canvas: work around Bash <= 4.1 for arithmetic recursion (fixup d56c7d2)

Author: akinomyoga

docs/ChangeLog.md

@@ -105,7 +105,7 @@
 - make: save commit id and branch name with `git archive` (requested by LecrisUT, blackteahamburger) `#D2290` 31f264ad
 - edit: revert edits with widget `discard-line` (reported by dezza) `#D2301` 3b2b4b81
 - vi_nmap: fix cursor position after <kbd>C-o</kbd> `#D2302` c106239a
-- decode (`ble-bind`): initialize specified keymaps (motivated by quantumfrost) `#D2324` xxxxxxxx
+- decode (`ble-bind`): initialize specified keymaps (motivated by quantumfrost) `#D2324` 66e450d7
 
 ## Fixes
 
@@ -231,7 +231,7 @@
   - histdb: support `top`, `stats`, `calendar`, and `week` `#D2167` 4d7dd1ee
   - histdb: unify the color palette selection `#D2167` 4d7dd1ee
   - histdb: fix the seasonal default palette names `#D2289` 4fee44e6
-  - histdb: fix the error with missing current working directory `#D2323` xxxxxxxx
+  - histdb: fix the error with missing current working directory `#D2323` 98985f38
 - contrib/fzf-git: update to be consistent with the upstream (motivated by arnoldmashava) `#D2054` c78e5c9f
 - contrib/layer/pattern: add `{pattern}` layer `#D2074` 449d92ca
 - contrib/fzf-git: fix unsupported command modes (reported by dgudim) `#D2083` ba2b8865
@@ -316,7 +316,7 @@
 - global: avoid raw word splitting `#D2309` b55c4003
 - global: use `ble/util/assign` in more places `#D2312` b0e39732
 - main: show details of the loading time (motivated by tessus, Darukutsu) `#D2313` 3d8f6264
-- canvas: optimize binary search in tables `#D2325` xxxxxxxx
+- canvas: optimize binary search in tables `#D2325` d56c7d2f xxxxxxxx
 
 <!---------------------------------------------------------------------------->
 # ble-0.4.0-devel3

lib/test-bash.sh

@@ -2,7 +2,7 @@
 
 ble-import lib/core-test
 
-ble/test/start-section 'bash' 69
+ble/test/start-section 'bash' 72
 
 # case $word を quote する必要がある条件は?
 
@@ -51,6 +51,22 @@ ble/test/start-section 'bash' 69
   ble/test 'read -r ret <<< $b' ret="/*"
 )
 
+# Arithmetic bugs
+(
+  # BUG bash 3.0..4.1
+  #   && の遅延評価が働かない。従って愚直な条件付き算術式再帰はできない。
+  L='0&&L'
+  if ((40200<=_ble_bash)); then
+    ble/test '((L,1))'
+  else
+    ble/test '! ((L,1))'
+  fi
+
+  i=0 M='i++,M[i>=10]'
+  ble/test '((M,1))'
+  ble/test code:'ret=$i' ret=10
+)
+
 # Variable bugs
 (
   # BUG bash-3.1

note.txt

@@ -7774,9 +7774,12 @@ bash_tips
     ん、bash の内部実装的に sparse だとかどうだとかは関係ない気がする。やはり単
     に遅いということだろう。
 
-    二分探索の while を再帰算術式に変えた方が速度が向上する。51 -> 45 という微
-    妙な向上だが折角分かったことなので実装に適用する事にする。
+    二分探索の while を再帰算術式に変えた方が速度が向上する。51us -> 45us とい
+    う微妙な向上だが折角分かったことなので実装に適用する事にする。
 
+    2025-03-21 bash <= 4.1 以下で無限再帰になってクラッシュするという事が分かっ
+    てしまった。bash <= 4.1 では遅延評価になっていないのだった。workaround とし
+    て再帰変数を配列要素として参照して、添字に条件を指定することにした。
 
   * decode (ble-bind): initialize specified keymaps (motivated by quantumfrost) [#D2324]
     https://github.com/akinomyoga/ble.sh/issues/561

src/canvas.sh

@@ -188,7 +188,7 @@ function ble/unicode/c2w {
     ret=${_ble_unicode_c2w_index[c<0x20000?c>>8:((c>>12)-32+512)]}
     if [[ $ret == *:* ]]; then
       local l=${ret%:*} u=${ret#*:} m
-      local L='_ble_unicode_c2w_ranges[m=(l+u)/2]<=c?(l=m):(u=m),l+1<u&&L'
+      local L='_ble_unicode_c2w_ranges[m=(l+u)/2]<=c?(l=m):(u=m),L[l+1>=u]'
       ((l+1<u&&L))
       ret=${_ble_unicode_c2w[_ble_unicode_c2w_ranges[l]]}
     fi
@@ -260,7 +260,7 @@ function ble/unicode/EmojiStatus {
     ret=$_ble_unicode_EmojiStatus_None
     if ((_ble_unicode_EmojiStatus_xmaybe)); then
       local l=0 u=${#_ble_unicode_EmojiStatus_ranges[@]} m
-      local L='_ble_unicode_EmojiStatus_ranges[m=(l+u)/2]<=code?(l=m):(u=m),l+1<u&&L'
+      local L='_ble_unicode_EmojiStatus_ranges[m=(l+u)/2]<=code?(l=m):(u=m),L[l+1>=u]'
       ((l+1<u&&L))
       ret=${_ble_unicode_EmojiStatus[_ble_unicode_EmojiStatus_ranges[l]]:-0}
     fi
@@ -373,7 +373,7 @@ function ble/util/c2w:emacs {
   fi
 
   local l=0 u=${#_ble_util_c2w_emacs_wranges[@]} m
-  local L='_ble_util_c2w_emacs_wranges[m=(l+u)/2]<=tIndex?(l=m):(u=m),l+1<u&&L'
+  local L='_ble_util_c2w_emacs_wranges[m=(l+u)/2]<=tIndex?(l=m):(u=m),L[l+1>=u]'
   ((l+1<u&&L))
   ((ret=((l&1)==0)?2:1))
   return 0
@@ -393,7 +393,7 @@ function ble/util/c2w:musl {
   fi
 
   local l=0 u=${#_ble_util_c2w_musl_ranges[@]} m
-  local L='_ble_util_c2w_musl_ranges[m=(l+u)/2]<=code?(l=m):(u=m),l+1<u&&L'
+  local L='_ble_util_c2w_musl_ranges[m=(l+u)/2]<=code?(l=m):(u=m),L[l+1>=u]'
   ((l+1<u&&L))
   ret=${_ble_util_c2w_musl[_ble_util_c2w_musl_ranges[l]]}
 }
@@ -585,7 +585,7 @@ function ble/unicode/GraphemeCluster/c2break {
   ((ret>_ble_unicode_GraphemeClusterBreak_MaxCode)) && { ret=0; return 0; }
 
   local l=0 u=${#_ble_unicode_GraphemeClusterBreak_ranges[@]} m
-  local L='_ble_unicode_GraphemeClusterBreak_ranges[m=(l+u)/2]<=code?(l=m):(u=m),l+1<u&&L'
+  local L='_ble_unicode_GraphemeClusterBreak_ranges[m=(l+u)/2]<=code?(l=m):(u=m),L[l+1>=u]'
   ((l+1<u&&L))
 
   ret=${_ble_unicode_GraphemeClusterBreak[_ble_unicode_GraphemeClusterBreak_ranges[l]]:-0}

src/color.sh

@@ -2034,7 +2034,7 @@ function ble/highlight/layer:{selection}/getg {
     # When there are multiple selections, we identify the position of `index`
     # using bisection.
     local l=0 u=$((olen-1)) m
-    local L='osel[m=(l+u)/2]<=index?(l=m):(u=m),l+1<u&&L'
+    local L='osel[m=(l+u)/2]<=index?(l=m):(u=m),L[l+1>=u]'
     ((l+1<u&&L))
 
     # When `l` sits at the end of a selection, check if the next selection