Add SCI_REPLACETARGETMINIMAL to change text without causing unchanged prefix and

suffix to be marked as modified in change history.

12 files changed, 128 insertions, 17 deletions

diff --git a/call/ScintillaCall.cxx b/call/ScintillaCall.cxx
index 816f25eb9..27ad8a738 100644
--- a/call/ScintillaCall.cxx
+++ b/call/ScintillaCall.cxx
@@ -130,6 +130,10 @@ Position ScintillaCall::ReplaceTargetRE(std::string_view text) {
 	return CallString(Message::ReplaceTargetRE, text.length(), text.data());
 }
 
+Position ScintillaCall::ReplaceTargetMinimal(std::string_view text) {
+	return CallString(Message::ReplaceTargetMinimal, text.length(), text.data());
+}
+
 Position ScintillaCall::SearchInTarget(std::string_view text) {
 	return CallString(Message::SearchInTarget, text.length(), text.data());
 }
@@ -1419,6 +1423,10 @@ Position ScintillaCall::ReplaceTargetRE(Position length, const char *text) {
 	return CallString(Message::ReplaceTargetRE, length, text);
 }
 
+Position ScintillaCall::ReplaceTargetMinimal(Position length, const char *text) {
+	return CallString(Message::ReplaceTargetMinimal, length, text);
+}
+
 Position ScintillaCall::SearchInTarget(Position length, const char *text) {
 	return CallString(Message::SearchInTarget, length, text);
 }
diff --git a/doc/ScintillaDoc.html b/doc/ScintillaDoc.html
index cab6e397c..8fe205014 100644
--- a/doc/ScintillaDoc.html
+++ b/doc/ScintillaDoc.html
@@ -129,7 +129,7 @@
 
     <h1>Scintilla Documentation</h1>
 
-    <p>Last edited 26 October 2022 NH</p>
+    <p>Last edited 15 November 2022 NH</p>
 
     <p style="background:#90F0C0">Scintilla 5 has moved the lexers from Scintilla into a new
     <a href="Lexilla.html">Lexilla</a> project.<br />
@@ -821,6 +821,7 @@ struct Sci_TextRangeFull {
      <a class="message" href="#SCI_SEARCHINTARGET">SCI_SEARCHINTARGET(position length, const char *text) &rarr; position</a><br />
      <a class="message" href="#SCI_GETTARGETTEXT">SCI_GETTARGETTEXT(&lt;unused&gt;, char *text) &rarr; position</a><br />
      <a class="message" href="#SCI_REPLACETARGET">SCI_REPLACETARGET(position length, const char *text) &rarr; position</a><br />
+     <a class="message" href="#SCI_REPLACETARGETMINIMAL">SCI_REPLACETARGETMINIMAL(position length, const char *text) &rarr; position</a><br />
      <a class="message" href="#SCI_REPLACETARGETRE">SCI_REPLACETARGETRE(position length, const char *text) &rarr; position</a><br />
      <a class="message" href="#SCI_GETTAG">SCI_GETTAG(int tagNumber, char *tagValue) &rarr; int</a><br />
     </code>
@@ -870,9 +871,21 @@ struct Sci_TextRangeFull {
     <p><b id="SCI_REPLACETARGET">SCI_REPLACETARGET(position length, const char *text) &rarr; position</b><br />
      If <code class="parameter">length</code> is -1, <code class="parameter">text</code> is a zero terminated string, otherwise
     <code class="parameter">length</code> sets the number of character to replace the target with.
-           After replacement, the target range refers to the replacement text.
-           The return value
-    is the length of the replacement string.<br />
+    After replacement, the target range refers to the replacement text.
+    The return value is the length of the replacement string.<br />
+    Note that the recommended way to delete text in the document is to set the target to the text to be removed,
+    and to perform a replace target with an empty string.</p>
+
+    <p><b id="SCI_REPLACETARGETMINIMAL">SCI_REPLACETARGETMINIMAL(position length, const char *text) &rarr; position</b><br />
+    This is similar to <a class="message" href="#SCI_REPLACETARGET"><code>SCI_REPLACETARGET</code></a>
+    but tries to minimize change history when the current target text shares a common prefix or suffix with the replacement.
+    Only the text that is actually different is marked as changed.
+    This might be used when automatically reformatting some text
+    so that the whole area formatted doesn't show change marks.
+     If <code class="parameter">length</code> is -1, <code class="parameter">text</code> is a zero terminated string, otherwise
+    <code class="parameter">length</code> sets the number of character to replace the target with.
+    After replacement, the target range refers to the replacement text.
+    The return value is the length of the replacement string.<br />
     Note that the recommended way to delete text in the document is to set the target to the text to be removed,
     and to perform a replace target with an empty string.</p>
 
@@ -882,8 +895,8 @@ struct Sci_TextRangeFull {
     characters to use. The replacement string is formed from the text string with any sequences of
     <code>\1</code> through <code>\9</code> replaced by tagged matches from the most recent regular
     expression search. <code>\0</code> is replaced with all the matched text from the most recent search.
-           After replacement, the target range refers to the replacement text.
-           The return value is the length of the replacement string.</p>
+    After replacement, the target range refers to the replacement text.
+    The return value is the length of the replacement string.</p>
 
     <p><b id="SCI_GETTAG">SCI_GETTAG(int tagNumber, char *tagValue NUL-terminated) &rarr; int</b><br />
      Discover what text was matched by tagged expressions in a regular expression search.
diff --git a/doc/ScintillaHistory.html b/doc/ScintillaHistory.html
index 87303cb4f..d3787329c 100644
--- a/doc/ScintillaHistory.html
+++ b/doc/ScintillaHistory.html
@@ -585,6 +585,10 @@
 	Released 12 October 2022.
 	</li>
 	<li>
+	Add SCI_REPLACETARGETMINIMAL to change text without causing unchanged prefix and suffix
+	to be marked as modified in change history.
+	</li>
+	<li>
 	Draw background colour for EOL annotations with standard and boxed visuals.
 	</li>
 	<li>
diff --git a/include/Scintilla.h b/include/Scintilla.h
index 1baee5e49..43a41e986 100644
--- a/include/Scintilla.h
+++ b/include/Scintilla.h
@@ -557,6 +557,7 @@ typedef sptr_t (*SciFnDirectStatus)(sptr_t ptr, unsigned int iMessage, uptr_t wP
 #define SCI_TARGETWHOLEDOCUMENT 2690
 #define SCI_REPLACETARGET 2194
 #define SCI_REPLACETARGETRE 2195
+#define SCI_REPLACETARGETMINIMAL 2779
 #define SCI_SEARCHINTARGET 2197
 #define SCI_SETSEARCHFLAGS 2198
 #define SCI_GETSEARCHFLAGS 2199
diff --git a/include/Scintilla.iface b/include/Scintilla.iface
index e65b5e5d7..9f02c78d2 100644
--- a/include/Scintilla.iface
+++ b/include/Scintilla.iface
@@ -1450,6 +1450,10 @@ fun position ReplaceTarget=2194(position length, string text)
 # caused by processing the \d patterns.
 fun position ReplaceTargetRE=2195(position length, string text)
 
+# Replace the target text with the argument text but ignore prefix and suffix that
+# are the same as current.
+fun position ReplaceTargetMinimal=2779(position length, string text)
+
 # Search for a counted string in the target and set the target to the found
 # range. Text is counted so it can contain NULs.
 # Returns start of found range or -1 for failure in which case target is not moved.
diff --git a/include/ScintillaCall.h b/include/ScintillaCall.h
index 9f3b7e40a..9c851d567 100644
--- a/include/ScintillaCall.h
+++ b/include/ScintillaCall.h
@@ -71,6 +71,7 @@ public:
 	std::string StringOfRange(Span span);
 	Position ReplaceTarget(std::string_view text);
 	Position ReplaceTargetRE(std::string_view text);
+	Position ReplaceTargetMinimal(std::string_view text);
 	Position SearchInTarget(std::string_view text);
 	Span SpanSearchInTarget(std::string_view text);
 
@@ -393,6 +394,7 @@ public:
 	void TargetWholeDocument();
 	Position ReplaceTarget(Position length, const char *text);
 	Position ReplaceTargetRE(Position length, const char *text);
+	Position ReplaceTargetMinimal(Position length, const char *text);
 	Position SearchInTarget(Position length, const char *text);
 	void SetSearchFlags(Scintilla::FindOption searchFlags);
 	Scintilla::FindOption SearchFlags();
diff --git a/include/ScintillaMessages.h b/include/ScintillaMessages.h
index 9d3034f79..12b2c2504 100644
--- a/include/ScintillaMessages.h
+++ b/include/ScintillaMessages.h
@@ -323,6 +323,7 @@ enum class Message {
 	TargetWholeDocument = 2690,
 	ReplaceTarget = 2194,
 	ReplaceTargetRE = 2195,
+	ReplaceTargetMinimal = 2779,
 	SearchInTarget = 2197,
 	SetSearchFlags = 2198,
 	GetSearchFlags = 2199,
diff --git a/src/Document.cxx b/src/Document.cxx
index 0237cef78..6a638471d 100644
--- a/src/Document.cxx
+++ b/src/Document.cxx
@@ -1242,6 +1242,17 @@ void Document::CheckReadOnly() {
 	}
 }
 
+void Document::TrimReplacement(std::string_view &text, Range &range) const noexcept {
+	while (!text.empty() && !range.Empty() && (text.front() == CharAt(range.start))) {
+		text.remove_prefix(1);
+		range.start++;
+	}
+	while (!text.empty() && !range.Empty() && (text.back() == CharAt(range.end-1))) {
+		text.remove_suffix(1);
+		range.end--;
+	}
+}
+
 // Document only modified by gateways DeleteChars, InsertString, Undo, Redo, and SetStyleAt.
 // SetStyleAt does not change the persistent state of a document
 
diff --git a/src/Document.h b/src/Document.h
index ae784180a..ac9c6670c 100644
--- a/src/Document.h
+++ b/src/Document.h
@@ -46,6 +46,10 @@ public:
 		return (start != Sci::invalidPosition) && (end != Sci::invalidPosition);
 	}
 
+	[[nodiscard]] bool Empty() const noexcept {
+		return start == end;
+	}
+
 	Sci::Position First() const noexcept {
 		return (start <= end) ? start : end;
 	}
@@ -369,6 +373,7 @@ public:
 	// Gateways to modifying document
 	void ModifiedAt(Sci::Position pos) noexcept;
 	void CheckReadOnly();
+	void TrimReplacement(std::string_view &text, Range &range) const noexcept;
 	bool DeleteChars(Sci::Position pos, Sci::Position len);
 	Sci::Position InsertString(Sci::Position position, const char *s, Sci::Position insertLength);
 	Sci::Position InsertString(Sci::Position position, std::string_view sv);
diff --git a/src/Editor.cxx b/src/Editor.cxx
index 2e1467e32..1fb6d960d 100644
--- a/src/Editor.cxx
+++ b/src/Editor.cxx
@@ -5696,15 +5696,27 @@ Sci::Position Editor::GetTag(char *tagValue, int tagNumber) {
 	return length;
 }
 
-Sci::Position Editor::ReplaceTarget(bool replacePatterns, const char *text, Sci::Position length) {
+Sci::Position Editor::ReplaceTarget(ReplaceType replaceType, std::string_view text) {
 	UndoGroup ug(pdoc);
-	if (length == -1)
-		length = strlen(text);
-	if (replacePatterns) {
-		text = pdoc->SubstituteByPosition(text, &length);
-		if (!text) {
+	if (replaceType == ReplaceType::patterns) {
+		Sci::Position length = text.length();
+		const char *p = pdoc->SubstituteByPosition(text.data(), &length);
+		if (!p) {
 			return 0;
 		}
+		text = std::string_view(p, length);
+	}
+
+	if (replaceType == ReplaceType::minimal) {
+		// Check for prefix and suffix and reduce text and target to match.
+		// This is performed with Range which doesn't support virtual space.
+		Range range(targetRange.start.Position(), targetRange.end.Position());
+		pdoc->TrimReplacement(text, range);
+		// Re-apply virtual space to start if start position didn't change.
+		// Don't bother with end as its virtual space is not used
+		const SelectionPosition start(range.start == targetRange.start.Position() ?
+			targetRange.start : SelectionPosition(range.start));
+		targetRange = SelectionSegment(start, SelectionPosition(range.end));
 	}
 
 	// Remove the text inside the range
@@ -5718,9 +5730,9 @@ Sci::Position Editor::ReplaceTarget(bool replacePatterns, const char *text, Sci:
 	targetRange.end = targetRange.start;
 
 	// Insert the new text
-	const Sci::Position lengthInserted = pdoc->InsertString(targetRange.start.Position(), text, length);
+	const Sci::Position lengthInserted = pdoc->InsertString(targetRange.start.Position(), text);
 	targetRange.end.SetPosition(targetRange.start.Position() + lengthInserted);
-	return length;
+	return text.length();
 }
 
 bool Editor::IsUnicodeMode() const noexcept {
@@ -6240,11 +6252,15 @@ sptr_t Editor::WndProc(Message iMessage, uptr_t wParam, sptr_t lParam) {
 
 	case Message::ReplaceTarget:
 		PLATFORM_ASSERT(lParam);
-		return ReplaceTarget(false, ConstCharPtrFromSPtr(lParam), PositionFromUPtr(wParam));
+		return ReplaceTarget(ReplaceType::basic, ViewFromParams(lParam, wParam));
 
 	case Message::ReplaceTargetRE:
 		PLATFORM_ASSERT(lParam);
-		return ReplaceTarget(true, ConstCharPtrFromSPtr(lParam), PositionFromUPtr(wParam));
+		return ReplaceTarget(ReplaceType::patterns, ViewFromParams(lParam, wParam));
+
+	case Message::ReplaceTargetMinimal:
+		PLATFORM_ASSERT(lParam);
+		return ReplaceTarget(ReplaceType::minimal, ViewFromParams(lParam, wParam));
 
 	case Message::SearchInTarget:
 		PLATFORM_ASSERT(lParam);
diff --git a/src/Editor.h b/src/Editor.h
index 128abf234..85d95e21d 100644
--- a/src/Editor.h
+++ b/src/Editor.h
@@ -581,7 +581,8 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	void FoldAll(Scintilla::FoldAction action);
 
 	Sci::Position GetTag(char *tagValue, int tagNumber);
-	Sci::Position ReplaceTarget(bool replacePatterns, const char *text, Sci::Position length=-1);
+	enum class ReplaceType {basic, patterns, minimal};
+	Sci::Position ReplaceTarget(ReplaceType replaceType, std::string_view text);
 
 	bool PositionIsHotspot(Sci::Position position) const noexcept;
 	bool PointIsHotspot(Point pt);
@@ -625,6 +626,12 @@ protected:	// ScintillaBase subclass needs access to much of Editor
 	static unsigned char *UCharPtrFromSPtr(Scintilla::sptr_t lParam) noexcept {
 		return static_cast<unsigned char *>(PtrFromSPtr(lParam));
 	}
+	static std::string_view ViewFromParams(Scintilla::sptr_t lParam, Scintilla::uptr_t wParam) noexcept {
+		if (SPtrFromUPtr(wParam) == -1) {
+			return std::string_view(CharPtrFromSPtr(lParam));
+		}
+		return std::string_view(CharPtrFromSPtr(lParam), wParam);
+	}
 	static void *PtrFromUPtr(Scintilla::uptr_t wParam) noexcept {
 		return reinterpret_cast<void *>(wParam);
 	}
diff --git a/test/simpleTests.py b/test/simpleTests.py
index 2b5d3bc0e..31ae42535 100644
--- a/test/simpleTests.py
+++ b/test/simpleTests.py
@@ -634,6 +634,45 @@ class TestSimple(unittest.TestCase):
 		self.assertEquals(self.ed.TargetStart, 4)
 		self.assertEquals(self.ed.TargetEnd, 5)
 
+	def testReplaceTargetMinimal(self):
+		# 1: No common characters
+		self.ed.SetContents(b"abcd")
+		self.ed.TargetStart = 1
+		self.ed.TargetEnd = 3
+		self.assertEquals(self.ed.TargetStart, 1)
+		self.assertEquals(self.ed.TargetEnd, 3)
+		rep = b"321"
+		self.ed.ReplaceTargetMinimal(len(rep), rep)
+		self.assertEquals(self.ed.Contents(), b"a321d")
+
+		# 2: New characters with common prefix and suffix
+		self.ed.TargetStart = 1
+		self.ed.TargetEnd = 4
+		rep = b"3<>1"
+		self.ed.ReplaceTargetMinimal(len(rep), rep)
+		self.assertEquals(self.ed.Contents(), b"a3<>1d")
+
+		# 3: Remove characters with common prefix and suffix
+		self.ed.TargetStart = 1
+		self.ed.TargetEnd = 5
+		rep = b"31"
+		self.ed.ReplaceTargetMinimal(len(rep), rep)
+		self.assertEquals(self.ed.Contents(), b"a31d")
+
+		# 4: Common prefix
+		self.ed.TargetStart = 1
+		self.ed.TargetEnd = 3
+		rep = b"3bc"
+		self.ed.ReplaceTargetMinimal(len(rep), rep)
+		self.assertEquals(self.ed.Contents(), b"a3bcd")
+
+		# 5: Common suffix
+		self.ed.TargetStart = 2
+		self.ed.TargetEnd = 5
+		rep = b"cd"
+		self.ed.ReplaceTargetMinimal(len(rep), rep)
+		self.assertEquals(self.ed.Contents(), b"a3cd")
+
 	def testTargetWhole(self):
 		self.ed.SetContents(b"abcd")
 		self.ed.TargetStart = 1