Add off-by-default smart truncation for tab titles.

ThirdParty/PSMTabBarControl/source/PSMTabBarCell.h

@@ -49,6 +49,7 @@
 @property(nonatomic, readonly) float minimumWidthOfCell;
 @property(nonatomic, readonly) float desiredWidthOfCell;
 @property(nonatomic, readonly) id<PSMTabStyle> style;
+@property(nonatomic, assign) NSLineBreakMode truncationStyle;  // How to truncate title.
 // creation/destruction
 - (id)initWithControlView:(PSMTabBarControl *)controlView;

ThirdParty/PSMTabBarControl/source/PSMTabBarCell.m

@@ -91,6 +91,7 @@ static NSTimeInterval kHighlightAnimationDuration = 0.5;
         _indicator.light = controlView.style.useLightControls;
         _hasCloseButton = YES;
         _modifierString = [@"" copy];
+        _truncationStyle = NSLineBreakByTruncatingTail;
     }
     return self;
 }
@@ -119,6 +120,7 @@ static NSTimeInterval kHighlightAnimationDuration = 0.5;
         _count = 0;
         _tabColor = nil;
         _modifierString = [@"" copy];
+        _truncationStyle = NSLineBreakByTruncatingTail;
         if (value) {
             [self setCurrentStep:(kPSMTabDragAnimationSteps - 1)];
         } else {

ThirdParty/PSMTabBarControl/source/PSMTabBarControl.h

@@ -169,6 +169,10 @@ enum {
 @property(nonatomic, assign) BOOL automaticallyAnimates;
 @property(nonatomic, assign) int tabLocation;
+// If off (the default) always ellipsize the ends of tab titles that don't fit.
+// Of on, ellipsize the start if more tabs share a prefix than a suffix.
+@property(nonatomic, assign) BOOL smartTruncation;
+
 @property(nonatomic, retain) IBOutlet NSTabView *tabView;
 @property(nonatomic, assign) id<PSMTabBarControlDelegate> delegate;
 @property(nonatomic, retain) id partnerView;

ThirdParty/PSMTabBarControl/source/PSMTabBarControl.m

@@ -367,9 +367,41 @@ const NSInteger kPSMStartResizeAnimation = 0;
 #pragma mark -
 #pragma mark Functionality
+- (NSLineBreakMode)truncationStyle {
+    if (_cells.count <= 1 || !self.smartTruncation) {
+        return NSLineBreakByTruncatingTail;
+    }
+    NSCountedSet *prefixCounts = [[[NSCountedSet alloc] init] autorelease];
+    NSCountedSet *suffixCounts = [[[NSCountedSet alloc] init] autorelease];
+    NSMutableSet *uniqueTitles = [NSMutableSet set];
+    static NSInteger const kPrefixOrSuffixLength = 5;
+    for (PSMTabBarCell *cell in _cells) {
+        NSString *title = [cell title];
+        if (title.length < kPrefixOrSuffixLength) {
+            continue;
+        }
+        [uniqueTitles addObject:title];
+        NSString *prefix = [title substringToIndex:kPrefixOrSuffixLength];
+        NSString *suffix = [title substringFromIndex:(NSInteger)title.length - kPrefixOrSuffixLength];
+        
+        [prefixCounts addObject:prefix];
+        [suffixCounts addObject:suffix];
+    }
+    if (uniqueTitles.count == 0) {
+        return NSLineBreakByTruncatingTail;
+    }
+
+    if (prefixCounts.count >= suffixCounts.count) {
+        return NSLineBreakByTruncatingTail;
+    } else {
+        return NSLineBreakByTruncatingHead;
+    }
+}
+
 - (void)addTabViewItem:(NSTabViewItem *)item atIndex:(NSUInteger)i {
     // create cell
     PSMTabBarCell *cell = [[PSMTabBarCell alloc] initWithControlView:self];
+    cell.truncationStyle = [self truncationStyle];
     [cell setRepresentedObject:item];
     [cell setModifierString:[self _modifierString]];
@@ -723,8 +755,11 @@ const NSInteger kPSMStartResizeAnimation = 0;
         currentOrigin = [[self style] topMarginForTabBarControl];
     }
+    NSLineBreakMode truncationStyle = [self truncationStyle];
+    
     for (i = 0; i < cellCount; i++) {
         PSMTabBarCell *cell = [_cells objectAtIndex:i];
+        cell.truncationStyle = truncationStyle;
         cell.hasCloseButton = _hasCloseButton;
         [cell updateForStyle];
         float width;

ThirdParty/PSMTabBarControl/source/PSMTabDragAssistant.m

@@ -760,6 +760,7 @@ static PSMTabDragAssistant *sharedDragAssistant = nil;
     // replace dragged cell with a placeholder, and clean up surrounding cells
     int cellIndex = [[control cells] indexOfObject:cell];
     PSMTabBarCell *pc = [[[PSMTabBarCell alloc] initPlaceholderWithFrame:[[self draggedCell] frame] expanded:YES inControlView:control] autorelease];
+    pc.truncationStyle = cell.truncationStyle;
     [[control cells] replaceObjectAtIndex:cellIndex withObject:pc];
     [[control cells] removeObjectAtIndex:(cellIndex + 1)];
     [[control cells] removeObjectAtIndex:(cellIndex - 1)];
@@ -771,17 +772,22 @@ static PSMTabDragAssistant *sharedDragAssistant = nil;
     int i, numVisibleTabs = [control numberOfVisibleTabs];
     PSMTabBarCell *draggedCell = [self draggedCell];
     NSRect draggedCellFrame;
+    NSLineBreakMode truncationStyle;
     if (draggedCell) {
         draggedCellFrame = [draggedCell frame];
+        truncationStyle = draggedCell.truncationStyle;
     } else {
         draggedCellFrame = [[[control cells] objectAtIndex:0] frame];
+        truncationStyle = [[[control cells] objectAtIndex:0] truncationStyle];
     }
     for(i = 0; i < numVisibleTabs; i++) {
         PSMTabBarCell *pc = [[[PSMTabBarCell alloc] initPlaceholderWithFrame:draggedCellFrame expanded:NO inControlView:control] autorelease];
+        pc.truncationStyle = truncationStyle;
         [[control cells] insertObject:pc atIndex:(2 * i)];
     }
     PSMTabBarCell *pc = [[[PSMTabBarCell alloc] initPlaceholderWithFrame:draggedCellFrame expanded:NO inControlView:control] autorelease];
+    pc.truncationStyle = truncationStyle;
     if ([[control cells] count] > (2 * numVisibleTabs)) {
         [[control cells] insertObject:pc atIndex:(2 * numVisibleTabs)];
     } else {

ThirdParty/PSMTabBarControl/source/PSMYosemiteTabStyle.m

@@ -307,13 +307,12 @@
                     range:range];
     // Paragraph Style for Truncating Long Text
-    static NSMutableParagraphStyle *truncatingTailParagraphStyle = nil;
-    if (!truncatingTailParagraphStyle) {
-        truncatingTailParagraphStyle =
-            [[[NSParagraphStyle defaultParagraphStyle] mutableCopy] retain];
-        [truncatingTailParagraphStyle setLineBreakMode:NSLineBreakByTruncatingTail];
-        [truncatingTailParagraphStyle setAlignment:NSCenterTextAlignment];
-    }
+    NSMutableParagraphStyle *truncatingTailParagraphStyle = nil;
+    truncatingTailParagraphStyle =
+        [[[NSParagraphStyle defaultParagraphStyle] mutableCopy] retain];
+    [truncatingTailParagraphStyle setLineBreakMode:[cell truncationStyle]];
+    [truncatingTailParagraphStyle setAlignment:NSCenterTextAlignment];
+
     [attrStr addAttribute:NSParagraphStyleAttributeName
                     value:truncatingTailParagraphStyle
                     range:range];

sources/iTermAdvancedSettingsModel.h

@@ -124,5 +124,6 @@
 + (BOOL)hideFromDockAndAppSwitcher;
 + (BOOL)hotkeyWindowIgnoresSpotlight;
++ (BOOL)tabTitlesUseSmartTruncation;
 @end

sources/iTermAdvancedSettingsModel.m

@@ -54,6 +54,7 @@ DEFINE_BOOL(navigatePanesInReadingOrder, YES, @"Tabs: Next Pane and Previous Pan
 DEFINE_BOOL(eliminateCloseButtons, NO, @"Tabs: Eliminate close buttons from tabs, even on mouse-over.");
 DEFINE_FLOAT(tabAutoShowHoldTime, 1.0, @"Tabs: How long in seconds to show tabs in fullscreen.\nThe tab bar appears briefly in fullscreen when the number of tabs changes or you switch tabs. This setting gives the time in seconds for it to remain visible.");
 DEFINE_BOOL(allowDragOfTabIntoNewWindow, YES, @"Tabs: Allow a tab to be dragged and dropped outside any existing tab bar to create a new window.");
+DEFINE_BOOL(tabTitlesUseSmartTruncation, NO, @"Tabs: Use “smart truncation” for tab titles.\nIf a tab‘s title is too long to fit, ellipsize the start of the title if more tabs have unique suffixes than prefixes in a given window.");
 #pragma mark Mouse
 DEFINE_BOOL(alternateMouseScroll, NO, @"Mouse: Scroll wheel sends arrow keys when in alternate screen mode.");

sources/iTermRootTerminalView.m

@@ -395,7 +395,8 @@ static const CGFloat kMaximumToolbeltSizeAsFractionOfWindow = 0.5;
     }
     [self.tabBarControl setSizeCellsToFit:[iTermAdvancedSettingsModel useUnevenTabs]];
     [self.tabBarControl setCellOptimumWidth:[iTermAdvancedSettingsModel optimumTabWidth]];
-
+    self.tabBarControl.smartTruncation = [iTermAdvancedSettingsModel tabTitlesUseSmartTruncation];
+    
     DLog(@"repositionWidgets - redraw view");
     // Note: this used to call setNeedsDisplay on each session in the current tab.
     [self setNeedsDisplay:YES];