Support 'tapas help' for more-detailed tapas help

Bug: 64844028
Test: tapas help
Change-Id: I5629ca781e8cacfa6bb09828acf4160bbca3c3a5

envsetup.sh

@@ -644,11 +644,17 @@ complete -F _lunch lunch
 # Run tapas with one or more app names (from LOCAL_PACKAGE_NAME)
 function tapas()
 {
+    local showHelp="$(echo $* | xargs -n 1 echo | \grep -E '^(help)$' | xargs)"
     local arch="$(echo $* | xargs -n 1 echo | \grep -E '^(arm|x86|mips|armv5|arm64|x86_64|mips64)$' | xargs)"
     local variant="$(echo $* | xargs -n 1 echo | \grep -E '^(user|userdebug|eng)$' | xargs)"
     local density="$(echo $* | xargs -n 1 echo | \grep -E '^(ldpi|mdpi|tvdpi|hdpi|xhdpi|xxhdpi|xxxhdpi|alldpi)$' | xargs)"
     local apps="$(echo $* | xargs -n 1 echo | \grep -E -v '^(user|userdebug|eng|arm|x86|mips|armv5|arm64|x86_64|mips64|ldpi|mdpi|tvdpi|hdpi|xhdpi|xxhdpi|xxxhdpi|alldpi)$' | xargs)"
 
+    if [ "$showHelp" != "" ]; then
+      $(gettop)/build/make/tapasHelp.sh
+      return
+    fi
+
     if [ $(echo $arch | wc -w) -gt 1 ]; then
         echo "tapas: Error: Multiple build archs supplied: $arch"
         return

tapasHelp.sh

@@ -0,0 +1,23 @@
+#!/bin/bash
+
+# locate some directories
+cd "$(dirname $0)"
+SCRIPT_DIR="${PWD}"
+cd ../..
+TOP="${PWD}"
+
+message='usage: tapas [<App1> <App2> ...] [arm|x86|mips|armv5|arm64|x86_64|mips64] [eng|userdebug|user]
+
+tapas selects individual apps to be built by the Android build system. Unlike
+"lunch", "tapas" does not request the building of images for a device.
+Additionally, an app built with "tapas" will have its dex file inside its apk,
+which should cause it to be suitable for installing on any api-compatible
+device. In other words, "tapas" configures the build of unbundled apps.
+
+The names <App1> <App2> ... should match LOCAL_PACKAGE_NAME as defined in an
+Android.mk
+
+The usage of the other arguments matches that of the rest of the platform
+build system and can be found by running `m help`'
+
+echo "$message"