[PATCH v6] gitk: add external diff file rename detection

["ToBoMi via GitGitGadget" <gitgitgadget@gmail.com>]

From: Tobias Boesch <tobias.boesch@miele.com>

If a file is renamed between commits and an external diff is started
through gitk on the original or the renamed file name,
gitk is unable to open the renamed file in the external diff editor.
It fails to fetch the renamed file from git, because it fetches it
using its original path in contrast to using the renamed path of the
file.
Detect the rename and open the external diff with the original and
the renamed file instead of no file (fetch the renamed file path and
name from git) no matter if the original or the renamed file is
selected in gitk.
Since moved or renamed file are handled the same way do this also
for moved files.

Signed-off-by: Tobias Boesch <tobias.boesch@miele.com>
---
    gitk: add external diff file rename detection
    
    Changes since v1:
    
     * Commit message ident
     * Commit message line length
    
    Changes since v2:
    
     * Removed option for rename detection (Adding GUI options seems to be
       not desired - which is understandable)
     * Rebased on current master of git-for-windows
     * Renamed variables for a better understanding
     * Made rename detection also work when the renamed file is selected in
       gitk
    
    Changes since v3:
    
     * Changed message to use present tense, removed bullet points and
       described changes in imperative mood
    
    Changes sine v4:
    
     * Use a git command to gather the changed file paths rather than
       parsing the text from the diff window panel for efficiency and to
       avoid regex containing the filename as a variable.
     * Change != to ne in string comparison
     * removed extra set of parentheses around &&
     * shorter variable names
    
    Changes sine v5:
    
     * Include filename in rename check. Find only the file and its renamed
       version that is selected in the GUI.
     * Escape special characters in the filename to prevent that they are
       intepreted as part of a regular expression

Published-As: https://github.com/gitgitgadget/git/releases/tag/pr-1774%2FToBoMi%2Fdetect_renamed_files_when_opening_diff-v6
Fetch-It-Via: git fetch https://github.com/gitgitgadget/git pr-1774/ToBoMi/detect_renamed_files_when_opening_diff-v6
Pull-Request: https://github.com/gitgitgadget/git/pull/1774

Range-diff vs v5:

 1:  0d28f189dc3 ! 1:  f1c71e56324 gitk: add external diff file rename detection
     @@ gitk-git/gitk: proc external_diff_get_one_file {diffid filename diffdir} {
      +                            $filepath $diffidfrom $diffidto] $cmd_result.\n\n"
      +    }
      +    set filename [file tail $filepath]
     -+    set regex_ren {\d+\s\d+\s\S+\s\S+\s\S+\s+(\S+)\s+(\S+)}
     -+    set regex_ren [subst -nobackslashes -nocommands $regex_ren]
     -+    if {[regexp -line -- $regex_ren $cmd_result whole_match ren_from ren_to]} {
     ++    set esc_chars {\\ | ? ^ * . $ \[ \] + \( \) \{ \}}
     ++    foreach char $esc_chars {
     ++        set filename [string map [list $char \\$char] $filename]
     ++    }
     ++    set regex_base {\d+\s\d+\s\S+\s\S+\s\S+\s+}
     ++    set regex_ren_from $regex_base[subst -nobackslashes -nocommands {(\S+$filename)\s+(\S+)}]
     ++    set regex_ren_to $regex_base[subst -nobackslashes -nocommands {(\S+)\s+(\S+$filename)}]
     ++    if {[regexp -line -- $regex_ren_from $cmd_result whole_match ren_from ren_to]} {
     ++        if {$ren_from ne {} && $ren_to ne {}} {
     ++            lappend renames $ren_from
     ++            lappend renames $ren_to
     ++        }
     ++    } elseif {[regexp -line -- $regex_ren_to $cmd_result whole_match ren_from ren_to]} {
      +        if {$ren_from ne {} && $ren_to ne {}} {
      +            lappend renames $ren_from
      +            lappend renames $ren_to


 gitk-git/gitk | 54 +++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/gitk-git/gitk b/gitk-git/gitk
index 19689765cde..5d4b0fd3a68 100755
--- a/gitk-git/gitk
+++ b/gitk-git/gitk
@@ -3775,6 +3775,48 @@ proc external_diff_get_one_file {diffid filename diffdir} {
                "revision $diffid"]
 }
 
+proc check_for_renames_in_diff {diffidfrom diffidto filepath} {
+    global nullid nullid2
+
+    if {$diffidfrom eq $nullid} {
+        set rev [list $diffidto -R]
+    } elseif {$diffidfrom eq $nullid2} {
+        set rev [list $diffidto --cached -R]
+    } elseif {$diffidto eq $nullid} {
+        set rev [list $diffidfrom]
+    } elseif {$diffidto eq $nullid2} {
+        set rev [list $diffidfrom --cached]
+    } else {
+        set rev [list $diffidfrom..$diffidto]
+    }
+
+    set renames [list {}]
+    if {[catch {eval exec git diff $rev --find-renames --stat --raw --diff-filter=R} cmd_result]} {
+        error_popup "[mc "Error getting file rename info for file \"%s\" from commit %s to %s." \
+                            $filepath $diffidfrom $diffidto] $cmd_result.\n\n"
+    }
+    set filename [file tail $filepath]
+    set esc_chars {\\ | ? ^ * . $ \[ \] + \( \) \{ \}}
+    foreach char $esc_chars {
+        set filename [string map [list $char \\$char] $filename]
+    }
+    set regex_base {\d+\s\d+\s\S+\s\S+\s\S+\s+}
+    set regex_ren_from $regex_base[subst -nobackslashes -nocommands {(\S+$filename)\s+(\S+)}]
+    set regex_ren_to $regex_base[subst -nobackslashes -nocommands {(\S+)\s+(\S+$filename)}]
+    if {[regexp -line -- $regex_ren_from $cmd_result whole_match ren_from ren_to]} {
+        if {$ren_from ne {} && $ren_to ne {}} {
+            lappend renames $ren_from
+            lappend renames $ren_to
+        }
+    } elseif {[regexp -line -- $regex_ren_to $cmd_result whole_match ren_from ren_to]} {
+        if {$ren_from ne {} && $ren_to ne {}} {
+            lappend renames $ren_from
+            lappend renames $ren_to
+        }
+    }
+    return $renames
+}
+
 proc external_diff {} {
     global nullid nullid2
     global flist_menu_file
@@ -3805,8 +3847,16 @@ proc external_diff {} {
     if {$diffdir eq {}} return
 
     # gather files to diff
-    set difffromfile [external_diff_get_one_file $diffidfrom $flist_menu_file $diffdir]
-    set difftofile [external_diff_get_one_file $diffidto $flist_menu_file $diffdir]
+    set renamed_filenames [check_for_renames_in_diff $diffidfrom $diffidto $flist_menu_file]
+    set rename_from_filename [lindex $renamed_filenames 1]
+    set rename_to_filename [lindex $renamed_filenames 2]
+    if { ($rename_from_filename != {}) && ($rename_to_filename != {}) } {
+        set difffromfile [external_diff_get_one_file $diffidfrom $rename_from_filename $diffdir]
+        set difftofile [external_diff_get_one_file $diffidto $rename_to_filename $diffdir]
+    } else {
+        set difffromfile [external_diff_get_one_file $diffidfrom $flist_menu_file $diffdir]
+        set difftofile [external_diff_get_one_file $diffidto $flist_menu_file $diffdir]
+    }
 
     if {$difffromfile ne {} && $difftofile ne {}} {
         set cmd [list [shellsplit $extdifftool] $difffromfile $difftofile]

base-commit: 14de3eb34435db79c6e7edc8082c302a26a8330a
-- 
gitgitgadget