feat: Add util class to remove comments from blocks

core/src/main/kotlin/cash/grammar/kotlindsl/utils/Comments.kt

@@ -57,16 +57,16 @@ public class Comments(
   }
 
   public fun getCommentsInBlock(ctx: KotlinParser.NamedBlockContext): List<Token> {
-    val comments = ArrayDeque<Token>()
-    var index = ctx.stop.tokenIndex
+    val comments = mutableListOf<Token>()
+    var index = ctx.start.tokenIndex
 
-    while (index > ctx.start.tokenIndex) {
-      var token = tokens.get(index)
+    while (index <= ctx.stop.tokenIndex) {
+      val token = tokens.get(index)
 
       if (token.isComment()) {
-        comments.addFirst(token)
+        comments.add(token)
       }
-      --index
+      ++index
     }
 
     return comments

core/src/main/kotlin/cash/grammar/kotlindsl/utils/CommentsInBlockRemover.kt

@@ -0,0 +1,113 @@
+package cash.grammar.kotlindsl.utils
+
+import cash.grammar.kotlindsl.parse.KotlinParseException
+import cash.grammar.kotlindsl.parse.Parser
+import cash.grammar.kotlindsl.parse.Rewriter
+import cash.grammar.kotlindsl.utils.Context.leafRule
+import cash.grammar.kotlindsl.utils.Whitespace.trimGently
+import cash.grammar.utils.ifNotEmpty
+import com.squareup.cash.grammar.KotlinParser
+import com.squareup.cash.grammar.KotlinParserBaseListener
+import org.antlr.v4.runtime.CharStream
+import org.antlr.v4.runtime.CommonTokenStream
+import org.antlr.v4.runtime.Token
+import java.io.InputStream
+import java.nio.file.Path
+
+/**
+ * Removes comments from a specified block in a build script.
+ *
+ * Example:
+ * ```
+ * dependencies {
+ *     /* This is a block comment
+ *     that spans multiple lines */
+ *     implementation("org.jetbrains.kotlin:kotlin-stdlib") // This is an inline comment
+ *     // This is a single-line comment
+ *     testImplementation("org.junit.jupiter:junit-jupiter")
+ * }
+ * ```
+ *
+ * The above script would be rewritten to:
+ * ```
+ * dependencies {
+ *     implementation("org.jetbrains.kotlin:kotlin-stdlib")
+ *     testImplementation("org.junit.jupiter:junit-jupiter")
+ * }
+ * ```
+ */
+public class CommentsInBlockRemover private constructor(
+  private val input: CharStream,
+  private val tokens: CommonTokenStream,
+  private val errorListener: CollectingErrorListener,
+  private val blockName: String,
+) : KotlinParserBaseListener() {
+  private var terminalNewlines = 0
+  private val rewriter = Rewriter(tokens)
+  private val indent = Whitespace.computeIndent(tokens, input)
+  private val comments = Comments(tokens, indent)
+
+  @Throws(KotlinParseException::class)
+  public fun rewritten(): String {
+    errorListener.getErrorMessages().ifNotEmpty {
+      throw KotlinParseException.withErrors(it)
+    }
+
+    return rewriter.text.trimGently(terminalNewlines)
+  }
+
+  override fun exitNamedBlock(ctx: KotlinParser.NamedBlockContext) {
+    if (ctx.name().text == blockName) {
+      // Delete inline comments (a comment after a statement)
+      val allInlineComments = mutableListOf<Token>()
+      ctx.statements().statement().forEach {
+        val leafRule = it.leafRule()
+        val inlineComments = rewriter.deleteCommentsAndBlankSpaceToRight(leafRule.stop).orEmpty()
+        allInlineComments += inlineComments
+      }
+
+      val nonInlineComments = comments.getCommentsInBlock(ctx).subtract(allInlineComments)
+      nonInlineComments.forEach { token ->
+        rewriter.deleteWhitespaceToLeft(token)
+        rewriter.deleteNewlineToRight(token)
+        rewriter.delete(token)
+      }
+    }
+  }
+
+  public companion object {
+    public fun of(
+      buildScript: Path,
+      blockName: String,
+    ): CommentsInBlockRemover {
+      return of(Parser.readOnlyInputStream(buildScript), blockName)
+    }
+
+    public fun of(
+      buildScript: String,
+      blockName: String,
+    ): CommentsInBlockRemover {
+      return of(buildScript.byteInputStream(), blockName)
+    }
+
+    private fun of(
+      buildScript: InputStream,
+      blockName: String,
+    ): CommentsInBlockRemover {
+      val errorListener = CollectingErrorListener()
+
+      return Parser(
+        file = buildScript,
+        errorListener = errorListener,
+        listenerFactory = { input, tokens, _ ->
+          CommentsInBlockRemover(
+            input = input,
+            tokens = tokens,
+            errorListener = errorListener,
+            blockName = blockName,
+          )
+        },
+      ).listener()
+    }
+  }
+}

core/src/test/kotlin/cash/grammar/kotlindsl/utils/CommentsInBlockRemoverTest.kt

@@ -0,0 +1,46 @@
+package cash.grammar.kotlindsl.utils
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+
+class CommentsInBlockRemoverTest {
+  @Test
+  fun `remove all comments in the given block`() {
+    // Given
+    val buildScript = """
+      |dependencies {
+      |  /* This is a block comment
+      |  that spans multiple lines */
+      |  implementation("org.jetbrains.kotlin:kotlin-stdlib") // This is an line comment
+      |  // This is a single-line comment
+      |  testImplementation("org.junit.jupiter:junit-jupiter")
+      |  // This is another single-line comment
+      |}
+      |
+      |// This is project bar
+      |project.name = bar 
+      |
+      |otherBlock {
+      |  // More comments 
+      |}
+    """.trimMargin()
+
+    // When
+    val rewrittenBuildScript = CommentsInBlockRemover.of(buildScript, "dependencies").rewritten()
+
+    // Then
+    assertThat(rewrittenBuildScript).isEqualTo("""
+      |dependencies {
+      |  implementation("org.jetbrains.kotlin:kotlin-stdlib")
+      |  testImplementation("org.junit.jupiter:junit-jupiter")
+      |}
+      |
+      |// This is project bar
+      |project.name = bar 
+      |
+      |otherBlock {
+      |  // More comments 
+      |}
+    """.trimMargin())
+  }
+}