propagate

#!/bin/bash
#
# Propagate include files down the inheritance tree
#

set -e -u -o pipefail -o noclobber
shopt -s nullglob

# Parent dir link regex
PARENT_DIR_LINK_RE='^\.\./\.\./[a-z0-9_]+$'

# .h (C) include file format string
INCLUDE_FORMAT_H="\
#include <%s>
"

# .mk (make) include file format string
INCLUDE_FORMAT_MK="\
include %s
"

# .S.inc (Assembly) include file format string
INCLUDE_FORMAT_S_INC="\
.include \"%s\"
"

# An include file glob -> format string dictionary
declare -r -A GLOB_FORMATS=(
    ["*.h"]="$INCLUDE_FORMAT_H"
    ["*.mk"]="$INCLUDE_FORMAT_MK"
    ["*.S.inc"]="$INCLUDE_FORMAT_S_INC"
)

# A dir -> child dirs dictionary
declare -A DIR_CHILDREN=()
# A dir -> parent dirs dictionary
declare -A DIR_PARENTS=()

# Collect parent -> child and child->parent links
for DIR_PARENT_DIR_LINK in */.parents/*; do
    DIR="${DIR_PARENT_DIR_LINK%/.parents/*}"
    PARENT_DIR_LINK=`readlink "$DIR_PARENT_DIR_LINK"`
    if [[ $PARENT_DIR_LINK =~ $PARENT_DIR_LINK_RE ]]; then
        PARENT_DIR="${PARENT_DIR_LINK#../../}"
        DIR_CHILDREN[$PARENT_DIR]+="${DIR_CHILDREN[$PARENT_DIR]:+ }$DIR"
        DIR_PARENTS[$DIR]+="${DIR_PARENTS[$DIR]:+ }$PARENT_DIR"
    else
        echo "Invalid link $DIR_PARENT_DIR_LINK: $PARENT_DIR_LINK" >&2
        echo "Expecting the link to match $PARENT_DIR_LINK_RE" >&2
        exit 1
    fi
done

# Propagate directory files into its children
# Args: dir
function propagate()
{
    local -r dir="$1"
    local child_dir
    local glob
    local dir_file
    local child_file

    for child_dir in ${DIR_CHILDREN[$dir]:-}; do
        for glob in "${!GLOB_FORMATS[@]}"; do
            for dir_file in "$dir/"$glob; do
                child_file="$child_dir${dir_file#$dir}"
                if [ ! -e "$child_file" ]; then
                    printf "${GLOB_FORMATS[$glob]}" "../$dir_file" \
                                > "$child_file"
                fi
            done
        done
        propagate "$child_dir"
    done
}

# For each directory with children and without parents
for DIR in "${!DIR_CHILDREN[@]}"; do
    if [ -z "${DIR_PARENTS[$DIR]:-}" ]; then
        propagate "$DIR"
    fi
done