*New* Add parseYaml() Function (#142)

## Description

This PR adds a new `parseYaml()` function to **sjsonnet**.

[JSONNET Reference
Doc](https://jsonnet.org/ref/stdlib.html#:~:text=yields%20%7B%20%22foo%22%3A%20%22bar%22%20%7D.-,std.parseYaml(str),-Available%20since%20version)

---
**Signed-off-by:** Rohit Agrawal <rohit.agrawal@databricks.com>

Signed-off-by: Rohit Agrawal <rohit.agrawal@databricks.com>

build.sbt

@@ -16,8 +16,10 @@ lazy val main = (project in file("sjsonnet"))
       "com.lihaoyi" %% "scalatags" % "0.9.3",
       "com.lihaoyi" %% "os-lib" % "0.7.2",
       "com.lihaoyi" %% "mainargs" % "0.2.0",
+      "org.json" % "json" % "20211205",
       "org.scala-lang.modules" %% "scala-collection-compat" % "2.4.0",
       "org.tukaani" % "xz" % "1.8",
+      "org.yaml" % "snakeyaml" % "1.30",
     ),
     libraryDependencies ++= Seq(
       "com.lihaoyi" %% "utest" % "0.7.7",

build.sc

@@ -105,7 +105,9 @@ class SjsonnetModule(val crossScalaVersion: String) extends Module {
       millSourcePath / "src-jvm-js"
     )
     def ivyDeps = super.ivyDeps() ++ Agg(
-      ivy"org.tukaani:xz::1.8"
+      ivy"org.json:json:20211205",
+      ivy"org.tukaani:xz::1.8",
+      ivy"org.yaml:snakeyaml::1.30"
     )
     def scalacOptions = Seq("-opt:l:inline", "-opt-inline-from:sjsonnet.**")
     //def compileIvyDeps = Agg( ivy"com.lihaoyi::acyclic:0.2.0")

sjsonnet/src-js/sjsonnet/Platform.scala

@@ -12,6 +12,9 @@ object Platform {
   def xzString(s: String): String = {
     throw new Exception("XZ not implemented in Scala.js")
   }
+  def yamlToJson(s: String): String = {
+    throw new Exception("parseYaml() not implemented in Scala.js")
+  }
   def md5(s: String): String = {
     throw new Exception("MD5 not implemented in Scala.js")
   }

sjsonnet/src-jvm/sjsonnet/Platform.scala

@@ -1,10 +1,14 @@
 package sjsonnet
 
+import org.json.JSONObject
+
 import java.io.ByteArrayOutputStream
 import java.util.Base64
 import java.util.zip.GZIPOutputStream
 import org.tukaani.xz.LZMA2Options
 import org.tukaani.xz.XZOutputStream
+import org.yaml.snakeyaml.Yaml
+import org.yaml.snakeyaml.constructor.Constructor
 
 object Platform {
   def gzipBytes(b: Array[Byte]): String = {
@@ -31,6 +35,10 @@ object Platform {
   def xzString(s: String): String = {
     xzBytes(s.getBytes())
   }
+  def yamlToJson(yamlString: String): String = {
+    val yaml: java.util.LinkedHashMap[String, Object] = new Yaml(new Constructor(classOf[java.util.LinkedHashMap[String, Object]])).load(yamlString)
+    new JSONObject(yaml).toString()
+  }
   def md5(s: String): String = {
     java.security.MessageDigest.getInstance("MD5")
       .digest(s.getBytes("UTF-8"))

sjsonnet/src-native/sjsonnet/Platform.scala

@@ -12,6 +12,9 @@ object Platform {
   def xzString(s: String): String = {
     throw new Exception("XZ not implemented in Scala Native")
   }
+  def yamlToJson(s: String): String = {
+    throw new Exception("parseYaml() not implemented in Scala Native")
+  }
   def md5(s: String): String = {
     throw new Exception("MD5 not implemented in Scala Native")
   }

sjsonnet/src/sjsonnet/Std.scala

@@ -5,10 +5,8 @@ import java.nio.charset.StandardCharsets.UTF_8
 import java.util.Base64
 import java.util
 import java.util.regex.Pattern
-
 import sjsonnet.Expr.Member.Visibility
 import sjsonnet.Expr.BinaryOp
-import sjsonnet.ArrayOps._
 
 import scala.collection.mutable
 import scala.util.matching.Regex
@@ -611,6 +609,16 @@ class Std {
       ujson.StringParser.transform(str.asString, new ValVisitor(pos))
   }
 
+  private object ParseYaml extends Val.Builtin1("str") {
+    def evalRhs(str: Val, ev: EvalScope, pos: Position): Val = {
+      try {
+        ujson.StringParser.transform(Platform.yamlToJson(str.asString), new ValVisitor(pos))
+      } catch {
+        case _: Exception => null
+      }
+    }
+  }
+
   private object Set_ extends Val.Builtin2("arr", "keyF", Array(null, Val.False(dummyPos))) {
     def evalRhs(arr: Val, keyF: Val, ev: EvalScope, pos: Position): Val = {
       uniqArr(pos, ev, sortArr(pos, ev, arr, keyF), keyF)
@@ -1183,6 +1191,7 @@ class Std {
     "parseOctal" -> ParseOctal,
     "parseHex" -> ParseHex,
     "parseJson" -> ParseJson,
+    "parseYaml" -> ParseYaml,
     "md5" -> MD5,
     builtin("prune", "x"){ (pos, ev, s: Val) =>
       def filter(x: Val) = x match{

sjsonnet/test/src-jvm/sjsonnet/ParseYamlTests.scala

@@ -0,0 +1,15 @@
+package sjsonnet
+
+import sjsonnet.TestUtils.eval
+import utest._
+
+object ParseYamlTests extends TestSuite {
+  def tests: Tests = Tests {
+    test {
+      eval("std.parseYaml('foo: bar')") ==> ujson.Value("""{"foo":"bar"}""")
+    }
+    test {
+      eval("std.parseYaml('')") ==> ujson.Value("""{}""")
+    }
+  }
+}