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Fix up javaslang FlavourImpl, modify some derivators to generate slightly more idiomatic code #29

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Feb 18, 2016
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Fix up javaslang FlavourImpl, modify some derivators to generate slightly more idiomatic code #29

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Fix up javaslang FlavourImpl, modify some derivators to generate slig… 
…htly more idiomatic code
  • Loading branch information
@rdegnan
rdegnan committed Feb 13, 2016
commit 2eb44fa9cf071cfdea8c621847094ede02e94280
61 changes: 32 additions & 29 deletions processor/src/main/java/org/derive4j/processor/derivator/CataDerivator.java
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,7 @@
import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;
import javax.lang.model.element.ExecutableElement;
import javax.lang.model.element.Modifier;
import javax.lang.model.element.TypeElement;
import javax.lang.model.element.VariableElement;
Expand Down Expand Up @@ -85,39 +86,41 @@ private DeriveResult<DerivedCodeSpec> functionDispatchImpl(List<DataConstructor>
TypeElement f = FlavourImpl.findF(context.flavour(), utils.elements());
TypeName returnType = TypeName.get(utils.types().getDeclaredType(f,
adt.typeConstructor().declaredType(), adt.matchMethod().returnTypeVariable()));
ExecutableElement abstractMethod = Utils.getAbstractMethods(f.getEnclosedElements()).get(0);

TypeSpec wrapper = TypeSpec.anonymousClassBuilder("")
.addField(FieldSpec.builder(returnType, nameAllocator.get("cata"))
.initializer(CodeBlock.builder().addStatement("$L -> $L.$L($L)",
nameAllocator.get("adt var"), nameAllocator.get("adt var"),
.addSuperinterface(returnType)
.addMethod(MethodSpec.methodBuilder(abstractMethod.getSimpleName().toString())
.addAnnotation(Override.class)
.addModifiers(abstractMethod.getModifiers().stream().filter(m -> m != Modifier.ABSTRACT).collect(Collectors.toList()))
.returns(TypeName.get(adt.matchMethod().returnTypeVariable()))
.addParameter(TypeName.get(adt.typeConstructor().declaredType()), nameAllocator.get("adt var"))
.addStatement("return $L.$L($L)",
nameAllocator.get("adt var"),
adt.matchMethod().element().getSimpleName(),
Utils.joinStringsAsArguments(constructors.stream().map(
constructor ->
constructor.arguments().stream()
.map(DataArguments::getType)
.noneMatch(tm -> utils.types().isSameType(tm, adt.typeConstructor().declaredType()))
Utils.joinStringsAsArguments(constructors.stream().map(constructor ->
constructor.arguments().stream()
.map(DataArguments::getType)
.noneMatch(tm -> utils.types().isSameType(tm, adt.typeConstructor().declaredType()))
? "\n" + constructor.name()
: CodeBlock.builder().add("\n($L) -> $L.$L($L)", Utils.joinStringsAsArguments(Stream.concat(
constructor.arguments().stream().map(DataArgument::fieldName)
.map(fn -> nameAllocator.clone().newName(fn, fn + " field")),
constructor.typeRestrictions().stream().map(TypeRestriction::idFunction).map(DataArgument::fieldName)
.map(fn -> nameAllocator.clone().newName(fn, fn + " field")))),
constructor.name(),
MapperDerivator.mapperApplyMethod(utils, context, constructor),
Utils.joinStringsAsArguments(Stream.concat(
constructor.arguments().stream().map(
argument ->
utils.types().isSameType(argument.type(),
adt.typeConstructor().declaredType())
? "() -> this." + nameAllocator.get("cata")
+ "." + FlavourImpl.functionApplyMethod(utils, context)
+ "(" + nameAllocator.clone().newName(argument.fieldName(), argument.fieldName() + " field") + ")"
: argument.fieldName()),
constructor.typeRestrictions().stream()
.map(TypeRestriction::idFunction)
.map(DataArgument::fieldName)))).build().toString())

)).build()).build()).build();
constructor.arguments().stream().map(DataArgument::fieldName)
.map(fn -> nameAllocator.clone().newName(fn, fn + " field")),
constructor.typeRestrictions().stream().map(TypeRestriction::idFunction).map(DataArgument::fieldName)
.map(fn -> nameAllocator.clone().newName(fn, fn + " field")))),
constructor.name(),
MapperDerivator.mapperApplyMethod(utils, context, constructor),
Utils.joinStringsAsArguments(Stream.concat(
constructor.arguments().stream().map(argument ->
utils.types().isSameType(argument.type(),
adt.typeConstructor().declaredType())
? "() -> " + FlavourImpl.functionApplyMethod(utils, context)
+ "(" + nameAllocator.clone().newName(argument.fieldName(), argument.fieldName() + " field") + ")"
: argument.fieldName()),
constructor.typeRestrictions().stream()
.map(TypeRestriction::idFunction)
.map(DataArgument::fieldName)))).build().toString())
)).build()).build();

MethodSpec cataMethod = MethodSpec.methodBuilder("cata")
.addModifiers(Modifier.PUBLIC, Modifier.STATIC)
Expand All @@ -127,7 +130,7 @@ private DeriveResult<DerivedCodeSpec> functionDispatchImpl(List<DataConstructor>
.addParameters(constructors.stream().map(dc
-> ParameterSpec.builder(cataMapperTypeName(dc), MapperDerivator.mapperFieldName(dc)).build())
.collect(toList()))
.addStatement("return $L.$L", wrapper, nameAllocator.get("cata"))
.addStatement("return $L", wrapper)
.build();

return result(methodSpec(cataMethod));
Expand Down
4 changes: 2 additions & 2 deletions processor/src/main/java/org/derive4j/processor/derivator/FlavourImpl.java
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Expand Up @@ -42,7 +42,7 @@ public static TypeElement findF0(Flavour flavour, Elements elements) {
.Fj(() -> "fj.F0")
.Fugue(() -> Supplier.class.getName())
.Fugue2(() -> "com.google.common.base.Supplier")
.Javaslang(() -> Supplier.class.getName())
.Javaslang(() -> "javaslang.Function0")
.apply(flavour)
);
}
Expand All @@ -54,7 +54,7 @@ public static TypeElement findF(Flavour flavour, Elements elements) {
.Fj(() -> "fj.F")
.Fugue(() -> Function.class.getName())
.Fugue2(() -> "com.google.common.base.Function")
.Javaslang(() -> Function.class.getName())
.Javaslang(() -> "javaslang.Function1")
.apply(flavour)
);
}
Expand Down
24 changes: 12 additions & 12 deletions processor/src/main/java/org/derive4j/processor/derivator/LazyConstructorDerivator.java
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Expand Up @@ -62,9 +62,9 @@ public static DeriveResult<DerivedCodeSpec> derive(AlgebraicDataType adt, Derive
TypeSpec.Builder typeSpecBuilder = TypeSpec.classBuilder(className)
.addModifiers(Modifier.PRIVATE, Modifier.STATIC, Modifier.FINAL)
.addTypeVariables(typeVariableNames)
.addField(FieldSpec.builder(TypeName.get(Object.class), "lock", Modifier.PRIVATE, Modifier.FINAL).initializer("new Object()").build())
.addField(FieldSpec.builder(lazyArgTypeName, "expression", Modifier.PRIVATE).build())
.addField(FieldSpec.builder(typeName, "evaluation", Modifier.PRIVATE, Modifier.VOLATILE).build())
.addField(FieldSpec.builder(TypeName.BOOLEAN, "initialized", Modifier.PRIVATE, Modifier.VOLATILE).build())
.addField(FieldSpec.builder(lazyArgTypeName, "expression", Modifier.PRIVATE, Modifier.FINAL).build())
.addField(FieldSpec.builder(typeName, "evaluation", Modifier.PRIVATE).build())
.addMethod(MethodSpec.constructorBuilder()
.addParameter(ParameterSpec.builder(lazyArgTypeName, lazyArgName).build())
.addStatement("this.expression = $N", lazyArgName).build())
Expand All @@ -73,20 +73,20 @@ public static DeriveResult<DerivedCodeSpec> derive(AlgebraicDataType adt, Derive
.addModifiers(Modifier.PRIVATE)
.returns(typeName)
.addCode(CodeBlock.builder()
.addStatement("$T _evaluation = this.evaluation", typeName)
.beginControlFlow("if (_evaluation == null)")
.beginControlFlow("synchronized (this.lock)")
.addStatement("_evaluation = this.evaluation")
.beginControlFlow("if (_evaluation == null)")
.addStatement("this.evaluation = _evaluation = expression.$L()", Utils.getAbstractMethods(lazyTypeElement.getEnclosedElements()).get(0).getSimpleName())
.addStatement("this.expression = null")
.endControlFlow().endControlFlow().endControlFlow()
.beginControlFlow("if (!initialized)")
.beginControlFlow("synchronized (this)")
.beginControlFlow("if (!initialized)")
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I did not synchronizing on this to avoid potential synchronization issues as the lazy value could potentially be used as a monitor. But then this would probably be bad practice. As a reference, I think Guava Suppliers.memoize does synchronize on this. I need to benchmark if avoiding the creation of the lock Object result in significative performance improvement.

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Good point, I was basing this on Suppliers.memoize, but I did not run any benchmarks — they seem to be trying to avoid making evaluation a volatile but I have no idea if that makes a difference in practice. I will see if I can come up with a benchmark to compare the different implementations.

On Feb 13, 2016, at 10:51 AM, JB Giraudeau [email protected] wrote:

In processor/src/main/java/org/derive4j/processor/derivator/LazyConstructorDerivator.java #29 (comment):

@@ -73,20 +73,20 @@
.addModifiers(Modifier.PRIVATE)
.returns(typeName)
.addCode(CodeBlock.builder()

  •                .addStatement("$T _evaluation = this.evaluation", typeName)

  •                .beginControlFlow("if (_evaluation == null)")

  •                .beginControlFlow("synchronized (this.lock)")
    I did not synchronizing on this to avoid potential synchronization issues as the lazy value could potentially be used as a monitor. But then this would probably be bad practice. As a reference, I think Guava Suppliers.memoize does synchronize on this. I need to benchmark if avoiding the creation of the lock Object result in significative performance improvement.

—
Reply to this email directly or view it on GitHub https://github.com/derive4j/derive4j/pull/29/files#r52831894.

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Suppliers.memoize also implements Serializable (without serializing the cached value) which limit the possible implementation much more than if we don't implement Serializable. I think using an initialized field is therefore not necessary if we don't implement Serializable. Benchmarking synchronization on this is worth it, though.

.addStatement("$T _evaluation = expression.$L()", typeName, Utils.getAbstractMethods(lazyTypeElement.getEnclosedElements()).get(0).getSimpleName())
.addStatement("evaluation = _evaluation")
.addStatement("initialized = true")
.addStatement("return _evaluation")
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the expression was set to null also to free-up memory.

.endControlFlow().endControlFlow().endControlFlow()
.addStatement("return evaluation")
.build())
.build())
.addMethod(
Utils.overrideMethodBuilder(adt.matchMethod().element())
.addStatement("return this.eval().$L($L)", adt.matchMethod().element().getSimpleName(), Utils.asArgumentsStringOld(adt.matchMethod().element().getParameters()))
.addStatement("return eval().$L($L)", adt.matchMethod().element().getSimpleName(), Utils.asArgumentsStringOld(adt.matchMethod().element().getParameters()))
.build());

if (adt.typeConstructor().declaredType().asElement().getKind() == ElementKind.INTERFACE) {
Expand Down
15 changes: 8 additions & 7 deletions .../main/java/org/derive4j/processor/derivator/patternmatching/PatternMatchingDerivator.java
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Expand Up @@ -27,6 +27,7 @@
import com.squareup.javapoet.TypeName;
import com.squareup.javapoet.TypeSpec;
import com.squareup.javapoet.TypeVariableName;
import com.squareup.javapoet.WildcardTypeName;
import java.util.List;
import java.util.function.Function;
import java.util.stream.Collectors;
Expand Down Expand Up @@ -65,27 +66,27 @@ public static DeriveResult<DerivedCodeSpec> derive(AlgebraicDataType adt, Derive
TypeName firstMatchBuilderTypeName = Utils.typeName(totalMatchBuilderClassName,
adt.typeConstructor().typeVariables().stream().map(TypeName::get));

TypeName firstMatchBuilderObjectifiedTypeName = Utils.typeName(totalMatchBuilderClassName,
adt.typeConstructor().typeVariables().stream().map(__ -> ClassName.get(Object.class)));
TypeName firstMatchBuilderWildcardTypeName = Utils.typeName(totalMatchBuilderClassName,
adt.typeConstructor().typeVariables().stream().map(__ -> WildcardTypeName.subtypeOf(Object.class)));

String initialCasesStepFieldName = Utils.uncapitalize(TotalMatchingStepDerivator.totalMatchBuilderClassName(firstConstructor));

FieldSpec.Builder initialCasesStepField = FieldSpec.builder(firstMatchBuilderObjectifiedTypeName, initialCasesStepFieldName)
.addModifiers(Modifier.PRIVATE, Modifier.STATIC, Modifier.FINAL)
.initializer("new $T()",
firstMatchBuilderObjectifiedTypeName);
FieldSpec.Builder initialCasesStepField = FieldSpec.builder(firstMatchBuilderWildcardTypeName, initialCasesStepFieldName)
.addModifiers(Modifier.PRIVATE, Modifier.STATIC, Modifier.FINAL);

MethodSpec.Builder matchFactory = MethodSpec.methodBuilder("cases")
.addModifiers(Modifier.PUBLIC, Modifier.STATIC)
.addTypeVariables(adt.typeConstructor().typeVariables().stream().map(TypeVariableName::get).collect(Collectors.toList()))
.returns(firstMatchBuilderTypeName);

if (adt.typeConstructor().typeVariables().isEmpty()) {
initialCasesStepField
.initializer("new $L()", totalMatchBuilderClassName.simpleName());

matchFactory.addStatement("return $L", initialCasesStepFieldName);
} else {
initialCasesStepField
.addAnnotation(AnnotationSpec.builder(SuppressWarnings.class).addMember("value", "$S", "rawtypes").build());
.initializer("new $L<>()", totalMatchBuilderClassName.simpleName());

matchFactory.addAnnotation(AnnotationSpec.builder(SuppressWarnings.class).addMember("value", "$S", "unchecked").build())
.addStatement("return ($T) $L", firstMatchBuilderTypeName, initialCasesStepFieldName);
Expand Down