Recipes/Metrics/MeasuringJava

Synopsis A few steps using the M3 model to compute basic metrics for a Java project in Eclipse

Details MeasuringClasses MeasuringMethods

Description This is a recipe for computing basic or more advanced metrics from a Java project in Eclipse. We assume:

You have Rascal installed in an Eclipse instance.
You have a Java project in your Eclipse workspace that compiles without errors. Let's call it HelloWorld.

Now we will follow the EASY paradigm:

a library will be used to parse the Java code generating Rascalopedia:AbstractSyntaxTree
the same library will generate a Rascal:Values/Relational model to represent interesting facts between Java source code artifacts
then we can write queries over the generated trees and relations using Rascal:Expressions.

These are a number of recipes for measuring different things about Java:

Examples First we import the basic data types for representing Java. The model is called M3, and its definition is split acros a generic language independent module called Rascal:analysis/m3/Core and a Java specific part called Rascal:lang/java/m3/Core. Have a look at the documentation of these modules later. For now we will go through using them in a few examples.

rascal>import lang::java::m3::Core;
ok

Then we import the API for extracting an M3 model from an Eclipse project.

rascal>import lang::java::jdt::m3::Core;
ok

Calling the following function generates an enormous value representing everything the Eclipse Java compiler knows about this project:

rascal>myModel = createM3FromEclipseProject(|project://example-project|);
M3: m3(|project://example-project|)[
  @annotations={
    <|java+method:///Apple/edible()|,|java+interface:///java/lang/Override|>,
    <|java+method:///Fruit/edible()|,|java+interface:///java/lang/Override|>
  },
  @typeDependency={
    <|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,|java+class:///java/io/PrintStream|>,
    <|java+method:///Apple/edible()|,|java+primitiveType:///boolean|>,
    <|java+method:///Apple/edible()|,|java+interface:///java/lang/Override|>,
    <|java+method:///Fruit/edible()|,|java+primitiveType:///boolean|>,
    <|java+method:///Fruit/edible()|,|java+interface:///java/lang/Override|>,
    <|java+parameter:///HelloWorld/main(java.lang.String%5B%5D)/args|,|java+array:///java/lang/String%5B%5D|>,
    <|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,|java+class:///java/lang/System|>,
    <|java+class:///Apple|,|java+class:///Fruit|>,
    <|java+method:///IFruit/edible()|,|java+primitiveType:///boolean|>,
    <|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,|java+primitiveType:///void|>,
    <|java+parameter:///HelloWorld/main(java.lang.String%5B%5D)/args|,|java+class:///java/lang/String|>,
    <|java+class:///Fruit|,|java+interface:///IFruit|>
  },
  @methodOverrides={
    <|java+method:///Apple/edible()|,|java+method:///IFruit/edible()|>,
    <|java+method:///Fruit/edible()|,|java+method:///IFruit/edible()|>,
    <|java+method:///Apple/edible()|,|java+method:///Fruit/edible()|>
  },
  @names={
    <"IFruit",|java+interface:///IFruit|>,
    <"HelloWorld",|java+class:///HelloWorld|>,
    <"args",|java+parameter:///HelloWorld/main(java.lang.String%5B%5D)/args|>,
    <"edible",|java+method:///Fruit/edible()|>,
    <"out",|java+field:///java/lang/System/out|>,
    <"edible",|java+method:///Apple/edible()|>,
    <"main",|java+method:///HelloWorld/main(java.lang.String%5B%5D)|>,
    <"String",|java+class:///java/lang/String|>,
    <"edible",|java+method:///IFruit/edible()|>,
    <"println",|java+method:///java/io/PrintStream/println(java.lang.String)|>,
    <"Override",|java+interface:///java/lang/Override|>,
    <"System",|java+class:///java/lang/System|>,
    <"Apple",|java+class:///Apple|>,
    <"Fruit",|java+class:///Fruit|>
  },
  @implements={<|java+class:///Fruit|,|java+interface:///IFruit|>},
  @methodInvocation={<|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,|java+method:///java/io/PrintStream/println(java.lang.String)|>},
  @containment={
    <|java+compilationUnit:///src/IFruit.java|,|java+interface:///IFruit|>,
    <|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,|java+parameter:///HelloWorld/main(java.lang.String%5B%5D)/args|>,
    <|java+class:///Fruit|,|java+method:///Fruit/edible()|>,
    <|java+class:///HelloWorld|,|java+method:///HelloWorld/main(java.lang.String%5B%5D)|>,
    <|java+compilationUnit:///src/Fruit.java|,|java+class:///Fruit|>,
    <|java+compilationUnit:///src/HelloWorld.java|,|java+class:///HelloWorld|>,
    <|java+class:///Apple|,|java+method:///Apple/edible()|>,
    <|java+interface:///IFruit|,|java+method:///IFruit/edible()|>,
    <|java+compilationUnit:///src/Apple.java|,|java+class:///Apple|>
  },
  @documentation={},
  @modifiers={
    <|java+interface:///IFruit|,public()>,
    <|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,static()>,
    <|java+class:///Fruit|,abstract()>,
    <|java+method:///Apple/edible()|,public()>,
    <|java+method:///Fruit/edible()|,public()>,
    <|java+class:///Apple|,public()>,
    <|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,public()>,
    <|java+class:///HelloWorld|,public()>,
    <|java+method:///Fruit/edible()|,abstract()>,
    <|java+class:///Fruit|,public()>
  },
  @fieldAccess={<|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,|java+field:///java/lang/System/out|>},
  @messages=[],
  @uses={
    <|project://example-project/src/Apple.java|(28,5,<2,27>,<2,32>),|java+class:///Fruit|>,
    <|project://example-project/src/HelloWorld.java|(71,6,<4,2>,<4,8>),|java+class:///java/lang/System|>,
    <|project://example-project/src/HelloWorld.java|(82,7,<4,13>,<4,20>),|java+method:///java/io/PrintStream/println(java.lang.String)|>,
    <|project://example-project/src/Fruit.java|(51,8,<3,2>,<3,10>),|java+interface:///java/lang/Override|>,
    <|project://example-project/src/Apple.java|(39,8,<4,2>,<4,10>),|java+interface:///java/lang/Override|>,
    <|project://example-project/src/HelloWorld.java|(78,3,<4,9>,<4,12>),|java+field:///java/lang/System/out|>,
    <|project://example-project/src/Fruit.java|(40,6,<2,39>,<2,45>),|java+interface:///IFruit|>,
    <|project://example-project/src/HelloWorld.java|(52,6,<3,25>,<3,31>),|java+class:///java/lang/String|>
  },
  @types={
    <|java+class:///HelloWorld|,class(
      |java+class:///HelloWorld|,
      [])>,
    <|java+class:///Fruit|,class(
      |java+class:///Fruit|,
      [])>,
    <|java+class:///Apple|,class(
      |java+class:///Apple|,
      [])>,
    <|java+method:///IFruit/edible()|,method(
      |java+method:///IFruit/edible()|,
      [],
      boolean(),
      [])>,
    <|java+parameter:///HelloWorld/main(java.lang.String%5B%5D)/args|,array(
      class(
        |java+class:///java/lang/String|,
        []),
      1)>,
    <|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,method(
      |java+method:///HelloWorld/main(java.lang.String%5B%5D)|,
      [],
      void(),
      [array(
          class(
            |java+class:///java/lang/String|,
            []),
          1)])>,
    <|java+method:///Apple/edible()|,method(
      |java+method:///Apple/edible()|,
      [],
      boolean(),
      [])>,
    <|java+method:///Fruit/edible()|,method(
      |java+method:///Fruit/edible()|,
      [],
      boolean(),
      [])>,
    <|java+interface:///IFruit|,interface(
      |java+interface:///IFruit|,
      [])>
  },
  @extends={<|java+class:///Apple|,|java+class:///Fruit|>},
  @declarations={
    <|java+method:///HelloWorld/main(java.lang.String%5B%5D)|,|project://example-project/src/HelloWorld.java|(28,82,<3,1>,<6,2>)>,
    <|java+compilationUnit:///src/IFruit.java|,|project://example-project/src/IFruit.java|(0,48,<1,0>,<4,2>)>,
    <|java+method:///Apple/edible()|,|project://example-project/src/Apple.java|(38,54,<4,1>,<7,2>)>,
    <|java+parameter:///HelloWorld/main(java.lang.String%5B%5D)/args|,|project://example-project/src/HelloWorld.java|(52,13,<3,25>,<3,38>)>,
    <|java+compilationUnit:///src/HelloWorld.java|,|project://example-project/src/HelloWorld.java|(0,113,<1,0>,<7,2>)>,
    <|java+class:///HelloWorld|,|project://example-project/src/HelloWorld.java|(1,111,<2,0>,<7,1>)>,
    <|java+compilationUnit:///src/Apple.java|,|project://example-project/src/Apple.java|(0,96,<1,0>,<9,2>)>,
    <|java+class:///Apple|,|project://example-project/src/Apple.java|(1,94,<2,0>,<9,1>)>,
    <|java+class:///Fruit|,|project://example-project/src/Fruit.java|(1,95,<2,0>,<5,1>)>,
    <|java+interface:///IFruit|,|project://example-project/src/IFruit.java|(1,46,<2,0>,<4,1>)>,
    <|java+compilationUnit:///src/Fruit.java|,|project://example-project/src/Fruit.java|(0,97,<1,0>,<5,2>)>,
    <|java+method:///IFruit/edible()|,|project://example-project/src/IFruit.java|(28,17,<3,1>,<3,18>)>,
    <|java+method:///Fruit/edible()|,|project://example-project/src/Fruit.java|(50,44,<3,1>,<4,34>)>
  }
]

Benefits

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