Refactored computation into folders

app/imports/api/creature/computation/engine/ComputationMemo.js

@@ -0,0 +1,307 @@
+import { includes, cloneDeep } from 'lodash';
+import findAncestorByType from '/imports/api/creature/computation/engine/findAncestorByType.js';
+
+// The computation memo is an in-memory data structure used only during the
+// computation process
+export default class ComputationMemo {
+  constructor(props, creature){
+    this.statsByVariableName = {};
+    this.extraStatsByVariableName = {};
+    this.statsById = {};
+    this.originalPropsById = {};
+    this.propsById = {};
+    this.skillsByAbility = {};
+    this.unassignedEffects = [];
+    this.classLevelsById = {};
+    this.classes = {};
+    this.togglesById = {};
+    this.toggleIds = new Set();
+    // Equipped items that might be used as ammo
+    this.equipmentById = {};
+    // Properties that have calculations, but don't impact other properties
+    this.endStepPropsById = {};
+    // First note all the ids of all the toggles
+    props.forEach((prop) => {
+      if (
+        prop.type === 'toggle'
+      ) {
+        this.toggleIds.add(prop._id);
+      }
+    });
+    props.filter((prop) => {
+      if (
+        prop.type === 'toggle'
+      ) {
+        this.addToggle(prop);
+      } else {
+        return true;
+      }
+    }).filter((prop) => {
+      if (
+        prop.type === 'attribute' ||
+        prop.type === 'skill'
+      ) {
+        // Add all the stats
+        this.addStat(prop);
+      } else if (
+        prop.type === 'item'
+      ) {
+        this.addEquipment(prop);
+      } else {
+        return true;
+      }
+    }).forEach((prop) => {
+      // Now add all effects and proficiencies
+      if (prop.type === 'effect'){
+        this.addEffect(prop);
+      } else if (prop.type === 'proficiency') {
+        this.addProficiency(prop);
+      } else if (prop.type === 'classLevel'){
+        this.addClassLevel(prop);
+      } else {
+        this.addEndStepProp(prop);
+      }
+    });
+    for (let name in creature.denormalizedStats){
+      if (!this.statsByVariableName[name]){
+        this.statsByVariableName[name] = {
+          variableName: name,
+          value: creature.denormalizedStats[name],
+          computationDetails: propDetailsByType.denormalizedStat(),
+        }
+      }
+    }
+  }
+  registerProperty(prop){
+    this.originalPropsById[prop._id] = cloneDeep(prop);
+    this.propsById[prop._id] = prop;
+    prop.dependencies = [];
+    prop.computationDetails = propDetails(prop);
+    prop.ancestors.forEach(ancestor => {
+      if (this.toggleIds.has(ancestor.id)){
+        prop.computationDetails.toggleAncestors.push(ancestor.id);
+      }
+    });
+    return prop;
+  }
+  addToggle(prop){
+    prop = this.registerProperty(prop);
+    this.togglesById[prop._id] = prop;
+  }
+  addClassLevel(prop){
+    prop = this.registerProperty(prop);
+    this.classLevelsById[prop._id] = prop;
+  }
+  addStat(prop){
+    let variableName = prop.variableName;
+    if (!variableName) return;
+    let existingStat = this.statsByVariableName[variableName];
+    if (existingStat){
+      existingStat.computationDetails.idsOfSameName.push(prop._id);
+      this.originalPropsById[prop._id] = cloneDeep(prop);
+      if (prop.baseValueCalculation){
+        existingStat.computationDetails.effects.push({
+          operation: 'base',
+          calculation: prop.baseValueCalculation,
+          stats: [variableName],
+          computationDetails: propDetailsByType.effect(),
+          statBase: true,
+          dependencies: [],
+        });
+      }
+      if (prop.baseProficiency){
+        existingStat.computationDetails.proficiencies.push({
+          value: prop.baseProficiency,
+          stats: [variableName],
+          computationDetails: propDetailsByType.proficiency(),
+          type: 'proficiency',
+          statBase: true,
+          dependencies: [],
+        });
+      }
+    } else {
+      prop = this.registerProperty(prop);
+      this.statsById[prop._id] = prop;
+      this.statsByVariableName[variableName] = prop;
+      if (
+        prop.type === 'skill' &&
+        isSkillCheck(prop) &&
+        prop.ability
+      ){
+        this.addSkillToAbility(prop, prop.ability)
+      }
+    }
+  }
+  addSkillToAbility(prop, ability){
+    if (!this.skillsByAbility[ability]){
+      this.skillsByAbility[ability] = [];
+    }
+    this.skillsByAbility[ability].push(prop);
+  }
+  addEffect(prop){
+    prop = this.registerProperty(prop);
+    let targets = this.getEffectTargets(prop);
+    targets.forEach(target => {
+      if (target.computationDetails && target.computationDetails.effects){
+        target.computationDetails.effects.push(prop);
+      }
+    });
+    if (!targets.size){
+      this.unassignedEffects.push(prop);
+    }
+  }
+  getEffectTargets(prop){
+    let targets = new Set();
+    if (!prop.stats) return targets;
+    prop.stats.forEach((statName) => {
+      let target;
+      if (statName[0] === '#'){
+        target = findAncestorByType({
+          type: statName.slice(1),
+          prop,
+          memo: this
+        });
+      } else {
+        target = this.statsByVariableName[statName];
+      }
+      if (!target) return;
+      targets.add(target);
+      if (isSkillOperation(prop) && isAbility(target)){
+        let extras = this.skillsByAbility[statName] || [];
+        extras.forEach(ex =>{
+          // Only pass on ability effects to skills and checks
+          if (ex.skillType === 'skill' || ex.skillType === 'check'){
+            targets.add(ex)
+          }
+        });
+      }
+    });
+    return targets;
+  }
+  addProficiency(prop){
+    prop = this.registerProperty(prop);
+    let targets = this.getProficiencyTargets(prop);
+    targets.forEach(target => {
+      target.computationDetails.proficiencies.push(prop);
+    });
+  }
+  getProficiencyTargets(prop){
+    let targets = new Set();
+    if (!prop.stats) return targets;
+    prop.stats.forEach(statName => {
+      let target = this.statsByVariableName[statName];
+      if (!target) return;
+      targets.add(target);
+      if (isAbility(target)) {
+        let extras = this.skillsByAbility[statName] || [];
+        extras.forEach(ex =>{
+          // Only pass on ability proficiencies to skills and checks
+          if (ex.skillType === 'skill' || ex.skillType === 'check'){
+            targets.add(ex)
+          }
+        });
+      }
+    });
+    return targets;
+  }
+  addEquipment(prop){
+    prop = this.registerProperty(prop);
+    this.equipmentById[prop._id] = prop;
+  }
+  addEndStepProp(prop){
+    prop = this.registerProperty(prop);
+    this.endStepPropsById[prop._id] = prop;
+  }
+}
+
+function isAbility(prop){
+  return prop.type === 'attribute' &&
+  prop.attributeType === 'ability'
+}
+
+function isSkillCheck(prop){
+  return includes(['skill', 'check', 'save', 'utility'], prop.skillType);
+}
+
+const skillOperations = [
+  'advantage',
+  'disadvantage',
+  'passiveAdd',
+  'fail',
+  'conditional',
+  'rollBonus',
+];
+
+function isSkillOperation(prop){
+  return skillOperations.includes(prop.operation);
+}
+
+function propDetails(prop){
+  return propDetailsByType[prop.type] && propDetailsByType[prop.type]() ||
+    propDetailsByType.default();
+}
+
+const propDetailsByType = {
+  default(){
+    return {
+      toggleAncestors: [],
+      disabledByToggle: false,
+    };
+  },
+  toggle(){
+    return {
+      computed: false,
+      busyComputing: false,
+      toggleAncestors: [],
+      disabledByToggle: false,
+    };
+  },
+  attribute(){
+    return {
+      computed: false,
+      busyComputing: false,
+      effects: [],
+      toggleAncestors: [],
+      disabledByToggle: false,
+      idsOfSameName: [],
+    };
+  },
+  skill(){
+    return {
+      computed: false,
+      busyComputing: false,
+      effects: [],
+      proficiencies: [],
+      toggleAncestors: [],
+      disabledByToggle: false,
+      idsOfSameName: [],
+    };
+  },
+  effect(){
+    return {
+      computed: false,
+      busyComputing: false,
+      toggleAncestors: [],
+      disabledByToggle: false,
+    };
+  },
+  classLevel(){
+    return {
+      computed: true,
+      toggleAncestors: [],
+      disabledByToggle: false,
+    };
+  },
+  proficiency(){
+    return {
+      toggleAncestors: [],
+      disabledByToggle: false,
+    };
+  },
+  denormalizedStat(){
+    return {
+      toggleAncestors: [],
+      disabledByToggle: false,
+    };
+  }
+}

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

@@ -0,0 +1,98 @@
+import evaluateCalculation from '/imports/api/creature/computation/engine/evaluateCalculation.js';
+
+export default class EffectAggregator{
+  constructor(stat, memo){
+    delete this.baseValueErrors;
+    if (stat.baseValueCalculation){
+      let {
+        result,
+        context,
+        dependencies
+      } = evaluateCalculation({
+        string: stat.baseValueCalculation,
+        prop: stat,
+        memo
+      });
+      this.statBaseValue = result.value;
+      stat.dependencies.push(...dependencies);
+      if (context.errors.length){
+        this.baseValueErrors = context.errors;
+      }
+      this.base = this.statBaseValue;
+    } else {
+      this.base = 0;
+    }
+    this.add = 0;
+    this.mul = 1;
+    this.min = Number.NEGATIVE_INFINITY;
+    this.max = Number.POSITIVE_INFINITY;
+    this.advantage = 0;
+    this.disadvantage = 0;
+    this.passiveAdd = undefined;
+    this.fail = 0;
+    this.set = undefined;
+    this.conditional = [];
+    this.rollBonus = [];
+    this.hasNoEffects = true;
+  }
+  addEffect(effect){
+    let result = effect.result;
+    if (this.hasNoEffects) this.hasNoEffects = false;
+    switch(effect.operation){
+      case 'base':
+        // Take the largest base value
+        this.base = result > this.base ? result : this.base;
+        if (effect.statBase){
+          if (this.statBaseValue === undefined || result > this.statBaseValue){
+            this.statBaseValue = result;
+          }
+        }
+        break;
+      case 'add':
+        // Add all adds together
+        this.add += result;
+        break;
+      case 'mul':
+        // Multiply the muls together
+        this.mul *= result;
+        break;
+      case 'min':
+        // Take the largest min value
+        this.min = result > this.min ? result : this.min;
+        break;
+      case 'max':
+        // Take the smallest max value
+        this.max = result < this.max ? result : this.max;
+        break;
+      case 'set':
+        // Take the highest set value
+        this.set = this.set === undefined || result > this.set ? result : this.set;
+        break;
+      case 'advantage':
+        // Sum number of advantages
+        this.advantage++;
+        break;
+      case 'disadvantage':
+        // Sum number of disadvantages
+        this.disadvantage++;
+        break;
+      case 'passiveAdd':
+        // Add all passive adds together
+        if (this.passiveAdd === undefined) this.passiveAdd = 0;
+        this.passiveAdd += result;
+        break;
+      case 'fail':
+        // Sum number of fails
+        this.fail++;
+        break;
+      case 'conditional':
+        // Store array of conditionals
+        this.conditional.push(result);
+        break;
+      case 'rollBonus':
+        // Store array of roll bonuses
+        this.rollBonus.push(result);
+        break;
+    }
+  }
+}

app/imports/api/creature/computation/engine/applyToggles.js

@@ -0,0 +1,12 @@
+import computeToggle from '/imports/api/creature/computation/engine/computeToggle.js';
+
+export default function applyToggles(prop, memo){
+  prop.computationDetails.toggleAncestors.forEach(toggleId => {
+    let toggle = memo.togglesById[toggleId];
+    computeToggle(toggle, memo);
+    prop.dependencies.push(toggle._id, ...toggle.dependencies);
+    if (!toggle.toggleResult){
+      prop.computationDetails.disabledByToggle = true;
+    }
+  });
+}

app/imports/api/creature/computation/engine/combineStat.js

@@ -0,0 +1,159 @@
+import computeStat from '/imports/api/creature/computation/engine/computeStat.js';
+import applyToggles from '/imports/api/creature/computation/engine/applyToggles.js';
+import evaluateCalculation from '/imports/api/creature/computation/engine/evaluateCalculation.js';
+
+export default function combineStat(stat, aggregator, memo){
+  if (stat.type === 'attribute'){
+    combineAttribute(stat, aggregator, memo);
+  } else if (stat.type === 'skill'){
+    combineSkill(stat, aggregator, memo);
+  } else if (stat.type === 'damageMultiplier'){
+    combineDamageMultiplier(stat, memo);
+  }
+}
+
+function getAggregatorResult(stat, aggregator){
+  let result = (aggregator.base + aggregator.add) * aggregator.mul;
+  if (result < aggregator.min) {
+    result = aggregator.min;
+  }
+  if (result > aggregator.max) {
+    result = aggregator.max;
+  }
+  if (aggregator.set !== undefined) {
+    result = aggregator.set;
+  }
+  if (!stat.decimal && Number.isFinite(result)){
+    result = Math.floor(result);
+  }
+  return result;
+}
+
+function combineAttribute(stat, aggregator, memo){
+  stat.value = getAggregatorResult(stat, aggregator);
+  stat.baseValue = aggregator.statBaseValue;
+  stat.baseValueErrors = aggregator.baseValueErrors;
+  if (stat.attributeType === 'spellSlot'){
+    let {
+      result,
+      context,
+      dependencies
+    } = evaluateCalculation({
+      string: stat.spellSlotLevelCalculation,
+      memo,
+      prop: stat,
+    });
+    stat.spellSlotLevelValue = result.value;
+    stat.spellSlotLevelErrors = context.errors;
+    stat.dependencies.push(...dependencies);
+  }
+  stat.currentValue = stat.value - (stat.damage || 0);
+  // Ability scores get modifiers
+  if (stat.attributeType === 'ability') {
+    stat.modifier = Math.floor((stat.currentValue - 10) / 2);
+  } else {
+    stat.modifier = undefined;
+  }
+  // Hit dice get constitution modifiers
+  stat.constitutionMod = undefined;
+  if (stat.attributeType === 'hitDice') {
+    let conStat = memo.statsByVariableName['constitution'];
+    if (conStat && 'modifier' in conStat){
+      stat.constitutionMod = conStat.modifier;
+      stat.dependencies.push(conStat._id, ...conStat.dependencies);
+    }
+  }
+  // Stats that have no effects can be hidden based on a sheet setting
+  stat.hide = aggregator.hasNoEffects &&
+    stat.baseValue === undefined ||
+    undefined
+}
+
+function combineSkill(stat, aggregator, memo){
+  // Skills are based on some ability Modifier
+  let ability = memo.statsByVariableName[stat.ability]
+  if (stat.ability && ability){
+    if (!ability.computationDetails.computed){
+      computeStat(ability, memo);
+    }
+    stat.abilityMod = ability.modifier;
+    stat.dependencies.push(ability._id, ...ability.dependencies);
+  }
+  // Combine all the child proficiencies
+  stat.proficiency = stat.baseProficiency || 0;
+  for (let i in stat.computationDetails.proficiencies){
+    let prof = stat.computationDetails.proficiencies[i];
+    applyToggles(prof, memo);
+    if (
+      !prof.computationDetails.disabledByToggle &&
+      prof.value > stat.proficiency
+    ){
+      stat.proficiency = prof.value;
+      stat.dependencies.push(prof._id, ...prof.dependencies);
+    }
+  }
+  // Get the character's proficiency bonus to apply
+  let profBonusStat = memo.statsByVariableName['proficiencyBonus'];
+  let profBonus = profBonusStat && profBonusStat.value;
+
+  if (typeof profBonus !== 'number' && memo.statsByVariableName['level']){
+    let level = memo.statsByVariableName['level'].value;
+    profBonus = Math.ceil(level / 4) + 1;
+    if (level._id) stat.dependencies.push(level._id);
+    if (level.dependencies) stat.dependencies.push(...level.dependencies);
+  } else {
+    stat.dependencies.push(profBonusStat._id, ...profBonusStat.dependencies);
+  }
+  // Multiply the proficiency bonus by the actual proficiency
+  profBonus *= stat.proficiency;
+  // Base value
+  stat.baseValue = aggregator.statBaseValue;
+  stat.baseValueErrors = aggregator.baseValueErrors;
+  // Combine everything to get the final result
+  let result = (aggregator.base + stat.abilityMod + profBonus + aggregator.add) * aggregator.mul;
+  if (result < aggregator.min) result = aggregator.min;
+  if (result > aggregator.max) result = aggregator.max;
+  if (aggregator.set !== undefined) {
+    result = aggregator.set;
+  }
+  if (Number.isFinite(result)){
+    result = Math.floor(result);
+  }
+  stat.value = result;
+  // Advantage/disadvantage
+  if (aggregator.advantage && !aggregator.disadvantage){
+    stat.advantage = 1;
+  } else if (aggregator.disadvantage && !aggregator.advantage){
+    stat.advantage = -1;
+  } else {
+    stat.advantage = 0;
+  }
+  // Passive bonus
+  stat.passiveBonus = aggregator.passiveAdd;
+  // conditional benefits
+  stat.conditionalBenefits = aggregator.conditional;
+  // Roll bonuses
+  stat.rollBonus = aggregator.rollBonus;
+  // Forced to fail
+  stat.fail = aggregator.fail;
+  // Rollbonus
+  stat.rollBonuses = aggregator.rollBonus;
+  // Hide
+  stat.hide = aggregator.hasNoEffects &&
+    stat.baseValue === undefined &&
+    stat.proficiency == 0 ||
+    undefined;
+}
+
+function combineDamageMultiplier(stat){
+  if (stat.immunityCount) return 0;
+  let result;
+  if (stat.ressistanceCount && !stat.vulnerabilityCount){
+    result = 0.5;
+  }  else if (!stat.ressistanceCount && stat.vulnerabilityCount){
+    result = 2;
+  } else {
+    result = 1;
+  }
+  stat.value = result;
+}

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

@@ -0,0 +1,54 @@
+import evaluateCalculation from '/imports/api/creature/computation/engine/evaluateCalculation.js';
+import applyToggles from '/imports/api/creature/computation/engine/applyToggles.js';
+
+export default function computeEffect(effect, memo){
+  if (effect.computationDetails.computed) return;
+  if (effect.computationDetails.busyComputing){
+    // Trying to compute this effect again while it is already computing.
+    // We must be in a dependency loop.
+    effect.computationDetails.computed = true;
+    effect.result = NaN;
+    effect.computationDetails.busyComputing = false;
+    effect.computationDetails.error = 'dependencyLoop';
+    if (Meteor.isClient) console.warn('dependencyLoop', effect);
+    return;
+  }
+  // Before doing any work, mark this effect as busy
+  effect.computationDetails.busyComputing = true;
+
+  // Apply any toggles
+  applyToggles(effect, memo);
+
+  // Determine result of effect calculation
+  delete effect.errors;
+  if (!effect.calculation){
+    if(effect.operation === 'add' || effect.operation === 'base'){
+      effect.result = 0;
+    } else {
+      delete effect.result
+    }
+  } else if (Number.isFinite(+effect.calculation)){
+    effect.result = +effect.calculation;
+  } else if(effect.operation === 'conditional' || effect.operation === 'rollBonus'){
+    effect.result = effect.calculation;
+  } else if(_.contains(['advantage', 'disadvantage', 'fail'], effect.operation)){
+    effect.result = 1;
+  } else {
+    let {
+      result,
+      context,
+      dependencies,
+    } = evaluateCalculation({
+      string: effect.calculation,
+      prop: effect,
+      memo
+    });
+    effect.result = result.value;
+    effect.dependencies.push(...dependencies);
+    if (context.errors.length){
+      effect.errors = context.errors;
+    }
+  }
+  effect.computationDetails.computed = true;
+  effect.computationDetails.busyComputing = false;
+}

app/imports/api/creature/computation/engine/computeEndStepProperty.js

@@ -0,0 +1,116 @@
+import evaluateCalculation from '/imports/api/creature/computation/engine/evaluateCalculation.js';
+import ConstantNode from '/imports/parser/parseTree/ConstantNode.js';
+
+export default function computeEndStepProperty(prop, memo){
+  switch (prop.type){
+    case 'action':
+    case 'spell':
+      computeAction(prop, memo);
+      break;
+    case 'adjustment':
+    case 'damage':
+      computePropertyField(prop, memo, 'amount', 'compile');
+      break;
+    case 'attack':
+      computeAction(prop, memo);
+      computeAttack(prop, memo);
+      break;
+    case 'savingThrow':
+      computeSavingThrow(prop, memo);
+      break;
+    case 'spellList':
+      computeSpellList(prop, memo);
+      break;
+    case 'propertySlot':
+      computeSlot(prop, memo);
+      break;
+  }
+}
+
+function computeAction(prop, memo){
+  // Uses
+  let {
+    result,
+    context,
+    dependencies,
+  } = evaluateCalculation({ string: prop.uses, prop, memo});
+  prop.usesResult = result.value;
+  prop.dependencies.push(...dependencies);
+  if (context.errors.length){
+    prop.usesErrors = context.errors;
+  } else {
+    delete prop.usesErrors;
+  }
+  prop.insufficientResources = undefined;
+  if (prop.usesUsed >= prop.usesResult){
+    prop.insufficientResources = true;
+  }
+  if (!prop.resources) return;
+  // Attributes consumed
+  prop.resources.attributesConsumed.forEach((attConsumed, i) => {
+    if (attConsumed.variableName){
+      let stat = memo.statsByVariableName[attConsumed.variableName];
+      prop.resources.attributesConsumed[i].statId = stat && stat._id;
+      prop.resources.attributesConsumed[i].statName = stat && stat.name;
+      let available = stat && stat.currentValue || 0;
+      prop.resources.attributesConsumed[i].available = available;
+      if (available < attConsumed.quantity){
+        prop.insufficientResources = true;
+      }
+      if (stat) prop.dependencies.push(stat._id, ...stat.dependencies);
+    }
+  });
+  // Items consumed
+  prop.resources.itemsConsumed.forEach((itemConsumed, i) => {
+    let item = itemConsumed.itemId && memo.equipmentById[itemConsumed.itemId];
+    prop.resources.itemsConsumed[i].itemId = item && item._id;
+    let available = item && item.quantity || 0;
+    prop.resources.itemsConsumed[i].available = available;
+    let name = item && item.name;
+    if (item && item.quantity !== 1 && item.plural){
+      name = item.plural;
+    }
+    prop.resources.itemsConsumed[i].itemName = name;
+    prop.resources.itemsConsumed[i].itemIcon = item && item.icon;
+    prop.resources.itemsConsumed[i].itemColor = item && item.color;
+    if (!item || available < itemConsumed.quantity){
+      prop.insufficientResources = true;
+    }
+    if (item) prop.dependencies.push(item._id, ...item.dependencies);
+  });
+}
+
+function computePropertyField(prop, memo, fieldName, fn){
+  let {
+    result,
+    context,
+    dependencies,
+  } = evaluateCalculation({string: prop[fieldName], prop, memo, fn});
+  if (result instanceof ConstantNode){
+    prop[`${fieldName}Result`] = result.value;
+  } else {
+    prop[`${fieldName}Result`] = result.toString();
+  }
+  prop.dependencies.push(...dependencies);
+  if (context.errors.length){
+    prop[`${fieldName}Errors`] = context.errors;
+  } else {
+    delete prop[`${fieldName}Errors`];
+  }
+}
+
+function computeAttack(prop, memo){
+  computePropertyField(prop, memo, 'rollBonus');
+}
+
+function computeSavingThrow(prop, memo){
+  computePropertyField(prop, memo, 'dc');
+}
+
+function computeSpellList(prop, memo){
+  computePropertyField(prop, memo, 'maxPrepared');
+}
+
+function computeSlot(prop, memo){
+  computePropertyField(prop, memo, 'slotCondition');
+}

app/imports/api/creature/computation/engine/computeInlineCalculations.js

@@ -0,0 +1,34 @@
+import evaluateCalculation from '/imports/api/creature/computation/engine/evaluateCalculation.js';
+
+export default function computeInlineCalculations(prop, memo){
+  if (prop.summary){
+    computeInlineCalcsForField(prop, memo, 'summary');
+  }
+  if (prop.description){
+    computeInlineCalcsForField(prop, memo, 'description');
+  }
+}
+
+function computeInlineCalcsForField(prop, memo, field){
+  let string = prop[field];
+  let inlineComputations = [];
+  let matches = string.matchAll(/\{([^{}]*)\}/g);
+  for (let match of matches){
+    let calculation = match[1];
+    let {
+      result,
+      context,
+      dependencies,
+    } = evaluateCalculation({string: calculation, prop, memo, fn: 'compile'});
+    let computation = {
+      calculation,
+      result: result.toString(),
+    };
+    if (context.errors.length){
+      computation.errors = context.errors;
+    }
+    inlineComputations.push(computation);
+    prop.dependencies.push(...dependencies);
+  }
+  prop[`${field}Calculations`] = inlineComputations;
+}

app/imports/api/creature/computation/engine/computeLevels.js

@@ -0,0 +1,50 @@
+import { forOwn, has } from 'lodash';
+
+export default function computeLevels(memo){
+  computeClassLevels(memo);
+  computeTotalLevel(memo);
+}
+
+function computeClassLevels(memo){
+  forOwn(memo.classLevelsById, classLevel => {
+    //  class levels are mutually dependent
+    classLevel.dependencies.push(Object.keys(memo.classLevelsById));
+    let name = classLevel.variableName;
+    let stat = memo.statsByVariableName[name];
+    if (!stat){
+      memo.statsByVariableName[name] = classLevel;
+      memo.classes[name] = classLevel;
+    } else if (!has(stat, 'level')){
+      // Stat is overriden by an attribute
+      return;
+    } else if (stat.level < classLevel.level) {
+      memo.statsByVariableName[name] = classLevel;
+      memo.classes[name] = classLevel;
+    }
+  });
+}
+
+function computeTotalLevel(memo){
+  let currentLevel = memo.statsByVariableName['level'];
+  if (!currentLevel){
+    currentLevel = {
+      value: 0,
+      dependencies: [],
+      computationDetails: {
+        builtIn: true,
+        computed: true,
+      }
+    };
+    memo.statsByVariableName['level'] = currentLevel;
+  }
+  // bail out if overriden by an attribute
+  if (!currentLevel.computationDetails.builtIn) return;
+  let level = 0;
+  for (let name in memo.classes){
+    let cls = memo.classes[name];
+    level += cls.level || 0;
+    if (cls._id) currentLevel.dependencies.push(cls._id);
+    if (cls.dependencies) currentLevel.dependencies.push(...cls.dependencies);
+  }
+  currentLevel.value = level;
+}

app/imports/api/creature/computation/engine/computeMemo.js

@@ -0,0 +1,32 @@
+import { each, forOwn } from 'lodash';
+import computeLevels from '/imports/api/creature/computation/engine/computeLevels.js';
+import computeStat from '/imports/api/creature/computation/engine/computeStat.js';
+import computeEffect from '/imports/api/creature/computation/engine/computeEffect.js';
+import computeToggle from '/imports/api/creature/computation/engine/computeToggle.js';
+import computeEndStepProperty from '/imports/api/creature/computation/engine/computeEndStepProperty.js';
+import computeInlineCalculations from '/imports/api/creature/computation/engine/computeInlineCalculations.js';
+
+export default function computeMemo(memo){
+  // Compute level
+  computeLevels(memo);
+  // Compute all stats, even if they are overriden
+  forOwn(memo.statsById, stat => {
+    computeStat (stat, memo);
+  });
+  // Compute effects which didn't end up targeting a stat
+  each(memo.unassignedEffects, effect => {
+    computeEffect(effect, memo);
+  });
+  // Compute toggles which didn't already get computed by dependencies
+  forOwn(memo.togglesById, toggle => {
+    computeToggle(toggle, memo);
+  });
+  // Compute end step properties
+  forOwn(memo.endStepPropsById, prop => {
+    computeEndStepProperty(prop, memo);
+  });
+  // Compute inline calculations
+  forOwn(memo.propsById, prop => {
+    computeInlineCalculations(prop, memo);
+  });
+}

app/imports/api/creature/computation/engine/computeStat.js

@@ -0,0 +1,42 @@
+import combineStat from '/imports/api/creature/computation/engine/combineStat.js';
+import computeEffect from '/imports/api/creature/computation/engine/computeEffect.js';
+import EffectAggregator from '/imports/api/creature/computation/engine/EffectAggregator.js';
+import applyToggles from '/imports/api/creature/computation/engine/applyToggles.js';
+import { each } from 'lodash';
+
+export default function computeStat(stat, memo){
+  // If the stat is already computed, skip it
+  if (stat.computationDetails.computed) return;
+  if (stat.computationDetails.busyComputing){
+    // Trying to compute this stat again while it is already computing.
+    // We must be in a dependency loop.
+    stat.computationDetails.computed = true;
+    stat.value = NaN;
+    stat.computationDetails.busyComputing = false;
+    stat.computationDetails.error = 'dependencyLoop';
+    if (Meteor.isClient) console.warn('dependencyLoop', stat);
+    return;
+  }
+  // Before doing any work, mark this stat as busy
+  stat.computationDetails.busyComputing = true;
+  // Apply any toggles
+  applyToggles(stat, memo);
+
+  if (!stat.computationDetails.disabledByToggle){
+    // Compute and aggregate all the effects
+    let aggregator = new EffectAggregator(stat, memo)
+    each(stat.computationDetails.effects, (effect) => {
+      computeEffect(effect, memo);
+      if (effect._id) stat.dependencies.push(effect._id);
+      stat.dependencies.push(...effect.dependencies);
+      if (!effect.computationDetails.disabledByToggle){
+        aggregator.addEffect(effect);
+      }
+    });
+    // Conglomerate all the effects to compute the final stat values
+    combineStat(stat, aggregator, memo);
+  }
+  // Mark the attribute as computed
+  stat.computationDetails.computed = true;
+  stat.computationDetails.busyComputing = false;
+}

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

@@ -0,0 +1,42 @@
+import evaluateCalculation from '/imports/api/creature/computation/engine/evaluateCalculation.js';
+
+export default function computeToggle(toggle, memo){
+  if (toggle.computationDetails.computed) return;
+  if (toggle.computationDetails.busyComputing){
+    // Trying to compute this effect again while it is already computing.
+    // We must be in a dependency loop.
+    toggle.computationDetails.computed = true;
+    toggle.result = false;
+    toggle.computationDetails.busyComputing = false;
+    toggle.computationDetails.error = 'dependencyLoop';
+    if (Meteor.isClient) console.warn('dependencyLoop', toggle);
+    return;
+  }
+  // Before doing any work, mark this toggle as busy
+  toggle.computationDetails.busyComputing = true;
+
+  // Do work
+  delete toggle.errors;
+  if (toggle.enabled){
+    toggle.toggleResult = true;
+  } else if (toggle.disabled){
+    toggle.toggleResult = false;
+  } else if (!toggle.condition){
+    toggle.toggleResult = false;
+  } else if (Number.isFinite(+toggle.condition)){
+    toggle.toggleResult = !!+toggle.condition;
+  } else {
+    let {
+      result,
+      context,
+      dependencies,
+    } = evaluateCalculation({string: toggle.condition, prop: toggle, memo});
+    toggle.toggleResult = !!result.value;
+    toggle.dependencies.push(...dependencies);
+    if (context.errors.length){
+      toggle.errors = context.errors;
+    }
+  }
+  toggle.computationDetails.computed = true;
+  toggle.computationDetails.busyComputing = false;
+}

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

@@ -0,0 +1,65 @@
+import computeStat from '/imports/api/creature/computation/engine/computeStat.js';
+import { parse, CompilationContext } from '/imports/parser/parser.js';
+import SymbolNode from '/imports/parser/parseTree/SymbolNode.js';
+import AccessorNode from '/imports/parser/parseTree/AccessorNode.js';
+import ConstantNode from '/imports/parser/parseTree/ConstantNode.js';
+import findAncestorByType from '/imports/api/creature/computation/engine/findAncestorByType.js';
+
+/* Convert a calculation into a constant output and errors*/
+export default function evaluateCalculation({
+  string,
+  prop,
+  memo,
+  fn = 'reduce',
+}){
+  let dependencies = [];
+  let errors = [];
+  if (!string) return {
+    context: {errors},
+    result: new ConstantNode({value: string, type: 'string'}),
+    dependencies,
+  };
+  // Parse the string
+  let calc;
+  try {
+    calc = parse(string);
+  } catch (e) {
+    errors.push({
+      type: 'parsing',
+      message: e.message || e
+    });
+    return {
+      context: {errors},
+      result: new ConstantNode({value: string, type: 'string'}),
+      dependencies,
+    };
+  }
+  if (!calc){
+    return {
+      context: {errors},
+      result: new ConstantNode({value: calc, type: 'string'}),
+      dependencies,
+    };
+  }
+  // Ensure all symbol nodes are defined and computed
+  calc.traverse(node => {
+    if (node instanceof SymbolNode || node instanceof AccessorNode){
+      // References up the tree start with $
+      let stat;
+      if (node.name[0] === '#'){
+        stat = findAncestorByType({type: node.name.slice(1), prop, memo});
+        memo.statsByVariableName[node.name] = stat;
+      } else {
+        stat = memo.statsByVariableName[node.name];
+      }
+      if (stat && stat.computationDetails && !stat.computationDetails.computed){
+        computeStat(stat, memo);
+      }
+      if (stat) dependencies.push(stat._id || node.name, ...stat.dependencies);
+    }
+  });
+  // Evaluate
+  let context = new CompilationContext();
+  let result = calc[fn](memo.statsByVariableName, context);
+  return {result, context, dependencies};
+}

app/imports/api/creature/computation/engine/findAncestorByType.js

@@ -0,0 +1,10 @@
+export default function findAncestorByType({type, prop, memo}){
+  if (!prop || !prop.ancestors) return;
+  let ancestor;
+  for (let i = prop.ancestors.length - 1; i >= 0; i--){
+    ancestor = memo.propsById[prop.ancestors[i].id];
+    if (ancestor && ancestor.type === type){
+      return ancestor;
+    }
+  }
+}

app/imports/api/creature/computation/engine/getComputationProperties.js

@@ -0,0 +1,35 @@
+import CreatureProperties from '/imports/api/creature/creatureProperties/CreatureProperties.js';
+
+export default function getComputationProperties(creatureId){
+  // find ids of all toggles that have conditions, even if they are inactive
+  let toggleIds = CreatureProperties.find({
+    'ancestors.id': creatureId,
+    type: 'toggle',
+    removed: {$ne: true},
+    condition: { $exists: true },
+  }, {
+    fields: {_id: 1},
+  }).map(t => t._id);
+  // Find all the relevant properties
+  return CreatureProperties.find({
+    'ancestors.id': creatureId,
+    removed: {$ne: true},
+    $or: [
+      // All active properties
+      {inactive: {$ne: true}},
+      // All active and inactive toggles with conditions
+      // Same as {$in: toggleIds}, but should be slightly faster
+      {type: 'toggle', condition: { $exists: true }},
+      // All decendents of the above toggles
+      {'ancestors.id': {$in: toggleIds}},
+    ]
+  }, {
+    // Filter out fields never used by calculations
+    fields: {
+      icon: 0,
+    },
+    sort: {
+      order: 1,
+    }
+  }).fetch();
+}

app/imports/api/creature/computation/engine/getDependentProperties.js

@@ -0,0 +1,42 @@
+import CreatureProperties from '/imports/api/creature/creatureProperties/CreatureProperties.js';
+
+export default function getDependentProperties({creatureId, dependencies}){
+  // find ids of all dependant toggles that have conditions, even if inactive
+  let toggleIds = CreatureProperties.find({
+    'ancestors.id': creatureId,
+    type: 'toggle',
+    removed: {$ne: true},
+    condition: { $exists: true },
+    dependencies: {$in: dependencies},
+  }, {
+    fields: {_id: 1},
+  }).map(t => t._id);
+  // Find all the dependant properties
+  let props = CreatureProperties.find({
+    'ancestors.id': creatureId,
+    removed: {$ne: true},
+    dependencies: {$in: dependencies},
+    $or: [
+      // All active properties
+      {inactive: {$ne: true}},
+      // All active and inactive toggles with conditions
+      // Same as {$in: toggleIds}, but should be slightly faster
+      {type: 'toggle', condition: { $exists: true }},
+      // All decendents of the above toggles
+      {'ancestors.id': {$in: toggleIds}},
+    ]
+  }, {
+    // Filter out fields never used by calculations
+    fields: {
+      icon: 0,
+    },
+    sort: {
+      order: 1,
+    }
+  }).fetch();
+  // Add on all the properties th
+  CreatureProperties.find({_id: {$in: dependencies}}).forEach(prop => {
+    props.push(prop)
+  });
+  return props;
+}

app/imports/api/creature/computation/engine/writeAlteredProperties.js

@@ -0,0 +1,105 @@
+import { Meteor } from 'meteor/meteor'
+import { isEqual, forOwn } from 'lodash';
+import CreatureProperties from '/imports/api/creature/creatureProperties/CreatureProperties.js';
+import propertySchemasIndex from '/imports/api/properties/computedOnlyPropertySchemasIndex.js';
+
+export default function writeAlteredProperties(memo){
+  let bulkWriteOperations = [];
+  // Loop through all properties on the memo
+  forOwn(memo.propsById, changed => {
+    let schema = propertySchemasIndex[changed.type];
+    if (!schema) return;
+    let extraIds = changed.computationDetails.idsOfSameName;
+    let ids;
+    if (extraIds && extraIds.length){
+      ids = [changed._id, ...extraIds];
+    } else {
+      ids = [changed._id];
+    }
+    ids.forEach(id => {
+      let op = undefined;
+      let original = memo.originalPropsById[id];
+      let keys = ['dependencies', ...schema.objectKeys()];
+      op = addChangedKeysToOp(op, keys, original, changed);
+      if (op){
+        bulkWriteOperations.push(op);
+      }
+    });
+  });
+  bulkWriteProperties(bulkWriteOperations);
+}
+
+function addChangedKeysToOp(op, keys, original, changed) {
+  // Loop through all keys that can be changed by computation
+  // and compile an operation that sets all those keys
+  for (let key of keys){
+    if (!isEqual(original[key], changed[key])){
+      if (!op) op = newOperation(original._id, changed.type);
+      let value = changed[key];
+      if (value === undefined){
+        // Unset values that become undefined
+        addUnsetOp(op, key);
+      } else {
+        // Set values that changed to something else
+        addSetOp(op, key, value);
+      }
+    }
+  }
+  return op;
+}
+
+function newOperation(_id, type){
+  let newOp = {
+    updateOne: {
+      filter: {_id},
+      update: {},
+    }
+  };
+  if (Meteor.isClient){
+    newOp.type = type;
+  }
+  return newOp;
+}
+
+function addSetOp(op, key, value){
+  if (op.updateOne.update.$set){
+    op.updateOne.update.$set[key] = value;
+  } else {
+    op.updateOne.update.$set = {[key]: value};
+  }
+}
+
+function addUnsetOp(op, key){
+  if (op.updateOne.update.$unset){
+    op.updateOne.update.$unset[key] = 1;
+  } else {
+    op.updateOne.update.$unset = {[key]: 1};
+  }
+}
+
+function bulkWriteProperties(bulkWriteOps){
+  if (!bulkWriteOps.length) return;
+  // Only use bulk writing if there are many writes to do
+  // it makes latency compensation janky, so we avoid it for smaller writes
+  if (Meteor.isServer && bulkWriteOps.length > 16){
+    CreatureProperties.rawCollection().bulkWrite(
+      bulkWriteOps,
+      {ordered : false},
+      function(e){
+        if (e) {
+          console.error('Bulk write failed: ');
+          console.error(e);
+        }
+      }
+    );
+  } else {
+    bulkWriteOps.forEach(op => {
+      let updateOneOrMany = op.updateOne || op.updateMany;
+      CreatureProperties.update(updateOneOrMany.filter, updateOneOrMany.update, {
+        // The bulk code is bypassing validation, so do the same here
+        // selector: {type: op.type} // include this if bypass is off
+        bypassCollection2: true,
+      });
+    });
+  }
+}

app/imports/api/creature/computation/engine/writeCreatureVariables.js

@@ -0,0 +1,40 @@
+import { pick, forOwn } from 'lodash';
+import Creatures from '/imports/api/creature/Creatures.js';
+import VERSION from '/imports/constants/VERSION.js';
+
+export default function writeCreatureVariables(memo, creatureId) {
+  const fields = [
+    'name',
+    'attributeType',
+    'baseValue',
+    'spellSlotLevelValue',
+    'damage',
+    'decimal',
+    'reset',
+    'resetMultiplier',
+    'value',
+    'currentValue',
+    'modifier',
+    'ability',
+    'skillType',
+    'baseProficiency',
+    'abilityMod',
+    'advantage',
+    'passiveBonus',
+    'proficiency',
+    'conditionalBenefits',
+    'rollBonuses',
+    'fail',
+    'level',
+  ];
+
+  memo.creatureVariables = {};
+  forOwn(memo.statsByVariableName, (stat, variableName) => {
+    let condensedStat = pick(stat, fields);
+    memo.creatureVariables[variableName] = condensedStat;
+  });
+  Creatures.update(creatureId, {$set: {
+    variables: memo.creatureVariables,
+    computeVersion: VERSION,
+  }});
+}