DEBUGGING DSLS WITH XTEXTS NEW TRACING API 1 Debugging of - - PowerPoint PPT Presentation

DEBUGGING DSLS WITH XTEXT’S NEW TRACING API

1

Christian Schneider, Miro Spönemann
 TypeFox.io

Debugging of Generated Code

What’s needed?

• Mapping of code regions in source 


to code regions in target

• Data structures implemented in org.eclipse.xtext

What’s already there?

• Xtext maps AST elements to


code regions in source

What’s missing?

• Mapping of AST elements to code regions in target

public class Debugging { public static void main(final String[] args) throws Throwable { IntegerRange _upTo = new IntegerRange(2, 100); final List<Integer> candidates = IterableExtensions.<Integer>toList(_upTo); List<Integer> _immutableCopy = ImmutableList.<Integer>copyOf(candidates); final Function1<Integer, Boolean> _function = new Function1<Integer, Boolean>() { @Override public Boolean apply(final Integer i) { return Boolean.valueOf(candidates.contains(i)); } }; Iterable<Integer> _filter = IterableExtensions.<Integer>filter(_immutableCopy final Function2<List<Integer>, Integer, List<Integer>> _function_1 = new Function2<List<Integer>, Integer, List<Integer>>() { @Override public List<Integer> apply(final List<Integer> res, final Integer i) { final Function1<Integer, Boolean> _function = new Function1<Integer, Boolean>() { @Override public Boolean apply(final Integer j) { return Boolean.valueOf((((j).intValue() % (i).intValue()) == 0)); } }; Iterable<Integer> _filter = IterableExtensions.<Integer>filter(candidates final List<Integer> sieved = IterableExtensions.<Integer>toList(_filter Iterables.removeAll(res, sieved); return res; } }; List<Integer> _fold = IterableExtensions.<Integer, List<Integer>>fold(_filter String _join = IterableExtensions.join(_fold, ", "); InputOutput.<String>println(_join); InputOutput.<String>println("done"); }

Requirements

• API for tracing code regions in code generators
• Should integrate nicely with Xtend’s template

expressions

• Trace code regions per eObject
• Attributes:


Distinguish code regions corresponding to attributes

• Containment:


Distinguish code regions corresponding to children

XTEND

def foo(Object parameter) ''' Code code «parameter» code code with leading white space «IF guard» guard is satisfied code «ELSE» guard is missed code «ENDIF» «FOR element : list» element «element.name» code: more element specific code «ENDFOR» ''' @Accessors @FinalFieldsConstructor class Foo implements Bar { @Delegate val Bar bar } def String name(Object o) { ... }

http://xtend-lang.org

Example

https://github.com/TypeFox/tracing_codegen

Model: types+=ClassDeclaration*; ClassDeclaration: 'class' name=ID '{' members+=Member* '}'; Member: Property | Operation; Property: name=ID ':' type=TypeRef; Operation: name=ID '(' parameters+=Parameter* ')' ':' type=TypeRef '{' expression=Expression? '}'; class Person { name: string bag: Bag getCash(): number { bag.wallet.cash } }

class MyDslGenerator extends AbstractGenerator {

• verride void doGenerate(Resource resource,

IFileSystemAccess2 fsa, IGeneratorContext context) { val model = resource.contents.head as Model val baseName = resource.baseName fsa.generateFile(baseName + '.h', ''' /******************************** * Header file for «resource.URI.lastSegment» */ #ifndef «baseName.toUpperCase»_H #define «baseName.toUpperCase»_H «FOR c : model.types» «generateHeader(c)» «ENDFOR» #endif ''') } }

class MyDslGenerator extends AbstractGenerator {

• verride void doGenerate(Resource resource,

IFileSystemAccess2 fsa, IGeneratorContext context) { val model = resource.contents.head as Model val baseName = resource.baseName fsa.generateTracedFile(baseName + '.h', model, ''' /******************************** * Header file for «resource.URI.lastSegment» */ #ifndef «baseName.toUpperCase»_H #define «baseName.toUpperCase»_H «FOR c : model.types» «generateHeader(c)» «ENDFOR» #endif ''') } }

protected def generateHeader(ClassDeclaration decl) ''' /* * Declaration of «decl.name» class */ struct «decl.name» { «FOR prop : decl.members.filter(Property)» /* Property «decl.name».«prop.name» */ «generateDeclaration(prop)» «ENDFOR» }; '''

@Traced protected def generateHeader(ClassDeclaration decl) ''' /* * Declaration of «decl.name» class */ struct «decl.name» { «FOR prop : decl.members.filter(Property)» /* Property «decl.name».«prop.name» */ «generateDeclaration(prop)» «ENDFOR» }; '''

@Traced protected def generateHeader(ClassDeclaration decl) ''' /* * Declaration of «decl.name» class */ struct «decl._name» { «FOR prop : decl.members.filter(Property)» /* Property «decl.name».«prop.name» */ «generateDeclaration(prop)» «ENDFOR» }; '''

ClassDeclaration: 'class' name=ID '{' members+=Member* '}'; @TracedAccessors(MyDslFactory) class MyDslTraceExtensions {}

ClassDeclaration name: String members: Member[] MyDslFactory createClassDeclaration() …

Xtext + EMF public IGeneratorNode _name(ClassDeclaration target) {…} Xtend Annotation Processor @Inject extension MyDslTraceExtensions

The Generator Tree

double __local_2 = __local_1

• >

cash ;

double __local_2 = __local_1->cash;

double __local_2 = __local_1

• >

cash ;

AST

Location Location Location

The Generator Tree

Building a Generator Tree

val node = trace(expression) node.append(generateType(expression.feature.type)) node.append(' ') node.append(resultVar) node.append(' = ') node.append(receiverVar ?: 'this') node.append('->') node.append(expression.feature.name)

Demo

What else?

• What if debugging the DSL is not possible?
• Feeding back changes in target to the source is

strongly recommended

What else?

https://github.com/TypeFox/tracing_codegen

To Go Further

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