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@ -1,23 +1,3 @@
# Assignment 03
## Lecture 12
Student: Claudio Maggioni
## Use of AI assistants / LLMs
I declare that I used the following AI assistants / LLMs (put an X where needed):
- [X] ChatGPT (GPT-4o mini)
Briefly, how helpful was the AI assistant for this assignment?
- assistance on how to pattern match complex quoted expressions for 'should have' and 'should contain' assertions
- assistance on how to build an AST for a lambda expression
## Exercises Completed
Please Mark the exercises that you chose/completed:
- [X] Exercise 1
- [X] Exercise 2
- [X] Exercise 3
- [X] Exercise 4 (with bonus)
Code for Lecture 12.

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@ -4,7 +4,7 @@ lazy val root = project
.in(file("."))
.settings(
organization := "ch.usi.si.msde.edsl",
name := "assignment-04a",
name := "lecture-10",
version := "2024.01",
scalaVersion := scala3Version,
libraryDependencies += "org.typelevel" %% "squants" % "1.8.3",

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@ -8,52 +8,6 @@ import scala.language.postfixOps
*/
object GenerativeFluentAssertionsDSL:
def shouldContainImpl[T](subject: Expr[T])(using Type[T])(using Quotes): Expr[Any] = {
import quotes.reflect.*
subject match {
case '{ $subject: Iterable[elementType] } => '{ ContainsVerb($subject) }
case _ => report.errorAndAbort(
"assertion subject must be an Iterable[?] in order to use a 'contain' assertion",
subject
)
}
}
extension (inline property: AssertionProperty)
inline def `unary_!`: AssertionProperty = NegatedAssertionProperty(property)
/**
* Due to operator precedence, '!==' is the only comparison operator that is considered an "assignment operation"
* and thus has lower precedence than alphanumeric operators. Therefore, we must handle "!==" as the final link of
* a method chain instead of a predicate builder on `satisfying`, like the other operators.
*/
extension [T](inline property: SatisfyingNotEquals[T])
inline def `!==`(inline obj: T)(using inline ord: Ordering[T]): AssertionProperty =
${ notEqualsImpl('property, 'obj, 'ord) }
private def notEqualsImpl[T: Type](property: Expr[SatisfyingNotEquals[T]], obj: Expr[T], ord: Expr[Ordering[T]])(
using Quotes
): Expr[AssertionProperty] = {
import quotes.reflect.*
property match
case '{ (${ typeProvider }: HavePropertyTypeProvider[subjectType])
.applyDynamic($propertyNameExpr: String)(satisfying)
.$asInstanceOf$[SatisfyingNotEquals[T]] } => '{
$typeProvider
.applyDynamic($propertyNameExpr)(satisfying.notEquals[T]($obj, $ord))
.$asInstanceOf$[AssertionProperty]
}
case '{ (${ typeProvider }: ContainsPropertyTypeProvider[subjectType])
.applyDynamic($propertyNameExpr: String)(satisfying)
.$asInstanceOf$[SatisfyingNotEquals[T]] } => '{
$typeProvider
.applyDynamic($propertyNameExpr)(satisfying.notEquals[T]($obj, $ord))
.$asInstanceOf$[AssertionProperty]
}
}
/** Entrypoint. This macro method takes an expression composed of
* AssertionProperty expressions and rewrites them into actual assertions.
*/
@ -61,19 +15,6 @@ object GenerativeFluentAssertionsDSL:
assertionsGenerativeImpl('assertions)
}
private def unwrapShouldBeNegatedAssertion(assertionExpr: Expr[AssertionProperty], negated: Boolean = false)(
using Quotes
): (Expr[String], Boolean) =
import quotes.reflect.*
assertionExpr match
case '{ NegatedAssertionProperty($innerExpr: AssertionProperty) } => unwrapShouldBeNegatedAssertion(innerExpr, !negated)
case '{ be.selectDynamic($propertyNameExpr: String) } => (propertyNameExpr, negated)
case what => report.errorAndAbort(
"'be' negation unwrapping: Invalid expression, must be a 'should be' assertion.",
what
)
/** Macro implementation. The method is recursive, each single expression is
* then separately rewritten into the generateAssertion method. The method
* returns a compiler error if the expression is not an AssertionProperty.
@ -119,46 +60,40 @@ object GenerativeFluentAssertionsDSL:
val generatedAssertion = assertionExpr match
// be assertion. Check the explicit selectDynamic to extract the property name
case '{ (${ subjectExpr }: subjectType) should ($assertionProperty: AssertionProperty) } =>
val (propertyNameExpr, negated) = unwrapShouldBeNegatedAssertion(assertionProperty)
generateShouldBeAssertion[subjectType](subjectExpr, propertyNameExpr, negated)
case '{
(${ subjectExpr }: subjectType) should be.selectDynamic(
$propertyNameExpr
)
} =>
generateShouldBeAssertion[subjectType](subjectExpr, propertyNameExpr)
// The more complicated structure of property type provider construction in
// the should have assertion. Again, the applyDynamic is explicit.
// The quoted pattern also extracts: the type of the assertion subject,
// and the type of the property (actually... not exactly that. Why?)
case '{
(${ typeProvider }: HavePropertyTypeProvider[subjectType])
.applyDynamic($propertyNameExpr: String)($valueExpr: Condition[valueType])
.applyDynamic($propertyNameExpr)($valueExpr: valueType => Boolean)
.$asInstanceOf$[AssertionProperty]
} =>
val subjectExpr = '{ $typeProvider.subject }
val checkerExpr = '{ $typeProvider.checker }
generateShouldHaveAssertion[subjectType, valueType](
subjectExpr,
checkerExpr,
propertyNameExpr,
valueExpr
)
case '{
(${ typeProvider }: ContainsPropertyTypeProvider[subjectType])
.applyDynamic($propertyNameExpr: String)($valueExpr: Condition[valueType])
.$asInstanceOf$[AssertionProperty]
} =>
val subjectExpr = '{ $typeProvider.subject }
val checkerExpr = '{ $typeProvider.checker }
generateShouldContainAssertion[subjectType, valueType](
subjectExpr,
checkerExpr,
propertyNameExpr,
valueExpr
)
case '{
(${ typeProvider }: BePropertyTypeProvider[subjectType])
.applyDynamic($propertyNameExpr)($end)
.applyDynamic($propertyNameExpr)($unit)
.$asInstanceOf$[AssertionProperty]
} =>
'{} // placeholder
case a =>
case '{
(${ typeProvider }: BePropertyTypeProvider[subjectType])
.selectDynamic($propertyNameExpr)
.$asInstanceOf$[AssertionProperty]
} =>
'{} // placeholder
case _ =>
report.errorAndAbort(
"Invalid expression, must be a 'should be' or 'should have' assertion. ",
assertionExpr
@ -169,8 +104,7 @@ object GenerativeFluentAssertionsDSL:
private def generateShouldBeAssertion[T](
subject: Expr[T],
propertyNameExpr: Expr[String],
negated: Boolean
propertyNameExpr: Expr[String]
)(using Type[T])(using Quotes): Expr[Unit] =
import quotes.reflect.*
@ -193,30 +127,27 @@ object GenerativeFluentAssertionsDSL:
// Constructs a 'select' tree, that is, a selection to the field or method
// of the subject.
val call = Select(subject.asTerm, validSymbol).asExprOf[Boolean]
val expected = '{ !${Expr(negated)} }
val assertion = '{
assert(
$call == $expected,
s"${$subject} was${if ($expected) " not" else ""} ${$propertyNameExpr} (${$validSymbolNameExpr} is ${if ($expected) "false" else "true"})"
$call,
s"${$subject} was not ${$propertyNameExpr} (${$validSymbolNameExpr} is false)"
)
}
assertion
end if
end generateShouldBeAssertion
private def generateShouldHaveAssertion[E, R](
subjectExpr: Expr[E],
checkerExpr: Expr[SinglePropertyChecker],
private def generateShouldHaveAssertion[T, R](
subjectExpr: Expr[T],
propertyNameExpr: Expr[String],
propertyValueExpr: Expr[Condition[R]]
)(using Type[E], Type[R])(using Quotes): Expr[Unit] =
propertyValueExpr: Expr[R => Boolean]
)(using Type[T], Type[R])(using Quotes): Expr[Unit] =
import quotes.reflect.*
val subjectTypeRepr = TypeRepr.of[E]
val subjectTypeRepr = TypeRepr.of[T]
val optionalCandidateSymbol =
findCandidateSymbol[E, R](propertyNameExpr.valueOrAbort)
findCandidateSymbol[T, R](propertyNameExpr.valueOrAbort)
if optionalCandidateSymbol.isEmpty then
report.errorAndAbort(
@ -225,63 +156,36 @@ object GenerativeFluentAssertionsDSL:
)
else
val candidateMethod = optionalCandidateSymbol.get
val assertion: Expr[Unit] = '{
/*
* This version is slightly different than the one presented during
* the lecture. In this case we also generate a proper message for
* the assertion violation, so we need to declare and reuse a local
* variable, otherwise the same expression with the type provider needs
* to be duplicated and inserted multiple times. So we take the subjectExpr,
* which contains the type provider and selects the subject, and we
* save it to a local val 'subject'. Then we use the low-level AST
* API to retrieve the result:
* first we take '(subject), which is the expression corresponding
* to the subject variable, and we take the low-level term version;
* then, we construct the Select AST which corresponds to the method
* invocation;
* finally, we convert all to an expression back again, which can be
* spliced in the quote.
*/
val assertion = '{
val subject = $subjectExpr
val checker = $checkerExpr
val condition = $propertyValueExpr
val tester = $propertyValueExpr
lazy val value = ${ Select(('subject).asTerm, candidateMethod).asExprOf[R] }
assert(
checker.check(value, condition),
s"$subject.${$propertyNameExpr} ${checker.failedMessage} ${condition.failedMessage} but ${value}"
tester.apply(value),
s"assertion failed for ${subject}.${$propertyNameExpr}"
)
}
report.info(assertion.show, subjectExpr.asTerm.pos)
assertion
end if
end generateShouldHaveAssertion
private def generateShouldContainAssertion[E, R](
subjectExpr: Expr[Iterable[E]],
checkerExpr: Expr[IterablePropertyChecker],
propertyNameExpr: Expr[String],
propertyValueExpr: Expr[Condition[R]]
)(using Type[E], Type[R])(using Quotes): Expr[Unit] =
import quotes.reflect.*
val subjectTypeRepr = TypeRepr.of[E]
val optionalCandidateSymbol =
findCandidateSymbol[E, R](propertyNameExpr.valueOrAbort)
if optionalCandidateSymbol.isEmpty then
report.errorAndAbort(
s"Assertion Error: No field or arity-0 method with name ${propertyNameExpr.valueOrAbort} on type ${subjectTypeRepr.show}",
propertyNameExpr
)
else
val candidateMethod = optionalCandidateSymbol.get
val assertion: Expr[Unit] = '{
val subject = $subjectExpr
val checker = $checkerExpr
val condition = $propertyValueExpr
lazy val values = subject.map(element => ${ Select(('element).asTerm, candidateMethod).asExprOf[R] })
assert(
checker.check(values, condition),
s"$subject ${checker.failedMessage} ${$propertyNameExpr} ${condition.failedMessage}"
)
}
report.info(assertion.show, subjectExpr.asTerm.pos)
assertion
end if
end generateShouldContainAssertion
/** Looks for candidate symbols with a given set of possible names on a type.
*
* Improved version w.r.t. the one presented during the lecture.

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@ -1,10 +1,8 @@
package ch.usi.si.msde.edsl.lecture10
import scala.language.dynamics
import scala.quoted.Expr
sealed trait AssertionProperty
case class NegatedAssertionProperty(prop: AssertionProperty) extends AssertionProperty
/** Represents (but with no implementation) the result of a call to
* be.selectDynamic(String), used to specify the property. The semantics of
@ -14,92 +12,50 @@ class DynamicShouldBeProperty extends AssertionProperty with Dynamic:
def applyDynamic(fieldName: String)(foo: Any*) = ???
end DynamicShouldBeProperty
sealed trait SatisfyingNotEquals[T]
case object satisfying
case class Condition[-T](predicate: T => Boolean, op: String, expected: Any):
def test(value: T): Boolean = predicate(value)
def failedMessage: String = s"${op} ${expected}"
case class AssertionCandidate[T](value: T, subject: String, propertyName: String):
private def comparison(other: T, predicate: (T, T) => Boolean, predicateOp: String): Unit =
assert(
predicate.apply(value, other),
s"${subject} did not have ${propertyName} ${predicateOp} ${other}, but it was equal to ${value}"
)
case object satisfying:
def `===`[T](toWhat: T)(using ord: Ordering[T]): Condition[T] = Condition(ord.equiv(_, toWhat), "===", toWhat)
def notEquals[T](toWhat: T, ord: Ordering[T]): Condition[T] = Condition(!ord.equiv(_, toWhat), "!==", toWhat)
def `<`[T](toWhat: T)(using ord: Ordering[T]): Condition[T] = Condition(ord.lt(_, toWhat), "<", toWhat)
def `>`[T](toWhat: T)(using ord: Ordering[T]): Condition[T] = Condition(ord.gt(_, toWhat), ">", toWhat)
def `<=`[T](toWhat: T)(using ord: Ordering[T]): Condition[T] = Condition(ord.lteq(_, toWhat), "<=", toWhat)
def `>=`[T](toWhat: T)(using ord: Ordering[T]): Condition[T] = Condition(ord.gteq(_, toWhat), ">=", toWhat)
def `===`(other: T)(using ord: Ordering[T]): Unit = comparison(other, ord.eq(_, _), "==")
def `!==`(other: T)(using ord: Ordering[T]): Unit = comparison(other, ord.ne(_, _), "!=")
def `<=`(other: T)(using ord: Ordering[T]): Unit = comparison(other, ord.lteq, "<=")
def `>=`(other: T)(using ord: Ordering[T]): Unit = comparison(other, ord.gteq, ">=")
def `<`(other: T)(using ord: Ordering[T]): Unit = comparison(other, ord.lt, "<")
def `>`(other: T)(using ord: Ordering[T]): Unit = comparison(other, ord.gt, ">")
end AssertionCandidate
class BePropertyTypeProvider[T](val subject: T) extends Selectable:
def selectDynamic(fieldName: String): AssertionProperty = ???
def applyDynamic(fieldName: String)(foo: Any*): AssertionProperty = ???
end BePropertyTypeProvider
sealed trait PropertyChecker:
val failedMessage: String
sealed trait SinglePropertyChecker extends PropertyChecker:
def check[T](t: T, condition: Condition[T]): Boolean
case object SingleChecker extends SinglePropertyChecker:
override def check[T](t: T, condition: Condition[T]): Boolean = condition.test(t)
override val failedMessage: String = "is not"
case object NegatedChecker extends SinglePropertyChecker:
override def check[T](t: T, condition: Condition[T]): Boolean = !condition.test(t)
override val failedMessage: String = "is"
sealed trait IterablePropertyChecker extends PropertyChecker:
def check[T](t: Iterable[T], condition: Condition[T]): Boolean
case object AllChecker extends IterablePropertyChecker:
override def check[T](t: Iterable[T], condition: Condition[T]): Boolean = t.forall(e => condition.test(e))
override val failedMessage: String = "has elements not satisfying"
case object SomeChecker extends IterablePropertyChecker:
override def check[T](t: Iterable[T], condition: Condition[T]): Boolean = t.exists(e => condition.test(e))
override val failedMessage: String = "has no elements satisfying"
case object NoChecker extends IterablePropertyChecker:
override def check[T](t: Iterable[T], condition: Condition[T]): Boolean = t.forall(e => !condition.test(e))
override val failedMessage: String = "has elements satisfying"
class HavePropertyTypeProvider[T](val subject: T, val checker: SinglePropertyChecker) extends Selectable:
def applyDynamic[U](fieldName: String)(arg: satisfying.type): SatisfyingNotEquals[U] = ???
def applyDynamic(fieldName: String)(arg: Any): AssertionProperty = ???
/** The class that implements the syntactic aspect of the type provider. It
* extends Selectable and implements applyDynamic with arity 1, so that any
* object of this type can be invoked with an arbitrary method with 1 argument,
* and a specific return type.
*
* Selectable types can be refined with a list of specific methods that are
* available and thus checked by the compiler. The macro in the should method
* generates a refinement of this type according to type T, so that - for any
* arity zero method or field in T - say foo: X, the type provider has a
* corresponding method def foo(arg: X): AssertionProperty.
*/
class HavePropertyTypeProvider[T](val subject: T) extends Selectable:
def applyDynamic(fieldName: String)(arg: Any): AssertionCandidate[T] = ???
end HavePropertyTypeProvider
class ContainsPropertyTypeProvider[T](val subject: Iterable[T], val checker: IterablePropertyChecker) extends Selectable:
def applyDynamic[U](fieldName: String)(arg: satisfying.type): SatisfyingNotEquals[U] = ???
def applyDynamic(fieldName: String)(arg: Any): AssertionProperty = ???
end ContainsPropertyTypeProvider
/** A trait for each type of assertion (be or have).
*/
sealed trait AssertionDSLVerb
case object be extends AssertionDSLVerb with Dynamic:
def selectDynamic(fieldName: String): AssertionProperty = ???
case object be_ extends AssertionDSLVerb
case object have extends AssertionDSLVerb:
inline def `unary_!`: have.type = ???
case object contain extends AssertionDSLVerb
case object `with` extends AssertionDSLVerb
case object `!!` extends AssertionDSLVerb
case class ContainsVerb[T](subject: Iterable[T])
extension [T](inline containsVerb: ContainsVerb[T])
transparent inline def allElements(inline verb: `with`.type) = ${
ShouldContainTypeProvider.generateShouldContainTypeProvider('containsVerb, '{ AllChecker })
}
transparent inline def someElements(inline verb: `with`.type) = ${
ShouldContainTypeProvider.generateShouldContainTypeProvider('containsVerb, '{ SomeChecker })
}
transparent inline def noElements(inline verb: `with`.type) = ${
ShouldContainTypeProvider.generateShouldContainTypeProvider('containsVerb, '{ NoChecker })
}
case object have extends AssertionDSLVerb
/** Implicit class to add 'should' assertions to a generic type T.
*
@ -107,15 +63,17 @@ extension [T](inline containsVerb: ContainsVerb[T])
* the object to which perform the assertion.
*/
extension [T](subject: T)
/** Specifies a 'be' assertion. The method is just a placeholder to fix the
* syntax, its semantics is performed by the assertions macro.
*
* @param verb
* The be word.
* @return
* a DynamicProperty object which allows to specify a further property
* name.
*/
def should(property: AssertionProperty) = ???
// we use the 'inline' modifier on subject as well to make sure that the expression
// generated by the 'shouldContainImpl' macro is a one-liner, so it does not contain
// intermediate '$proxy<n>' variable declarations that would make expression pattern
// matching impossible. Using the 'inline' modifier requires all extension methods
// to be 'inline', so we separate the original 'should be' implementation in the
// extension methods block above.
extension [T](inline subject: T)
transparent inline def should(inline verbWord: be_.type) = ${
ShouldBeTypeProvider.generateShouldBeTypeProvider[T]('subject)
}
@ -129,21 +87,11 @@ extension [T](inline subject: T)
*
* The method semantics is then provided by the assertions macro.
*
* @param verb
* @param verbWord
* The have word.
* @return
* a type provider for properties of type T.
*/
transparent inline def should(inline verb: have.type) = ${
ShouldHaveTypeProvider.generateShouldHaveTypeProvider[T]('subject, 'verb)
}
// We define here the 'should contain' extension method. It is not possible to
// write an extension method for Iterable[T] as that method would shadow the
// 'should be' and 'should have' assertions defined for all objects. Therefore,
// we check the subject is an instance of Iterable[T] with a macro, and we use
// report.errorAndAbort to provide a clear error message stating that an Iterable[T]
// is required for this kind of assertion.
transparent inline def should(inline verb: contain.type) = ${
GenerativeFluentAssertionsDSL.shouldContainImpl('subject)
transparent inline def should(inline verbWord: have.type) = ${
ShouldHaveTypeProvider.generateShouldHaveTypeProvider[T]('subject)
}

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@ -2,12 +2,12 @@ package ch.usi.si.msde.edsl.lecture10
// import scala.language.postfixOps
import ch.usi.si.msde.edsl.lecture10.GenerativeFluentAssertionsDSL.*
import squants.market.Money
import squants.market.MoneyConversions.MoneyConversions
import squants.mass.Mass
import squants.mass.MassConversions.MassConversions
import scala.collection.immutable._
import squants.market.MoneyConversions.MoneyConversions
import GenerativeFluentAssertionsDSL.*
import squants.mass.Mass
import squants.market.Money
extension (value: Double) def i = Complex(0, value)
@ -17,7 +17,6 @@ case class Complex(re: Double, im: Double):
case class Person(firstName: String, lastName: String, age: Int):
def adult: Boolean = age >= 18
def minor: Boolean = !adult
case class Box(label: String, weight: Mass, price: Money)
@ -26,43 +25,38 @@ case class Box(label: String, weight: Mass, price: Money)
val box = Box("aBox", 30.kg, 10.CHF)
assertions:
// Exercise 1 solution:
// It is possible to implement a DSL for 'should be' assertions that uses a type provider like the 'should have'
// assertion. However, a slight change to the syntax is needed in order to maintain the 'subject [method value]+'
// pattern that DSL statements should maintain in order to be parsed correctly by the Scala parser. To do this,
// we define an extra token named '!!' as a case object that should be appended at the end of the assertion. This
// object will serve as a dummy parameter to the method called on the type provider to allow the assertion
// statement to be parsed correctly.
// (note that the verb is 'be_' instead of 'be' to avoid a clash with the original implementation)
person should be_ adult !!
/* be.property assertions */
// assert(person.adult, ...)
person should be.adult
// assert(List().isEmpty, ...)
List() should be.empty
// assert(List(1,2,3).nonEmpty)
List(1, 2, 3) should be.nonEmpty
// Exercise 2
List(1) should have head satisfying === 1
box should have weight satisfying === 30.kg
box should have weight satisfying === 3.kg
List() should have size satisfying >= 0
List(3) should have size satisfying !== 0
List(50, 2, 3) should have head satisfying < 100
box should have.weight satisfying >= 10.kg
person should have age satisfying >= 10
// Exercise 3
box should !(!have) weight satisfying <= 300.0.kg
person should !(!be.adult)
person should !be.minor
// New syntax for `be` with type provider
// either adult is a method with a dummy Unit parameter
person should be_ adult()
// or adult is a property but braces are needed to resolve the type provider
(person should be_).adult
// Exercise 4
// we wrap the strings in StringOps instances in order to resolve the scala method "size". This would otherwise
// not happen automatically as the string types would resolve to "java.lang.String" thus not allowing the type
// provider to resolve the "size" method. This is due to the String -> StringOps conversion being an 'implicit def'
// that does not trigger here as we do not access the 'size' method directly, but instead we resolve it via reflection.
List(
new StringOps("bar"),
new StringOps("foo"),
new StringOps(""),
new StringOps("alice")
) should contain someElements `with` size satisfying === 0
List(Seq(), Seq(), Seq()) should contain allElements `with` size satisfying >= 0
List(List(1,2), List(20,1), List(3,4)) should contain noElements `with` head satisfying === 3 // this assertion fails
/* should have assertions */
// // assert(List(1).head == 1, ...)
// List(1) should have head 1
// // assert(box.weight == 30.kg, ...)
// box should have weight 30.kg
// // assert(person.age == 0x29, ...)
// person should have age 0x29
// List(2, 3) should have tail List(3)
// 3.i + 1 should have re 1.0
end assertionsExample

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@ -16,8 +16,8 @@ object ShouldBeTypeProvider:
): TypeRepr =
// refine both as unary method with unit parameter and as property
// and let client code choose
val methodType = MethodType(List("end"))(
_ => List(TypeRepr.of[`!!`.type]),
val methodType = MethodType(List("unit"))(
_ => List(TypeRepr.of[Unit]),
_ => TypeRepr.of[AssertionProperty]
)
Refinement(
@ -53,6 +53,8 @@ object ShouldBeTypeProvider:
members
)
// println(refinedType)
// This is the way to extract a (reflection) type to a
// type that can be used in some quoted code.
// it's the equivalent of .asExpr for expressions,

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@ -1,92 +0,0 @@
package ch.usi.si.msde.edsl.lecture10
import scala.quoted.*
object ShouldContainTypeProvider:
/** The type provider for the should have assertion, which generates a refined
* structural type for type T.
*/
def generateShouldContainTypeProvider[T](containsExpr: Expr[ContainsVerb[T]], checker: Expr[IterablePropertyChecker])
(using Type[T], Quotes): Expr[Any] =
import quotes.reflect.*
val subject: Expr[Iterable[T]] = containsExpr match
case '{ ContainsVerb.apply[T]($s: Iterable[T]) } => s
// hack to get the equivalent of `TypeRepr.of[Function1[?, ?]]` (i.e. an arity-1 function type constructor).
// Getting it as is returns an applied type with useless bounds (Nothing to Any), and the returned TypeRepr,
// if re-applied to some `I` input type and `O` output type would be incompatible with `TypeRepr.of[I => O]` for
// some reason
def typeConstructor[U](using Type[U]): TypeRepr =
AppliedType.unapply(TypeRepr.of[U].asInstanceOf[AppliedType])._1
val subjectTypeRepr = TypeRepr.of[T].widen
/** Given a refinable current type, and the symbol of a arity-0 method or a
* field of type foo: X, generates a refinement containing a method with
* signature def foo(arg: X): AssertionProperty.
*/
def refineTypeBySymbol(
currentTypeRepr: TypeRepr,
symbol: Symbol
): TypeRepr =
// The type of the field, or the return type of the method.
val fieldTypeRepr = subjectTypeRepr.memberType(symbol).widen
val methodType = MethodType(List("arg"))(
_ => List(AppliedType(typeConstructor[Condition[?]], List(fieldTypeRepr))),
_ => TypeRepr.of[AssertionProperty]
)
val chainedMethodType = MethodType(List("arg"))(
_ => List(TypeRepr.of[satisfying.type]),
_ => AppliedType(typeConstructor[SatisfyingNotEquals[?]], List(fieldTypeRepr))
)
Refinement(
Refinement(currentTypeRepr, symbol.name, chainedMethodType),
symbol.name,
methodType
)
/** Refines a type according to a list of fields or methods of arity 0.
*/
def refineTypeBySymbols(
currentTypeRepr: TypeRepr,
fields: List[Symbol]
): TypeRepr =
fields match
// this is pattern matching on list - like head :: rest
case symbol :: symbols =>
refineTypeBySymbols(
refineTypeBySymbol(currentTypeRepr, symbol),
symbols
)
// empty list case
case Nil =>
currentTypeRepr
val fields = subjectTypeRepr.typeSymbol.fieldMembers
val arityZeroMethods = subjectTypeRepr.typeSymbol.methodMembers
.filter: methodMember =>
methodMember.paramSymss.size == 0 && !methodMember.flags.is(
Flags.Synthetic
)
val refinedType = refineTypeBySymbols(
TypeRepr.of[ContainsPropertyTypeProvider[T]],
fields ++ arityZeroMethods
)
// This is the way to extract a (reflection) type to a
// type that can be used in some quoted code.
// it's the equivalent of .asExpr for expressions,
// but it's more complicated because in this case the
// exact type is unknown until compilation time.
refinedType.asType match
case '[tpe] => // tpe is the exact refined type
'{ ContainsPropertyTypeProvider[T]($subject, $checker).asInstanceOf[tpe] }
end ShouldContainTypeProvider

View file

@ -4,30 +4,14 @@ import scala.quoted.*
object ShouldHaveTypeProvider:
/** The type provider for the should have assertion, which generates a refined
* structural type for type T.
*/
def generateShouldHaveTypeProvider[T](subject: Expr[T], verb: Expr[have.type])(using Type[T])(using
def generateShouldHaveTypeProvider[T](subject: Expr[T])(using Type[T])(using
Quotes
): Expr[Any] =
import quotes.reflect.*
def isNegated(verb: Expr[have.type]): Boolean =
verb match
case '{ ($inner: have.type).`unary_!` } => !isNegated(inner)
case '{ have: have.type } => false
val negated = isNegated(verb)
// hack to get the equivalent of `TypeRepr.of[Function1[?, ?]]` (i.e. an arity-1 function type constructor).
// Getting it as is returns an applied type with useless bounds (Nothing to Any), and the returned TypeRepr,
// if re-applied to some `I` input type and `O` output type would be incompatible with `TypeRepr.of[I => O]` for
// some reason
def typeConstructor[U](using Type[U]): TypeRepr =
AppliedType.unapply(TypeRepr.of[U].asInstanceOf[AppliedType])._1
val subjectTypeRepr = TypeRepr.of[T]
/** Given a refinable current type, and the symbol of a arity-0 method or a
@ -41,21 +25,18 @@ object ShouldHaveTypeProvider:
// The type of the field, or the return type of the method.
val fieldTypeRepr = subjectTypeRepr.memberType(symbol).widen
val methodType = MethodType(List("arg"))(
_ => List(AppliedType(typeConstructor[Condition[?]], List(fieldTypeRepr))),
_ => TypeRepr.of[AssertionProperty]
)
// hack to get the equivalent of `TypeRepr.of[Function1[?, ?]]` (i.e. an arity-1 function type constructor).
// Getting it as is returns an applied type with useless bounds (Nothing to Any), and the returned TypeRepr,
// if re-applied to some `I` input type and `O` output type would be incompatible with `TypeRepr.of[I => O]` for
// some reason
val acTypeCtor = AppliedType.unapply(TypeRepr.of[AssertionCandidate[Unit]].asInstanceOf[AppliedType])._1
val assertionCandidateType = AppliedType(acTypeCtor, List(fieldTypeRepr))
val chainedMethodType = MethodType(List("arg"))(
val methodType = MethodType(List("satisfying"))(
_ => List(TypeRepr.of[satisfying.type]),
_ => AppliedType(typeConstructor[SatisfyingNotEquals[?]], List(fieldTypeRepr))
)
Refinement(
Refinement(currentTypeRepr, symbol.name, chainedMethodType),
symbol.name,
methodType
_ => assertionCandidateType
)
Refinement(currentTypeRepr, symbol.name, methodType)
/** Refines a type according to a list of fields or methods of arity 0.
*/
@ -86,7 +67,7 @@ object ShouldHaveTypeProvider:
fields ++ arityZeroMethods
)
val checker = if (negated) '{ NegatedChecker } else '{ SingleChecker }
println(refinedType.show)
// This is the way to extract a (reflection) type to a
// type that can be used in some quoted code.
@ -95,6 +76,10 @@ object ShouldHaveTypeProvider:
// exact type is unknown until compilation time.
refinedType.asType match
case '[tpe] => // tpe is the exact refined type
'{ HavePropertyTypeProvider[T]($subject, $checker).asInstanceOf[tpe] }
val res = '{
val p = HavePropertyTypeProvider[T]($subject)
p.asInstanceOf[tpe]
}
res
end ShouldHaveTypeProvider