Began implementing dice rolls in the maths parser

app/imports/api/creature/actions/applyDamage.js

@@ -1,4 +1,4 @@
-import evaluateString from '/imports/api/creature/computation/afterComputation/evaluateString.js';
+import evaluateAndRollString from '/imports/api/creature/computation/afterComputation/evaluateAndRollString.js';
 
 export default function applyDamage({
   prop,
@@ -11,9 +11,9 @@ export default function applyDamage({
     ...creature.variables,
     ...actionContext,
   };
-  let {result, errors} = evaluateString(prop.amount, scope);
-  if (Meteor.isClient) errors.forEach(e => console.error(e));
-  if (Number.isFinite(result)) {
-    damageTargets.forEach()
+  let {result, errors} = evaluateAndRollString(prop.amount, scope);
+  if (Meteor.isClient){
+    errors.forEach(e => console.error(e));
+    console.log(result);
   }
 }

app/imports/api/creature/actions/applyProperties.js

@@ -1,5 +1,5 @@
 import applyAction from '/imports/api/creature/actions/applyAction.js';
-//import applyDamage from '/imports/api/creature/actions/applyDamage.js';
+import applyDamage from '/imports/api/creature/actions/applyDamage.js';
 import applyBuff from '/imports/api/creature/actions/applyBuff.js';
 
 function applyProperty(options){
@@ -19,7 +19,7 @@ function applyProperty(options){
       applyAction(options);
       return true;
     case 'damage':
-      // applyDamage(options);
+      applyDamage(options);
       return true;
     case 'adjustment':
       // applyAdjustment(options);

app/imports/api/creature/computation/afterComputation/evaluateAndRollString.js

@@ -0,0 +1,77 @@
+import math from '/imports/math.js';
+import bareSymbolSubtitutor from '/imports/api/creature/computation/utility/bareSymbolSubtitutor.js';
+import substituteRollsWithFunctions from '/imports/api/creature/computation/afterComputation/substituteRollsWithFunctions.js'
+
+export default function evaluateAndRollString(string, scope){
+  let errors = [];
+  if (!string){
+    errors.push('No string provided');
+    return {result: string, errors};
+  }
+
+  if (!scope) errors.push('No scope provided');
+
+  // Parse the string using mathjs
+  let calc;
+  try {
+    calc = math.parse(string);
+  } catch (e) {
+    errors.push(e);
+    return {result: string, errors};
+  }
+
+  // Replace all bare symbols with symbol.value
+  let transformedCalc = calc.transform(bareSymbolSubtitutor(scope));
+  // Replace all rolls with the function to call them
+  transformedCalc = calc.transform(substituteRollsWithFunctions);
+
+  // Evaluate the expression to a number or return with substitutions
+  try {
+    let result = transformedCalc.evaluate(scope);
+    return {result, errors};
+  } catch (e1){
+    errors.push(e1);
+    try {
+      let result = simplifyWithAccessors(transformedCalc, scope).toHTML();
+      return {result, errors};
+    } catch (e2){
+      errors.push(e2);
+      return {result: transformedCalc.toHTML(), errors};
+    }
+  }
+}
+
+function simplifyWithAccessors(calc, scope){
+  let noAccessorCalc = calc.transform(substituteAccessors(scope));
+  return math.simplify(noAccessorCalc);
+}
+
+// returns a function to replace all accessors with either their resolved value
+// or a symbol to simplify with
+function substituteAccessors(scope){
+  return function(node){
+    if (node.isAccessorNode){
+      try {
+        return evaluateAccessor(node, scope);
+      } catch (e) {
+        return replaceAccessorWithSymbol(node);
+      }
+    } else {
+      return node;
+    }
+  }
+}
+
+// Throws error if symbol is undefined in scope
+function evaluateAccessor(node, scope){
+  let value = node.evaluate(scope);
+  if (value === undefined){
+    throw 'Undefined symbol'
+  }
+  return new math.ConstantNode(value);
+}
+
+function replaceAccessorWithSymbol(node){
+  let symbolNode = new math.SymbolNode(node.toString());
+  return symbolNode;
+}

app/imports/api/creature/computation/afterComputation/substituteRollsWithFunctions.js

@@ -0,0 +1,20 @@
+import math from '/imports/math.js';
+
+const diceRegex = /d\d+/;
+
+export default function substituteRollsWithFunctions(node){
+  // TODO also replace dx as 1dx
+  if (
+    node.isOperatorNode &&
+    node.fn === 'multiply' &&
+    node.implicit &&
+    node.args[1].isSymbolNode &&
+    diceRegex.test(node.args[1].name)
+  ){
+    let diceSize = node.args[1].name.slice(1);
+    let diceSizeNode = new math.ConstantNode(diceSize);
+    return new math.FunctionNode('roll', [node.args[0], diceSizeNode]);
+  } else {
+    return node;
+  }
+}

app/imports/math.js

@@ -1,8 +1,20 @@
 import { create, all } from 'mathjs';
+import { Random } from 'meteor/random'
+
 const math = create(all);
 math.import({
   'if': function(pred, a, b) {
       return pred ? a : b;
+  },
+  'roll': function(number, diceSize){
+    if (number > 100) throw 'Can only roll 100 dice at a time';
+    let rollTotal = 0;
+    let i, roll;
+    for (i = 0; i < number; i++){
+      roll = ~~(Random.fraction() * diceSize) + 1
+      rollTotal += roll;
+    }
+    return rollTotal;
   }
 });