Implement precision mechanism for JSON Logic; I'll probably release this soon.

Author: TotalTechGeek

defaultMethods.js

@@ -947,6 +947,9 @@ defaultMethods.var.compile = function (data, buildState) {
 // @ts-ignore Allowing a optimizeUnary attribute that can be used for performance optimizations
 defaultMethods['+'].optimizeUnary = defaultMethods['-'].optimizeUnary = defaultMethods.var.optimizeUnary = defaultMethods['!'].optimizeUnary = defaultMethods['!!'].optimizeUnary = defaultMethods.cat.optimizeUnary = true
 
+// @ts-ignore Allowing a optimizeUnary attribute that can be used for performance optimizations
+defaultMethods['<'].precise = defaultMethods['<='].precise = defaultMethods['>'].precise = defaultMethods['>='].precise = defaultMethods['=='].precise = defaultMethods['==='].precise = defaultMethods['!='].precise = defaultMethods['!=='].precise = true
+
 export default {
   ...defaultMethods
 }

logic.js

@@ -32,6 +32,7 @@ class LogicEngine {
     this.disableInline = options.disableInline
     this.disableInterpretedOptimization = options.disableInterpretedOptimization
     this.methods = { ...methods }
+    this.precision = null
 
     this.optimizedMap = new WeakMap()
     this.missesSinceSeen = 0
@@ -67,7 +68,7 @@ class LogicEngine {
     const [func] = Object.keys(logic)
     const data = logic[func]
 
-    if (this.isData(logic, func)) return logic
+    if (this.isData(logic, func) || (this.precision && logic instanceof this.precision)) return logic
 
     if (!this.methods[func]) throw new Error(`Method '${func}' was not found in the Logic Engine.`)
 
@@ -77,9 +78,9 @@ class LogicEngine {
     }
 
     if (typeof this.methods[func] === 'object') {
-      const { method, traverse } = this.methods[func]
+      const { method, traverse, precise } = this.methods[func]
       const shouldTraverse = typeof traverse === 'undefined' ? true : traverse
-      const parsedData = shouldTraverse ? ((!data || typeof data !== 'object') ? [data] : coerceArray(this.run(data, context, { above }))) : data
+      const parsedData = shouldTraverse ? ((!data || typeof data !== 'object') ? [data] : coerceArray(this.run(data, context, { above, precise }))) : data
       return method(parsedData, context, above, this)
     }
 
@@ -123,7 +124,7 @@ class LogicEngine {
    *
    * @param {*} logic The logic to be executed
    * @param {*} data The data being passed in to the logic to be executed against.
-   * @param {{ above?: any }} options Options for the invocation
+   * @param {{ above?: any, precise?: boolean }} options Options for the invocation
    * @returns {*}
    */
   run (logic, data = {}, options = {}) {
@@ -149,11 +150,14 @@ class LogicEngine {
 
     if (Array.isArray(logic)) {
       const res = []
-      for (let i = 0; i < logic.length; i++) res.push(this.run(logic[i], data, { above }))
+      for (let i = 0; i < logic.length; i++) res.push(this.run(logic[i], data, options))
       return res
     }
 
-    if (logic && typeof logic === 'object' && Object.keys(logic).length > 0) return this._parse(logic, data, above)
+    if (logic && typeof logic === 'object') {
+      if (this.precision && !options.precise && logic.toNumber) return Number(logic)
+      if (Object.keys(logic).length > 0) return this._parse(logic, data, above)
+    }
 
     return logic
   }

optimizer.js

@@ -53,7 +53,7 @@ export function optimize (logic, engine, above = []) {
     const keys = Object.keys(logic)
     const methodName = keys[0]
 
-    const isData = engine.isData(logic, methodName)
+    const isData = engine.isData(logic, methodName) || (engine.precision && logic instanceof engine.precision)
     if (isData) return () => logic
 
     // If we have a deterministic function, we can just return the result of the evaluation,

precision/index.js

@@ -0,0 +1,98 @@
+export function configurePrecision (engine, constructor) {
+  engine.precision = constructor
+  engine.addMethod('+', {
+    method: (data) => {
+      if (typeof data === 'string') return constructor(data)
+      if (typeof data === 'number') return constructor(data)
+      let res = constructor(data[0])
+      for (let i = 1; i < data.length; i++) res = res.plus(data[i])
+      return res
+    },
+    compile: (args, buildState) => {
+      if (Array.isArray(args)) {
+        let res = buildState.compile`(engine.precision(${args[0]}))`
+        for (let i = 1; i < args.length; i++) res = buildState.compile`(${res}.plus(${args[i]}))`
+        return res
+      }
+      return false
+    },
+    optimizeUnary: true,
+    deterministic: true,
+    precise: true
+  })
+
+  engine.addMethod('-', {
+    method: (data) => {
+      if (typeof data === 'string') return constructor(data).mul(-1)
+      if (typeof data === 'number') return constructor(data).mul(-1)
+      let res = constructor(data[0])
+      for (let i = 1; i < data.length; i++) res = res.minus(data[i])
+      return res
+    },
+    compile: (args, buildState) => {
+      if (Array.isArray(args)) {
+        let res = buildState.compile`(engine.precision(${args[0]}))`
+        for (let i = 1; i < args.length; i++) res = buildState.compile`(${res}.minus(${args[i]}))`
+        return res
+      }
+      return false
+    },
+    optimizeUnary: true,
+    deterministic: true,
+    precise: true
+  })
+
+  engine.addMethod('*', {
+    method: (data) => {
+      let res = constructor(data[0])
+      for (let i = 1; i < data.length; i++) res = res.mul(data[i])
+      return res
+    },
+    compile: (args, buildState) => {
+      if (Array.isArray(args)) {
+        let res = buildState.compile`(engine.precision(${args[0]}))`
+        for (let i = 1; i < args.length; i++) res = buildState.compile`(${res}.mul(${args[i]}))`
+        return res
+      }
+      return false
+    },
+    deterministic: true,
+    precise: true
+  })
+
+  engine.addMethod('/', {
+    method: (data) => {
+      let res = constructor(data[0])
+      for (let i = 1; i < data.length; i++) res = res.div(data[i])
+      return res
+    },
+    compile: (args, buildState) => {
+      if (Array.isArray(args)) {
+        let res = buildState.compile`(engine.precision(${args[0]}))`
+        for (let i = 1; i < args.length; i++) res = buildState.compile`(${res}.div(${args[i]}))`
+        return res
+      }
+      return false
+    },
+    deterministic: true,
+    precise: true
+  })
+
+  engine.addMethod('%', {
+    method: (data) => {
+      let res = constructor(data[0])
+      for (let i = 1; i < data.length; i++) res = res.mod(data[i])
+      return res
+    },
+    compile: (args, buildState) => {
+      if (Array.isArray(args)) {
+        let res = buildState.compile`(engine.precision(${args[0]}))`
+        for (let i = 1; i < args.length; i++) res = buildState.compile`(${res}.mod(${args[i]}))`
+        return res
+      }
+      return false
+    },
+    deterministic: true,
+    precise: true
+  })
+}

precision/package.json

@@ -0,0 +1,10 @@
+{
+  "name": "precision",
+  "version": "1.0.0",
+  "main": "index.js",
+  "license": "MIT",
+  "dependencies": {
+    "decimal.js": "^10.4.3"
+  },
+  "type": "module"
+}

precision/scratch.js

@@ -0,0 +1,13 @@
+import { LogicEngine } from '../index.js'
+import { Decimal } from 'decimal.js'
+import { configurePrecision } from './index.js'
+
+const ieee754Engine = new LogicEngine()
+const decimalEngine = new LogicEngine()
+configurePrecision(decimalEngine, Decimal.clone({ precision: 100 }))
+
+console.log(decimalEngine.build({ '+': ['85070591730234615847396907784232501249', 100] })().toFixed()) // 85070591730234615847396907784232501349
+console.log(decimalEngine.run({ '+': [0.1, 0.2] })) // 0.3
+
+console.log(ieee754Engine.run({ '>': [{ '+': [0.1, 0.2] }, 0.3] })) // true, because 0.1 + 0.2 = 0.30000000000000004
+console.log(decimalEngine.run({ '>': [{ '+': [0.1, 0.2] }, 0.3] })) // false, because 0.1 + 0.2 = 0.3

precision/yarn.lock

@@ -0,0 +1,8 @@
+# THIS IS AN AUTOGENERATED FILE. DO NOT EDIT THIS FILE DIRECTLY.
+# yarn lockfile v1
+
+
+decimal.js@^10.4.3:
+  version "10.4.3"
+  resolved "https://registry.yarnpkg.com/decimal.js/-/decimal.js-10.4.3.tgz#1044092884d245d1b7f65725fa4ad4c6f781cc23"
+  integrity sha512-VBBaLc1MgL5XpzgIP7ny5Z6Nx3UrRkIViUkPUdtl9aya5amy3De1gsUUSB1g3+3sExYNjCAsAznmukyxCb1GRA==