Adds command line property source. (#217)

* Adds command line property source.

* Adds map property source and tests for map and command line.

Co-authored-by: Frederic Kneier <[email protected]>

hoplite-core/src/main/kotlin/com/sksamuel/hoplite/PropertySource.kt

@@ -65,6 +65,24 @@ interface PropertySource {
     fun stream(input: InputStream, ext: String) =
       InputStreamPropertySource(input, ext)
 
+    /**
+     * Returns a [PropertySource] that read the specified map values.
+     *
+     * @param map map
+     */
+    fun map(map: Map<String, Any>) =
+      MapPropertySource(map)
+
+    /**
+     * Returns a [PropertySource] that will read the specified command line arguments.
+     *
+     * @param arguments command line arguments as passed to main method
+     * @param prefix argument prefix
+     * @param delimiter key value delimiter
+     */
+    fun commandLine(arguments: Array<String>, prefix: String = "--", delimiter: String = "=") =
+      CommandLinePropertySource(arguments, prefix, delimiter)
+
     /**
      * Returns a [PropertySource] that will read from the specified string.
      *
@@ -132,6 +150,53 @@ class EnvironmentVariablesPropertySource(
   }
 }
 
+/**
+ * An implementation of [PropertySource] that provides config based on command line arguments.
+ *
+ * Parameters will be processed if they start with a given prefix. Key and value are split by a given delimiter.
+ */
+class MapPropertySource(
+  private val map: Map<String, Any?>,
+) : PropertySource {
+  override fun node(context: PropertySourceContext): ConfigResult<Node> {
+    return when {
+      map.isEmpty() -> Undefined.valid()
+      else -> map.toNode("map").valid()
+    }
+  }
+}
+
+/**
+ * An implementation of [PropertySource] that provides config based on command line arguments.
+ *
+ * Parameters will be processed if they start with a given prefix. Key and value are split by a given delimiter.
+ */
+class CommandLinePropertySource(
+  private val arguments: Array<String>,
+  private val prefix: String,
+  private val delimiter: String,
+) : PropertySource {
+  override fun node(context: PropertySourceContext): ConfigResult<Node> {
+    val values = arguments.asSequence().filter {
+      it.startsWith(prefix) && it.contains(delimiter)
+    }.map {
+      it.removePrefix(prefix).split(delimiter, limit = 2)
+    }.groupingBy {
+      it[0]
+    }.aggregate { _, accumulator: Any?, element, _ ->
+      when (accumulator) {
+        null -> element[1]
+        is List<*> -> accumulator + element[1]
+        else -> listOf(accumulator, element[1])
+      }
+    }
+    return when {
+      values.isEmpty() -> Undefined.valid()
+      else -> values.toNode("commandLine").valid()
+    }
+  }
+}
+
 /**
  * An implementation of [PropertySource] that provides config through a config file
  * defined at ~/.userconfig.ext

hoplite-core/src/main/kotlin/com/sksamuel/hoplite/parsers/loadProps.kt

@@ -1,43 +1,71 @@
 package com.sksamuel.hoplite.parsers
 
-import com.sksamuel.hoplite.MapNode
-import com.sksamuel.hoplite.Pos
-import com.sksamuel.hoplite.StringNode
-import com.sksamuel.hoplite.Node
+import com.sksamuel.hoplite.*
 import java.util.*
 
 @Suppress("UNCHECKED_CAST")
-fun Properties.toNode(source: String): Node {
+fun Properties.toNode(source: String) = asIterable().toNode(
+  source = source,
+  keyExtractor = { it.key.toString() },
+  valueExtractor = { it.value }
+)
 
-  val valueMarker = "____value"
+@Suppress("UNCHECKED_CAST")
+fun <T : Any> Map<String, T?>.toNode(source: String) = entries.toNode(
+  source = source,
+  keyExtractor = { it.key },
+  valueExtractor = { it.value },
+)
+
+data class Element(
+  val values: MutableMap<String, Element> = hashMapOf(),
+  var value: Any? = null,
+)
+
+@Suppress("UNCHECKED_CAST")
+private fun <T> Iterable<T>.toNode(source: String, keyExtractor: (T) -> String, valueExtractor: (T) -> Any?): Node {
+  val map = Element()
 
-  val root = mutableMapOf<String, Any>()
-  stringPropertyNames().toList().map { key ->
+  forEach { item ->
+    val key = keyExtractor(item)
+    val value = valueExtractor(item)
+    val segments = key.split(".")
 
-    val components = key.split('.')
-    val map = components.fold(root) { acc, k ->
-      acc.getOrPut(k) { mutableMapOf<String, Any>() } as MutableMap<String, Any>
+    segments.foldIndexed(map) { index, element, segment ->
+      element.values.computeIfAbsent(segment) { Element() }.also {
+        if (index == segments.size - 1) it.value = value
+      }
     }
-    map.put(valueMarker, getProperty(key))
   }
 
   val pos = Pos.FilePos(source)
 
-  fun Map<String, Any>.toNode(): Node {
-    val maps = filterValues { it is MutableMap<*, *> }.mapValues {
-      when (val v = it.value) {
-        is MutableMap<*, *> -> (v as MutableMap<String, Any>).toNode()
-        else -> throw java.lang.RuntimeException("Bug: unsupported state $it")
-      }
-    }
-    val value = this[valueMarker]
-    return when {
-      value == null && maps.isEmpty() -> MapNode(emptyMap(), pos)
-      value == null && maps.isNotEmpty() -> MapNode(maps.toMap(), pos)
-      maps.isEmpty() -> StringNode(value.toString(), pos)
-      else -> MapNode(maps.toMap(), pos, StringNode(value.toString(), pos))
+  fun Any.transform(): Node = when (this) {
+    is Element -> when {
+      value != null && values.isEmpty() -> value?.transform() ?: Undefined
+      else -> MapNode(
+        map = values.takeUnless { it.isEmpty() }?.mapValues { it.value.transform() } ?: emptyMap(),
+        value = value?.transform() ?: Undefined,
+        pos = pos,
+      )
     }
+    is Array<*> -> ArrayNode(
+      elements = mapNotNull { it?.transform() },
+      pos = pos,
+    )
+    is Collection<*> -> ArrayNode(
+      elements = mapNotNull { it?.transform() },
+      pos = pos,
+    )
+    is Map<*, *> -> MapNode(
+      map = takeUnless { it.isEmpty() }?.mapNotNull { entry ->
+        entry.value?.let { entry.key.toString() to it.transform() }
+      }?.toMap() ?: emptyMap(),
+      pos = pos,
+    )
+    else -> StringNode(this.toString(), pos)
   }
 
-  return root.toNode()
+  val result = map.transform()
+  return result
 }

hoplite-core/src/test/kotlin/com/sksamuel/hoplite/PropertySourceTest.kt

@@ -8,11 +8,16 @@ class PropertySourceTest : FunSpec() {
 
     test("reads config from string") {
       data class TestConfig(val a: String, val b: Int)
+
       val config = ConfigLoader.Builder()
-        .addPropertySource(PropertySource.string("""
+        .addPropertySource(
+          PropertySource.string(
+            """
           a = A value
           b = 42
-          """.trimIndent(), "props"))
+          """.trimIndent(), "props"
+          )
+        )
         .build()
         .loadConfigOrThrow<TestConfig>()
 
@@ -35,5 +40,41 @@ class PropertySourceTest : FunSpec() {
       config shouldBe TestConfig("A value", 42)
     }
 
+    test("reads config from map") {
+      data class TestConfig(val a: String, val b: Int, val other: List<String>)
+
+      val arguments = mapOf(
+        "a" to "A value",
+        "b" to "42",
+        "other" to listOf("Value1", "Value2"),
+      )
+
+      val config = ConfigLoader.Builder()
+        .addPropertySource(PropertySource.map(arguments))
+        .build()
+        .loadConfigOrThrow<TestConfig>()
+
+      config shouldBe TestConfig("A value", 42, listOf("Value1", "Value2"))
+    }
+
+    test("reads config from command line") {
+      data class TestConfig(val a: String, val b: Int, val other: List<String>)
+
+      val arguments = arrayOf(
+        "--a=A value",
+        "--b=42",
+        "some other value",
+        "--other=Value1",
+        "--other=Value2",
+      )
+
+      val config = ConfigLoader.Builder()
+        .addPropertySource(PropertySource.commandLine(arguments))
+        .build()
+        .loadConfigOrThrow<TestConfig>()
+
+      config shouldBe TestConfig("A value", 42, listOf("Value1", "Value2"))
+    }
+
   }
 }