Added check for conclusion in pattern (closes #91)

langium/src/language/services/validation/validators/pattern-validator.ts

@@ -1,24 +1,56 @@
 import { diagnosticData, ValidationAcceptor } from "langium";
-import { JustificationPattern } from "../../../generated/ast.js";
+import { JustificationPattern, Variable } from "../../../generated/ast.js";
 import { Validator } from "./abstract-validator.js";
 
 //Class to validate patterns in the jpipe language
 export class PatternValidator extends Validator<JustificationPattern, "JustificationPattern">{
     //function to provide validation of a given node
     validate(model: JustificationPattern, accept: ValidationAcceptor): void {
         if(model.kind === "pattern"){
-            let support_found = false;
+            PatternValidator.checkConclusion(model, accept);
+            PatternValidator.checkSupport(model, accept);
+        }
+    }
 
-            model.variables.forEach( variable => {
-                if(variable.kind === "@support"){
-                    support_found = true;
-                }
-            });
+    //helper function to check existence of support variable
+    private static checkSupport(model: JustificationPattern, accept: ValidationAcceptor): void{
+        let support_found = false;
 
-            if(!support_found){
-                accept("warning", "No @support variables found in pattern", {node: model, property: "name", data: diagnosticData("noSupportInPattern")})
+        model.variables.forEach( variable => {
+            if(variable.kind === "@support"){
+                support_found = true;
             }
+        });
+
+        if(!support_found){
+            accept("warning", "No @support variables found in pattern", {node: model, property: "name", data: diagnosticData("noSupportInPattern")})
+        }
+    }
+
+    //helper function to check if conclusion exists in a pattern
+    private static checkConclusion(model: JustificationPattern, accept: ValidationAcceptor): void{
+        let conclusion_exists = PatternValidator.conclusionExists(model.variables);
+
+        if(!conclusion_exists){
+            accept("error", "All justification diagrams must have a conclusion", {node: model, property: "name", data: diagnosticData("noConclusionInPattern")})
         }
     }
 
+    //helper function to determine if a conclusion exists in a given set of variables
+    private static conclusionExists(variables: Array<Variable>): boolean{
+        let conclusion_exists: boolean = false;
+        let i = 0;
+
+        while(i < variables.length && !conclusion_exists){
+            let variable = variables[i];
+
+            if(variable.kind === "conclusion"){
+                conclusion_exists = true;
+            }
+
+            i++
+        }
+
+        return conclusion_exists;
+    }
 }