
+    if (is_space) *is_space = true;
+    return Utf16BackwardUntil(str, position,
+                              [](CodePoint c) { return !IsSpace(c); });
+  } else {
+    if (is_space) *is_space = false;
+    return Utf16BackwardUntil(str, position, IsSpace);
+  }
+}
+
+gsl::index Utf16NextWord(std::u16string_view str, gsl::index position,
+                         bool* is_space) {
+  if (position >= static_cast<gsl::index>(str.size())) return position;
+  auto c = Utf16NextCodePoint(str, position, nullptr);
+  if (IsSpace(c)) {  // TODO: Currently only test against 0x20(space).
+    if (is_space) *is_space = true;
+    return Utf16ForwardUntil(str, position,
+                             [](CodePoint c) { return !IsSpace(c); });
+  } else {
+    if (is_space) *is_space = false;
+    return Utf16ForwardUntil(str, position, IsSpace);
+  }
+}
 }  // namespace cru
diff --git a/src/ui/controls/TextHostControlService.cpp b/src/ui/controls/TextHostControlService.cpp
index 91ec53ff..4bfd6715 100644
--- a/src/ui/controls/TextHostControlService.cpp
+++ b/src/ui/controls/TextHostControlService.cpp
@@ -419,6 +419,14 @@ void TextHostControlService::SetUpShortcuts() {
         return true;
       });
 
+  shortcut_hub_.RegisterShortcut(
+      u"CtrlLeft", {KeyCode::Left, KeyModifiers::ctrl}, [this] {
+        auto text = this->GetTextView();
+        auto caret = this->GetCaretPosition();
+        this->SetSelection(Utf16PreviousWord(text, caret));
+        return true;
+      });
+
   shortcut_hub_.RegisterShortcut(u"Right", KeyCode::Right, [this] {
     auto text = this->GetTextView();
     const auto caret = this->GetCaretPosition();
@@ -438,5 +446,13 @@ void TextHostControlService::SetUpShortcuts() {
         this->SetSelection(selection);
         return true;
       });
+
+  shortcut_hub_.RegisterShortcut(
+      u"CtrlRight", {KeyCode::Right, KeyModifiers::ctrl}, [this] {
+        auto text = this->GetTextView();
+        auto caret = this->GetCaretPosition();
+        this->SetSelection(Utf16NextWord(text, caret));
+        return true;
+      });
 }
 }  // namespace cru::ui::controls