AAML: The Simplest Markup Language for Android

You may find this stupid, but I do not like the IDE. Usually I do all the work in vim + tmux + terminal. I recognize all the advantages of the IDE, it’s just more convenient for me in a good text editor. But this is not about that.

When I write something for android, I often edit XML (markup, styles, lines, ...). So in a text editor, this is not very convenient. And I decided to spend a couple of hours and write an XML generator based on a simplified markup language (such as lesscss or stylus for CSS). Still, NIH is a very seductive stimulus.

The AAML language (another android markup language) turned out with a very simple syntax. Elements begin with a colon. Commas (or line breaks) separate attributes. Tabs (or spaces, or both) determine the nesting of elements. Comments begin with a pound. Some simple layout looks like this:

# Main layout
:LinearLayout layout fill, padding 0dp 16dp, orientation vertical
        :EditText
                layout fill wrap
                hint @string/to
        :EditText
                layout fill wrap
                hint @string/subject
        :EditText
                layout fill 0dp 1
                gravity top
                hint @string/message
        :Button#btn_send
                layout 100dp wrap
                gravity right
                text @string/send

Such AAML markup compiles into:

<?xml version="1.0" encoding="utf-8"?><!-- Main layout --><LinearLayoutxmlns:android="http://schemas.android.com/apk/res/android"android:layout_width="fill_parent"android:layout_height="fill_parent"android:paddingTop="0dp"android:paddingRight="16dp"android:paddingBottom="0dp"android:paddingLeft="16dp"android:orientation="vertical"><EditTextandroid:layout_width="fill_parent"android:layout_height="match_parent"android:hint="@string/to" /><EditTextandroid:layout_width="fill_parent"android:layout_height="match_parent"android:hint="@string/subject" /><EditTextandroid:layout_width="fill_parent"android:layout_height="0dp"android:layout_weight="1"android:gravity="top"android:hint="@string/message" /><Buttonandroid:id="@+id/btn_send"android:layout_width="100dp"android:layout_height="match_parent"android:gravity="right"android:text="@string/send" /></LinearLayout>

The DRY principle also supports macros and aliases. Aliases allow you to set a new name for something - an attribute (to write “wrap” instead of “wrap_content”), a value (to determine the color or size of the font once and use the alias as the name of the variable), etc.

Macros take a number of arguments. True, names cannot be given to arguments (and macros are supposed to be only the simplest). Instead, positional arguments are used, as in Bash ($ 1, $ 2, $ 3, etc.). Here are the macros and aliases used in the example above:

# Алиасы
:def wrap wrap_content
:def fill match_parent
:def match match_parent
# Макросы
:def layout:3 layout_widht $1, layout_height $2, layout_weight $3
:def layout:2 layout_widht $1, layout_height $2
:def layout:1 layout $1$1
:def padding:4 paddingTop $1, paddingRight $2, paddingBottom $3, paddingLeft $4
:def padding:2 padding $1$2$1$2
:def padding:1 padding $1$1

Probably, such macros should be made standard for different types of XML (for layout - one, for strings - others, etc.)

AAML is written in python. It has no dependencies, there are only 200 lines of code there. It works in two modes - it converts a * .aaml file to * .xml or recursively processes all files from one folder and puts the resulting xml into another. This is convenient if you create aaml / layout, aaml / values, aaml / xml and add the results to res / layout, etc.

To automate this process, you can create custom_rules.xml:

<?xml version="1.0" encoding="UTF-8"?><project><targetname="-pre-build"><execexecutable="aaml"><argvalue="aaml"/><argvalue="res"/></exec></target></project>

Now aaml will be converted to xml every time you build the project automatically.

Sources are located at bitbucket: bitbucket.org/zserge/aaml
License - MIT.

At the end of the post I have a question for the Khabrovsk residents - is it worth developing this project? Are there any other freaks that write XML manually? If so, then any suggestions, feature requests, comments, bugs, criticism are welcome.