Development in a Blink » MGrammar

10 PowerShell Posts I Did in 2009

Doug Finke — Fri, 01 Jan 2010 20:05:15 +0000

I had fun doing these PowerShell posts.

Try PowerShell – An Interactive Tutorial	Michael Foord inspired this with his Try Python Silverlight application
How to Host PowerShell in a WPF Application	A How To video
PowerShell Out-ExcelPivotTable – Quickly Create Pivot Tables in Microsoft Excel	Automating Excel Pivot tables with PowerShell
PowerShell, An Exercise in Species Barcoding	Inspired by Peter Norvig’s (Director of research at Google) python version
PowerShell – Find the K most common words in a file	Based on Jon Bentley’s approach in “Little Languages”
PowerShell ISE-Cream – Alias Expansion	Uses PowerShell’s tokenizer to expand aliases like %, ? etc. into ForEach and Where
Update: Dynamic GUIs and the PowerShell Pipeline	How to inject GUIs into a PowerShell Pipeline
PowerShell yUML Workbench	yUML is a web service. A How To using PowerShell to generate UML diagrams
PowerShell, PowerBoots and an Oslo DSL Grammar	Blending MGrammar and PowerShell
Creating and Displaying Trigrams with PowerShell	Based on Wolfram\|Alphas Trigram visuals. Combines PowerShell and yUML

Parsing JSON with Oslo’s MGrammar

Doug Finke — Fri, 17 Apr 2009 02:34:12 +0000

Thanks to Kalani, friend and colleague, for great discussions on this, S-expressions and more.

This MGrammar Parses

This JSON example

Download MGrammar Code

Kris Horrocks, Oslo product planner, shows off his Oslo DSL for X10 Home Automation devices

Doug Finke — Wed, 25 Mar 2009 01:28:59 +0000

Kris goes the whole nine yards implementing the MGrammar, Intellipad syntax highlighting and Intellipad X10 Mode.

He chose this example for several reasons, one of them being:

Not Enterprise: Oslo has value to application development in general, not just enterprise application development

Where is the MGrammar for C#? …for VB? …for CSV? …for VS solution files? …for XML?

Doug Finke — Sat, 13 Dec 2008 15:34:20 +0000

Paul Vick, formerly language architect for Visual Basic, joined the Oslo team. He has a nice post on Answering some questions about MGrammar….

In general, the Oslo team is just one little team and can only do so much. Although we endeavor to provide you with the maximum number of samples, in truth we are limited in what we can do at any one time. You should expect to see more samples as time goes on. I’ll also note, though, that some of those languages do present interesting challenges to a parser generator. I’ve already covered VB, but XML also has challenges, which I think is really a subject for another entry.

Draw a Spirograph in Logo using MGrammar and WPF

Doug Finke — Sun, 30 Nov 2008 16:01:58 +0000

I ported The Hogg Blog post Creating a Logo / Turtle Graphics Textual DSL using Oslo MGrammar from .NET 4.0 to .NET 3.5 and approximated David Jung’s Logo script in the pared down syntax.

The .NET 4.0 version tweaks the MSBuild (csproj) so it compiles Logo.mg and embeds the mgx file on each run.

I’m trying to get that to work in the port. It is a significant time saver when working with .NET and MGrammars.

References

David Jung posted a Logo Spirograph script, which runs in Microsoft’s new Small Basic. Small Basic has support for Logo.

Download .NET 3.5 Logo Textual DSL

I’ve added a lot of new feeds to my Google Reader

Doug Finke — Wed, 26 Nov 2008 00:06:39 +0000

Oslo, an interesting suite of tools. Working with MGrammar in Intellipad is fantastic. Here’s a list of posts.

Claudio Perrone builds a BDD Grammar in Oslo’s MGrammar

Doug Finke — Sun, 16 Nov 2008 23:19:19 +0000

Claudio Perrone spun up a project to parse plain text stories using the Behavior-Driven Development language. He points out that InnerWorkings experimented with several frameworks for BDD and settled on Cucumber, a Ruby framework.

He hasn’t built a story runner yet for his language and shares the grammar here.

Example BDD input for the parser.

Story: View music chart
As a music fan
I want to browse a list of popular songs
So that I can be motivated to buy something from the catalog

Building Parsers with MGrammar for .Net applications

Doug Finke — Sun, 02 Nov 2008 20:01:59 +0000

MGrammar, part of the M Language, is Microsoft’s new addition for writing textual, domain-specific languages. Combined with Microsoft’s Intellipad, it lowers the barrier for developing DSLs for the .Net platform.

"M" is a core feature of "Oslo" and is a language for textually describing and authoring domains. "M" comprises the following: MGraph, MSchema, and MGrammar. MGraph is for serializing data values to a graph structure similar to syntaxes like JSON. MSchema builds on MGraph by providing a structural type system, extent declarations for storing values, and computed values, which are queries over values and extents. MGrammar is used to describe domain-specific languages in terms of rules that are used to transform input text to MGraph.

The following is right out of Steve Metsker’s book Building Parsers with Java. It is amazing how easy it is to use his grammar shorthand to ramp up with MGrammar.

Example: Designing a Grammar for a Track Robot

The idea is to create a command language for a simple factory. The robot can pick up, place and scan material on different conveyor belts. Here are some example commands for the robot:

   1: pick carrier from LineIn   2: place carrier at DBOut   3: scan DBOut

Grammar Rules

Using the shorthand rules we have this

command = pickcommand | placeCommand | scanCommand;
pickCommand = "pick" "carrier" "from" location;
location = Word;

Intellipad and MGrammar

Create a file called Robot.mg, start Intellipad. Make sure to start Intellipad (Samples Enabled).

Once launched, press Ctrl-Shift-T. In the open file dialog specify the location of Robot.mg. There should be 4 panes.

The middle pane, in MGrammarMode, is where we will define the Robot grammar using MGrammar. The left pane, DynamicParserMode, is where we can type the example commands. The right pane, MGrammarPreviewMode, will contain the parse tree when the example commands are successfully processed by the grammar. The bottom pane, HyperlinkMode, shows errors from either the left pane or middle pane.

As you specify the grammar in the middle, errors will show up in the bottom. For things like invalid MGrammar syntax or errors in your example commands being fed into your grammar.

Productivity

Intellipad is productive. Typing in either the left or middle pane kicks off the cycle. Meaning, it compiles the grammar and takes whatever is in the DynamicParserMode and runs it against your parser. Errors will show up as squiggles and hyperlinked elements in the error pane.

Let’s start by defining the pickCommand. In the DynamicParserMode pane I enter the example command and then flesh out the grammar in the middle.

Here, I use MGrammar’s module, language and syntax keywords. I do not compile the grammar, Intellipad does this as I type, and reports errors as I go. Intellipad also runs the text in the DynamicParserMode pane against the grammar. This streamlines the process. I don’t have to set up a test harness, or compile the grammar or create the code for feeding the commands to my DSL.

Defining the pickCommand

Below I define pickCommand taking the literal “pick”. The MGrammar statement syntax Main = command; kicks off the matching against the process.

Intellipad reports an error showing a red squiggle in my robot command. You can click the error line in the HyperlinkMode window and it will jump to that location.

Add a few more literals to pickCommand and the interleave keyword to handle whitespace.

Notice the the error moves to LineIn in the example command. LineIn is a ‘variable’ and we’ll treat it as a Word. We’ll build this pattern next.

Finishing the pickCommand

Below a few things have been done:

Added another example command
Defined Word and added it to our pickCommand syntax
Indicated in Main that commands can be 1 or more with the + sign

Our grammar compiles, the example commands process and the parsed results appear in the PreviewMode on the right.

The Full Robot Grammar

Next Steps

This is just scratching the surface. Both Intellipad and MGrammar have far more to explore. Intellipad is highly customizable. Its use of IronPython is just one way to extend it. MGrammar also supports modularity, advanced grammar techniques, including parameterization and recursion and custom projections.

Next we need to use the language in a .Net application. This requires the mgx compiler, and new namespaces, System.Dataflow and Microsoft.M.Grammar.

Source for Robot Grammar

module RobotLibrary{    language Robot    {                syntax command             = pickCommand             | placeCommand             | scanCommand;                    syntax pickCommand             = "pick" "carrier" "from" Word;         syntax placeCommand             = "place" "carrier" "at" Word;         syntax scanCommand             = "scan" Word;                token Word = ('A'..'Z' | 'a'..'z')+;                syntax Main = command+;        interleave Whitespace = " " | "\r" | "\n";    }}

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