functions: add parseopts for longopt fun

Signed-off-by: Dave Reisner <dreisner@archlinux.org>

1 files changed, 138 insertions, 0 deletions

diff --git a/functions b/functions
index 5485578..eebf3a4 100644
--- a/functions
+++ b/functions
@@ -1,5 +1,143 @@
 #!/bin/bash
 
+parseopts() {
+    local opt= optarg= i= shortopts=$1
+    local -a longopts=() unused_argv=()
+
+    shift
+    while [[ $1 && $1 != '--' ]]; do
+        longopts+=("$1")
+        shift
+    done
+    shift
+
+    longoptmatch() {
+        local o longmatch=()
+        for o in "${longopts[@]}"; do
+            if [[ ${o%:} = "$1" ]]; then
+                longmatch=("$o")
+                break
+            fi
+            [[ ${o%:} = "$1"* ]] && longmatch+=("$o")
+        done
+
+        case ${#longmatch[*]} in
+            1)
+                # success, override with opt and return arg req (0 == none, 1 == required)
+                opt=${longmatch%:}
+                if [[ $longmatch = *: ]]; then
+                    return 1
+                else
+                    return 0
+                fi ;;
+            0)
+                # fail, no match found
+                return 255 ;;
+            *)
+                # fail, ambiguous match
+                error "option '%s' is ambiguous; possibilities:%s" \
+                    "--$1" "$(printf " '%s'" "${longmatch[@]%:}")"
+                return 254 ;;
+        esac
+    }
+
+    while (( $# )); do
+        case $1 in
+            --) # explicit end of options
+                shift
+                break
+                ;;
+            -[!-]*) # short option
+                for (( i = 1; i < ${#1}; i++ )); do
+                    opt=${1:i:1}
+
+                    # option doesn't exist
+                    if [[ $shortopts != *$opt* ]]; then
+                        error "invalid option '%s'" "$opt"
+                        OPTRET=(--)
+                        return 1
+                    fi
+
+                    OPTRET+=("-$opt")
+                    # option requires optarg
+                    if [[ $shortopts = *$opt:* ]]; then
+                        # if we're not at the end of the option chunk, the rest is the optarg
+                        if (( i < ${#1} - 1 )); then
+                            OPTRET+=("${1:i+1}")
+                            break
+                        # if we're at the end, grab the the next positional, if it exists
+                        elif (( i == ${#1} - 1 )) && [[ $2 ]]; then
+                            OPTRET+=("$2")
+                            shift
+                            break
+                        # parse failure
+                        else
+                            error "option '%s' requires an argument" "-$opt"
+                            OPTRET=(--)
+                            return 1
+                        fi
+                    fi
+                done
+                ;;
+            --?*=*|--?*) # long option
+                IFS='=' read -r opt optarg <<< "${1#--}"
+                longoptmatch "$opt"
+                case $? in
+                    0)
+                        if [[ $optarg ]]; then
+                            error "option '%s' does not allow an argument" "--$opt"
+                            OPTRET=(--)
+                            return 1
+                        else
+                            OPTRET+=("--$opt")
+                            shift
+                            continue 2
+                        fi
+                        ;;
+                    1)
+                        # --longopt=optarg
+                        if [[ $optarg ]]; then
+                            OPTRET+=("--$opt" "$optarg")
+                            shift
+                        # --longopt optarg
+                        elif [[ $2 ]]; then
+                            OPTRET+=("--$opt" "$2" )
+                            shift 2
+                        else
+                            error "option '%s' requires an argument" "--$opt"
+                            OPTRET=(--)
+                            return 1
+                        fi
+                        continue 2
+                        ;;
+                    254)
+                        # ambiguous option -- error was reported for us by longoptmatch()
+                        OPTRET=(--)
+                        return 1
+                        ;;
+                    255)
+                        error "invalid option '%s'" "--$opt"
+                        OPTRET=(--)
+                        return 1
+                        ;;
+                    *)
+                        error "internal error: invalid option in longopt array '%s'" "--$opt"
+                esac
+                ;;
+            *) # non-option arg encountered, add it as a parameter
+                unused_argv+=("$1")
+                ;;
+        esac
+        shift
+    done
+
+    # add end-of-opt terminator and any leftover positional parameters
+    OPTRET+=('--' "${unused_argv[@]}" "$@")
+    unset longoptmatch
+
+    return 0
+}
+
 plain() {
     local mesg=$1; shift
     printf "$BOLD    $mesg$NC\n" "$@" >&1