学习Source Generators之IncrementalValueProvider

前面我们使用了IIncrementalGenerator来生成代码，接下来我们来详细相识下IIncrementalGenerator的核心部分IncrementalValueProvider。
先容

IncrementalValueProvider是基于管道的模式，将我们需要的数据进行处理转换后传递给SourceOutput。
现在官方提供可用的Providers有如下几种：

• CompilationProvider
  
• AdditionalTextsProvider
  
• AnalyzerConfigOptionsProvider
  
• MetadataReferencesProvider
  
• ParseOptionsProvider
  

实操

接下来我们来使用AdditionalTextsProvider来学习IncrementalValueProvider的运行方式。
创建项目

首先创建LearnIncrementalValueProvider的控制台程序和LearnIncrementalValueProvider.Analysis的netstandard2.0类库两个项目。

按照前面HelloWorld项目的项目设置进行设置和引用。
添加LearnIncrementalValueProviderGenerator

在LearnIncrementalValueProvider.Analysis中添加LearnIncrementalValueProviderGenerator继承并实现IIncrementalGenerator接口。

1. using Microsoft.CodeAnalysis;
2. using System;
3. using System.Diagnostics;
5. namespace LearnIncrementalValueProvider.Analysis
6. {
7. <ItemGroup>
8.   <AdditionalFiles Include="Files/*" />
9. </ItemGroup><ItemGroup>
10.   <AdditionalFiles Include="Files/*" />
11. </ItemGroup>[Generator]
12. <ItemGroup>
13.   <AdditionalFiles Include="Files/*" />
14. </ItemGroup><ItemGroup>
15.   <AdditionalFiles Include="Files/*" />
16. </ItemGroup>public class LearnIncrementalValueProviderGenerator : IIncrementalGenerator
17. <ItemGroup>
18.   <AdditionalFiles Include="Files/*" />
19. </ItemGroup><ItemGroup>
20.   <AdditionalFiles Include="Files/*" />
21. </ItemGroup>{
22. <ItemGroup>
23.   <AdditionalFiles Include="Files/*" />
24. </ItemGroup><ItemGroup>
25.   <AdditionalFiles Include="Files/*" />
26. </ItemGroup><ItemGroup>
27.   <AdditionalFiles Include="Files/*" />
28. </ItemGroup><ItemGroup>
29.   <AdditionalFiles Include="Files/*" />
30. </ItemGroup>public void Initialize(IncrementalGeneratorInitializationContext context)
31. <ItemGroup>
32.   <AdditionalFiles Include="Files/*" />
33. </ItemGroup><ItemGroup>
34.   <AdditionalFiles Include="Files/*" />
35. </ItemGroup><ItemGroup>
36.   <AdditionalFiles Include="Files/*" />
37. </ItemGroup><ItemGroup>
38.   <AdditionalFiles Include="Files/*" />
39. </ItemGroup>{
40. <ItemGroup>
41.   <AdditionalFiles Include="Files/*" />
42. </ItemGroup><ItemGroup>
43.   <AdditionalFiles Include="Files/*" />
44. </ItemGroup><ItemGroup>
45.   <AdditionalFiles Include="Files/*" />
46. </ItemGroup><ItemGroup>
47.   <AdditionalFiles Include="Files/*" />
48. </ItemGroup><ItemGroup>
49.   <AdditionalFiles Include="Files/*" />
50. </ItemGroup><ItemGroup>
51.   <AdditionalFiles Include="Files/*" />
52. </ItemGroup>Debugger.Launch();
53. <ItemGroup>
54.   <AdditionalFiles Include="Files/*" />
55. </ItemGroup><ItemGroup>
56.   <AdditionalFiles Include="Files/*" />
57. </ItemGroup><ItemGroup>
58.   <AdditionalFiles Include="Files/*" />
59. </ItemGroup><ItemGroup>
60.   <AdditionalFiles Include="Files/*" />
61. </ItemGroup><ItemGroup>
62.   <AdditionalFiles Include="Files/*" />
63. </ItemGroup><ItemGroup>
64.   <AdditionalFiles Include="Files/*" />
65. </ItemGroup>var additionalTextsProvider = context.AdditionalTextsProvider;
67. <ItemGroup>
68.   <AdditionalFiles Include="Files/*" />
69. </ItemGroup><ItemGroup>
70.   <AdditionalFiles Include="Files/*" />
71. </ItemGroup><ItemGroup>
72.   <AdditionalFiles Include="Files/*" />
73. </ItemGroup><ItemGroup>
74.   <AdditionalFiles Include="Files/*" />
75. </ItemGroup><ItemGroup>
76.   <AdditionalFiles Include="Files/*" />
77. </ItemGroup><ItemGroup>
78.   <AdditionalFiles Include="Files/*" />
79. </ItemGroup>context.RegisterSourceOutput(additionalTextsProvider, (ctx, additionalTexts) =>
80. <ItemGroup>
81.   <AdditionalFiles Include="Files/*" />
82. </ItemGroup><ItemGroup>
83.   <AdditionalFiles Include="Files/*" />
84. </ItemGroup><ItemGroup>
85.   <AdditionalFiles Include="Files/*" />
86. </ItemGroup><ItemGroup>
87.   <AdditionalFiles Include="Files/*" />
88. </ItemGroup><ItemGroup>
89.   <AdditionalFiles Include="Files/*" />
90. </ItemGroup><ItemGroup>
91.   <AdditionalFiles Include="Files/*" />
92. </ItemGroup><ItemGroup>
93.   <AdditionalFiles Include="Files/*" />
94. </ItemGroup><ItemGroup>
95.   <AdditionalFiles Include="Files/*" />
96. </ItemGroup><ItemGroup>
97.   <AdditionalFiles Include="Files/*" />
98. </ItemGroup><ItemGroup>
99.   <AdditionalFiles Include="Files/*" />
100. </ItemGroup><ItemGroup>
101.   <AdditionalFiles Include="Files/*" />
102. </ItemGroup><ItemGroup>
103.   <AdditionalFiles Include="Files/*" />
104. </ItemGroup><ItemGroup>
105.   <AdditionalFiles Include="Files/*" />
106. </ItemGroup><ItemGroup>
107.   <AdditionalFiles Include="Files/*" />
108. </ItemGroup><ItemGroup>
109.   <AdditionalFiles Include="Files/*" />
110. </ItemGroup><ItemGroup>
111.   <AdditionalFiles Include="Files/*" />
112. </ItemGroup><ItemGroup>
113.   <AdditionalFiles Include="Files/*" />
114. </ItemGroup><ItemGroup>
115.   <AdditionalFiles Include="Files/*" />
116. </ItemGroup><ItemGroup>
117.   <AdditionalFiles Include="Files/*" />
118. </ItemGroup><ItemGroup>
119.   <AdditionalFiles Include="Files/*" />
120. </ItemGroup> {
121. <ItemGroup>
122.   <AdditionalFiles Include="Files/*" />
123. </ItemGroup><ItemGroup>
124.   <AdditionalFiles Include="Files/*" />
125. </ItemGroup><ItemGroup>
126.   <AdditionalFiles Include="Files/*" />
127. </ItemGroup><ItemGroup>
128.   <AdditionalFiles Include="Files/*" />
129. </ItemGroup><ItemGroup>
130.   <AdditionalFiles Include="Files/*" />
131. </ItemGroup><ItemGroup>
132.   <AdditionalFiles Include="Files/*" />
133. </ItemGroup><ItemGroup>
134.   <AdditionalFiles Include="Files/*" />
135. </ItemGroup><ItemGroup>
136.   <AdditionalFiles Include="Files/*" />
137. </ItemGroup><ItemGroup>
138.   <AdditionalFiles Include="Files/*" />
139. </ItemGroup><ItemGroup>
140.   <AdditionalFiles Include="Files/*" />
141. </ItemGroup><ItemGroup>
142.   <AdditionalFiles Include="Files/*" />
143. </ItemGroup><ItemGroup>
144.   <AdditionalFiles Include="Files/*" />
145. </ItemGroup><ItemGroup>
146.   <AdditionalFiles Include="Files/*" />
147. </ItemGroup><ItemGroup>
148.   <AdditionalFiles Include="Files/*" />
149. </ItemGroup><ItemGroup>
150.   <AdditionalFiles Include="Files/*" />
151. </ItemGroup><ItemGroup>
152.   <AdditionalFiles Include="Files/*" />
153. </ItemGroup><ItemGroup>
154.   <AdditionalFiles Include="Files/*" />
155. </ItemGroup><ItemGroup>
156.   <AdditionalFiles Include="Files/*" />
157. </ItemGroup><ItemGroup>
158.   <AdditionalFiles Include="Files/*" />
159. </ItemGroup><ItemGroup>
160.   <AdditionalFiles Include="Files/*" />
161. </ItemGroup><ItemGroup>
162.   <AdditionalFiles Include="Files/*" />
163. </ItemGroup><ItemGroup>
164.   <AdditionalFiles Include="Files/*" />
165. </ItemGroup> var path = additionalTexts.Path;
166. <ItemGroup>
167.   <AdditionalFiles Include="Files/*" />
168. </ItemGroup><ItemGroup>
169.   <AdditionalFiles Include="Files/*" />
170. </ItemGroup><ItemGroup>
171.   <AdditionalFiles Include="Files/*" />
172. </ItemGroup><ItemGroup>
173.   <AdditionalFiles Include="Files/*" />
174. </ItemGroup><ItemGroup>
175.   <AdditionalFiles Include="Files/*" />
176. </ItemGroup><ItemGroup>
177.   <AdditionalFiles Include="Files/*" />
178. </ItemGroup><ItemGroup>
179.   <AdditionalFiles Include="Files/*" />
180. </ItemGroup><ItemGroup>
181.   <AdditionalFiles Include="Files/*" />
182. </ItemGroup><ItemGroup>
183.   <AdditionalFiles Include="Files/*" />
184. </ItemGroup><ItemGroup>
185.   <AdditionalFiles Include="Files/*" />
186. </ItemGroup><ItemGroup>
187.   <AdditionalFiles Include="Files/*" />
188. </ItemGroup><ItemGroup>
189.   <AdditionalFiles Include="Files/*" />
190. </ItemGroup><ItemGroup>
191.   <AdditionalFiles Include="Files/*" />
192. </ItemGroup><ItemGroup>
193.   <AdditionalFiles Include="Files/*" />
194. </ItemGroup><ItemGroup>
195.   <AdditionalFiles Include="Files/*" />
196. </ItemGroup><ItemGroup>
197.   <AdditionalFiles Include="Files/*" />
198. </ItemGroup><ItemGroup>
199.   <AdditionalFiles Include="Files/*" />
200. </ItemGroup><ItemGroup>
201.   <AdditionalFiles Include="Files/*" />
202. </ItemGroup><ItemGroup>
203.   <AdditionalFiles Include="Files/*" />
204. </ItemGroup><ItemGroup>
205.   <AdditionalFiles Include="Files/*" />
206. </ItemGroup><ItemGroup>
207.   <AdditionalFiles Include="Files/*" />
208. </ItemGroup><ItemGroup>
209.   <AdditionalFiles Include="Files/*" />
210. </ItemGroup> var text = additionalTexts.GetText(ctx.CancellationToken);
211. <ItemGroup>
212.   <AdditionalFiles Include="Files/*" />
213. </ItemGroup><ItemGroup>
214.   <AdditionalFiles Include="Files/*" />
215. </ItemGroup><ItemGroup>
216.   <AdditionalFiles Include="Files/*" />
217. </ItemGroup><ItemGroup>
218.   <AdditionalFiles Include="Files/*" />
219. </ItemGroup><ItemGroup>
220.   <AdditionalFiles Include="Files/*" />
221. </ItemGroup><ItemGroup>
222.   <AdditionalFiles Include="Files/*" />
223. </ItemGroup><ItemGroup>
224.   <AdditionalFiles Include="Files/*" />
225. </ItemGroup><ItemGroup>
226.   <AdditionalFiles Include="Files/*" />
227. </ItemGroup><ItemGroup>
228.   <AdditionalFiles Include="Files/*" />
229. </ItemGroup><ItemGroup>
230.   <AdditionalFiles Include="Files/*" />
231. </ItemGroup><ItemGroup>
232.   <AdditionalFiles Include="Files/*" />
233. </ItemGroup><ItemGroup>
234.   <AdditionalFiles Include="Files/*" />
235. </ItemGroup><ItemGroup>
236.   <AdditionalFiles Include="Files/*" />
237. </ItemGroup><ItemGroup>
238.   <AdditionalFiles Include="Files/*" />
239. </ItemGroup><ItemGroup>
240.   <AdditionalFiles Include="Files/*" />
241. </ItemGroup><ItemGroup>
242.   <AdditionalFiles Include="Files/*" />
243. </ItemGroup><ItemGroup>
244.   <AdditionalFiles Include="Files/*" />
245. </ItemGroup><ItemGroup>
246.   <AdditionalFiles Include="Files/*" />
247. </ItemGroup><ItemGroup>
248.   <AdditionalFiles Include="Files/*" />
249. </ItemGroup><ItemGroup>
250.   <AdditionalFiles Include="Files/*" />
251. </ItemGroup> });
252. <ItemGroup>
253.   <AdditionalFiles Include="Files/*" />
254. </ItemGroup><ItemGroup>
255.   <AdditionalFiles Include="Files/*" />
256. </ItemGroup><ItemGroup>
257.   <AdditionalFiles Include="Files/*" />
258. </ItemGroup><ItemGroup>
259.   <AdditionalFiles Include="Files/*" />
260. </ItemGroup>}
261. <ItemGroup>
262.   <AdditionalFiles Include="Files/*" />
263. </ItemGroup><ItemGroup>
264.   <AdditionalFiles Include="Files/*" />
265. </ItemGroup>}
266. }

复制代码

在实现的代码中，获取到AdditionalTextsProvider，并直接传递给RegisterSourceOutput，并在委托方法中直接获取AdditionalTextsProvider的文件路径以及文本内容。
在方法中参加Debugger.Launch();方便调试。
添加文件和调试

在控制台程序中，添加一个Files目次。往里面塞入一个swagger.json文件。
此时直接调试会发现，断点并不会进入到RegisterSourceOutput的委托中。

这是因为AdditionalTextsProvider并没有找到任何需要加载的文件。
我们需要在控制台程序的项目文件中添加AdditionalFiles，指定需要监听的文件。

1. <ItemGroup>
2.   <AdditionalFiles Include="Files/*" />
3. </ItemGroup>

复制代码

添加AdditionalFiles后，在调试一次。

可以看到断点成功进来了。并且可以看到获取的文件路径以及文件的文本内容。

多个文件

在Files目次中添加一个txt文件。并写入文本HelloWorld

然后再调试一次。可以发现，每一个文件都会单独执行一次委托的方法。

过滤文件

当我们只需要其中一种类型的文件的时间，我们可以通过Where来进行过滤筛选。

通过Debugger.Log可以发现，只输出了json的文件路径。

处理数据

可以使用Select来处理我们的数据，比如这里我只获取文件名称。通过Debugger.Log可以看到输出了两个文件名称。

集合

假如不想多次处理文件的话，可以使用Collect方法，直接把多个文件归并在一起。

这里可以看到，使用Collect，2个文件可以同时处理。
组合多个IncrementalValueProvider

除了对单个IncrementalValueProvider进行处理外，我们还可以组合不同的IncrementalValueProvider。
比如将CompilationProvider和AdditionalTextsProvider组合起来。
使用Combine方法。

可以看到 paris的Right和Left分别是CompilationProvider和AdditionalTextsProvider两种类型。
结语

以上就是IncrementalValueProvider比较常用的方式。通过这些操作可以机动的实现我们的代码生成逻辑。
当然还有其他的IncrementalValueProvider，这里就不都写出来了。其他的可以自己实操玩起来~
本文代码堆栈地址https://github.com/fanslead/Learn-SourceGenerator

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