Added paths and simple completion.

com.typesafe.hocon.ui/src/com/typesafe/config/ui/contentassist/HoconProposalProvider.xtend

@@ -3,11 +3,67 @@
  */
 package com.typesafe.config.ui.contentassist
 
-import com.typesafe.config.ui.contentassist.AbstractHoconProposalProvider
+import com.typesafe.config.hocon.HObject
+import com.typesafe.config.hocon.Path
+import com.typesafe.config.hocon.Root
+import org.eclipse.emf.ecore.EObject
+import org.eclipse.xtext.Assignment
+import org.eclipse.xtext.EcoreUtil2
+import org.eclipse.xtext.ui.editor.contentassist.ContentAssistContext
+import org.eclipse.xtext.ui.editor.contentassist.ICompletionProposalAcceptor
 
 /**
  * See https://www.eclipse.org/Xtext/documentation/304_ide_concepts.html#content-assist
  * on how to customize the content assistant.
  */
 class HoconProposalProvider extends AbstractHoconProposalProvider {
+
+  /**
+   * Return the member object that corresponds to the given path. For example,
+   * if the path is `foo, bar` it will walk through the members of `owner` using
+   * the first key that matches `foo` and that is an HObject, and then the same for
+   * bar.
+   *
+   * @note Using `Root` instead of `HObject` because HObject is a subtype of Root,
+   *       and we treat Root as an object anyway
+   * @return null if no such path is found
+   */
+  private def Root findMemberObject(Root owner, Iterable<String> path) {
+    if (path.isEmpty)
+      owner
+    else {
+      val tmp = owner.members.findFirst [
+        (it.value instanceof Root) && (path.head == it.key.elements.get(0).name)
+      ]
+      if (tmp != null)
+        findMemberObject(tmp.value as HObject, path.tail)
+      else
+        null
+    }
+  }
+
+  override def void completePath_Elements(EObject model, Assignment assignment, ContentAssistContext context,
+    ICompletionProposalAcceptor acceptor) {
+    super.completePath_Elements(model, assignment, context, acceptor)
+
+    val owner = switch prefix: model {
+      Path: {
+        val base = EcoreUtil2.getContainerOfType(prefix, typeof(Root))
+        val t = prefix.elements.map[it.name].toList
+        findMemberObject(base, t)
+      }
+      Root:
+        prefix
+    }
+
+    val keys = owner.members.map[it.key]
+
+    val names = keys.map [
+      val elems = it.elements
+      elems.drop(1).fold(elems.head.name)[p1, p2|p1 + '.' + p2.name]
+    ]
+
+    for (n : names)
+      acceptor.accept(createCompletionProposal(n, context))
+  }
 }

com.typesafe.hocon.ui/src/com/typesafe/config/ui/labeling/HoconLabelProvider.xtend

@@ -23,13 +23,18 @@ class HoconLabelProvider extends org.eclipse.xtext.ui.label.DefaultEObjectLabelP
 
 	// Labels and icons can be computed like this:
 
-	def text(Member ele) {
-	  if (ele.value != null
-	     && ele.value.value.size == 1 
-	     && ele.value.value.get(0) instanceof EString)
-		  ele.name.getText + ": " + ele.value.value.get(0).getText
+	def text(Member m) {
+	  // concatenate the path, in case there are several elements
+	  // we know there is at least one element (from the grammar)
+	  val elems = m.key.elements
+	  val name = elems.drop(1).fold(elems.head.name) [p1, p2| p1 + '.' + p2.name]
+
+	  if (m.value != null
+	     && m.value.value.size == 1 
+	     && m.value.value.get(0) instanceof EString)
+		  name + ": " + m.value.value.get(0).getText
 		else
-		  ele.name.getText
+		  name
 	}
 
 	def text(Array l) {

com.typesafe.hocon/src/com/typesafe/config/Hocon.xtext

@@ -6,26 +6,28 @@ import "http://www.eclipse.org/emf/2002/Ecore" as ecore
 
 generate hocon "http://www.typesafe.com/config/Hocon"
 
+// here it would be good to find a way to
+// create a synthetic HObject around the members...
 Root: 
   NL*
-  ( Object 
+  ( HObject
     | ( members += Member (',' | NL) NL* )*
   )
   NL*
 ;
 
-Object:
+HObject:
  '{' NL*
-    ( members+=Member (',' | NL) NL* )*  
+    ( members += Member (',' | NL) NL* )*
  '}';
 
 
 Member:
-  name = StringLiteral (':' NL* | '=' NL*)? value=Literal
+  key = Path (':' NL* | '=' NL*)? value = Literal
 ;
 
 Literal:
-  (value += SimpleLiteral)+ | Object | Array ;
+  (value += SimpleLiteral)+ | HObject | Array ;
 
 SimpleLiteral returns EString:
   (StringLiteral | name = Boolean | Null | NumberLiteral)
@@ -46,11 +48,15 @@ Boolean:
 Null:
   {Null} 'null';
 
+Path:
+  elements += StringLiteral ( '.' elements += StringLiteral)*
+;
 
 StringLiteral returns EString: 
   (name = STRING | name = UNQUOTED_STRING)
 ;
 
+
 NumberLiteral:
   value = Number
 ;
@@ -62,7 +68,7 @@ terminal UNQUOTED_STRING:
   ( !(' ' | '\n' |'\t' | '\\' | '"' | '$' |
       '{' |  '}' | '[' | ']'  | ':' | '=' |
       '|' |  '+' | '#' | '`'  | '^' | '?' |
-      '!' |  '@' | '*' | '&'  | '//'| ','
+      '!' |  '@' | '*' | '&'  | '//'| ',' | '.'
   ) )+
 ;