Set up NaN coercion properly

Author: TotalTechGeek

compiler.js

@@ -11,7 +11,7 @@ import {
 import asyncIterators from './async_iterators.js'
 import { coerceArray } from './utilities/coerceArray.js'
 import { countArguments } from './utilities/countArguments.js'
-import { downgrade } from './utilities/downgrade.js'
+import { downgrade, precoerceNumber } from './utilities/downgrade.js'
 
 /**
  * Provides a simple way to compile logic into a function that can be run.
@@ -194,7 +194,7 @@ function buildString (method, buildState = {}) {
     }
 
     let lower = method[func]
-    if (!lower || typeof lower !== 'object') lower = [lower]
+    if ((!lower || typeof lower !== 'object') && (typeof engine.methods[func].traverse === 'undefined' || engine.methods[func].traverse)) lower = [lower]
 
     if (engine.methods[func] && engine.methods[func].compile) {
       let str = engine.methods[func].compile(lower, buildState)
@@ -308,12 +308,12 @@ function processBuiltString (method, str, buildState) {
     str = str.replace(`__%%%${x}%%%__`, item)
   })
 
-  const final = `(values, methods, notTraversed, asyncIterators, engine, above, coerceArray, downgrade) => ${buildState.asyncDetected ? 'async' : ''} (context ${buildState.extraArguments ? ',' + buildState.extraArguments : ''}) => { let prev; const result = ${str}; return result }`
+  const final = `(values, methods, notTraversed, asyncIterators, engine, above, coerceArray, downgrade, precoerceNumber) => ${buildState.asyncDetected ? 'async' : ''} (context ${buildState.extraArguments ? ',' + buildState.extraArguments : ''}) => { let prev; const result = ${str}; return result }`
   // console.log(str)
   // console.log(final)
   // eslint-disable-next-line no-eval
   return Object.assign(
-    (typeof globalThis !== 'undefined' ? globalThis : global).eval(final)(values, methods, notTraversed, asyncIterators, engine, above, coerceArray, downgrade), {
+    (typeof globalThis !== 'undefined' ? globalThis : global).eval(final)(values, methods, notTraversed, asyncIterators, engine, above, coerceArray, downgrade, precoerceNumber), {
       [Sync]: !buildState.asyncDetected,
       aboveDetected: typeof str === 'string' && str.includes(', above')
     })

defaultMethods.js

@@ -887,36 +887,27 @@ defaultMethods['==='].compile = function (data, buildState) {
   for (let i = 2; i < data.length; i++) res = buildState.compile`(${res} && ${data[i - 1]} === ${data[i]})`
   return res
 }
+
+/**
+ * Transforms the operands of the arithmetic operation to numbers.
+ */
+function numberCoercion (i, buildState) {
+  if (Array.isArray(i)) return 'NaN'
+  if (typeof i === 'string' || typeof i === 'number' || typeof i === 'boolean') return `(+${buildString(i, buildState)})`
+  return `(+precoerceNumber(${buildString(i, buildState)}))`
+}
+
 // @ts-ignore Allow custom attribute
 defaultMethods['+'].compile = function (data, buildState) {
-  if (Array.isArray(data)) {
-    return `(${data
-      .map((i) => {
-        // Todo: Actually make this correct, this is a decent optimization but
-        // does not coerce the built string.
-        if (Array.isArray(i)) return 'NaN'
-        return `(+${buildString(i, buildState)})`
-      })
-      .join(' + ')})`
-  } else if (typeof data === 'string' || typeof data === 'number' || typeof data === 'boolean') {
-    return `(+${buildString(data, buildState)})`
-  } else {
-    return `([].concat(${buildString(
-      data,
-      buildState
-    )})).reduce((a,b) => (+a)+(+b), 0)`
-  }
+  if (Array.isArray(data)) return `(${data.map(i => numberCoercion(i, buildState)).join(' + ')})`
+  if (typeof data === 'string' || typeof data === 'number' || typeof data === 'boolean') return `(+${buildString(data, buildState)})`
+  return `([].concat(${buildString(data, buildState)})).reduce((a,b) => (+a)+(+precoerceNumber(b)), 0)`
 }
 
 // @ts-ignore Allow custom attribute
 defaultMethods['%'].compile = function (data, buildState) {
-  if (Array.isArray(data)) {
-    return `(${data
-      .map((i) => `(+${buildString(i, buildState)})`)
-      .join(' % ')})`
-  } else {
-    return `(${buildString(data, buildState)}).reduce((a,b) => (+a)%(+b))`
-  }
+  if (Array.isArray(data)) return `(${data.map(i => numberCoercion(i, buildState)).join(' % ')})`
+  return `(${buildString(data, buildState)}).reduce((a,b) => (+a)%(+precoerceNumber(b)))`
 }
 
 // @ts-ignore Allow custom attribute
@@ -927,11 +918,7 @@ defaultMethods.in.compile = function (data, buildState) {
 
 // @ts-ignore Allow custom attribute
 defaultMethods['-'].compile = function (data, buildState) {
-  if (Array.isArray(data)) {
-    return `${data.length === 1 ? '-' : ''}(${data
-      .map((i) => `(+${buildString(i, buildState)})`)
-      .join(' - ')})`
-  }
+  if (Array.isArray(data)) return `${data.length === 1 ? '-' : ''}(${data.map(i => numberCoercion(i, buildState)).join(' - ')})`
   if (typeof data === 'string' || typeof data === 'number') {
     return `(-${buildString(data, buildState)})`
   } else {
@@ -943,23 +930,13 @@ defaultMethods['-'].compile = function (data, buildState) {
 }
 // @ts-ignore Allow custom attribute
 defaultMethods['/'].compile = function (data, buildState) {
-  if (Array.isArray(data)) {
-    return `(${data
-      .map((i) => `(+${buildString(i, buildState)})`)
-      .join(' / ')})`
-  } else {
-    return `(${buildString(data, buildState)}).reduce((a,b) => (+a)/(+b))`
-  }
+  if (Array.isArray(data)) return `(${data.map(i => numberCoercion(i, buildState)).join(' / ')})`
+  return `(${buildString(data, buildState)}).reduce((a,b) => (+a)/(+b))`
 }
 // @ts-ignore Allow custom attribute
 defaultMethods['*'].compile = function (data, buildState) {
-  if (Array.isArray(data)) {
-    return `(${data
-      .map((i) => `(+${buildString(i, buildState)})`)
-      .join(' * ')})`
-  } else {
-    return `(${buildString(data, buildState)}).reduce((a,b) => (+a)*(+b))`
-  }
+  if (Array.isArray(data)) return `(${data.map(i => numberCoercion(i, buildState)).join(' * ')})`
+  return `(${buildString(data, buildState)}).reduce((a,b) => (+a)*(+b))`
 }
 // @ts-ignore Allow custom attribute
 defaultMethods.cat.compile = function (data, buildState) {

suites/plus.json

@@ -159,6 +159,12 @@
         "result": { "error": "NaN" },
         "data": null
     },
+    {
+        "description": "Addition with Array from context produces NaN",
+        "rule": { "+": [{ "val": "x" }, 1] },
+        "result": { "error": "NaN" },
+        "data": { "x": [1] }
+    },
     {
         "description": "Addition with Object produces NaN",
         "rule": { "+": [{ "val": "x" }, 1] },

utilities/downgrade.js

@@ -8,3 +8,13 @@ export function downgrade (item) {
   if (Number.isNaN(item)) return null
   return item
 }
+
+/**
+ * Used to precoerce a data value to a number, for the purposes of coalescing.
+ * @param {any} item
+ */
+export function precoerceNumber (item) {
+  if (!item) return item
+  if (typeof item === 'object') return Number.isNaN
+  return item
+}