6 files changed, 48 insertions, 21 deletions

diff --git a/language-web/src/main/js/editor/EditorParent.ts b/language-web/src/main/js/editor/EditorParent.ts
index 316c5072..a2f6c266 100644
--- a/language-web/src/main/js/editor/EditorParent.ts
+++ b/language-web/src/main/js/editor/EditorParent.ts
@@ -65,6 +65,9 @@ export const EditorParent = styled('div')(({ theme }) => ({
   '.cmt-number': {
     color: '#6188a6',
   },
+  '.cmt-string': {
+    color: theme.palette.secondary.dark,
+  },
   '.cmt-keyword': {
     color: theme.palette.primary.main,
   },
diff --git a/language-web/src/main/js/editor/problem.grammar b/language-web/src/main/js/editor/problem.grammar
index 921cec53..cf940698 100644
--- a/language-web/src/main/js/editor/problem.grammar
+++ b/language-web/src/main/js/editor/problem.grammar
@@ -1,4 +1,3 @@
-
 @top Problem { statement* }
 
 statement {
@@ -7,6 +6,7 @@ statement {
   } |
   ClassDefinition {
     ckw<"abstract">? ckw<"class"> RelationName
+    (ckw<"extends"> sep<",", RelationName>)?
     (ClassBody {  "{" ReferenceDeclaration* "}" } | ".")
   } |
   EnumDefinition {
@@ -21,6 +21,9 @@ statement {
     ckw<"default">? (NotOp | UnknownOp)? RelationName
     ParameterList<AssertionArgument> (":" LogicValue)? "."
   } |
+  NodeValueAssertion {
+    UniqueNodeName ":" Constant "."
+  } |
   UniqueDeclaration {
     ckw<"unique"> sep<",", UniqueNodeName> "."
   } |
@@ -30,18 +33,17 @@ statement {
 }
 
 ReferenceDeclaration {
-  ((kw<"refers"> | kw<"contains">) !times RelationName | !plus RelationName)
+  (kw<"refers"> | kw<"contains">)?
+  RelationName
   RelationName
   ( "[" Multiplicity? "]" )?
   (kw<"opposite"> RelationName)?
   ";"?
 }
 
-@precedence { times @left, plus }
-
 Parameter { RelationName? VariableName }
 
-Conjunction { sep1<",", Literal> }
+Conjunction { ("," | Literal)+ }
 
 OrOp { ";" }
 
@@ -49,9 +51,11 @@ Literal { NotOp? Atom }
 
 Atom { RelationName ParameterList<Argument>? }
 
-Argument { VariableName | Real }
+Argument { VariableName | Constant }
 
-AssertionArgument { NodeName | StarArgument | Real }
+AssertionArgument { NodeName | StarArgument | Constant }
+
+Constant { Real | String }
 
 LogicValue {
   ckw<"true"> | ckw<"false"> | ckw<"unknown"> | ckw<"error">
@@ -108,6 +112,11 @@ sep1<separator, content> { content (separator content?)* }
 
   exponential { int ("e" | "E") ("+" | "-")? int }
 
+  String {
+    "'" (![\\'\n] | "\\" ![\n] | "\\\n")+ "'" |
+    "\"" (![\\"\n] | "\\" (![\n] | "\n"))* "\""
+  }
+
   NotOp { "!" }
 
   UnknownOp { "?" }
diff --git a/language-web/src/main/js/editor/problemLanguageSupport.ts b/language-web/src/main/js/editor/problemLanguageSupport.ts
index 2bf7c7a4..c9e61b31 100644
--- a/language-web/src/main/js/editor/problemLanguageSupport.ts
+++ b/language-web/src/main/js/editor/problemLanguageSupport.ts
@@ -26,7 +26,7 @@ const parserWithMetadata = (parser as LRParser).configure({
       LineComment: t.lineComment,
       BlockComment: t.blockComment,
       'problem class enum pred unique scope': t.definitionKeyword,
-      'abstract refers contains opposite error default': t.modifier,
+      'abstract extends refers contains opposite error default': t.modifier,
       'true false unknown error': t.keyword,
       NotOp: t.keyword,
       UnknownOp: t.keyword,
@@ -34,6 +34,7 @@ const parserWithMetadata = (parser as LRParser).configure({
       StarArgument: t.keyword,
       'IntMult StarMult Real': t.number,
       StarMult: t.number,
+      String: t.string,
       'RelationName/QualifiedName': t.typeName,
       'UniqueNodeName/QualifiedName': t.atom,
       'VariableName/QualifiedName': t.variableName,
diff --git a/language-web/src/main/js/index.tsx b/language-web/src/main/js/index.tsx
index 1b24eadb..9316db4d 100644
--- a/language-web/src/main/js/index.tsx
+++ b/language-web/src/main/js/index.tsx
@@ -26,7 +26,7 @@ enum TaxStatus {
 % A child cannot have any dependents.
 error invalidTaxStatus(Person p) <->
   taxStatus(p, child),
-  children(p, _q)
+  children(p, _q),
 ; taxStatus(p, retired),
   parent(p, q),
   !taxStatus(q, retired).
diff --git a/language/src/main/java/tools/refinery/language/GenerateProblem.mwe2 b/language/src/main/java/tools/refinery/language/GenerateProblem.mwe2
index 79eb79a7..58620d6a 100644
--- a/language/src/main/java/tools/refinery/language/GenerateProblem.mwe2
+++ b/language/src/main/java/tools/refinery/language/GenerateProblem.mwe2
@@ -3,35 +3,39 @@ module tools.refinery.language.GenerateProblem
 import org.eclipse.xtext.xtext.generator.*
 import org.eclipse.xtext.xtext.generator.model.project.*
 
-var rootPath = ".."
+var rootPath = '..'
 
 Workflow {
         component = XtextGenerator {
                 configuration = {
                         project = StandardProjectConfig {
-                                baseName = "language"
+                                baseName = 'language'
                                 rootPath = rootPath
                                 runtimeTest = {
                                         enabled = true
                                         srcGen = 'src/testFixtures/xtext-gen'
                                 }
                                 genericIde = {
-                                        name = "language-ide"
+                                        name = 'language-ide'
+                                }
+                                web = {
+                                        enabled = true
+                                        name = 'language-web'
                                 }
                                 mavenLayout = true
                         }
                         code = {
-                                encoding = "UTF-8"
-                                lineDelimiter = "\n"
-                                fileHeader = "/*\n * generated by Xtext \${version}\n */"
+                                encoding = 'UTF-8'
+                                lineDelimiter = '\n'
+                                fileHeader = '/*\n * generated by Xtext \${version}\n */'
                                 preferXtendStubs = false
                         }
                 }
 
                 language = StandardLanguage {
-                        name = "tools.refinery.language.Problem"
-                        fileExtensions = "problem"
-                        referencedResource = "platform:/resource/refinery-language-model/model/problem.genmodel"
+                        name = 'tools.refinery.language.Problem'
+                        fileExtensions = 'problem'
+                        referencedResource = 'platform:/resource/refinery-language-model/model/problem.genmodel'
                         serializer = {
                                 generateStub = false
                         }
@@ -44,7 +48,17 @@ Workflow {
                         junitSupport = {
                                 generateStub = false
                                 skipXbaseTestingPackage = true
-                                junitVersion = "5"
+                                junitVersion = '5'
+                        }
+                        webSupport = {
+                                // We only generate the {@code AbstractProblemWebModule},
+                                // because we write our own integration code for CodeMirror 6. 
+                                framework = 'codemirror'
+                                generateHtmlExample = false
+                                generateJettyLauncher = false
+                                generateJsHighlighting = false
+                                generateServlet = false
+                                generateWebXml = false
                         }
                 }
         }
diff --git a/language/src/main/java/tools/refinery/language/Problem.xtext b/language/src/main/java/tools/refinery/language/Problem.xtext
index c4c890e3..6f6a8588 100644
--- a/language/src/main/java/tools/refinery/language/Problem.xtext
+++ b/language/src/main/java/tools/refinery/language/Problem.xtext
@@ -26,7 +26,7 @@ EnumLiteral returns Node:
         name=Identifier;
 
 ReferenceDeclaration:
-        (-> (containment?="contains" | "refers"))?
+        (containment?="contains" | "refers")?
         referenceType=[Relation|QualifiedName]
         ("[" multiplicity=Multiplicity "]")?
         name=Identifier
@@ -184,7 +184,7 @@ QualifiedName hidden():
 
 Identifier:
         ID | "true" | "false" | "unknown" | "error" | "class" | "abstract" | "extends" | "enum" | "pred" | "scope" |
-        "unique" | "default" | "problem" | "contains" | "refers" | "new" | "delete";
+        "unique" | "default" | "problem" | "new" | "delete";
 
 Integer returns ecore::EInt hidden():
         "-"? INT;