Support empty yaml files

sksamuel · May 27, 2023 · 0aabb74 · 0aabb74
1 parent 1a0f95a
commit 0aabb74
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Showing 4 changed files with 23 additions and 7 deletions.
diff --git a/hoplite-core/src/main/kotlin/com/sksamuel/hoplite/ConfigLoader.kt b/hoplite-core/src/main/kotlin/com/sksamuel/hoplite/ConfigLoader.kt
@@ -30,7 +30,7 @@ class ConfigLoader(
   val onFailure: List<(Throwable) -> Unit> = emptyList(),
   val decodeMode: DecodeMode = DecodeMode.Lenient,
   val useReport: Boolean = false,
-  val allowEmptyTree: Boolean, // if true then we allow config files to be empty
+  val allowEmptyTree: Boolean, // if true then we allow the cascaded tree to be empty
   val allowUnresolvedSubstitutions: Boolean,
   val classLoader: ClassLoader? = null, // if null, then the current context thread loader
   val preprocessingIterations: Int = 1,

diff --git a/hoplite-yaml/src/main/kotlin/com/sksamuel/hoplite/yaml/YamlParser.kt b/hoplite-yaml/src/main/kotlin/com/sksamuel/hoplite/yaml/YamlParser.kt
@@ -11,9 +11,7 @@ import com.sksamuel.hoplite.decoder.DotPath
 import com.sksamuel.hoplite.parsers.Parser
 import com.sksamuel.hoplite.withPath
 import org.yaml.snakeyaml.DumperOptions
-import org.yaml.snakeyaml.LoaderOptions
 import org.yaml.snakeyaml.Yaml
-import org.yaml.snakeyaml.constructor.SafeConstructor
 import org.yaml.snakeyaml.error.Mark
 import org.yaml.snakeyaml.events.AliasEvent
 import org.yaml.snakeyaml.events.DocumentEndEvent
@@ -37,9 +35,14 @@ class YamlParser : Parser {
     val events = yaml.parse(reader).iterator()
     val stream = TokenStream(events)
     require(stream.next().`is`(Event.ID.StreamStart)) { "Expected stream start at ${stream.current().startMark}" }
-    require(stream.next().`is`(Event.ID.DocumentStart)) { "Expected document start at ${stream.current().startMark}" }
-    stream.next()
-    return TokenProduction(stream, source, emptyMap(), DotPath.root).first
+    return when (stream.next().eventId) {
+      Event.ID.StreamEnd -> Undefined
+      Event.ID.DocumentStart -> {
+        stream.next() // move past the doc start
+        TokenProduction(stream, source, emptyMap(), DotPath.root).first
+      }
+      else -> error { "Expected document start at ${stream.current().startMark}" }
+    }
   }
 }
 

diff --git a/...om/sksamuel/hoplite/yaml/EmptyFileTest.kt → .../sksamuel/hoplite/yaml/EmptySourceTest.kt b/...om/sksamuel/hoplite/yaml/EmptyFileTest.kt → .../sksamuel/hoplite/yaml/EmptySourceTest.kt
@@ -4,7 +4,7 @@ import com.sksamuel.hoplite.ConfigLoaderBuilder
 import io.kotest.core.spec.style.StringSpec
 import io.kotest.matchers.shouldBe
 
-class EmptyFileTest : StringSpec({
+class EmptySourceTest : StringSpec({
 
   "empty files should be skipped when enabled in config builder" {
     data class Test(val foo: String)
@@ -16,4 +16,15 @@ class EmptyFileTest : StringSpec({
 
     config shouldBe Test("bar")
   }
+
+  "empty files should support files with only comments" {
+    data class Test(val foo: String)
+
+    val config = ConfigLoaderBuilder.default()
+      .allowEmptySources()
+      .build()
+      .loadConfigOrThrow<Test>("/foo.yml", "/empty_with_comments.yml")
+
+    config shouldBe Test("bar")
+  }
 })
diff --git a/hoplite-yaml/src/test/resources/empty_with_comments.yml b/hoplite-yaml/src/test/resources/empty_with_comments.yml
@@ -0,0 +1,2 @@
+#a:
+# b: value