iOS Swift Common Architecture

meta-programming(元编程-code write code)

可以从两个层面上来理解：

在运行时通过反射之类的技术来动态修改程序自身的结构。比如说我们都非常熟悉的Objective-C Runtime。

通过DSL来生成特定的代码，这通常发生在编译期预处理阶段。

Sourcery

sourcery read config from .sourcery.yml

• pod 'Sourcery'
• Shell Config (Under Check Pods Manifest.lock)

if [ "$CONFIGURATION" == "Debug" ] ; then
$PODS_ROOT/Sourcery/bin/sourcery
fi

• Config File

- sources: source file
- templates: stencil file
- output: generated file

• 命令行实现

sourcery \
   --sources ./YourProject \
   --templates ./YourTemplates \
   --output ./YourProject/AutoGenerated.swift

• yml配置文件实现

.sourcery.yml

sources:
  - SourceryT/Class
templates:
  - Templates/AutoEquatable.stencil
  #- Templates/Colors.stencil
  #- Templates/ModelConvert.stencil
  #- Templates/Router.stencil
  #...
output:
  Generated

AutoEquatable.stencil

{# AutoEquatable Generator Template #}
{{"//autoequatable"|uppercase}}
{% for type in types.implementing.AutoEquatable %}
//MARK: - {{type.name}}
extension {{type.name}}: Equatable {
    static func == (lhs:{{type.name}}, rhs: {{type.name}}) -> Bool {
        {% for variable in type.storedVariables %}
        guard lhs.{{variable.name}} == rhs.{{variable.name}} else {
            return false
        }
        {% endfor %}
        return true
    }
}
{% endfor %}

Sourcery Annotation

Sourcery自定义 规则

• Documents

e.g.
/// sourcery: key = value
/// sourcery: anotherKey = someOtherValue
also
/// sourcery: key = value, anotherKey = someOtherValue
contain some basic types

/// sourcery: maxSpeed = 1500, hasHyperdrive = true
/// sourcery: codename = "blacksaber"

• Exp

enum SpaceshipsAPI {
    /// sourcery: method = "GET", path = "/spaceships"
    /// sourcery: timeout = 5
    case ships
    ...
}

//SpaceshipsAPI+Properties.stencil
extension SpaceshipsAPI {
  public var path: String? {
    switch self {
      {% for c in type.SpaceshipsAPI.cases %}
      {% if c.annotations.path %}
      case .{{ c.name }}: return "{{c.annotations.path}}"
      {% endif %}
    {% endfor %}
    default: return nil
    }
  }

  // ... etc
}

Stencil

Stencil是一门用Swift实现的专门为Swift设计的模板语言

• GitHub

• {{ ... }}

变量语法，将中间的部分作为变量（或变量的表达式）来解析，解析后的值会作为结果插入到模板中的相应位置上。

• {% ... %}

标签语法（Tag），标签用来表示一些具有特殊功能的语法，比如用来实现判断的if和循环的for。

• {# ... #}

注释语法，不会出现在解析后的结果中

除此之外还有一个名为Filter的概念，它的语法是这样的：{{ "stencil"|uppercase }}。符号|左边是输入的变量，右边就是一个Filter，这里输出了字符串的大写形式. String Filter

StencilSwiftKit

• Documentation

Projects that use Stencil

• Soucery
• SwiftGen
• Weaver

VSCode - Stencil/YAML 插件

YAML

YAML: YAML Ain't Markup Language

• ORG
• 1.2

YamlSwift

解析一串YAML文档( 或者JSON文档) 并返回一个表示该字符串的Yaml enum 值

• GitHub

Apple/SwiftSyntax

It allows for Swift tools to parse, inspect, generate, and transform Swift source code.

• SwiftSyntax

SwiftGen/StencilSwiftKit

• Documents

Others

• SwiftGen
• SwiftLint
• URLNavigator
• XCConfig
• SwiftMonkey(Paws) (Test)
• DoraemonKit
• SwifterSwift(more than 500 native Swift extensions)
• MonkeyKing(Handle Open URL)