B4J Code Snippet Simple Macros: An Modest Hack

Recently there was a post about sum++.

It made me think. Not really about ++ and -- but about a lot of code sections that we all repeatedly type.
So simple macros. A single variable name as an parameter and one or more lines of generated code.
Because of the fx.Clipboard object, it is most convenient to implement it in B4J (but using the Log instead, could be done in B4A and B4i)

For this to be useful, the amount of typing has to be minimal. I chose the following schema, but you can make your own.
To stop the IDE from complaining I start a macro with a single quote. This is followed by the name of the variable.
And this is immediately followed by the name of the macro.

In my scheme the macro names are two or three characters from the top of a standard keyboard.
(Loosely: ^=initialize *=list @=map ~=stringbuilder)

The generated code is shown below the macro reference in the examples.

    x = x + 1

    y = y - 1

    Dim sb As StringBuilder

    Dim bList As List
    For i = 0 To bList.Size - 1


    For i = bList.Size - 1 To 0 Step -1

    For Each str As String In bList

    Dim aMap As Map
    For Each str As String In aMap.Keys


To use it:
1. Register a Macro - add it to the smart string in "Private Sub registerMacros"
2. Highlight the macro reference - Cntl C to copy to clipboard
3. Run applyMacros (this can be done each time you need it or for a cluster of macros)
4. Paste the generated code (You can leave the macro reference or delete it)

Non-macro lines on the clipboard are ignored, it doesn't hurt to include them on the clipboard.

Private Sub registerMacros
    macros.Initialize        'macros is a global map
    Dim m As String = $"
++    ? = ? + 1
--    ? = ? - 1
*^    Dim ? As List|?.Initialize
@^    Dim ? As Map|?.Initialize
~^    Dim ? As StringBuilder|?.Initialize
*+    For i = 0 To ?.Size - 1||Next
*-    For i = ?.Size - 1 To 0 Step -1||Next
()+    For i = 0 To ?.Length - 1||Next
()-    For i = ?.Length - 1 To 0 Step -1||Next
*i    For Each itm As Int In ?||Next
*o    For Each obj As Object In ?||Next
*s    For Each str As String In ?||Next
@i    For each itm As Int In ?.Keys||Next
@o    For each obj As Object In ?.Keys||Next
@s    For each str As String In ?.Keys||Next
    Dim v() As String = Regex.Split(CRLF, m)
    For Each s As String In v
        s = s.trim
        If s.Length > 0 Then
            Dim w() As String = Regex.Split(TAB, s)
            macros.Put(w(0), w(1))
        End If
End Sub

Private Sub applyMacros
    Dim s As String = fx.clipboard.GetString
    Dim v() As String = Regex.Split(CRLF, s)
    Dim sb As StringBuilder
    For Each t As String In v
        t = t.trim
        If t.StartsWith("'") Then
            For Each kw As String In macros.keys
                If t.EndsWith(kw) Then
                    Dim vname As String = t.SubString2(1, t.IndexOf(kw))
                    Dim g As String = macros.Get(kw)
                    sb.Append(TAB).Append(g.replace("?", vname).Replace("|", CRLF)).Append(CRLF)
                End If
        End If
    fx.clipboard.SetString(sb.toString)        'fx needs to be defined in global
    'You could also put sb.toString on the Log and cut and paste from there when needed.
End Sub

If you're offended by the ugliness of this hack, turn your eyes away and ignore it.
Or offer something more elegant.

William Lancee

Well-Known Member
Licensed User
Longtime User
I have transferred the macro parser and macro collection to it's own app/form.
I made this form small and put it at the top of the screen. It is just two buttons.
The form is a standard B4J app and is activated by running Macros.b4j in the attached zip file.
When the small form is visible, minimize the app's B4J IDE and then you can use the button in any of other B4X app's IDE.

The Apply Copied Macro button converts what's on the clipboard to the rendered macro and puts the result back on the clipboard.
The X button simply closes that form - which you don't need to do until you've done with all macros. Before clicking button1, copy the macro to the Clipboard. After Clicking, paste the result in the code window.

It is simple, efficient, cross-platform, and it is slightly less ugly.



  • macros.zip
    8.9 KB · Views: 112
Last edited: