Add leadingSpaces/trailingSpaces methods to TokenList

project/Mima.scala

@@ -24,11 +24,14 @@ object Mima {
       ProblemFilters.exclude[DirectMissingMethodProblem](
         "scalafix.rule.RuleCtx.printLintMessage"),
       ProblemFilters.exclude[ReversedMissingMethodProblem](
-        "scalafix.rule.RuleCtx.filterLintMessage"
-      ),
+        "scalafix.rule.RuleCtx.filterLintMessage"),
       ProblemFilters.exclude[DirectMissingMethodProblem](
-        "scalafix.cli.CliRunner.this"
-      )
+        "scalafix.cli.CliRunner.this"),
+      ProblemFilters.exclude[FinalClassProblem]("scalafix.util.TokenList"),
+      ProblemFilters.exclude[ReversedMissingMethodProblem](
+        "scalafix.util.TokenList.leadingSpaces"),
+      ProblemFilters.exclude[ReversedMissingMethodProblem](
+        "scalafix.util.TokenList.trailingSpaces")
     )
   }
 }

scalafix-core/shared/src/main/scala/scalafix/internal/rule/RuleCtxImpl.scala

@@ -32,7 +32,7 @@ case class RuleCtxImpl(tree: Tree, config: ScalafixConfig) extends RuleCtx {
   override def toString: String = syntax
   def toks(t: Tree): Tokens = t.tokens(config.dialect)
   lazy val tokens: Tokens = tree.tokens(config.dialect)
-  lazy val tokenList: TokenList = new TokenList(tokens)
+  lazy val tokenList: TokenList = TokenList(tokens)
   lazy val matchingParens: MatchingParens = MatchingParens(tokens)
   lazy val comments: AssociatedComments = AssociatedComments(tokens)
   lazy val input: Input = tokens.head.input

scalafix-core/shared/src/main/scala/scalafix/util/TokenList.scala

@@ -6,7 +6,7 @@ import scala.meta.tokens.Token
 import scala.meta.tokens.Tokens
 
 /** Helper to traverse tokens as a doubly linked list.  */
-class TokenList(tokens: Tokens) {
+final class TokenList private (tokens: Tokens) {
   def trailing(token: Token): SeqView[Token, IndexedSeq[Token]] =
     tokens.view(tok2idx(token), tokens.length).drop(1)
   def leading(token: Token): SeqView[Token, IndexedSeq[Token]] =
@@ -59,4 +59,13 @@ class TokenList(tokens: Tokens) {
     }
   }
 
+  def leadingSpaces(token: Token): SeqView[Token, IndexedSeq[Token]] =
+    leading(token).takeWhile(_.is[Token.Space])
+
+  def trailingSpaces(token: Token): SeqView[Token, IndexedSeq[Token]] =
+    trailing(token).takeWhile(_.is[Token.Space])
+}
+
+object TokenList {
+  def apply(tokens: Tokens): TokenList = new TokenList(tokens)
 }

scalafix-tests/unit/src/test/scala/scalafix/tests/core/util/TokenListTest.scala

@@ -6,21 +6,90 @@ import scalafix.util.TokenList
 
 class TokenListTest extends FunSuite {
 
-  val tokens = "".tokenize.get // this contains two tokens: beginningOfFile and endOfFile
-  val firstToken = tokens.head
-  val lastToken = tokens.last
-  val tokenList = new TokenList(tokens)
+  val emptyFileTokens = "".tokenize.get // this contains two tokens: BOF and EOF
+  val nonEmptyFileTokens =
+    """package foo
+      |
+      |object Bar {
+      | val baz   =   10
+      |}
+    """.stripMargin.tokenize.get
 
-  test("Prev returns the firstToken when is given the firstToken") {
-    assert(tokenList.prev(firstToken) == firstToken)
-    assert(tokenList.prev(tokens.last) == firstToken)
+  test("prev returns the preceding token") {
+    val tokenList = TokenList(emptyFileTokens)
+    assert(tokenList.prev(emptyFileTokens.last) == emptyFileTokens.head)
   }
 
-  test("Slice gives an empty list with same token as inputs") {
-    assert(tokenList.slice(firstToken, firstToken) == Seq())
+  test("prev returns self if there is no preceding token") {
+    val tokenList = TokenList(emptyFileTokens)
+    assert(tokenList.prev(emptyFileTokens.head) == emptyFileTokens.head)
   }
 
-  test("Next breaks gives the lastToken if it is given lastToken") {
-    assert(tokenList.next(lastToken) == lastToken)
+  test("next returns the following token") {
+    val tokenList = TokenList(emptyFileTokens)
+    assert(tokenList.next(emptyFileTokens.head) == emptyFileTokens.last)
+  }
+
+  test("next returns self if there is no following token") {
+    val tokenList = TokenList(emptyFileTokens)
+    assert(tokenList.next(emptyFileTokens.last) == emptyFileTokens.last)
+  }
+
+  test("slice returns an empty seq if there is no token in between") {
+    val tokenList = TokenList(emptyFileTokens)
+    assert(tokenList.slice(emptyFileTokens.head, emptyFileTokens.head) == Seq())
+  }
+
+  test("slice returns all tokens between from/to tokens") {
+    val Some(kwObject) = nonEmptyFileTokens.find(_.is[Token.KwObject])
+    val Some(leftBrace) = nonEmptyFileTokens.find(_.is[Token.LeftBrace])
+    val tokenList = TokenList(nonEmptyFileTokens)
+
+    val slice = tokenList.slice(kwObject, leftBrace)
+    assert(slice.size == 3)
+    val Seq(space1, bar, space2) = slice
+    assert(space1.is[Token.Space])
+    assert(bar.syntax.equals("Bar"))
+    assert(space2.is[Token.Space])
+  }
+
+  test("leadingSpaces returns all spaces preceding a token") {
+    val Some(equals) = nonEmptyFileTokens.find(_.is[Token.Equals])
+    val tokenList = TokenList(nonEmptyFileTokens)
+
+    val spaces = tokenList.leadingSpaces(equals)
+    assert(spaces.size == 3)
+    val Seq(s1, s2, s3) = spaces
+    assert(s1 == tokenList.prev(equals))
+    assert(s2 == tokenList.prev(s1))
+    assert(s3 == tokenList.prev(s2))
+  }
+
+  test(
+    "leadingSpaces returns an empty seq if there are no spaces preceding a token") {
+    val Some(kwPackage) = nonEmptyFileTokens.find(_.is[Token.KwPackage])
+    val tokenList = TokenList(nonEmptyFileTokens)
+
+    assert(tokenList.leadingSpaces(kwPackage) == Seq())
+  }
+
+  test("trailingSpaces returns all spaces following a token") {
+    val Some(equals) = nonEmptyFileTokens.find(_.is[Token.Equals])
+    val tokenList = TokenList(nonEmptyFileTokens)
+
+    val spaces = tokenList.trailingSpaces(equals)
+    assert(spaces.size == 3)
+    val Seq(s1, s2, s3) = spaces
+    assert(s1 == tokenList.next(equals))
+    assert(s2 == tokenList.next(s1))
+    assert(s3 == tokenList.next(s2))
+  }
+
+  test(
+    "trailingSpaces returns an empty seq if there are no spaces following a token") {
+    val Some(rightBrace) = nonEmptyFileTokens.find(_.is[Token.RightBrace])
+    val tokenList = TokenList(nonEmptyFileTokens)
+
+    assert(tokenList.trailingSpaces(rightBrace) == Seq())
   }
 }