chore(web): remove CodeMirror 5 MWE2 integration

CodeMirror 6 uses a hand-writter Lezer parser instead of the stream
parser generated by Xtext for CodeMirror 5.

3 files changed, 16 insertions, 15 deletions

diff --git a/language-web/build.gradle b/language-web/build.gradle
index 1f1457d6..f2b9b43f 100644
--- a/language-web/build.gradle
+++ b/language-web/build.gradle
@@ -51,12 +51,12 @@ def generateLezerGrammar = tasks.register('generateLezerGrammar', RunNpmYarn) {
 
 def assembleFrontend = tasks.named('assembleFrontend')
 assembleFrontend.configure {
-        dependsOn generateXtextLanguage
         dependsOn generateLezerGrammar
         inputs.dir 'src/main/css'
         inputs.dir 'src/main/html'
         inputs.dir 'src/main/js'
-        inputs.dir "${buildDir}/generated/sources/xtext/js"
+        inputs.file "${buildDir}/generated/sources/lezer/problem.ts"
+        inputs.file "${buildDir}/generated/sources/lezer/problem.terms.ts"
         inputs.files('package.json', 'yarn.lock', 'webpack.config.js')
         outputs.dir productionResources
 }
@@ -135,7 +135,7 @@ def jettyRun = tasks.register('jettyRun', JavaExec) {
 
 tasks.register('webpackServe', RunNpmYarn) {
         dependsOn installFrontend
-        dependsOn generateXtextLanguage
+        dependsOn generateLezerGrammar
         outputs.dir "${webpackOutputDir}/development"
         script = 'run serve'
         group = 'run'
diff --git a/language-web/src/main/js/editor/problem.grammar b/language-web/src/main/js/editor/problem.grammar
index c64402b0..921cec53 100644
--- a/language-web/src/main/js/editor/problem.grammar
+++ b/language-web/src/main/js/editor/problem.grammar
@@ -3,41 +3,42 @@
 
 statement {
   ProblemDeclaration {
-    kw<"problem"> QualifiedName "."
+    ckw<"problem"> QualifiedName "."
   } |
   ClassDefinition {
-    kw<"abstract">? kw<"class"> RelationName
+    ckw<"abstract">? ckw<"class"> RelationName
     (ClassBody {  "{" ReferenceDeclaration* "}" } | ".")
   } |
   EnumDefinition {
-    kw<"enum"> RelationName
+    ckw<"enum"> RelationName
     (EnumBody { "{" sep<",", UniqueNodeName> "}" } | ".")
   } |
   PredicateDefinition {
-    (kw<"error"> kw<"pred">? | kw<"pred">) RelationName ParameterList<Parameter>?
+    (ckw<"error"> ckw<"pred">? | ckw<"pred">) RelationName ParameterList<Parameter>?
     PredicateBody { ("<->" sep<OrOp, Conjunction>)?  "." }
   } |
   Assertion {
-    kw<"default">? (NotOp | UnknownOp)? RelationName
+    ckw<"default">? (NotOp | UnknownOp)? RelationName
     ParameterList<AssertionArgument> (":" LogicValue)? "."
   } |
   UniqueDeclaration {
-    kw<"unique"> sep<",", UniqueNodeName> "."
+    ckw<"unique"> sep<",", UniqueNodeName> "."
   } |
   ScopeDeclaration {
-    kw<"scope"> sep<",", ScopeElement> "."
+    ckw<"scope"> sep<",", ScopeElement> "."
   }
 }
 
 ReferenceDeclaration {
-  (kw<"refers"> | kw<"contains">)?
-  RelationName
+  ((kw<"refers"> | kw<"contains">) !times RelationName | !plus RelationName)
   RelationName
   ( "[" Multiplicity? "]" )?
   (kw<"opposite"> RelationName)?
   ";"?
 }
 
+@precedence { times @left, plus }
+
 Parameter { RelationName? VariableName }
 
 Conjunction { sep1<",", Literal> }
@@ -53,7 +54,7 @@ Argument { VariableName | Real }
 AssertionArgument { NodeName | StarArgument | Real }
 
 LogicValue {
-  kw<"true"> | kw<"false"> | kw<"unknown"> | kw<"error">
+  ckw<"true"> | ckw<"false"> | ckw<"unknown"> | ckw<"error">
 }
 
 ScopeElement { RelationName ("=" | "+=") Multiplicity }
@@ -72,6 +73,8 @@ QualifiedName { identifier ("::" identifier)* }
 
 kw<term> { @specialize[@name={term}]<identifier, term> }
 
+ckw<term> { @extend[@name={term}]<identifier, term> }
+
 ParameterList<content> { "(" sep<",", content> ")" }
 
 sep<separator, content> { sep1<separator, content>? }
diff --git a/language-web/webpack.config.js b/language-web/webpack.config.js
index c51d55d6..55b590ca 100644
--- a/language-web/webpack.config.js
+++ b/language-web/webpack.config.js
@@ -25,7 +25,6 @@ const publicHost = process.env['PUBLIC_HOST'] || listenHost;
 const publicPort = portNumberOrElse('PUBLIC_PORT', listenPort);
 
 const resolveSources = sources => path.resolve(__dirname, 'src', sources);
-const resolveGenerated = sources => path.resolve(__dirname, 'build/generated/sources', sources);
 const mainJsSources = resolveSources('main/js');
 const babelLoaderFilters = {
   include: [mainJsSources],
@@ -150,7 +149,6 @@ module.exports = {
     modules: [
       'node_modules',
       mainJsSources,
-      resolveGenerated('xtext/js'),
     ],
     extensions: ['.js', '.jsx', '.ts', '.tsx'],
     alias: {