From 5e75e4044f7f5a70d743af6b47009354ab518c4e Mon Sep 17 00:00:00 2001
From: Tom Ryder <tom@sanctum.geek.nz>
Date: Thu, 6 Dec 2018 11:26:14 +1300
Subject: Refactor bd()/sd() completion a lot

Avoid very many forks; and work around Bash 3.0 bugs with array
behaviour:

    bash-3.0$ nodes=(a b c)
    bash-3.0$ printf '%s\n' "${nodes[@]:1}"
    b
    c
    bash-3.0$ nodes=(a b)
    bash-3.0$ printf '%s\n' "${nodes[@]:1}"

    bash-3.0

Compare:

    bash-5.0$ nodes=(a b c)
    bash-5.0$ printf '%s\n' "${nodes[@]:1}"
    b
    c
    bash-5.0$ nodes=(a b)
    bash-5.0$ printf '%s\n' "${nodes[@]:1}"
    b
    bash-5.0$
---
 bash/bash_completion.d/bd.bash | 50 +++++++++++++++++++++++++++---------------
 bash/bash_completion.d/sd.bash | 47 ++++++++++++++++++++++++++++-----------
 2 files changed, 66 insertions(+), 31 deletions(-)

(limited to 'bash')

diff --git a/bash/bash_completion.d/bd.bash b/bash/bash_completion.d/bd.bash
index 32969522..f6ca3a6b 100644
--- a/bash/bash_completion.d/bd.bash
+++ b/bash/bash_completion.d/bd.bash
@@ -12,38 +12,52 @@ _bd() {
         COMPREPLY[ci++]=$comp
     done < <(
 
-        # Build an array of path nodes, leaf to root
+        # Build an array of path ancestors
         path=$PWD
         while [[ -n $path ]] ; do
-            node=${path##*/}
+
+            # Peel off the leaf of the path
+            ancestor=${path##*/}
             path=${path%/*}
-            [[ -n $node ]] || continue
-            nodes[ni++]=$node
+
+            # Skip if this is a null string; root, trailing/double slash...
+            [[ -n $ancestor ]] || continue
+
+            # Skip the first non-null element (current dir)
+            ((generation++)) || continue
+
+            # Push node onto ancestry list
+            ancestors[ai++]=$ancestor
         done
 
-        # Continue if we have at least two nodes, counting the leaf
-        ((ni > 1)) || return
+        # Continue if we have at least one non-root ancestor
+        ((ai)) || return
 
-        # Shift off the leaf, since it is not meaningful to go "back to" the
-        # current directory
-        nodes=("${nodes[@]:1}")
+        # Add quoted ancestors to new array; for long paths, this is faster than
+        # forking a subshell for `printf %q` on each item
+        while read -d / -r ancestor ; do
+            ancestors_quoted[aqi++]=$ancestor
+        done < <(printf '%q/' "${ancestors[@]}")
 
         # Make matching behave appropriately
         if _completion_ignore_case ; then
             shopt -s nocasematch 2>/dev/null
         fi
 
-        # Iterate through the nodes and print the ones that match the word
-        # being completed, with a trailing slash as terminator
-        for node in "${nodes[@]}" ; do
-            node_quoted=$(printf '%q' "$node")
-            # Check the quoted and unquoted word for matching
-            for match in "$node" "$(printf '%q' "$node")" ; do
-                # Print any match, slash-terminated
+        # Iterate through keys of the ancestors array
+        for ai in "${!ancestors[@]}" ; do
+
+            # Get ancestor and associated quoted ancestor
+            ancestor=${ancestors[ai]}
+            ancestor_quoted=${ancestors_quoted[ai]}
+
+            # If either the unquoted or quoted ancestor matches, print the
+            # unquoted one as a completion reply
+            for match in "$ancestor" "$ancestor_quoted" ; do
                 case $match in
                     ("$2"*)
-                        printf '%s/' "$node"
-                        continue
+                        printf '%s/' "$ancestor"
+                        break
                         ;;
                 esac
             done
diff --git a/bash/bash_completion.d/sd.bash b/bash/bash_completion.d/sd.bash
index 4dc72f31..8adc9810 100644
--- a/bash/bash_completion.d/sd.bash
+++ b/bash/bash_completion.d/sd.bash
@@ -14,25 +14,46 @@ _sd() {
 
         # Make globs expand appropriately
         shopt -s dotglob nullglob
+
+        # Get list of siblings; use trailing slashes to limit to directories
+        # There should always be at least one (self)
+        siblings=(../*/)
+
+        # Strip leading dot-dot-slash and trailing slash
+        siblings=("${siblings[@]#../}")
+        siblings=("${siblings[@]%/}")
+
+        # Add quoted siblings to new array; for large directories, this is
+        # faster than forking a subshell for `printf %q` on each item
+        while read -d / -r sibling ; do
+            siblings_quoted[sqi++]=$sibling
+        done < <(printf '%q/' "${siblings[@]}")
+
+        # Make matching work appropriately
         if _completion_ignore_case ; then
             shopt -s nocasematch 2>/dev/null
         fi
 
-        # Print matching sibling dirs that are not the current dir
-        for sib in ../*/ ; do
-            # Strip leading ../
-            sib=${sib#../}
-            # Strip trailing slash
-            sib=${sib%/}
-            # Skip self
-            [[ $sib != "${PWD##*/}" ]] || continue
-            # Check the quoted and unquoted word for matching
-            for match in "$sib" "$(printf '%q' "$sib")" ; do
-                # Print any match, slash-terminated
+        # Get current dir
+        self=${PWD##*/}
+
+        # Iterate through keys of the siblings array
+        for si in "${!siblings[@]}" ; do
+
+            # Get sibling and associated quoted sibling
+            sibling=${siblings[si]}
+            sibling_quoted=${siblings_quoted[si]}
+
+            # Skip if this sibling looks like the current dir
+            [[ $sibling != "$self" ]] || continue
+
+            # If either the unquoted or quoted sibling matches, print the
+            # unquoted one as a completion reply
+            for match in "$sibling" "$sibling_quoted" ; do
                 case $match in
                     ("$2"*)
-                        printf '%s/' "$sib"
-                        continue
+                        printf '%s/' "$sibling"
+                        break
                         ;;
                 esac
             done
-- 
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