Update objc-build-scripts

script/bootstrap

@@ -1,11 +1,73 @@
 #!/bin/bash
 
-SCRIPT_DIR=$(dirname "$0")
-cd "$SCRIPT_DIR/.."
+export SCRIPT_DIR=$(dirname "$0")
 
-set -o errexit
+##
+## Configuration Variables
+##
 
-echo "*** Updating submodules..."
-git submodule sync --quiet
-git submodule update --init
-git submodule foreach --recursive --quiet "git submodule sync --quiet && git submodule update --init"
+config ()
+{
+    # A whitespace-separated list of executables that must be present and locatable.
+    : ${REQUIRED_TOOLS="xctool"}
+    
+    export REQUIRED_TOOLS
+}
+
+##
+## Bootstrap Process
+##
+
+main ()
+{
+    config
+
+    if [ -n "$REQUIRED_TOOLS" ]
+    then
+        echo "*** Checking dependencies..."
+        check_deps
+    fi
+
+    local submodules=$(git submodule status 2>/dev/null)
+    if [ -n "$submodules" ]
+    then
+        echo "*** Updating submodules..."
+        update_submodules
+    fi
+}
+
+check_deps ()
+{
+    for tool in $REQUIRED_TOOLS
+    do
+        which -s "$tool"
+        if [ "$?" -ne "0" ]
+        then
+            echo "*** Error: $tool not found. Please install it and bootstrap again."
+            exit 1
+        fi
+    done
+}
+
+bootstrap_submodule ()
+{
+    local bootstrap="script/bootstrap"
+
+    if [ -e "$bootstrap" ]
+    then
+        echo "*** Bootstrapping $name..."
+        "$bootstrap" >/dev/null
+    else
+        update_submodules
+    fi
+}
+
+update_submodules ()
+{
+    git submodule sync --quiet && git submodule update --init && git submodule foreach --quiet bootstrap_submodule
+}
+
+export -f bootstrap_submodule
+export -f update_submodules
+
+main