#1 - Scala macros tutorial.md

3/5/2015 - 2:46 PM

#1 - Scala macros tutorial.md

...
[error] exception during macro expansion: 
[error] java.util.regex.PatternSyntaxException: Unclosed character class near index 3
[error] [a-z
[error]    ^
[error]   at java.util.regex.Pattern.error(Pattern.java:1713)
[error]   at java.util.regex.Pattern.clazz(Pattern.java:2254)
[error] 	at java.util.regex.Pattern.sequence(Pattern.java:1818)
[error] 	at java.util.regex.Pattern.expr(Pattern.java:1752)
[error] 	at java.util.regex.Pattern.compile(Pattern.java:1460)
[error] 	at java.util.regex.Pattern.<init>(Pattern.java:1133)
[error] 	at java.util.regex.Pattern.compile(Pattern.java:823)
[error] 	at scala.util.matching.Regex.<init>(Regex.scala:156)
[error] 	at scala.collection.immutable.StringLike$class.r(StringLike.scala:222)
[error] 	at scala.collection.immutable.StringOps.r(StringOps.scala:29)
[error] 	at scala.collection.immutable.StringLike$class.r(StringLike.scala:211)
[error] 	at scala.collection.immutable.StringOps.r(StringOps.scala:29)
[error] 	at gd.wa.Macros$.regexImpl(Macros.scala:19)
[error] one error found
[error] (macrostest/compile:compile) Compilation failed
[error] Total time: 16 s, completed Dec 27, 2012 9:36:27 PM

#8 - compile_and_see_error.sh

sbt compile

#7 - MacrosTest.scala

// macrostest/src/main/scala/gd/wa/MacrosTest.scala

package gd.wa

import scala.language.experimental.macros

object MacrosTest extends App {

  import Macros._

  regex("[a-z")
}

#6 - Macros.scala

// macros/src/main/scala/gd/wa/Macros.scala

package gd.wa

import scala.language.experimental.macros

import scala.reflect.macros.Context
import scala.util.matching.Regex

object Macros {

  def regex(str: String): Regex = macro regexImpl

  def regexImpl(c: Context)
               (str: c.Expr[String]): c.Expr[Regex] = {

    import c.universe._

    str.tree match {
      case Literal(Constant(string: String)) =>
        string.r
        reify { str.splice.r }
    }
  }
}

#5 - Build.scala

// project/Build.scala

import sbt._
import Keys._

object BuildSettings {

  val buildSettings = Defaults.defaultSettings ++ Seq(
    organization := "gd.wa",
    version := "1.0.0",
    resolvers += Resolver.sonatypeRepo("snapshots"),
    scalacOptions ++= Seq(),
    scalaVersion := "2.11.0-SNAPSHOT",
    scalaOrganization := "org.scala-lang.macro-paradise"
  )
}

object MyBuild extends Build {

  import BuildSettings._

  lazy val root: Project = Project(
    "root",
    file("."),
    settings = buildSettings) aggregate(macros, macrosTest)

  lazy val macros: Project = Project(
    "macros",
    file("macros"),
    settings = buildSettings ++ Seq(
      libraryDependencies <+= (scalaVersion)("org.scala-lang.macro-paradise" % "scala-reflect" % _)
    ))

  lazy val macrosTest: Project = Project(
    "macrostest",
    file("macrostest"),
    settings = buildSettings) dependsOn(macros)
}

#4 - setup_gen-idea.sh

echo 'resolvers += "sbt-idea-repo" at "http://mpeltonen.github.com/maven/"' >> project/plugins.sbt
echo >> project/plugins.sbt
echo 'addSbtPlugin("com.github.mpeltonen" % "sbt-idea" % "1.2.0")' >> project/plugins.sbt

#3 - setup_sbt.sh

echo sbt.version=0.12.1 > project/build.properties

#2 - create_folders.sh

mkdir -p project {macros,macrostest}/src/main/scala/gd/wa

#1 - Scala macros tutorial.md

Rendered
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Scala macros tutorial, using sbt

The following steps executed in order will;

create the project file structure
set the sbt version
add the gen-idea sbt plugin (if you want to import your project into intellij)
create an sbt build, that builds the macros project prior to the macrostest project (so the regex macro is usable in the macrostest project)
create the macros project scala file
create the macrostest project scala file
compile the two projects
fail compilation of macrotest, as the invalid regex [a-z is created compile time by the regex macro

Versions:

scala 2.11.0-SNAPSHOT (from org.scala-lang.macro-paradise)
sbt 0.12.1
gen-idea 1.2.0

References:

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#1 - Scala macros tutorial.md

Scala macros tutorial, using sbt