feat: Add stream insertion operator and unit symbols for various quan…

.clang-format

@@ -0,0 +1,12 @@
+---
+Language: Cpp
+BasedOnStyle: LLVM
+IndentWidth: 2
+ColumnLimit: 80
+AllowShortBlocksOnASingleLine: Never
+AllowShortFunctionsOnASingleLine: All
+AllowShortEnumsOnASingleLine: true
+AllowShortIfStatementsOnASingleLine: Never
+AllowShortLoopsOnASingleLine: false
+AllowShortLambdasOnASingleLine: All
+AlwaysBreakTemplateDeclarations: MultiLine

.github/workflows/ci.yml

@@ -34,9 +34,18 @@ jobs:
           sudo apt-get install -y --no-install-recommends \
             cmake \
             ninja-build \
-            clang-format \
             clang-tidy
 
+      - name: Install clang-format 18
+        shell: bash
+        run: |
+          set -euo pipefail
+          wget -qO /tmp/llvm.sh https://apt.llvm.org/llvm.sh
+          sudo bash /tmp/llvm.sh 18
+          sudo apt-get install -y --no-install-recommends clang-format-18
+          sudo ln -sf /usr/bin/clang-format-18 /usr/local/bin/clang-format
+          clang-format --version
+
       - name: Set up Rust (stable)
         uses: actions-rust-lang/setup-rust-toolchain@v1
         with:
@@ -46,7 +55,7 @@ jobs:
         shell: bash
         run: |
           set -euo pipefail
-          cmake -S . -B build -G Ninja -DQTTY_BUILD_DOCS=OFF -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
+          cmake -S . -B build -G Ninja -DQTTY_BUILD_DOCS=OFF -DQTTY_FFI_FEATURES="serde" -DCMAKE_EXPORT_COMPILE_COMMANDS=ON
 
       - name: clang-format check
         shell: bash
@@ -147,7 +156,7 @@ jobs:
         shell: bash
         run: |
           set -euo pipefail
-          cmake -S . -B build -G Ninja -DQTTY_BUILD_DOCS=ON
+          cmake -S . -B build -G Ninja -DQTTY_BUILD_DOCS=ON -DQTTY_FFI_FEATURES="serde"
 
       - name: Build
         shell: bash
@@ -205,6 +214,7 @@ jobs:
           set -euo pipefail
           cmake -S . -B build-coverage -G Ninja \
             -DQTTY_BUILD_DOCS=OFF \
+            -DQTTY_FFI_FEATURES="serde" \
             -DCMAKE_BUILD_TYPE=Debug \
             -DCMAKE_CXX_FLAGS="--coverage" \
             -DCMAKE_EXE_LINKER_FLAGS="--coverage"

examples/demo.cpp

@@ -20,65 +20,62 @@ int main() {
   // Example 1: Basic construction and conversion
   std::cout << "1. Distance Conversion:" << std::endl;
   Meter distance(1500.0);
-  std::cout << "   Distance: " << distance.value() << " m" << std::endl;
+  std::cout << "   Distance: " << distance << std::endl;
 
   Kilometer km = distance.to<Kilometer>();
-  std::cout << "   Distance: " << km.value() << " km" << std::endl;
+  std::cout << "   Distance: " << km << std::endl;
 
   // Example 2: Using literals
   std::cout << "\n2. Using Literals:" << std::endl;
   auto height = 10.5_m;
   auto width = 5.0_m;
   auto area_side = height + width;
-  std::cout << "   Height: " << height.value() << " m" << std::endl;
-  std::cout << "   Width: " << width.value() << " m" << std::endl;
-  std::cout << "   Sum: " << area_side.value() << " m" << std::endl;
+  std::cout << "   Height: " << height << std::endl;
+  std::cout << "   Width: " << width << std::endl;
+  std::cout << "   Sum: " << area_side << std::endl;
 
   // Example 3: Velocity calculation
   std::cout << "\n3. Velocity Calculation:" << std::endl;
   auto car_distance = 100.0_km;
   auto travel_time = 2.0_h;
   auto speed = car_distance / travel_time;
-  std::cout << "   Distance: " << car_distance.value() << " km" << std::endl;
-  std::cout << "   Time: " << travel_time.value() << " h" << std::endl;
-  std::cout << "   Speed: " << speed.value() << " km/h" << std::endl;
+  std::cout << "   Distance: " << car_distance << std::endl;
+  std::cout << "   Time: " << travel_time << std::endl;
+  std::cout << "   Speed: " << speed << std::endl;
 
   // Example 4: Angular conversions
   std::cout << "\n4. Angular Conversions:" << std::endl;
   auto angle_deg = 180.0_deg;
   Radian angle_rad = angle_deg.to<Radian>();
-  std::cout << "   Angle: " << angle_deg.value() << " degrees" << std::endl;
+  std::cout << "   Angle: " << angle_deg << std::endl;
   std::cout << std::setprecision(6);
-  std::cout << "   Angle: " << angle_rad.value() << " radians" << std::endl;
+  std::cout << "   Angle: " << angle_rad << std::endl;
 
   // Example 5: Time conversions
   std::cout << "\n5. Time Conversions:" << std::endl;
   auto duration_seconds = 3665.0_s;
   Hour duration_hours = duration_seconds.to<Hour>();
   Minute duration_minutes = duration_seconds.to<Minute>();
-  std::cout << "   Duration: " << duration_seconds.value() << " seconds"
-            << std::endl;
+  std::cout << "   Duration: " << duration_seconds << std::endl;
   std::cout << std::setprecision(4);
-  std::cout << "   Duration: " << duration_hours.value() << " hours"
-            << std::endl;
+  std::cout << "   Duration: " << duration_hours << std::endl;
   std::cout << std::setprecision(2);
-  std::cout << "   Duration: " << duration_minutes.value() << " minutes"
-            << std::endl;
+  std::cout << "   Duration: " << duration_minutes << std::endl;
 
   // Example 6: Compound operations
   std::cout << "\n6. Compound Operations:" << std::endl;
   Meter total(100.0);
-  std::cout << "   Initial: " << total.value() << " m" << std::endl;
+  std::cout << "   Initial: " << total << std::endl;
 
   total += 50.0_m;
-  std::cout << "   After += 50m: " << total.value() << " m" << std::endl;
+  std::cout << "   After += 50m: " << total << std::endl;
 
   total *= 2.0;
-  std::cout << "   After *= 2: " << total.value() << " m" << std::endl;
+  std::cout << "   After *= 2: " << total << std::endl;
 
   total /= 3.0;
   std::cout << std::setprecision(2) << std::fixed;
-  std::cout << "   After /= 3: " << total.value() << " m" << std::endl;
+  std::cout << "   After /= 3: " << total << std::endl;
 
   // Example 7: Comparisons
   std::cout << "\n7. Comparisons:" << std::endl;
@@ -94,9 +91,9 @@ int main() {
   Meter negative(-42.5);
   auto positive = negative.abs();
   auto double_negative = -negative;
-  std::cout << "   Original: " << negative.value() << " m" << std::endl;
-  std::cout << "   Absolute: " << positive.value() << " m" << std::endl;
-  std::cout << "   Negated: " << double_negative.value() << " m" << std::endl;
+  std::cout << "   Original: " << negative << std::endl;
+  std::cout << "   Absolute: " << positive << std::endl;
+  std::cout << "   Negated: " << double_negative << std::endl;
 
   std::cout << "\n=== All examples completed successfully! ===" << std::endl;
 

gen_cpp_units.py

@@ -138,9 +138,10 @@ def generate_header_for_dimension(dimension: str, units: List[Tuple[str, str, st
 
     # Generate unit traits specializations
     unit_traits = []
-    for const_name, name, _ in units:
+    for const_name, name, symbol in units:
         unit_traits.append(f"""template<> struct UnitTraits<{name}Tag> {{
     static constexpr UnitId unit_id() {{ return UNIT_ID_{const_name}; }}
+    static constexpr std::string_view symbol() {{ return "{symbol}"; }}
 }};""")
 
     # Generate type aliases

include/qtty/ffi_core.hpp

@@ -9,8 +9,10 @@
  */
 
 #include <cmath>
+#include <iostream>
 #include <stdexcept>
 #include <string>
+#include <string_view>
 #include <type_traits>
 extern "C" {
 #include "qtty_ffi.h"
@@ -278,4 +280,15 @@ template <typename UnitTag> class Quantity {
   Quantity abs() const { return Quantity(std::abs(m_value)); }
 };
 
+// ============================================================================
+// Stream Insertion Operator
+// ============================================================================
+// Prints a quantity with its unit symbol, e.g., "1500 m" or "42.5 km"
+
+template <typename UnitTag>
+std::ostream &operator<<(std::ostream &os, const Quantity<UnitTag> &q) {
+  os << q.value() << " " << UnitTraits<UnitTag>::symbol();
+  return os;
+}
+
 } // namespace qtty

include/qtty/units/angular.hpp

@@ -20,33 +20,43 @@ struct HourAngleTag {};
 
 template <> struct UnitTraits<MilliradianTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_MILLIRADIAN; }
+  static constexpr std::string_view symbol() { return "mrad"; }
 };
 template <> struct UnitTraits<RadianTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_RADIAN; }
+  static constexpr std::string_view symbol() { return "rad"; }
 };
 template <> struct UnitTraits<MicroArcsecondTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_MICRO_ARCSECOND; }
+  static constexpr std::string_view symbol() { return "µas"; }
 };
 template <> struct UnitTraits<MilliArcsecondTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_MILLI_ARCSECOND; }
+  static constexpr std::string_view symbol() { return "mas"; }
 };
 template <> struct UnitTraits<ArcsecondTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_ARCSECOND; }
+  static constexpr std::string_view symbol() { return "″"; }
 };
 template <> struct UnitTraits<ArcminuteTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_ARCMINUTE; }
+  static constexpr std::string_view symbol() { return "′"; }
 };
 template <> struct UnitTraits<DegreeTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_DEGREE; }
+  static constexpr std::string_view symbol() { return "°"; }
 };
 template <> struct UnitTraits<GradianTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_GRADIAN; }
+  static constexpr std::string_view symbol() { return "gon"; }
 };
 template <> struct UnitTraits<TurnTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_TURN; }
+  static constexpr std::string_view symbol() { return "tr"; }
 };
 template <> struct UnitTraits<HourAngleTag> {
   static constexpr UnitId unit_id() { return UNIT_ID_HOUR_ANGLE; }
+  static constexpr std::string_view symbol() { return "ʰ"; }
 };
 
 using Milliradian = Quantity<MilliradianTag>;