Add default basic constructor and operator!= to SelectionPosition to ease use.

Use default member initializer, constexpr for constructors and equality
operators and <, [[nodiscard]] for comparison operators.
Add simple unit tests for Selection. Not trying to be exhaustive here, just
start the process of adding tests.

6 files changed, 179 insertions, 26 deletions

diff --git a/src/Selection.cxx b/src/Selection.cxx
index 5b99b7c3a..ad63afd70 100644
--- a/src/Selection.cxx
+++ b/src/Selection.cxx
@@ -52,13 +52,6 @@ void SelectionPosition::MoveForInsertDelete(bool insertion, Sci::Position startC
 	}
 }
 
-bool SelectionPosition::operator <(const SelectionPosition &other) const noexcept {
-	if (position == other.position)
-		return virtualSpace < other.virtualSpace;
-	else
-		return position < other.position;
-}
-
 bool SelectionPosition::operator >(const SelectionPosition &other) const noexcept {
 	if (position == other.position)
 		return virtualSpace > other.virtualSpace;
diff --git a/src/Selection.h b/src/Selection.h
index c0d785870..7f3fd937b 100644
--- a/src/Selection.h
+++ b/src/Selection.h
@@ -11,10 +11,11 @@
 namespace Scintilla::Internal {
 
 class SelectionPosition {
-	Sci::Position position;
-	Sci::Position virtualSpace;
+	Sci::Position position = Sci::invalidPosition;
+	Sci::Position virtualSpace = 0;
 public:
-	explicit SelectionPosition(Sci::Position position_= Sci::invalidPosition, Sci::Position virtualSpace_=0) noexcept : position(position_), virtualSpace(virtualSpace_) {
+	constexpr SelectionPosition() noexcept = default;
+	constexpr explicit SelectionPosition(Sci::Position position_, Sci::Position virtualSpace_=0) noexcept : position(position_), virtualSpace(virtualSpace_) {
 		PLATFORM_ASSERT(virtualSpace < 800000000);
 		if (virtualSpace < 0)
 			virtualSpace = 0;
@@ -24,13 +25,20 @@ public:
 		virtualSpace = 0;
 	}
 	void MoveForInsertDelete(bool insertion, Sci::Position startChange, Sci::Position length, bool moveForEqual) noexcept;
-	bool operator ==(const SelectionPosition &other) const noexcept {
-		return position == other.position && virtualSpace == other.virtualSpace;
+	[[nodiscard]] constexpr bool operator ==(const SelectionPosition &other) const noexcept {
+		return (position == other.position) && (virtualSpace == other.virtualSpace);
 	}
-	bool operator <(const SelectionPosition &other) const noexcept;
-	bool operator >(const SelectionPosition &other) const noexcept;
-	bool operator <=(const SelectionPosition &other) const noexcept;
-	bool operator >=(const SelectionPosition &other) const noexcept;
+	[[nodiscard]] constexpr bool operator !=(const SelectionPosition &other) const noexcept {
+		return (position != other.position) || (virtualSpace != other.virtualSpace);
+	}
+	[[nodiscard]] constexpr bool operator <(const SelectionPosition &other) const noexcept {
+		if (position == other.position)
+			return virtualSpace < other.virtualSpace;
+		return position < other.position;
+	}
+	[[nodiscard]] bool operator >(const SelectionPosition &other) const noexcept;
+	[[nodiscard]] bool operator <=(const SelectionPosition &other) const noexcept;
+	[[nodiscard]] bool operator >=(const SelectionPosition &other) const noexcept;
 	Sci::Position Position() const noexcept {
 		return position;
 	}
@@ -61,9 +69,8 @@ public:
 struct SelectionSegment {
 	SelectionPosition start;
 	SelectionPosition end;
-	SelectionSegment() noexcept : start(), end() {
-	}
-	SelectionSegment(SelectionPosition a, SelectionPosition b) noexcept {
+	constexpr SelectionSegment() noexcept = default;
+	constexpr SelectionSegment(SelectionPosition a, SelectionPosition b) noexcept {
 		if (a < b) {
 			start = a;
 			end = b;
@@ -96,15 +103,14 @@ struct SelectionRange {
 	SelectionPosition caret;
 	SelectionPosition anchor;
 
-	SelectionRange() noexcept : caret(), anchor() {
-	}
-	explicit SelectionRange(SelectionPosition single) noexcept : caret(single), anchor(single) {
+	constexpr SelectionRange() noexcept = default;
+	constexpr explicit SelectionRange(SelectionPosition single) noexcept : caret(single), anchor(single) {
 	}
-	explicit SelectionRange(Sci::Position single) noexcept : caret(single), anchor(single) {
+	constexpr explicit SelectionRange(Sci::Position single) noexcept : caret(single), anchor(single) {
 	}
-	SelectionRange(SelectionPosition caret_, SelectionPosition anchor_) noexcept : caret(caret_), anchor(anchor_) {
+	constexpr SelectionRange(SelectionPosition caret_, SelectionPosition anchor_) noexcept : caret(caret_), anchor(anchor_) {
 	}
-	SelectionRange(Sci::Position caret_, Sci::Position anchor_) noexcept : caret(caret_), anchor(anchor_) {
+	constexpr SelectionRange(Sci::Position caret_, Sci::Position anchor_) noexcept : caret(caret_), anchor(anchor_) {
 	}
 	bool Empty() const noexcept {
 		return anchor == caret;
@@ -158,7 +164,7 @@ public:
 	enum class SelTypes { none, stream, rectangle, lines, thin };
 	SelTypes selType;
 
-	Selection();
+	Selection();	// Allocates so may throw.
 	bool IsRectangular() const noexcept;
 	Sci::Position MainCaret() const noexcept;
 	Sci::Position MainAnchor() const noexcept;
diff --git a/test/unit/UnitTester.vcxproj b/test/unit/UnitTester.vcxproj
index fdf567cff..87688523b 100644
--- a/test/unit/UnitTester.vcxproj
+++ b/test/unit/UnitTester.vcxproj
@@ -165,6 +165,7 @@
     <ClCompile Include="..\..\src\PerLine.cxx" />

     <ClCompile Include="..\..\src\RESearch.cxx" />

     <ClCompile Include="..\..\src\RunStyles.cxx" />

+    <ClCompile Include="..\..\src\Selection.cxx" />

     <ClCompile Include="..\..\src\UndoHistory.cxx" />

     <ClCompile Include="..\..\src\UniConversion.cxx" />

     <ClCompile Include="..\..\src\UniqueString.cxx" />

diff --git a/test/unit/makefile b/test/unit/makefile
index 866727505..695551fc9 100644
--- a/test/unit/makefile
+++ b/test/unit/makefile
@@ -68,6 +68,7 @@ Geometry.o \
 PerLine.o \
 RESearch.o \
 RunStyles.o \
+Selection.o \
 UndoHistory.o \
 UniConversion.o \
 UniqueString.o
diff --git a/test/unit/test.mak b/test/unit/test.mak
index e4a448f8c..15d9eba43 100644
--- a/test/unit/test.mak
+++ b/test/unit/test.mak
@@ -25,6 +25,7 @@ TESTEDSRC=\
  ../../src/PerLine.cxx \
  ../../src/RESearch.cxx \
  ../../src/RunStyles.cxx \
+ ../../src/Selection.cxx \
  ../../src/UndoHistory.cxx \
  ../../src/UniConversion.cxx \
  ../../src/UniqueString.cxx
diff --git a/test/unit/testSelection.cxx b/test/unit/testSelection.cxx
new file mode 100644
index 000000000..8c27b42e8
--- /dev/null
+++ b/test/unit/testSelection.cxx
@@ -0,0 +1,151 @@
+/** @file testSelection.cxx
+ ** Unit Tests for Scintilla internal data structures
+ **/
+
+#include <cstdint>
+
+#include <stdexcept>
+#include <string_view>
+#include <vector>
+
+#include "Debugging.h"
+
+#include "Position.h"
+#include "Selection.h"
+
+#include "catch.hpp"
+
+using namespace Scintilla;
+using namespace Scintilla::Internal;
+
+// Test Selection.
+
+namespace {
+
+constexpr SelectionPosition invalid;
+constexpr SelectionPosition zero(0);
+constexpr SelectionRange rangeInvalid;
+constexpr SelectionRange rangeZero(0);
+
+}
+
+TEST_CASE("SelectionPosition") {
+
+	SECTION("SelectionPosition") {
+		SelectionPosition sel;
+		REQUIRE(sel.Position() == Sci::invalidPosition);
+		REQUIRE(sel.VirtualSpace() == 0);
+		REQUIRE(!sel.IsValid());
+		REQUIRE(sel.VirtualSpace() == 0);
+
+		REQUIRE(sel == invalid);
+		REQUIRE(sel != zero);
+		sel.Reset();
+		REQUIRE(sel != invalid);
+		REQUIRE(sel == zero);
+	}
+
+	SECTION("Comparison") {
+		constexpr SelectionPosition sel(2,3);
+		REQUIRE(sel > invalid);
+		REQUIRE(sel > zero);
+		REQUIRE(sel >= zero);
+		REQUIRE(zero < sel);
+		REQUIRE(zero <= sel);
+
+		SelectionPosition virtuous(0, 4);
+		REQUIRE(virtuous > zero);
+		REQUIRE(virtuous >= zero);
+		REQUIRE(zero < virtuous);
+		REQUIRE(zero <= virtuous);
+
+		REQUIRE(virtuous.Position() == 0);
+		REQUIRE(virtuous.VirtualSpace() == 4);
+
+		virtuous.SetPosition(1);	// Also resets virtualSpace
+		REQUIRE(virtuous.Position() == 1);
+		REQUIRE(virtuous.VirtualSpace() == 0);
+		virtuous.SetVirtualSpace(3);	// Does not reset position
+		REQUIRE(virtuous.Position() == 1);
+		REQUIRE(virtuous.VirtualSpace() == 3);
+	}
+
+	SECTION("Add") {
+		SelectionPosition sel(2,3);
+		sel.Add(1);
+		REQUIRE(sel.Position() == 3);
+		REQUIRE(sel.VirtualSpace() == 3);
+		sel.AddVirtualSpace(2);
+		REQUIRE(sel.Position() == 3);
+		REQUIRE(sel.VirtualSpace() == 5);
+	}
+
+	SECTION("MoveForInsertDelete") {
+		// There are multiple details implemented in MoveForInsertDelete that are supposed to
+		// move selections in a way that appears to be natural to a user.
+
+		SelectionPosition sel(2,3);
+		sel.MoveForInsertDelete(true, 0,1, false);
+		REQUIRE(sel == SelectionPosition(3,3));
+
+		// Converts a virtual space to real space
+		sel.MoveForInsertDelete(true, 3,1, false);
+		REQUIRE(sel == SelectionPosition(4,2));
+
+		// Deletion at position clears virtual space
+		sel.MoveForInsertDelete(false, 4,1, false);
+		REQUIRE(sel == SelectionPosition(4,0));
+
+		sel.MoveForInsertDelete(false, 3,1, false);
+		REQUIRE(sel == SelectionPosition(3,0));
+
+		// Insert at position with and without move for equal
+		sel.MoveForInsertDelete(true, 3, 1, false);
+		REQUIRE(sel == SelectionPosition(3, 0));
+		sel.MoveForInsertDelete(true, 3, 1, true);
+		REQUIRE(sel == SelectionPosition(4, 0));
+
+		// Deletion over the position moves to start of deletion
+		sel.MoveForInsertDelete(false, 2, 5, false);
+		REQUIRE(sel == SelectionPosition(2, 0));
+	}
+
+}
+
+TEST_CASE("SelectionSegment") {
+
+	SECTION("SelectionSegment") {
+		SelectionSegment ss;
+		REQUIRE(ss.start == invalid);
+		REQUIRE(ss.end == invalid);
+	}
+
+}
+
+TEST_CASE("SelectionRange") {
+
+	SECTION("SelectionRange") {
+		SelectionRange sr;
+		REQUIRE(sr.anchor == invalid);
+		REQUIRE(sr.caret == invalid);
+	}
+
+}
+
+TEST_CASE("Selection") {
+
+	SECTION("Selection") {
+		Selection sel;
+		
+		REQUIRE(sel.selType == Selection::SelTypes::stream);
+		REQUIRE(!sel.IsRectangular());
+		REQUIRE(sel.Count() == 1);
+		REQUIRE(sel.Main() == 0);
+
+		REQUIRE(sel.Range(0) == rangeZero);
+		REQUIRE(sel.RangeMain() == rangeZero);
+		REQUIRE(sel.Rectangular() == rangeInvalid);
+		REQUIRE(sel.Empty());
+	}
+
+}