Add alias-finder plugin (#7768)

plugins/alias-finder/README.md

+# alias-finder plugin
+
+This plugin searches the defined aliases and outputs any that match the command inputted. This makes learning new aliases easier.
+
+To use it, add `alias-finder` to the `plugins` array of your zshrc file:
+```
+plugins=(... alias-finder)
+```
+
+## Usage
+To see if there is an alias defined for the command, pass it as an argument to `alias-finder`. This can also run automatically before each command you input - add `ZSH_ALIAS_FINDER_AUTOMATIC=true` to your zshrc if you want this.
+
+## Options
+
+- Use `--longer` or `-l` to allow the aliases to be longer than the input (match aliases if they contain the input).
+- Use `--exact` or `-e` to avoid matching aliases that are shorter than the input.
+
+## Examples
+```
+$ alias-finder "git pull"
+gl='git pull'
+g=git
+```
+```
+$ alias-finder "web_search google oh my zsh"
+google='web_search google'
+```
+```
+$ alias-finder "git commit -v"
+gc="git commit -v"
+g=git
+```
+```
+$ alias-finder -e "git commit -v"
+gc='git commit -v'
+```
+```
+$ alias-finder -l "git commit -v"
+gc='git commit -v'
+'gc!'='git commit -v --amend'
+gca='git commit -v -a'
+'gca!'='git commit -v -a --amend'
+'gcan!'='git commit -v -a --no-edit --amend'
+'gcans!'='git commit -v -a -s --no-edit --amend'
+'gcn!'='git commit -v --no-edit --amend'
+```

plugins/alias-finder/alias-finder.plugin.zsh

+alias-finder() {
+  local cmd="" exact="" longer="" wordStart="" wordEnd="" multiWordEnd=""
+  for i in $@; do
+    case $i in
+      -e|--exact) exact=true;;
+      -l|--longer) longer=true;;
+      *) 
+        if [[ -z $cmd ]]; then
+          cmd=$i
+        else
+          cmd="$cmd $i"
+        fi
+        ;;
+    esac
+  done
+  cmd=$(sed 's/[].\|$(){}?+*^[]/\\&/g' <<< $cmd) # adds escaping for grep
+  if [[ $(wc -l <<< $cmd) == 1 ]]; then
+    while [[ $cmd != "" ]]; do
+      if [[ $longer = true ]]; then
+        wordStart="'{0,1}"
+      else
+        wordEnd="$"
+        multiWordEnd="'$"
+      fi
+      if [[ $cmd == *" "* ]]; then
+        local finder="'$cmd$multiWordEnd"
+      else
+        local finder=$wordStart$cmd$wordEnd
+      fi
+      alias | grep -E "=$finder"
+      if [[ $exact = true || $longer = true ]]; then
+        break
+      else
+        cmd=$(sed -E 's/ {0,1}[^ ]*$//' <<< $cmd) # removes last word
+      fi
+    done
+  fi
+}
+
+preexec_alias-finder() {
+  if [[ $ZSH_ALIAS_FINDER_AUTOMATIC = true ]]; then
+    alias-finder $1
+  fi
+}
+
+preexec_functions+=(preexec_alias-finder)