https://github.com/wsargent/scala3-inspections
https://github.com/wsargent/scala3-inspections
Last synced: 3 months ago
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- Host: GitHub
- URL: https://github.com/wsargent/scala3-inspections
- Owner: wsargent
- Created: 2021-07-05T01:20:37.000Z (over 4 years ago)
- Default Branch: main
- Last Pushed: 2021-07-15T17:48:53.000Z (about 4 years ago)
- Last Synced: 2025-01-09T18:02:52.778Z (9 months ago)
- Language: Scala
- Size: 23.4 KB
- Stars: 3
- Watchers: 3
- Forks: 1
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
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README
# Scala 3 Inspection Macro
This is an implementation of inspection macros in Scala 3, which rewrites the AST to insert logging statements.
There's already an implementation for [Scala 2](https://tersesystems.github.io/blindsight/usage/inspections.html) but Scala 3 macros are different enough that they must be re-implemented from scratch.
Other macro example projects are mostly concerned with types rather than rewriting trees, so this is hopefully breaking new territory for Scala 3.
## Decorate If
```scala
InspectionMacros.decorateIfs(dif => logger.debug(s"${dif.code} = ${dif.result}")) {
if (System.currentTimeMillis() - 1 < 0) {
println("decorateIfs: if block")
} else if (System.getProperty("derp") != null) {
println("decorateIfs: if else block")
} else {
println("decorateIfs: else block")
}
}
```
will stick block of `logger.debug` into each branch, so the end result is:
```scala
if (java.lang.System.currentTimeMillis().-(1).<(0)) {
output$proxy2.apply(example.BranchInspection.apply("java.lang.System.currentTimeMillis().-(1).<(0)", true))
scala.Predef.println("decorateIfs: if block")
} else {
output$proxy2.apply(example.BranchInspection.apply("java.lang.System.currentTimeMillis().-(1).<(0)", false))
if (java.lang.System.getProperty("derp").!=(null)) {
output$proxy2.apply(example.BranchInspection.apply("java.lang.System.getProperty(\"derp\").!=(null)", true))
scala.Predef.println("decorateIfs: if else block")
} else {
output$proxy2.apply(example.BranchInspection.apply("java.lang.System.getProperty(\"derp\").!=(null)", false))
scala.Predef.println("decorateIfs: else block")
}
}
```
## Decorate Match
`decorateMatch` inserts statements into each case, so that:
```scala
val string = java.time.Instant.now().toString
InspectionMacros.decorateMatch(dm => logger.debug(s"${dm.code} = ${dm.result}")) {
string match {
case s if s.startsWith("20") =>
println("this example is still valid")
case _ =>
println("oh dear")
}
}
```
produces the following code:
```scala
string match {
case s if s.startsWith("20") =>
{
output$proxy2.apply(example.BranchInspection.apply("case s if s.startsWith(\"20\")", true))
scala.Predef.println("this example is still valid")
}
case _ =>
{
output$proxy2.apply(example.BranchInspection.apply("case _", true))
scala.Predef.println("oh dear")
}
}
```
and the given output:
```
62 [run-main-5] DEBUG example.Main - case s if s.startsWith("20") = true
```
## Dump Expression
```scala
val dr: ExprInspection[Int] = InspectionMacros.dumpExpression(1 + 1)
println(s"result: ${dr.code} = ${dr.value}")
```
produces:
```
result: 1 + 1 = 2
```