Split yunq compliation to library and use it in build process.

rust/lib/yellowstone/build.rs

@@ -1,18 +1,14 @@
-use std::process::Command;
+use std::fs;
 
 fn main() {
+    let input_file = "../../../sys/yellowstone/lib/yellowstone/yellowstone.yunq";
+
+    println!("cargo::rerun-if-changed={input_file}");
+
+    let input = fs::read_to_string(input_file).expect("Failed to read input file");
+
+    let code = yunqc::codegen(&input).expect("Failed to generate yunq code.");
+
     let out = std::env::var("OUT_DIR").unwrap() + "/yunq.rs";
-
-    let status = Command::new("cargo")
-        .current_dir("../../../yunq/rust")
-        .arg("run")
-        .arg("--")
-        .arg("--input-path")
-        .arg("../../sys/yellowstone/lib/yellowstone/yellowstone.yunq")
-        .arg("--output-path")
-        .arg(out)
-        .status()
-        .expect("Failed to start execution");
-
-    assert!(status.success());
+    fs::write(out, code).expect("Failed to write generated code.");
 }