nixpkgs/pkgs/test/make-binary-wrapper/golden-test-utils.sh

#!/usr/bin/env bash
# Split a generated C-file into the command used to generate it,
# and the outputted code itself.

# This is useful because it allows input and output to be inside the same file

# How it works:
# - The first line needs to start with '//' (and becomes the command).
# - Whitespace/padding between the comment and the generated code is ignored
# - To write a command using multiple lines, end each line with backslash (\)

# Count the number of lines before the output text starts
# commandLineCount FILE
commandLineCount() {
    local n state
    n=0
    state="init"
    while IFS="" read -r p || [ -n "$p" ]; do
        case $state in
            init)
                if [[ $p =~ ^//.*\\$ ]]; then state="comment"
                elif [[ $p =~ ^//.* ]]; then state="padding"
                else break
                fi
            ;;
            comment) [[ ! $p =~ ^.*\\$ ]] && state="padding";;
            padding) [ -n "${p// }" ] && break;;
        esac
        n=$((n+1))
    done < "$1"
    printf '%s' "$n"
}

# getInputCommand FILE
getInputCommand() {
    n=$(commandLineCount "$1")
    head -n "$n" "$1" | awk '{ if (NR == 1) print substr($0, 3); else print $0 }'
}

# getOutputText FILE
getOutputText() {
    n=$(commandLineCount "$1")
    sed "1,${n}d" "$1"
}