gitk: Limit diff display to listed paths by default

When the user has specified a list of paths, either on the command line
or when creating a view, gitk currently displays the diffs for all files
that a commit has modified, not just the ones that match the path list.
This is different from other git commands such as git log.  This change
makes gitk behave the same as these other git commands by default, that
is, gitk only displays the diffs for files that match the path list.

There is now a checkbox labelled "Limit diffs to listed paths" in the
Edit/Preferences pane.  If that is unchecked, gitk will display the
diffs for all files as before.

When gitk is run with the --merge flag, it will get the list of unmerged
files at startup, intersect that with the paths listed on the command line
(if any), and use that as the list of paths.

Signed-off-by: Paul Mackerras <paulus@samba.org>

gitk

@@ -1019,7 +1019,7 @@ proc savestuff {w} {
     global stuffsaved findmergefiles maxgraphpct
     global maxwidth showneartags showlocalchanges
     global viewname viewfiles viewargs viewperm nextviewnum
-    global cmitmode wrapcomment datetimeformat
+    global cmitmode wrapcomment datetimeformat limitdiffs
     global colors bgcolor fgcolor diffcolors diffcontext selectbgcolor
 
     if {$stuffsaved} return
@@ -1038,6 +1038,7 @@ proc savestuff {w} {
 	puts $f [list set showneartags $showneartags]
 	puts $f [list set showlocalchanges $showlocalchanges]
 	puts $f [list set datetimeformat $datetimeformat]
+	puts $f [list set limitdiffs $limitdiffs]
 	puts $f [list set bgcolor $bgcolor]
 	puts $f [list set fgcolor $fgcolor]
 	puts $f [list set colors $colors]
@@ -5015,9 +5016,31 @@ proc startdiff {ids} {
     }
 }
 
+proc path_filter {filter name} {
+    foreach p $filter {
+	set l [string length $p]
+	if {[string compare -length $l $p $name] == 0 &&
+	    ([string length $name] == $l || [string index $name $l] eq "/")} {
+	    return 1
+	}
+    }
+    return 0
+}
+
 proc addtocflist {ids} {
-    global treediffs cflist
-    add_flist $treediffs($ids)
+    global treediffs cflist viewfiles curview limitdiffs
+
+    if {$limitdiffs && $viewfiles($curview) ne {}} {
+	set flist {}
+	foreach f $treediffs($ids) {
+	    if {[path_filter $viewfiles($curview) $f]} {
+		lappend flist $f
+	    }
+	}
+    } else {
+	set flist $treediffs($ids)
+    }
+    add_flist $flist
     getblobdiffs $ids
 }
 
@@ -5124,9 +5147,14 @@ proc getblobdiffs {ids} {
     global diffopts blobdifffd diffids env
     global diffinhdr treediffs
     global diffcontext
+    global limitdiffs viewfiles curview
 
     set env(GIT_DIFF_OPTS) $diffopts
-    if {[catch {set bdf [open [diffcmd $ids "-p -C --no-commit-id -U$diffcontext"] r]} err]} {
+    set cmd [diffcmd $ids "-p -C --no-commit-id -U$diffcontext"]
+    if {$limitdiffs && $viewfiles($curview) ne {}} {
+	set cmd [concat $cmd $viewfiles($curview)]
+    }
+    if {[catch {set bdf [open $cmd r]} err]} {
 	puts "error getting diffs: $err"
 	return
     }
@@ -7382,7 +7410,7 @@ proc doprefs {} {
     global maxwidth maxgraphpct diffopts
     global oldprefs prefstop showneartags showlocalchanges
     global bgcolor fgcolor ctext diffcolors selectbgcolor
-    global uifont tabstop
+    global uifont tabstop limitdiffs
 
     set top .gitkprefs
     set prefstop $top
@@ -7390,7 +7418,8 @@ proc doprefs {} {
 	raise $top
 	return
     }
-    foreach v {maxwidth maxgraphpct diffopts showneartags showlocalchanges} {
+    foreach v {maxwidth maxgraphpct diffopts showneartags showlocalchanges \
+		   limitdiffs} {
 	set oldprefs($v) [set $v]
     }
     toplevel $top
@@ -7428,6 +7457,11 @@ proc doprefs {} {
     label $top.tabstopl -text "tabstop" -font optionfont
     spinbox $top.tabstop -from 1 -to 20 -width 4 -textvariable tabstop
     grid x $top.tabstopl $top.tabstop -sticky w
+    frame $top.ldiff
+    label $top.ldiff.l -text "Limit diffs to listed paths" -font optionfont
+    checkbutton $top.ldiff.b -variable limitdiffs
+    pack $top.ldiff.b $top.ldiff.l -side left
+    grid x $top.ldiff -sticky w
 
     label $top.cdisp -text "Colors: press to choose"
     $top.cdisp configure -font $uifont
@@ -7514,9 +7548,10 @@ proc setfg {c} {
 
 proc prefscan {} {
     global maxwidth maxgraphpct diffopts
-    global oldprefs prefstop showneartags showlocalchanges
+    global oldprefs prefstop showneartags showlocalchanges limitdiffs
 
-    foreach v {maxwidth maxgraphpct diffopts showneartags showlocalchanges} {
+    foreach v {maxwidth maxgraphpct diffopts showneartags showlocalchanges \
+		   limitdiffs} {
 	set $v $oldprefs($v)
     }
     catch {destroy $prefstop}
@@ -7526,7 +7561,7 @@ proc prefscan {} {
 proc prefsok {} {
     global maxwidth maxgraphpct
     global oldprefs prefstop showneartags showlocalchanges
-    global charspc ctext tabstop
+    global charspc ctext tabstop limitdiffs
 
     catch {destroy $prefstop}
     unset prefstop
@@ -7541,7 +7576,8 @@ proc prefsok {} {
     if {$maxwidth != $oldprefs(maxwidth)
 	|| $maxgraphpct != $oldprefs(maxgraphpct)} {
 	redisplay
-    } elseif {$showneartags != $oldprefs(showneartags)} {
+    } elseif {$showneartags != $oldprefs(showneartags) ||
+	  $limitdiffs != $oldprefs(limitdiffs)} {
 	reselectline
     }
 }
@@ -7869,6 +7905,7 @@ set showneartags 1
 set maxrefs 20
 set maxlinelen 200
 set showlocalchanges 1
+set limitdiffs 1
 set datetimeformat "%Y-%m-%d %H:%M:%S"
 
 set colors {green red blue magenta darkgrey brown orange}
@@ -7892,6 +7929,7 @@ if {![file isdirectory $gitdir]} {
     exit 1
 }
 
+set mergeonly 0
 set revtreeargs {}
 set cmdline_files {}
 set i 0
@@ -7899,6 +7937,10 @@ foreach arg $argv {
     switch -- $arg {
 	"" { }
 	"-d" { set datemode 1 }
+	"--merge" {
+	    set mergeonly 1
+	    lappend revtreeargs $arg
+	}
 	"--" {
 	    set cmdline_files [lrange $argv [expr {$i + 1}] end]
 	    break
@@ -7939,6 +7981,40 @@ if {$i >= [llength $argv] && $revtreeargs ne {}} {
     }
 }
 
+if {$mergeonly} {
+    # find the list of unmerged files
+    set mlist {}
+    set nr_unmerged 0
+    if {[catch {
+	set fd [open "| git ls-files -u" r]
+    } err]} {
+	show_error {} . "Couldn't get list of unmerged files: $err"
+	exit 1
+    }
+    while {[gets $fd line] >= 0} {
+	set i [string first "\t" $line]
+	if {$i < 0} continue
+	set fname [string range $line [expr {$i+1}] end]
+	if {[lsearch -exact $mlist $fname] >= 0} continue
+	incr nr_unmerged
+	if {$cmdline_files eq {} || [path_filter $cmdline_files $fname]} {
+	    lappend mlist $fname
+	}
+    }
+    catch {close $fd}
+    if {$mlist eq {}} {
+	if {$nr_unmerged == 0} {
+	    show_error {} . "No files selected: --merge specified but\
+			     no files are unmerged."
+	} else {
+	    show_error {} . "No files selected: --merge specified but\
+			     no unmerged files are within file limit."
+	}
+	exit 1
+    }
+    set cmdline_files $mlist
+}
+
 set nullid "0000000000000000000000000000000000000000"
 set nullid2 "0000000000000000000000000000000000000001"