Refactor SyntaxHighlight.scala

Added comments to updateLastToken function
Use syntax highlight tests proposed in pr #4441
instead of the file based solution

Author: benkobalog

compiler/src/dotty/tools/dotc/printing/SyntaxHighlighting.scala

@@ -287,18 +287,24 @@ object SyntaxHighlighting {
         case '@' => true
         case ',' => true
         case '.' => true
-        case ',' => true
-        case ')' => true
         case _ => false
       }
 
-      def shouldUpdateLastToken(currentPotentialToken: String): Boolean =
-        (lastToken, currentPotentialToken) match {
-          case (_, ("var" | "val" | "def" | "case")) => true
-          case (("val" | "var"), "=") => true
-          case ("case", ("=>" | "class" | "object")) => true
-          case ("def", _) => true
-          case _ => false
+      val valDefStarterTokens = "var" :: "val" :: "def" :: "case" :: Nil
+
+      /** lastToken is used to check whether we want to show something
+       *  in valDef color or not. There are only a few cases when lastToken
+       *  should be updated, that way we can avoid stopping coloring too early.
+       *  eg.: case A(x, y, z) => ???
+       *  Without this function only x would be colored.
+       */
+      def updateLastToken(currentToken: String): String =
+        (lastToken, currentToken) match {
+          case _ if valDefStarterTokens.contains(currentToken) => currentToken
+          case (("val" | "var"), "=") => currentToken
+          case ("case", ("=>" | "class" | "object")) => currentToken
+          case ("def", _) => currentToken
+          case _ => lastToken
         }
 
       while (remaining.nonEmpty && !delim(curr)) {
@@ -310,13 +316,12 @@ object SyntaxHighlighting {
       val toAdd  =
         if (shouldHL(str))
           highlight(str)
-        else if (("var" :: "val" :: "def" :: "case" :: Nil).contains(lastToken) &&
-          !List("=", "=>").contains(str))
+        else if (valDefStarterTokens.contains(lastToken) && !List("=", "=>").contains(str))
           valDef(str)
         else str
       val suffix = if (delim(curr)) s"$curr" else ""
       newBuf append (toAdd + suffix)
-      if (shouldUpdateLastToken(str)) lastToken = str
+      lastToken = updateLastToken(str)
       prev = curr
     }
 

compiler/test-resources/printing/defs

@@ -1,53 +1,167 @@
 package dotty.tools.dotc.printing
 
-import java.io.PrintWriter
-
-import dotty.tools.io.JFile
-import org.junit.Assert.fail
+import org.junit.Assert._
 import org.junit.Test
 
-import scala.io.Source
-
-/** Runs all tests contained in `compiler/test-resources/printing/`
-  * To check test cases, you can use "cat" or "less -r" from bash
-  * To generate test files you can call the generateTestFile method*/
+/** Adapted from Ammonite HighlightTests
+ */
 class SyntaxHighlightingTests {
+  import SyntaxHighlighting._
+
+  private def test(source: String, expected: String): Unit = {
+    val highlighted = SyntaxHighlighting.apply(source)
+      .mkString
+      .replace(NoColor,         ">")
+      .replace(CommentColor,    "<C|")
+      .replace(KeywordColor,    "<K|")
+      .replace(ValDefColor,     "<V|")
+      .replace(LiteralColor,    "<L|")
+      .replace(StringColor,     "<S|")
+      .replace(TypeColor,       "<T|")
+      // .replace(AnnotationColor, "<A|") // is the same color as type color
 
-  private def scripts(path: String): Array[JFile] = {
-    val dir = new JFile(getClass.getResource(path).getPath)
-    assert(dir.exists && dir.isDirectory, "Couldn't load scripts dir")
-    dir.listFiles
+    if (expected != highlighted) {
+      // assertEquals produces weird expected/found message
+      fail(s"expected: $expected but was: $highlighted")
+    }
   }
 
-  private def testFile(f: JFile): Unit = {
-    val lines = Source.fromFile(f).getLines()
-    val input = lines.takeWhile(_ != "result:").mkString("\n")
-    val expectedOutput = lines.mkString("\n")
-    val actualOutput = SyntaxHighlighting(input).mkString
+  @Test
+  def comments = {
+    test("//a", "<C|//a>")
+    test("/** a */", "<C|/** a */>")
+    test("/* a */", "<C|/* a */>")
+  }
 
-    if (expectedOutput != actualOutput) {
-      println("Expected output:")
-      println(expectedOutput)
-      println("Actual output:")
-      println(actualOutput)
+  @Test
+  def types = {
+    test("type Foo = Int", "<K|type> <T|Foo> = <T|Int>")
+  }
 
-      // Call generateTestFile when you want to update a test file
-      // or generate a test from a scala source file
-      // if (f.getName == "nameOfFileToConvertToATest") generateTestFile()
+  @Test
+  def literals = {
+    test("1", "<L|1>")
+    // test("1L", "<L|1L>")
+  }
 
-      fail(s"Error in file $f, expected output did not match actual")
-    }
+  @Test
+  def strings = {
+    // For some reason we currently use literal color for string
+    test("\"Hello\"", "<L|\"Hello\">")
+  }
 
-    /** Writes `input` and `actualOutput` to the current test file*/
-    def generateTestFile(): Unit = {
-      val path = "compiler/test-resources/printing/" + f.getName
-      new PrintWriter(path) {
-        write(input + "\nresult:\n" + actualOutput)
-        close()
-      }
-      println(s"Test file for ${f.getName} has been generated")
-    }
+  @Test
+  def annotations = {
+    test("@tailrec", "<T|@tailrec>")
+  }
+
+  @Test
+  def expressions = {
+    test("val x = 1 + 2 + 3", "<K|val> <V|x> = <L|1> + <L|2> + <L|3>")
+  }
+
+  @Test
+  def valVarDef = {
+    val source =
+      """
+        |package test
+        |
+        |object A {
+        | val a = 123
+        | var b = 123 /*Int*/
+        | var c = "123" // String
+        | var d: Int = 123
+        | var e:Int = 123;e
+        | e
+        | print(a)
+        | 123;123
+        | def f = 123
+        | def f1(x: Int) = 123
+        | def f2[T](x: T) = { 123 }
+        |}
+      """.stripMargin
+    val expected =
+      """
+        |<K|package> test
+        |
+        |<K|object> <T|A> {
+        | <K|val> <V|a> = <L|123>
+        | <K|var> <V|b> = <L|123> <C|/*Int*/>
+        | <K|var> <V|c> = <L|"123"> <C|// String
+        |> <K|var> <V|d>: <T|Int> = <L|123>
+        | <K|var> <V|e>:<T|Int> = <L|123>;e
+        | e
+        | print(a)
+        | <L|123>;<L|123>
+        | <K|def> <V|f> = <L|123>
+        | <K|def> <V|f1>(x: <T|Int>) = <L|123>
+        | <K|def> <V|f2>[<T|T>](x: <T|T>) = { <L|123> }
+        |}
+      """.stripMargin
+    test(source, expected)
+  }
+
+  @Test
+  def patternMatching = {
+    val source =
+      """
+        |val aFruit: Fruit = Apple("red", 123)
+        |
+        |val Apple(color, weight) = aFruit
+        |
+        |sealed trait Fruit
+        |case class Apple(color: String, weight: Double) extends Fruit
+        |case class Orange(weight: Double) extends Fruit
+        |case class Melon(weight: Double) extends Fruit
+        |
+        |aFruit match {
+        |  case Apple(_, weight) => println(s"apple: $weight kgs")
+        |  case o: Orange => println(s"orange ${o.weight} kgs")
+        |  case m @ Melon(weight) => println(s"melon: ${m.weight} kgs")
+        |}
+      """.stripMargin
+    val expected =
+      """
+        |<K|val> <V|aFruit>: <T|Fruit> = <T|Apple>(<L|"red">, <L|123>)
+        |
+        |<K|val> <T|Apple>(<V|color>, <V|weight>) = aFruit
+        |
+        |<K|sealed> <K|trait> <T|Fruit>
+        |<K|case> <K|class> <T|Apple>(color: <T|String>, weight: <T|Double>) <K|extends> <T|Fruit>
+        |<K|case> <K|class> <T|Orange>(weight: <T|Double>) <K|extends> <T|Fruit>
+        |<K|case> <K|class> <T|Melon>(weight: <T|Double>) <K|extends> <T|Fruit>
+        |
+        |aFruit <K|match> {
+        |  <K|case> <T|Apple>(<V|_>, <V|weight>) <T|=>> println(s<L|"apple: <V|$weight <L|kgs">)
+        |  <K|case> <V|o>: <T|Orange> <T|=>> println(s<L|"orange <V|${o.weight}<L| kgs">)
+        |  <K|case> <V|m> @ <T|Melon>(<V|weight>) <T|=>> println(s<L|"melon: <V|${m.weight}<L| kgs">)
+        |}
+      """.stripMargin
+    test(source, expected)
   }
 
-  @Test def syntaxHighlight = scripts("/printing").foreach(testFile)
+  @Test
+  def unionTypes = {
+    val source =
+      """
+        |type A = String|Int| Long
+        |type B = String |Int| Long
+        |type C = String | Int | Long
+        |type D = String&Int& Long
+        |type E = String &Int& Long
+        |type F = String & Int & Long
+        |fn[String|Char](input)
+      """.stripMargin
+    val expected =
+      """
+        |<K|type> <T|A> = <T|String>|<T|Int>| <T|Long>
+        |<K|type> <T|B> = <T|String> |<T|Int>| <T|Long>
+        |<K|type> <T|C> = <T|String> | <T|Int> | <T|Long>
+        |<K|type> <T|D> = <T|String>&<T|Int>& <T|Long>
+        |<K|type> <T|E> = <T|String> &<T|Int>& <T|Long>
+        |<K|type> <T|F> = <T|String> & <T|Int> & <T|Long>
+        |fn[<T|String>|<T|Char>](input)
+      """.stripMargin
+    test(source, expected)
+  }
 }