Current implementation of tcl_encoding uses linear search,
and is rather slow when called hundreds of times. This commit
reimplements it using a lookup table, which is efficiently
calculated on the first run. After that, resolution costs two
calls to [info exists], and one actual fetch from the table.
This is a port of git-gui commit a1c3feb7fac7.
Signed-off-by: Alexander Gavrilov <angavrilov@xxxxxxxxx>
---
gitk | 84 ++++++++++++++++++++++++++++++++++++++++++-----------------------
1 files changed, 54 insertions(+), 30 deletions(-)
diff --git a/gitk b/gitk
index 8cd3171..134df00 100755
--- a/gitk
+++ b/gitk
@@ -9783,39 +9783,63 @@ set encoding_aliases {
{ Big5 csBig5 }
}
-proc tcl_encoding {enc} {
- global encoding_aliases
- set names [encoding names]
- set lcnames [string tolower $names]
- set enc [string tolower $enc]
- set i [lsearch -exact $lcnames $enc]
- if {$i < 0} {
- # look for "isonnn" instead of "iso-nnn" or "iso_nnn"
- if {[regsub {^(iso|cp|ibm|jis)[-_]} $enc {\1} encx]} {
- set i [lsearch -exact $lcnames $encx]
+proc build_encoding_table {} {
+ global encoding_aliases encoding_lookup_table
+
+ # Prepare the lookup list; cannot use lsort -nocase because
+ # of compatibility issues with older Tcl (e.g. in msysgit)
+ set names [list]
+ foreach item [encoding names] {
+ lappend names [list [string tolower $item] $item]
+ }
+ set names [lsort -ascii -index 0 $names]
+ # neither can we use lsearch -index
+ set lnames [list]
+ foreach item $names {
+ lappend lnames [lindex $item 0]
+ }
+
+ foreach grp $encoding_aliases {
+ set target {}
+ foreach item $grp {
+ set i [lsearch -sorted -ascii $lnames \
+ [string tolower $item]]
+ if {$i >= 0} {
+ set target [lindex $names $i 1]
+ break
+ }
+ }
+ if {$target eq {}} continue
+ foreach item $grp {
+ set encoding_lookup_table([string tolower $item]) $target
+ }
}
- }
- if {$i < 0} {
- foreach l $encoding_aliases {
- set ll [string tolower $l]
- if {[lsearch -exact $ll $enc] < 0} continue
- # look through the aliases for one that tcl knows about
- foreach e $ll {
- set i [lsearch -exact $lcnames $e]
- if {$i < 0} {
- if {[regsub {^(iso|cp|ibm|jis)[-_]} $e {\1} ex]} {
- set i [lsearch -exact $lcnames $ex]
- }
+
+ foreach item $names {
+ set encoding_lookup_table([lindex $item 0]) [lindex $item 1]
+ }
+}
+
+proc tcl_encoding {enc} {
+ global encoding_lookup_table
+ if {$enc eq {}} {
+ return {}
+ }
+ if {![info exists encoding_lookup_table]} {
+ build_encoding_table
+ }
+ set enc [string tolower $enc]
+ if {![info exists encoding_lookup_table($enc)]} {
+ # look for "isonnn" instead of "iso-nnn" or "iso_nnn"
+ if {[regsub {^(iso|cp|ibm|jis)[-_]} $enc {\1} encx]} {
+ set enc $encx
}
- if {$i >= 0} break
- }
- break
}
- }
- if {$i >= 0} {
- return [lindex $names $i]
- }
- return {}
+ if {[info exists encoding_lookup_table($enc)]} {
+ return $encoding_lookup_table($enc)
+ } else {
+ return {}
+ }
}
proc gitattr {path attr default} {
--
1.6.0.20.g6148bc
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