reorganized the directories

projects/pattern_syntax_demo/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "pattern_syntax_demo"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

projects/pattern_syntax_demo/src/main.rs

@@ -0,0 +1,17 @@
+fn main() {
+    enum Message {
+        Hello { id: u32 },
+    }
+
+    let msg = Message::Hello { id: 5 };
+
+    match msg {
+        Message::Hello {
+            id: id_variable @ 3..=7,
+        } => println! ("找到位于范围内的一个 id: {}", id_variable),
+        Message::Hello { id: 10..=12 } => {
+            println! ("找到位于另一范围的一个 {}", id);
+        },
+        Message::Hello { id } => println! ("找到别的一个 id: {}", id),
+    }
+}