Referencing a missing variable in an effect now returns zero, not an error

app/imports/api/creature/computation/EffectAggregator.js

@@ -3,8 +3,14 @@ import evaluateCalculation from '/imports/api/creature/computation/evaluateCalcu
 export default class EffectAggregator{
   constructor(stat, memo){
     if (stat.baseValueCalculation){
-      this.statBaseValue = evaluateCalculation(stat.baseValueCalculation, memo);
-      this.base = +this.statBaseValue;
+      let {value, errors} = evaluateCalculation(stat.baseValueCalculation, memo);
+      this.statBaseValue = value;
+      if (errors.length){
+        this.baseValueErrors = errors;
+      } else {
+        delete this.baseValueErrors;
+      }
+      this.base = this.statBaseValue;
     } else {
       this.base = 0;
     }

app/imports/api/creature/computation/computeEffect.js

@@ -20,6 +20,7 @@ export default function computeEffect(effect, memo){
   applyToggles(effect, memo);
 
   // Determine result of effect calculation
+  delete effect.errors;
   if (!effect.calculation){
     if(effect.operation === 'add' || effect.operation === 'base'){
       effect.result = 0;
@@ -31,7 +32,11 @@ export default function computeEffect(effect, memo){
   } else if(_.contains(['advantage', 'disadvantage', 'fail'], effect.operation)){
     effect.result = 1;
   } else {
-    effect.result = evaluateCalculation(effect.calculation, memo);
+    let {value, errors} = evaluateCalculation(effect.calculation, memo);
+    effect.result = value;
+    if (errors.length){
+      effect.errors = errors;
+    }
   }
   effect.computationDetails.computed = true;
   effect.computationDetails.busyComputing = false;

app/imports/api/creature/computation/computeToggle.js

@@ -25,7 +25,13 @@ export default function computeToggle(toggle, memo){
   } else if (Number.isFinite(+toggle.condition)){
     toggle.toggleResult = !!+toggle.condition;
   } else {
-    toggle.toggleResult = evaluateCalculation(toggle.condition, memo);
+    let {value, errors} = evaluateCalculation(toggle.condition, memo);
+    toggle.toggleResult = value;
+    if (errors.length){
+      toggle.errors = errors;
+    } else {
+      delete toggle.errors;
+    }
   }
   toggle.computationDetails.computed = true;
   toggle.computationDetails.busyComputing = false;

app/imports/api/creature/computation/evaluateCalculation.js

@@ -1,15 +1,20 @@
-import bareSymbolSubtitutor from '/imports/api/creature/computation/utility/bareSymbolSubtitutor.js';
 import computeStat from '/imports/api/creature/computation/computeStat.js';
 import math from '/imports/math.js';
 
+/* Convert a calculation into a constant output and errors*/
 export default function evaluateCalculation(string, memo){
   if (!string) return string;
+  let errors = [];
   // Parse the string using mathjs
   let calc;
   try {
     calc = math.parse(string);
   } catch (e) {
-    return string;
+    errors.push({
+      type: 'parsing',
+      message: e.message || e
+    });
+    return {errors, value: string};
   }
   // Ensure all symbol nodes are defined and coputed
   calc.traverse(node => {
@@ -20,12 +25,73 @@ export default function evaluateCalculation(string, memo){
       }
     }
   });
-  // Ensure any bare symbols are value accessors instead
-  let substitutedCalc = calc.transform(bareSymbolSubtitutor(memo.statsByVariableName));
+  // Replace all symbols with their subtitution
+  let substitutedCalc = calc.transform(
+    symbolSubtitutor(memo.statsByVariableName, errors)
+  );
   // Evaluate the expression to a number or return with substitutions
   try {
-    return substitutedCalc.evaluate(memo.statsByVariableName);
+    let value = substitutedCalc.evaluate(memo.statsByVariableName);
+    return {errors, value};
   } catch (e){
-    return substitutedCalc.toString();
+    errors.push({
+      type: 'evaluation',
+      message: e.message || e
+    });
+    let value = substitutedCalc.toString();
+    return {errors, value};
+  }
+}
+
+// returns a function to replace all symbols with either their resolved value
+// or zero, keeping the errors
+function symbolSubtitutor(scope, errors){
+  return function(node){
+    // mark symbol nodes that are children of function nodes to be skipped
+    if (node.isFunctionNode){
+      let fn = node.fn;
+      if (fn && fn.isSymbolNode){
+        fn.skipReplacement = true;
+      }
+      return node;
+    } else if (node.isSymbolNode && node.skipReplacement !== true){
+      //bare symbols of name "stat", should search for stat.value
+      let stat = scope[node.name];
+      if (stat){
+        if (stat.value === undefined){
+          errors.push({
+            type: 'subsitution',
+            message: `${node.name} does not have a value, set to 0`
+          });
+          return new math.ConstantNode(0);
+        } else {
+          return new math.ConstantNode(stat.value);
+        }
+      } else {
+        try {
+          return new math.ConstantNode(node.evaluate(scope));
+        } catch (e) {
+          errors.push({
+            type: 'subsitution',
+            message: `${node.name} not found, set to 0`
+          });
+          return new math.ConstantNode(0);
+        }
+      }
+    } else if (node.isAccessorNode){
+      try {
+        let value = node.evaluate(scope);
+        if (value === undefined) throw 'Not found';
+        return new math.ConstantNode(value);
+      } catch (e) {
+        errors.push({
+          type: 'subsitution',
+          message: `${node.toString()} not found, set to 0`
+        });
+        return new math.ConstantNode(0);
+      }
+    } else {
+      return node;
+    }
   }
 }

app/imports/api/properties/Effects.js

@@ -1,5 +1,5 @@
 import SimpleSchema from 'simpl-schema';
-
+import ErrorSchema from '/imports/api/properties/subSchemas/ErrorSchema.js';
 /*
  * Effects are reason-value attached to skills and abilities
  * that modify their final value or presentation in some way
@@ -48,7 +48,15 @@ const ComputedOnlyEffectSchema = new SimpleSchema({
 		type: SimpleSchema.oneOf(Number, String, Boolean),
 		optional: true,
 	},
-})
+  // The errors encountered while computing the result
+  errors: {
+    type: Array,
+    optional: true,
+  },
+  'errors.$':{
+    type: ErrorSchema,
+  },
+});
 
 const ComputedEffectSchema = new SimpleSchema()
 	.extend(ComputedOnlyEffectSchema)

app/imports/api/properties/Toggles.js

@@ -27,6 +27,14 @@ const ComputedOnlyToggleSchema = new SimpleSchema({
 		type: SimpleSchema.oneOf(Number, String, Boolean),
 		optional: true,
 	},
+  // The errors encountered while computing the result
+  errors: {
+    type: Array,
+    optional: true,
+  },
+  'errors.$':{
+    type: String,
+  },
 });
 
 const ComputedToggleSchema = new SimpleSchema()

app/imports/api/properties/subSchemas/ErrorSchema.js

@@ -0,0 +1,14 @@
+import SimpleSchema from 'simpl-schema';
+
+const ErrorSchema = new SimpleSchema({
+	// The roll that determines how much to change the attribute
+  message: {
+    type: String,
+  },
+	// Who this adjustment applies to
+	type: {
+    type: String,
+	},
+});
+
+export default ErrorSchema;

app/imports/ui/properties/forms/EffectForm.vue

@@ -6,48 +6,35 @@
       :error-messages="errors.name"
       @change="change('name', ...arguments)"
     />
-    <div class="layout row wrap justify-start">
-      <smart-select
-        label="Operation"
-        append-icon="arrow_drop_down"
-        class="mx-2"
-        :error-messages="errors.operation"
-        :menu-props="{transition: 'slide-y-transition', lazy: true}"
-        :items="operations"
-        :value="model.operation"
-        @change="change('operation', ...arguments)"
+    <smart-select
+      label="Operation"
+      append-icon="arrow_drop_down"
+      class="mx-2"
+      :error-messages="errors.operation"
+      :menu-props="{transition: 'slide-y-transition', lazy: true}"
+      :items="operations"
+      :value="model.operation"
+      @change="change('operation', ...arguments)"
+    >
+      <v-icon
+        slot="prepend"
+        class="icon"
+        :class="iconClass"
+      >
+        {{ displayedIcon }}
+      </v-icon>
+      <template
+        slot="item"
+        slot-scope="item"
       >
         <v-icon
-          slot="prepend"
-          class="icon"
-          :class="iconClass"
+          class="icon mr-2"
         >
-          {{ displayedIcon }}
+          {{ getEffectIcon(item.item.value, 1) }}
         </v-icon>
-        <template
-          slot="item"
-          slot-scope="item"
-        >
-          <v-icon
-            class="icon mr-2"
-          >
-            {{ getEffectIcon(item.item.value, 1) }}
-          </v-icon>
-          {{ item.item.text }}
-        </template>
-      </smart-select>
-
-      <text-field
-        label="Value"
-        class="mr-2"
-        :persistent-hint="needsValue"
-        :value="needsValue ? (model.calculation) : ' '"
-        :disabled="!needsValue"
-        :error-messages="errors.calculation"
-        :hint="!isFinite(model.calculation) && model.result ? model.result + '' : '' "
-        @change="change('calculation', ...arguments)"
-      />
-    </div>
+        {{ item.item.text }}
+      </template>
+    </smart-select>
     <smart-combobox
       label="Stats"
       class="mr-2"
@@ -59,6 +46,36 @@
       :error-messages="errors.stats"
       @change="change('stats', ...arguments)"
     />
+    <text-field
+      label="Value"
+      class="mr-2"
+      :persistent-hint="needsValue"
+      :value="needsValue ? (model.calculation) : ' '"
+      :disabled="!needsValue"
+      :error-messages="errors.calculation"
+      :hint="!isFinite(model.calculation) && model.result ? model.result + '' : '' "
+      @change="change('calculation', ...arguments)"
+    />
+    <div
+      v-if="model.errors && model.errors.length"
+      two-line
+    >
+      <v-slide-x-transition
+        group
+        leave-absolute
+      >
+        <v-alert
+          v-for="error in model.errors"
+          :key="error.message"
+          :value="true"
+          :icon="errorIcon(error.type)"
+          :color="errorColor(error.type)"
+          outline
+        >
+          {{ error.message }}
+        </v-alert>
+      </v-slide-x-transition>
+    </div>
   </div>
 </template>
 
@@ -128,6 +145,24 @@
 			},
 		},
 		methods: {
+      errorIcon(type){
+        if (type === 'subsitution'){
+          return 'info';
+        } else if (type === 'evaluation'){
+          return 'warning';
+        } else {
+          return 'error'
+        }
+      },
+      errorColor(type){
+        if (type === 'subsitution'){
+          return 'info';
+        } else if (type === 'evaluation'){
+          return 'warning';
+        } else {
+          return 'error'
+        }
+      },
 			getEffectIcon,
 		}
 	};