Rewrite Xml Literals to Xml Interpolator (#146)

* Rewrite boilerplate

* First basic tests pass

* WIP

* WIP

* Fix #10: XML Interpolator rewrite

* Skip failing test due to scalameta/issues/836

* Emit warning on `{{`

* Address reviewers comments

* Address reviewers comments: second pass

* Failing test case

* Bump scala-xml-quote version

* Fix #150

Author: allanrenucci

build.sbt

@@ -228,9 +228,12 @@ lazy val tests = project
         "; tests/it:testQuick" // hack to workaround cyclic dependencies in test.
     )(state.value),
     parallelExecution in Test := true,
+    // TODO: Remove once scala-xml-quote is merged into scala-xml
+    resolvers += Resolver.bintrayRepo("allanrenucci", "maven"),
     libraryDependencies ++= Seq(
       scalahost % Test,
       // integration property tests
+      "org.renucci"        %% "scala-xml-quote"    % "0.1.1"    % Test,
       "org.typelevel"      %% "catalysts-platform" % "0.0.5"    % Test,
       "com.typesafe.slick" %% "slick"              % "3.2.0-M2" % Test,
       "com.chuusai"        %% "shapeless"          % "2.3.2"    % Test,

project/Dependencies.scala

@@ -5,6 +5,7 @@ object Dependencies {
   val scalametaV = "1.8.0-650-890aeec1"
   val paradiseV = "3.0.0-308-ec15a2f8"
   val metaconfigV = "0.3.2"
+
   var testClasspath: String = "empty"
   def scalahost: ModuleID = "org.scalameta" % s"scalahost" % scalametaV cross CrossVersion.full
   def scalatest: ModuleID = "org.scalatest" %% "scalatest" % "3.0.0"

project/build.properties

@@ -1 +1 @@
-sbt.version=0.13.13
+sbt.version=0.13.15

scalafix-core/src/main/scala/scalafix/rewrite/RemoveXmlLiterals.scala

@@ -0,0 +1,120 @@
+package scalafix
+package rewrite
+
+import scala.meta._
+
+/** Rewrite Xml Literal to Xml Interpolator
+  *
+  * e.g.
+  * {{{
+  *   // before:
+  *   <div>{ "Hello" }</div>
+  *
+  *   // after:
+  *   xml"<div>${ "Hello" }</div>"
+  * }}}
+  */
+case object RemoveXmlLiterals extends Rewrite {
+
+  override def rewrite(ctx: RewriteCtx): Patch = {
+    object Xml {
+      def unapply(tree: Tree): Option[Seq[Lit]] =
+        tree match {
+          case Pat.Xml(parts, _) => Some(parts)
+          case Term.Xml(parts, _) => Some(parts)
+          case _ => None
+        }
+    }
+
+    def isMultiLine(xml: Tree) =
+      xml.pos.start.line != xml.pos.end.line
+
+    /** Contains '"' or '\' */
+    def containsEscapeSequence(xmlPart: Lit) = {
+      val Lit(value: String) = xmlPart
+      value.exists(c => c == '\"' || c == '\\')
+    }
+
+    /** Rewrite xml literal to interpolator */
+    def patchXml(xml: Tree, tripleQuoted: Boolean) = {
+
+      // We don't want to patch inner xml literals multiple times
+      def removeSplices(tokens: Tokens) = {
+        var depth = 0
+
+        tokens.filter {
+          case Token.Xml.SpliceStart() =>
+            depth += 1
+            depth == 1
+          case Token.Xml.SpliceEnd() =>
+            depth -= 1
+            depth == 0
+          case _ =>
+            depth == 0
+        }
+      }
+
+      /** Substitute {{ by { */
+      def patchEscapedBraces(tok: Token.Xml.Part) = {
+        ctx.reporter.warn(
+          """Single opening braces don't need be escaped with {{ inside the xml interpolator,
+            |unlike xml literals. For example <x>{{</x> is identical to xml"<x>{</x>".
+            |This Rewrite will replace all occurrences of {{. Make sure this is intended.
+          """.stripMargin,
+          tok.pos
+        )
+        ctx.replaceToken(tok, tok.value.replaceAllLiterally("{{", "{"))
+      }
+
+      removeSplices(xml.tokens).collect {
+        case tok @ Token.Xml.Start() =>
+          val toAdd =
+            if (tripleQuoted) "xml\"\"\""
+            else "xml\""
+          ctx.addLeft(tok, toAdd)
+
+        case tok @ Token.Xml.End() =>
+          val toAdd =
+            if (tripleQuoted) "\"\"\""
+            else "\""
+          ctx.addRight(tok, toAdd)
+
+        case tok @ Token.Xml.SpliceStart() =>
+          ctx.addLeft(tok, "$")
+
+        case tok @ Token.Xml.Part(part) =>
+          var patch = Patch.empty
+          if (part.contains('$'))
+            patch += ctx.replaceToken(tok, part.replaceAllLiterally("$", "$$"))
+          if (part.contains("{{"))
+            patch += patchEscapedBraces(tok)
+          patch
+
+      }.asPatch
+    }
+
+    /** add `import scala.xml.quote._` */
+    def importXmlQuote = {
+      val nextToken = {
+        def loop(tree: Tree): Token = tree match {
+          case Source(stat :: _) => loop(stat)
+          case Pkg(_, stat :: _) => loop(stat)
+          case els => els.tokens.head
+        }
+        loop(ctx.tree)
+      }
+
+      ctx.addLeft(nextToken, "import scala.xml.quote._\n")
+    }
+
+    val patch = ctx.tree.collect {
+      case xml @ Xml(parts) =>
+        val tripleQuoted = isMultiLine(xml) || parts.exists(
+          containsEscapeSequence)
+        patchXml(xml, tripleQuoted)
+    }.asPatch
+
+    if (patch.nonEmpty) patch + importXmlQuote
+    else patch
+  }
+}

scalafix-core/src/main/scala/scalafix/rewrite/ScalafixRewrites.scala

@@ -6,6 +6,7 @@ object ScalafixRewrites {
   val syntax: List[Rewrite] = List(
     ProcedureSyntax,
     VolatileLazyVal,
+    RemoveXmlLiterals,
     ExplicitUnit
   )
   def semantic(mirror: Mirror): List[Rewrite] = List(

scalafix-testkit/src/main/scala/scalafix/testkit/SemanticRewriteSuite.scala

@@ -22,6 +22,7 @@ import java.net.URL
 import java.net.URLClassLoader
 
 import metaconfig.ConfError
+import org.scalameta.logger
 import org.scalatest.FunSuite
 
 /**
@@ -84,11 +85,11 @@ abstract class SemanticRewriteSuite(
     }
 
     val fixed = fix(diffTest.wrapped(), diffTest.config)
+    logger.elem(diffTest.unwrap(fixed))
     val obtained = parse(diffTest.unwrap(fixed))
     val expected = parse(expectedStr)
     try {
       typeChecks(diffTest.wrapped(fixed))
-      checkMismatchesModuloDesugarings(obtained, expected)
       if (diffTest.checkSyntax) {
         assertNoDiff(obtained, expected)
       } else {

scalafix-tests/src/test/resources/checkSyntax/RemoveXmlLiterals.source

@@ -0,0 +1,132 @@
+rewrites = [RemoveXmlLiterals]
+
+<<< don't add import when not needed
+object A {}
+>>>
+object A {}
+
+<<< single line, no splice
+object A {
+  <div></div>
+}
+>>>
+import scala.xml.quote._
+object A {
+  xml"<div></div>"
+}
+
+<<< single line, triple quoted
+object A {
+  val a = <div b="Hello"/>
+  val b = <a>\</a>
+}
+>>>
+import scala.xml.quote._
+object A {
+  val a = xml"""<div b="Hello"/>"""
+  val b = xml"""<a>\</a>"""
+}
+
+<<< single line, splice
+object A {
+  val bar = "bar"
+  <div>{bar}</div>
+}
+>>>
+import scala.xml.quote._
+object A {
+  val bar = "bar"
+  xml"<div>${bar}</div>"
+}
+
+<<< multi-line, no splice
+object A {
+  val foo =
+    <div>
+      <span>Hello</span>
+    </div>
+}
+>>>
+import scala.xml.quote._
+object A {
+  val foo =
+    xml"""<div>
+      <span>Hello</span>
+    </div>"""
+}
+
+<<< multi-line, splice
+object A {
+  val foo =
+    <div>
+      <span>{"Hello"}</span>
+    </div>
+}
+>>>
+import scala.xml.quote._
+object A {
+  val foo =
+    xml"""<div>
+      <span>${"Hello"}</span>
+    </div>"""
+}
+
+<<< splice in attribute position
+object A {
+  <foo bar={"Hello"}/>
+}
+>>>
+import scala.xml.quote._
+object A {
+  xml"<foo bar=${"Hello"}/>"
+}
+
+<<< nested xml literals
+object A {
+  <a>{<a>{"Hello"}</a>}</a>
+}
+>>>
+import scala.xml.quote._
+object A {
+  xml"<a>${xml"<a>${"Hello"}</a>"}</a>"
+}
+
+<<< protect $
+object A {
+  <div>$</div>
+}
+>>>
+import scala.xml.quote._
+object A {
+  xml"<div>$$</div>"
+}
+
+<<< protect curly brace
+object A {
+  <div>{{</div>
+}
+>>>
+import scala.xml.quote._
+object A {
+  xml"<div>{</div>"
+}
+
+<<< SKIP protect curly brace 2
+object A {
+  <div b="{{"/>
+}
+>>>
+import scala.xml.quote._
+object A {
+  xml"""<div b="{{"/>"""
+}
+
+<<< multiple splices
+object A {
+  <a>{1}{2}</a>
+}
+>>>
+import scala.xml.quote._
+object A {
+  xml"<a>${1}${2}</a>"
+}