Adding a literal helper which can make sure the output of an operation is a literal value.

packages/string-templates/src/helpers/constants.js

@@ -18,4 +18,7 @@ module.exports.HelperFunctionBuiltin = [
 module.exports.HelperFunctionNames = {
   OBJECT: "object",
   ALL: "all",
+  LITERAL: "literal",
 }
+
+module.exports.LITERAL_MARKER = "%LITERAL%"

packages/string-templates/src/helpers/index.js

@@ -1,7 +1,7 @@
 const Helper = require("./Helper")
 const { SafeString } = require("handlebars")
 const externalHandlebars = require("./external")
-const { HelperFunctionNames, HelperFunctionBuiltin } = require("./constants")
+const { HelperFunctionNames, HelperFunctionBuiltin, LITERAL_MARKER } = require("./constants")
 
 const HTML_SWAPS = {
   "<": "&lt;",
@@ -27,6 +27,12 @@ const HELPERS = [
       return HTML_SWAPS[tag] || tag
     })
   }),
+  // adds a note for post-processor
+  new Helper(HelperFunctionNames.LITERAL, value => {
+    const type = typeof(value)
+    const outputVal = type === "object" ? JSON.stringify(value) : value
+    return `{{-${LITERAL_MARKER}-${type}-${outputVal}-}}`
+  })
 ]
 
 module.exports.HelperNames = () => {

packages/string-templates/src/processors/index.js

@@ -2,19 +2,23 @@ const { FIND_HBS_REGEX } = require("../utilities")
 const preprocessor = require("./preprocessor")
 const postprocessor = require("./postprocessor")
 
-function process(string, processors) {
+function process(output, processors) {
   for (let processor of processors) {
+    // if a literal statement has occurred stop
+    if (typeof output !== "string") {
+      break
+    }
     // re-run search each time incase previous processor updated/removed a match
-    let regex = new RegExp(FIND_HBS_REGEX)
-    let matches = string.match(regex)
+    let regexp = new RegExp(FIND_HBS_REGEX)
+    let matches = output.match(regexp)
     if (matches == null) {
       continue
     }
     for (let match of matches) {
-      string = processor.process(string, match)
+      output = processor.process(output, match)
     }
   }
-  return string
+  return output
 }
 
 module.exports.preprocess = (string, finalise = true) => {

packages/string-templates/src/processors/postprocessor.js

@@ -1,9 +1,43 @@
+const { LITERAL_MARKER } = require("../helpers/constants")
+
+const PostProcessorNames = {
+  CONVERT_LITERALS: "convert-literals",
+}
+
 /* eslint-disable no-unused-vars */
 class Postprocessor {
   constructor(name, fn) {
     this.name = name
     this.fn = fn
   }
+
+  process(statement) {
+    return this.fn(statement)
+  }
 }
 
-module.exports.processors = []
+module.exports.processors = [
+  new Postprocessor(PostProcessorNames.CONVERT_LITERALS, statement => {
+    if (!statement.includes(LITERAL_MARKER)) {
+      return statement
+    }
+
+    const components = statement.split("-")
+    // pop and shift remove the empty array elements from the first and last dash
+    components.pop()
+    components.shift()
+    const type = components[1]
+    const value = components[2]
+    switch (type) {
+      case "string":
+        return value
+      case "number":
+        return parseFloat(value)
+      case "boolean":
+        return value === "true"
+      case "object":
+        return JSON.parse(value)
+    }
+    return value
+  })
+]

packages/string-templates/src/utilities.js

@@ -1,7 +1,7 @@
 const _ = require("lodash")
 const ALPHA_NUMERIC_REGEX = /^[A-Za-z0-9]+$/g
 
-module.exports.FIND_HBS_REGEX = /{{([^{}])+}}/g
+module.exports.FIND_HBS_REGEX = /{{([^{].*?)}}/g
 
 module.exports.isAlphaNumeric = char => {
   return char.match(ALPHA_NUMERIC_REGEX)

packages/string-templates/test/helpers.spec.js

@@ -259,3 +259,19 @@ describe("test the comparison helpers", () => {
     expect(output).toBe("s")
   })
 })
+
+describe("Test the literal helper", () => {
+  it("should allow use of the literal specifier for a number", async () => {
+    const output = await processString(`{{literal a}}`, {
+      a: 51,
+    })
+    expect(output).toBe(51)
+  })
+
+  it("should allow use of the literal specifier for an object", async () => {
+    const output = await processString(`{{literal a}}`, {
+      a: {b: 1},
+    })
+    expect(output.b).toBe(1)
+  })
+})