Terminal: added basic conditional title patterns.

* You can now insert arbitrary text only if the following or previous
  placeholder does not resolve to an empty value using the %<, %> and
  %- placeholders.
* Additionally, any non-alpha numeric character between % and the
  placeholder character will only be displayed if the placeholder does
  not resolve to an empty value, too.
* All of this allows you to get rid of the extra space between
  "Terminal" and ":" before the current path -- which is now the
  default.

src/apps/terminal/AppearPrefView.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2001-2010, Haiku, Inc.
+ * Copyright 2001-2015, Haiku, Inc.
  * Copyright 2003-2004 Kian Duffy, [email protected]
  * Parts Copyright 1998-1999 Kazuho Okui and Takashi Murai.
  * All rights reserved. Distributed under the terms of the MIT license.
@@ -133,7 +133,8 @@ AppearancePrefView::AppearancePrefView(const char* name,
 		new BMessage(MSG_TAB_TITLE_SETTING_CHANGED));
 	fTabTitle->SetToolTip(BString(B_TRANSLATE(
 		"The pattern specifying the tab titles. The following placeholders\n"
-		"can be used:\n")) << kTooTipSetTabTitlePlaceholders);
+		"can be used:")) << "\n" << kTooTipSetTabTitlePlaceholders
+		<< "\n" << kToolTipCommonTitlePlaceholders);
 
 	fWindowTitle = new BTextControl("windowTitle", B_TRANSLATE("Window title:"),
 		"", NULL);
@@ -141,7 +142,8 @@ AppearancePrefView::AppearancePrefView(const char* name,
 		new BMessage(MSG_WINDOW_TITLE_SETTING_CHANGED));
 	fWindowTitle->SetToolTip(BString(B_TRANSLATE(
 		"The pattern specifying the window titles. The following placeholders\n"
-		"can be used:\n")) << kTooTipSetWindowTitlePlaceholders);
+		"can be used:")) << "\n" << kTooTipSetWindowTitlePlaceholders
+		<< "\n" << kToolTipCommonTitlePlaceholders);
 
 	BLayoutBuilder::Group<>(this)
 		.SetInsets(5, 5, 5, 5)

src/apps/terminal/PatternEvaluator.cpp

@@ -1,5 +1,6 @@
 /*
  * Copyright 2010, Ingo Weinhold, [email protected].
+ * Copyright 2015, Axel Dörfler, [email protected].
  * Distributed under the terms of the MIT License.
  */
 
@@ -19,24 +20,69 @@
 PatternEvaluator::Evaluate(const char* pattern, PlaceholderMapper& mapper)
 {
 	BString result;
+	BString before;
+	bool isBefore = false;
+	bool isAfter = false;
+	bool hadResult = false;
+	bool began = false;
 
 	while (*pattern != '\0') {
 		// find next placeholder
 		const char* placeholder = strchr(pattern, '%');
-		if (placeholder == NULL)
+		size_t length = 0;
-			return result.Append(pattern);
+		if (placeholder != NULL)
+			length = placeholder - pattern;
+		else
+			length = INT_MAX;
 
 		// append skipped chars
-		if (placeholder != pattern)
+		if (placeholder != pattern) {
-			result.Append(pattern, placeholder - pattern);
+			if (isBefore) {
+				before.SetTo(pattern, length);
+				isBefore = false;
+			} else if (!isAfter || hadResult) {
+				result.Append(pattern, length);
+				isBefore = false;
+				before.SetTo(NULL);
+				isAfter = false;
+			}
+		}
+		if (placeholder == NULL)
+			return result;
 
 		pattern = placeholder + 1;
 
-		// check for an escaped '%'
+		// check for special placeholders
-		if (*pattern == '%') {
+		switch (pattern[0]) {
-			result += '%';
+			case '%':
+				// An escaped '%'
+				result += '%';
+				pattern++;
+				continue;
+			case '<':
+				// An optional before string
+				isBefore = began = true;
+				hadResult = false;
+				pattern++;
+				continue;
+			case '>':
+				// An optional after string
+				isAfter = true;
+				began = false;
+				before.SetTo(NULL);
+				pattern++;
+				continue;
+			case '-':
+				// End of any other section; ignore
+				pattern++;
+				isBefore = false;
+				isAfter = false;
+				continue;
+		}
+		// Count non alpha numeric characters to the before section
+		while (pattern[0] != '\0' && !isalnum(pattern[0])) {
+			before.Append(pattern[0], 1);
 			pattern++;
-			continue;
 		}
 
 		// parse a number, if there is one
@@ -53,12 +99,19 @@ PatternEvaluator::Evaluate(const char* pattern, PlaceholderMapper& mapper)
 		if (*pattern != '\0' && mapper.MapPlaceholder(*pattern,
 				number, hasNumber, mappedValue)) {
 			// mapped successfully -- append the replacement string
+			if (began && !mappedValue.IsEmpty())
+				hadResult = true;
+			if (!before.IsEmpty() && !mappedValue.IsEmpty()) {
+				result += before;
+				before.SetTo(NULL);
+			}
+
 			result += mappedValue;
 			pattern++;
 		} else {
 			// something went wrong -- just append the literal part of the
 			// pattern
-			result.Append(placeholder, pattern - placeholder);
+			result.Append(placeholder, length);
 		}
 	}
 
@@ -66,7 +119,6 @@ PatternEvaluator::Evaluate(const char* pattern, PlaceholderMapper& mapper)
 }
 
 
-
 // #pragma mark - PlaceholderMapper
 
 

src/apps/terminal/PrefHandler.cpp

@@ -1,5 +1,5 @@
 /*
- * Copyright 2003-2013, Haiku, Inc. All Rights Reserved.
+ * Copyright 2003-2015, Haiku, Inc. All Rights Reserved.
  * Copyright (c) 2004 Daniel Furrer <[email protected]>
  * Copyright (c) 2003-4 Kian Duffy <[email protected]>
  * Copyright (c) 1998,99 Kazuho Okui and Takashi Murai.
@@ -85,7 +85,7 @@ static const pref_defaults kTermDefaults[] = {
 	{ PREF_IM_AWARE,			"0"},
 
 	{ PREF_TAB_TITLE,			"%1d: %p%e" },
-	{ PREF_WINDOW_TITLE,		"%T %i: %t" },
+	{ PREF_WINDOW_TITLE,		"%T% i: %t" },
 	{ PREF_BLINK_CURSOR,		PREF_TRUE },
 	{ PREF_WARN_ON_EXIT,		PREF_TRUE },
 	{ PREF_CURSOR_STYLE,		PREF_BLOCK_CURSOR },

src/apps/terminal/TermConst.cpp

@@ -30,8 +30,18 @@ const char* const kTooTipSetWindowTitlePlaceholders = B_TRANSLATE(
 	"\t%e\t-\tThe encoding of the current tab. Not shown for UTF-8.\n"
 	"\t%i\t-\tThe index of the window.\n"
 	"\t%p\t-\tThe name of the active process in the current tab.\n"
-	"\t%t\t-\tThe title of the current tab.\n"
+	"\t%t\t-\tThe title of the current tab.");
-	"\t%%\t-\tThe character '%'.");
+
+const char* const kToolTipCommonTitlePlaceholders = B_TRANSLATE(
+	"\t%%\t-\tThe character '%'.\n"
+	"\t%<\t-\tStarts a section that will only be shown if a placeholder\n"
+	"\t\t\tafterwards is not empty.\n"
+	"\t%>\t-\tStarts a section that will only be shown if a placeholder\n"
+	"\t\t\tbetween a previous %< section and this one is not empty.\n"
+	"\t%-\t-\tEnds a %< or %> section.\n\n"
+	"Any non alpha numeric character between '%' and the format "
+	"letter will insert a space only\nif the placeholder value is not "
+	"empty. It will add to the %< section.");
 
 const char* const kShellEscapeCharacters = " ~`#$&*()\\|[]{};'\"<>?!";
 const char* const kDefaultAdditionalWordCharacters = ":@-./_~";

src/apps/terminal/TermConst.h

@@ -143,6 +143,7 @@ static const char* const PREF_WINDOW_TITLE = "Window title";
 // shared strings
 extern const char* const kTooTipSetTabTitlePlaceholders;
 extern const char* const kTooTipSetWindowTitlePlaceholders;
+extern const char* const kToolTipCommonTitlePlaceholders;
 
 extern const char* const kShellEscapeCharacters;
 extern const char* const kDefaultAdditionalWordCharacters;