Enhance position handling by adding utility methods for conversion

src/measurements/MeasurementContainer.js

@@ -95,9 +95,7 @@ class MeasurementContainer {
 
     // Turn string positions into numeric values
     if (typeof positionValue == "string") {
-      positionValue = positionValue == "upstream" ? Number.NEGATIVE_INFINITY : positionValue;
-      positionValue = positionValue == "atEquipment" ? 0.0 : positionValue;
-      positionValue = positionValue == "downstream" ? Number.POSITIVE_INFINITY : positionValue;
+      positionValue = this._convertPositionStr2Num(positionValue);
     }
 
     this._currentPosition = positionValue;
@@ -330,7 +328,7 @@ class MeasurementContainer {
       Object.keys(this.measurements[this._currentType]) : [];
   }
 
-  getPositions() {
+  getPositions(asNumber = false) {
     if (!this._currentType || !this._currentVariant) {
       throw new Error('Type and variant must be specified before listing positions');
     }
@@ -339,6 +337,10 @@ class MeasurementContainer {
         !this.measurements[this._currentType][this._currentVariant]) {
       return [];
     }
+
+    if (asNumber) {
+      return Object.keys(this.measurements[this._currentType][this._currentVariant]).map(this._convertPositionNum2Str);
+    }
     
     return Object.keys(this.measurements[this._currentType][this._currentVariant]);
   }
@@ -415,6 +417,34 @@ class MeasurementContainer {
     }
   }
 
+  _convertPositionStr2Num(positionString) {
+    switch(positionString) {
+      case "atEquipment":
+        return 0;
+      case "upstream":
+        return Number.POSITIVE_INFINITY;
+      case "downstream":
+        return Number.NEGATIVE_INFINITY;
+      
+      default:
+        this.logger.error(`Invalid positionVsParent provided: ${positionString}`);
+        return;
+    }
+  }
+
+  _convertPositionNum2Str(positionValue) {
+    if (positionValue == 0) {
+      return "atEquipment";
+    }
+    if (positionValue < 0) {
+      return "upstream";
+    }
+    if (positionValue > 0) {
+      return "downstream";
+    }
+    this.logger.error(`Invalid position provided: ${positionValue}`);
+  }
+
 }
 
 module.exports = MeasurementContainer;