lib/log: Refactor _@go.log_format_level_labels

The updates to `lib/format` from #107 make this function much shorter.
Also, the logic to check the file descriptors was sort of confused and
not really doing anything, at least not anything helpful, since the
decision to print or strip formatting codes is now made per log level
file descriptor in `@go.log`.

Author: mbland

lib/log

@@ -651,57 +651,18 @@ _@go.log_init() {
 
 # Assigns formatted log level labels to __GO_LOG_LEVELS_FORMATTED.
 #
-# If `_GO_LOG_FORMATTING` is not empty, or the file descriptor corresponding to
-# a log level corresponds to a terminal, this will assign a corresponding value
-# wrapped by terminal formatting codes to __GO_LOG_LEVELS_FORMATTED. Otherwise
-# the original label value is assigned.
-#
 # Each element of `__GO_LOG_LEVELS_FORMATTED` will also be padded with trailing
 # spaces so that each element will be the same length.
 #
 # Globals:
 #   _GO_LOG_LEVELS:                    List of valid log level labels
-#   _GO_LOG_FORMATTING                 If set, always produce formatted labels
 #   __GO_LOG_LEVELS_FORMAT_CODES:      Terminal format codes for each log level
-#   __GO_LOG_LEVELS_FILE_DESCRIPTORS:  Output descriptors for each log level
 #   __GO_LOG_LEVELS_FORMATTED:         Formatted labels
 _@go.log_format_level_labels() {
-  local num_levels="${#_GO_LOG_LEVELS[@]}"
-  local label_length
-  local longest_label_length
-  local padding=''
-  local log_level
-  local padding_len
-  local level_var
-  local level_fd
-  local i
-
-  for ((i=0; i != num_levels; ++i)); do
-    label_length="${#_GO_LOG_LEVELS[$i]}"
-    if [[ "$label_length" -gt "$longest_label_length" ]]; then
-      longest_label_length="$label_length"
-    fi
-  done
-
-  for ((i=0; i != longest_label_length; ++i)); do
-    padding+=' '
-  done
-
-  for ((i=0; i != num_levels; ++i)); do
-    log_level="${_GO_LOG_LEVELS[$i]}"
-    padding_len="$((${#padding} - ${#log_level}))"
-
-    local __go_log_level_file_descriptors=()
-    _@go.log_level_file_descriptors "$i"
-
-    for level_fd in "${__go_log_level_file_descriptors[@]}"; do
-      if [[ -n "$_GO_LOG_FORMATTING" || -t "$level_fd" ]]; then
-        log_level="${__GO_LOG_LEVELS_FORMAT_CODES[$i]}$log_level\e[0m"
-        break
-      fi
-    done
-    __GO_LOG_LEVELS_FORMATTED[$i]="${log_level}${padding:0:$padding_len}"
-  done
+  __GO_LOG_LEVELS_FORMATTED=("${_GO_LOG_LEVELS[@]/%/\\e[0m}")
+  @go.pad_items __GO_LOG_LEVELS_FORMATTED "${__GO_LOG_LEVELS_FORMATTED[@]}"
+  @go.zip_items __GO_LOG_LEVELS_FORMAT_CODES __GO_LOG_LEVELS_FORMATTED '' \
+    __GO_LOG_LEVELS_FORMATTED
 }
 
 # Returns the set of file descriptors for the specified log level index.