$ref support

README.md

@@ -26,6 +26,7 @@ fast-json-stringify obj x 5,085,148 ops/sec ±1.56% (89 runs sampled)
  - <a href="#missingFields">`Missing fields`</a>
  - <a href="#patternProperties">`Pattern Properties`</a>
  - <a href="#additionalProperties">`Additional Properties`</a>
+ - <a href="#ref">`Reuse - $ref`</a>
 - <a href="#acknowledgements">`Acknowledgements`</a>
 - <a href="#license">`License`</a>
 
@@ -214,6 +215,85 @@ const obj = {
 console.log(stringify(obj)) // '{"matchfoo":"42","otherfoo":"str","matchnum":3,"nomatchstr":"valar morghulis",nomatchint:"313","nickname":"nick"}'
 ```
 
+<a name="ref"></a>
+#### Reuse - $ref
+If you want to reuse a definition of a value, you can use the property `$ref`.  
+The value of `$ref` must be a string in [JSON Pointer](https://tools.ietf.org/html/rfc6901) format.  
+Example:
+```javascript
+const schema = {
+  title: 'Example Schema',
+  definitions: {
+    num: {
+      type: 'object',
+      properties: {
+        int: {
+          type: 'integer'
+        }
+      }
+    },
+    str: {
+      type: 'string'
+    }
+  },
+  type: 'object',
+  properties: {
+    nickname: {
+      $ref: '#/definitions/str'
+    }
+  },
+  patternProperties: {
+    'num': {
+      $ref: '#/definitions/num'
+    }
+  },
+  additionalProperties: {
+    $ref: '#/definitions/def'
+  }
+}
+
+const stringify = fastJson(schema)
+```
+If you need to use an external definition, you can pass it as an option to `fast-json-stringify`.  
+Example:
+```javascript
+const schema = {
+  title: 'Example Schema',
+  type: 'object',
+  properties: {
+    nickname: {
+      $ref: 'strings#/definitions/str'
+    }
+  },
+  patternProperties: {
+    'num': {
+      $ref: 'numbers#/definitions/num'
+    }
+  },
+  additionalProperties: {
+    $ref: 'strings#/definitions/def'
+  }
+}
+
+const externalSchema = {
+  numbers: {
+    definitions: {
+      num: {
+        type: 'object',
+        properties: {
+          int: {
+            type: 'integer'
+          }
+        }
+      }
+    }
+  },
+  strings: require('./string-def.json')
+}
+
+const stringify = fastJson(schema, { schema: externalSchema })
+```
+
 <a name="acknowledgements"></a>
 ## Acknowledgements
 

index.js

@@ -2,7 +2,8 @@
 
 const fastSafeStringify = require('fast-safe-stringify')
 
-function build (schema) {
+function build (schema, options) {
+  options = options || {}
   /* eslint no-new-func: "off" */
   var code = `
     'use strict'
@@ -26,7 +27,7 @@ function build (schema) {
   switch (schema.type) {
     case 'object':
       main = '$main'
-      code = buildObject(schema, code, main)
+      code = buildObject(schema, code, main, options.schema)
       break
     case 'string':
       main = $asString.name
@@ -43,7 +44,7 @@ function build (schema) {
       break
     case 'array':
       main = '$main'
-      code = buildArray(schema, code, main)
+      code = buildArray(schema, code, main, options.schema)
       break
     default:
       throw new Error(`${schema.type} unsupported`)
@@ -141,24 +142,28 @@ function $asRegExp (reg) {
   return '"' + reg + '"'
 }
 
-function addPatternProperties (pp, ap) {
+function addPatternProperties (schema, externalSchema) {
+  var pp = schema.patternProperties
   let code = `
       var keys = Object.keys(obj)
       for (var i = 0; i < keys.length; i++) {
         if (properties[keys[i]]) continue
   `
   Object.keys(pp).forEach((regex, index) => {
+    if (pp[regex]['$ref']) {
+      pp[regex] = refFinder(pp[regex]['$ref'], schema, externalSchema)
+    }
     var type = pp[regex].type
     code += `
         if (/${regex}/.test(keys[i])) {
     `
     if (type === 'object') {
-      code += buildObject(pp[regex], '', 'buildObjectPP' + index)
+      code += buildObject(pp[regex], '', 'buildObjectPP' + index, externalSchema)
       code += `
           json += $asString(keys[i]) + ':' + buildObjectPP${index}(obj[keys[i]]) + ','
       `
     } else if (type === 'array') {
-      code += buildArray(pp[regex], '', 'buildArrayPP' + index)
+      code += buildArray(pp[regex], '', 'buildArrayPP' + index, externalSchema)
       code += `
           json += $asString(keys[i]) + ':' + buildArrayPP${index}(obj[keys[i]]) + ','
       `
@@ -189,8 +194,8 @@ function addPatternProperties (pp, ap) {
         }
     `
   })
-  if (ap) {
-    code += additionalProperty(ap)
+  if (schema.additionalProperties) {
+    code += additionalProperty(schema, externalSchema)
   }
 
   code += `
@@ -199,21 +204,26 @@ function addPatternProperties (pp, ap) {
   return code
 }
 
-function additionalProperty (ap) {
+function additionalProperty (schema, externalSchema) {
+  var ap = schema.additionalProperties
   let code = ''
   if (ap === true) {
     return `
         json += $asString(keys[i]) + ':' + fastSafeStringify(obj[keys[i]]) + ','
     `
   }
+  if (ap['$ref']) {
+    ap = refFinder(ap['$ref'], schema, externalSchema)
+  }
+
   let type = ap.type
   if (type === 'object') {
-    code += buildObject(ap, '', 'buildObjectAP')
+    code += buildObject(ap, '', 'buildObjectAP', externalSchema)
     code += `
         json += $asString(keys[i]) + ':' + buildObjectAP(obj[keys[i]]) + ','
     `
   } else if (type === 'array') {
-    code += buildArray(ap, '', 'buildArrayAP')
+    code += buildArray(ap, '', 'buildArrayAP', externalSchema)
     code += `
         json += $asString(keys[i]) + ':' + buildArrayAP(obj[keys[i]]) + ','
     `
@@ -241,26 +251,41 @@ function additionalProperty (ap) {
   return code
 }
 
-function addAdditionalProperties (ap) {
+function addAdditionalProperties (schema, externalSchema) {
   return `
       var keys = Object.keys(obj)
       for (var i = 0; i < keys.length; i++) {
         if (properties[keys[i]]) continue
-        ${additionalProperty(ap)}
+        ${additionalProperty(schema, externalSchema)}
       }
   `
 }
 
-function buildObject (schema, code, name) {
+function refFinder (ref, schema, externalSchema) {
+  // Split file from walk
+  ref = ref.split('#')
+  // If external file
+  if (ref[0]) {
+    schema = externalSchema[ref[0]]
+  }
+  const walk = ref[1].split('/')
+  let code = 'return schema'
+  for (let i = 1; i < walk.length; i++) {
+    code += `['${walk[i]}']`
+  }
+  return (new Function('schema', code))(schema)
+}
+
+function buildObject (schema, code, name, externalSchema) {
   code += `
     function ${name} (obj) {
       var json = '{'
   `
 
   if (schema.patternProperties) {
-    code += addPatternProperties(schema.patternProperties, schema.additionalProperties)
+    code += addPatternProperties(schema, externalSchema)
   } else if (schema.additionalProperties && !schema.patternProperties) {
-    code += addAdditionalProperties(schema.additionalProperties)
+    code += addAdditionalProperties(schema, externalSchema)
   }
 
   var laterCode = ''
@@ -273,7 +298,11 @@ function buildObject (schema, code, name) {
         json += '${$asString(key)}:'
       `
 
-    const result = nested(laterCode, name, '.' + key, schema.properties[key])
+    if (schema.properties[key]['$ref']) {
+      schema.properties[key] = refFinder(schema.properties[key]['$ref'], schema, externalSchema)
+    }
+
+    const result = nested(laterCode, name, '.' + key, schema.properties[key], externalSchema)
 
     code += result.code
     laterCode = result.laterCode
@@ -308,15 +337,15 @@ function buildObject (schema, code, name) {
   return code
 }
 
-function buildArray (schema, code, name) {
+function buildArray (schema, code, name, externalSchema) {
   code += `
     function ${name} (obj) {
       var json = '['
   `
 
   var laterCode = ''
 
-  const result = nested(laterCode, name, '[i]', schema.items)
+  const result = nested(laterCode, name, '[i]', schema.items, externalSchema)
 
   code += `
     const l = obj.length
@@ -342,7 +371,7 @@ function buildArray (schema, code, name) {
   return code
 }
 
-function nested (laterCode, name, key, schema) {
+function nested (laterCode, name, key, schema, externalSchema) {
   var code = ''
   var funcName
   const type = schema.type
@@ -370,14 +399,14 @@ function nested (laterCode, name, key, schema) {
       break
     case 'object':
       funcName = (name + key).replace(/[-.\[\]]/g, '')
-      laterCode = buildObject(schema, laterCode, funcName)
+      laterCode = buildObject(schema, laterCode, funcName, externalSchema)
       code += `
         json += ${funcName}(obj${key})
       `
       break
     case 'array':
       funcName = (name + key).replace(/[-.\[\]]/g, '')
-      laterCode = buildArray(schema, laterCode, funcName)
+      laterCode = buildArray(schema, laterCode, funcName, externalSchema)
       code += `
         json += ${funcName}(obj${key})
       `

test/ref.json

@@ -0,0 +1,12 @@
+{
+  "definitions": {
+    "def": {
+      "type": "object",
+      "properties": {
+        "str": {
+          "type": "string"
+        }
+      }
+    }
+  }
+}