Handle schema loading

spec/config-spec.coffee

@@ -399,3 +399,90 @@ describe "Config", ->
         it "updates the config data and resumes saving", ->
           atom.config.set("hair", "blonde")
           expect(atom.config.save).toHaveBeenCalled()
+
+  describe "when there is a schema specified", ->
+    schema = null
+
+    describe '.setSchema(keyPath, schema)', ->
+      it 'sets defaults specified by the schema', ->
+        schema =
+          type: 'object'
+          properties:
+            anInt:
+              type: 'integer'
+              default: 12
+            anObject:
+              type: 'object'
+              properties:
+                nestedInt:
+                  type: 'integer'
+                  default: 24
+                nestedObject:
+                  type: 'object'
+                  properties:
+                    superNestedInt:
+                      type: 'integer'
+                      default: 36
+
+        atom.config.setSchema('foo.bar', schema)
+        expect(atom.config.get("foo.bar.anInt")).toBe 12
+        expect(atom.config.get("foo.bar.anObject")).toEqual
+          nestedInt: 24
+          nestedObject:
+            superNestedInt: 36
+
+      it 'can set a non-object schema', ->
+        schema =
+          type: 'integer'
+          default: 12
+
+        atom.config.setSchema('foo.bar.anInt', schema)
+        expect(atom.config.get("foo.bar.anInt")).toBe 12
+        expect(atom.config.getSchema('foo.bar.anInt')).toEqual
+          type: 'integer'
+          default: 12
+
+      it 'creates a properly nested schema', ->
+        schema =
+          type: 'object'
+          properties:
+            anInt:
+              type: 'integer'
+              default: 12
+
+        atom.config.setSchema('foo.bar', schema)
+
+        expect(atom.config.schema).toEqual
+          type: 'object'
+          properties:
+            foo:
+              type: 'object'
+              properties:
+                bar:
+                  type: 'object'
+                  properties:
+                    anInt:
+                      type: 'integer'
+                      default: 12
+
+    describe '.getSchema(keyPath)', ->
+      schema =
+        type: 'object'
+        properties:
+          anInt:
+            type: 'integer'
+            default: 12
+
+      atom.config.setSchema('foo.bar', schema)
+
+      expect(atom.config.getSchema('foo.bar')).toEqual
+        type: 'object'
+        properties:
+          anInt:
+            type: 'integer'
+            default: 12
+
+      expect(atom.config.getSchema('foo.bar.anInt')).toEqual
+        type: 'integer'
+        default: 12
+

src/config.coffee

@@ -31,6 +31,9 @@ class Config
   # Created during initialization, available as `atom.config`
   constructor: ({@configDirPath, @resourcePath}={}) ->
     @emitter = new Emitter
+    @schema =
+      type: 'object'
+      properties: {}
     @defaultSettings = {}
     @settings = {}
     @configFileHasErrors = false
@@ -162,6 +165,13 @@ class Config
   isDefault: (keyPath) ->
     not _.valueForKeyPath(@settings, keyPath)?
 
+  getSchema: (keyPath) ->
+    keys = keyPath.split('.')
+    schema = @schema
+    for key in keys
+      schema = schema.properties[key]
+    schema
+
   ###
   Section: To Deprecate
   ###
@@ -300,6 +310,9 @@ class Config
     @watchSubscription = null
 
   setDefaults: (keyPath, defaults) ->
+    if typeof defaults isnt 'object'
+      return _.setValueForKeyPath(@defaultSettings, keyPath, defaults)
+
     keys = keyPath.split('.')
     hash = @defaultSettings
     for key in keys
@@ -310,6 +323,34 @@ class Config
     @emit 'updated'
     @emitter.emit 'did-change'
 
+  setSchema: (keyPath, schema) ->
+    unless typeof schema is "object"
+      throw new Error("Schemas can only be objects!")
+
+    unless typeof schema.type?
+      throw new Error("Schema object's must have a type attribute")
+
+    keys = keyPath.split('.')
+    rootSchema = @schema
+    for key in keys
+      rootSchema.type = 'object'
+      rootSchema.properties ?= {}
+      properties = rootSchema.properties
+      properties[key] ?= {}
+      rootSchema = properties[key]
+
+    _.extend rootSchema, schema
+    @setDefaults(keyPath, @extractDefaultsFromSchema(schema))
+
+  extractDefaultsFromSchema: (schema) ->
+    if schema.default?
+      schema.default
+    else if schema.type is 'object' and schema.properties? and typeof schema.properties is "object"
+      defaults = {}
+      properties = schema.properties or {}
+      defaults[key] = @extractDefaultsFromSchema(value) for key, value of properties
+      defaults
+
   update: ->
     return if @configFileHasErrors
     @save()