feat(nanotimer): New nanotimer plugin

plugins/nanotimer/nanotimer.plugin.zsh

@@ -0,0 +1,70 @@
+#!/usr/bin/env zsh
+
+## nanotimer - Oh-My-Zsh plugin
+##
+## Utilizes the 'preexec' and 'precmd' hooks. Timer is setup during 'preexec', and stopped at
+## 'precmd'. This time difference is very accurate, and is displayed in the right prompt.
+##
+## More information about hooks like 'preexec' and 'precmd', and many others:
+## https://zsh.sourceforge.io/Doc/Release/Functions.html#index-hook-functions
+
+## * __exectimer_preexec()
+## Executed just after a command has been read and is about to be executed. This hook is used to
+## start a high-precision timer before command execution. Additional tasks can be completed in this
+## function; for example, update active network interface. By doing that here, it ensures the
+## network interface stays updated.
+__exectimer_preexec() {
+  timer=$(($(date +%s%0N)))
+}
+
+## * __exectimer_precmd()
+## Executed before each prompt, or in other words, after previous command. Stops the timer from
+## 'preexec', and updates rprompt with elapsed time. This is modified for higher precision from the
+## following code snippet: https://gist.github.com/knadh/123bca5cfdae8645db750bfb49cb44b0
+__exectimer_precmd() {
+  if [ $timer ]; then
+    now=$(($(date +%s%0N)))
+    elapsed=$(($now-$timer))
+
+    # Unset elapsed variables to make below syntax work (work-around to prevent more work)
+    unset elns elmcs elms els
+
+    # Depending on digits in nanoseconds, set the elapsed milliseconds, seconds etc.
+    # I should document this more later as ZSH syntax is kinda weird sometimes.
+    case ${#elapsed} in
+      [0-3])
+        elns=$elapsed
+        ;;
+      [4-6])
+        elapsed=${elapsed%${elns=${elapsed:(-3):3}}}
+        elmcs=$elapsed
+        ;;
+      [7-9])
+        elapsed=${elapsed%${elns=${elapsed:(-3):3}}}
+        elapsed=${elapsed%${elmcs=${elapsed:(-3):3}}}
+        elms=$elapsed
+        ;;
+      *)
+        elapsed=${elapsed%${elns=${elapsed:(-3):3}}}
+        elapsed=${elapsed%${elmcs=${elapsed:(-3):3}}}
+        elapsed=${elapsed%${elms=${elapsed:(-3):3}}}
+        els=$elapsed
+        ;;
+    esac
+
+    # Zero values for all, when e.g. under a second execution.
+    for v in elns elmcs elms els; do
+      [[ ! "${(P)v}" =~ ^[0-9]+$ ]] && read $v <<< $((0))
+    done
+
+    # Set right prompt and reset timer.
+    export RPROMPT="%(?.%F{195}[%?].%S%B%F{009}[%?]%b%s) %F{215}%B${els}%b%F{250}s %F{192}%B${elms}%b%F{250}ms %F{194}%B${elmcs}%b%F{250}μs %F{231}%B${elns}%b%F{250}ns%{$reset_color%}"
+
+    unset timer
+  fi
+}
+
+# Add functions to Zsh hooks.
+autoload -U add-zsh-hook
+add-zsh-hook preexec __exectimer_preexec
+add-zsh-hook precmd __exectimer_precmd