makefile help

makefile-help.sh

#!/bin/bash

# This script displays help information for the Makefile.
# Usage: ./makefile-help.sh Makefile
# Based on https://medium.com/@vildmedpap/make-your-makefile-user-friendly-create-a-custom-make-help-target-88c9ef130879

# Set colors for output
color_off='\033[0m'
example_color='\033[32m'
target_color='\033[36m'
variable_color='\033[93m'
grey='\033[90m'

# https://stackoverflow.com/a/35663407
# two_columns $tabstop $title_color $title $description [$default_color $default]
function two_columns() {
  tabstop=$1
  cols=$(tput cols)
  firstline=0
  while read -r line; do
    if [[ "${firstline}" -eq 0 ]]; then
      header="$3"
      firstline=1
    else
      header=" "
    fi
    printf "  %b%-${tabstop-5}s%b%s\n" "$2" "${header}" "$color_off" "${line}"
  done <<< "$(fold -w$((cols-$tabstop-2)) -s <<< $4)"
  if [ $5 ]; then
    printf "%*c  %b( default: %b)%b\n" "$tabstop" " " "$5" "$6" "$color_off"
  fi
}

# Main function to display help information
help() {
    # Display usage information
    echo "Usage:"
    printf "  make %b[target]%b %b[variables]%b\n\n" "$target_color" "$color_off" "$variable_color" "$color_off"

    # Display targets information
    _help_targets "$1"

    # Display variables information
    _help_variables "$1"

    # Display examples
    _help_examples "$1"
}

# Function to display targets information
_help_targets() {
    local pattern
    pattern='^[a-zA-Z0-9_-]+:\s.*?##.*$'

    echo "Target(s):"
    grep -E "$pattern" "$1" | sort | while read -r line; do
        target=${line%%:*}
        description=${line#*## }
        two_columns 25 "$target_color" "$target" "$description"
    done
    echo ""
}

# Function to display variables information
_help_variables() {
    local pattern
    pattern='^[a-zA-Z0-9_-]+\s*[:?!+]?=.*?##.*$'

    echo "Variable(s):"
    grep -E "$pattern" "$1" | while read -r line; do
        variable=${line%% *}
        default=${line#*= }
        default=${default%%##*}
        description=${line##*## }
        two_columns 25 "$variable_color" "$variable" "$description" "$grey" "$default"
    done
    echo ""
}

# Function to display examples
_help_examples() {
    local pattern
    pattern='^.EXAMPLE\s*:=?\s*(.+)\s*##.*$'

    echo "Example(s):"
    grep -E "$pattern" "$1" | while read -r line; do
        example_cmd="$(printf "%s" "$line" | sed -E "s/${pattern}/\1/")"
        description=${line#*## }
        printf " %b%s%b\n" "$example_color" "$example_cmd" "$color_off"
        two_columns 2 "$color_off" "" "$description"
    done
}

# Call main function
help "$1"

# Return exit code indicating success
exit 0