Initialize Aster project with basic structure, including Cargo configuration, lexer, parser, interpreter, and AST definitions. Add a sample script and README documentation. Implement basic error handling and environment management for variable storage.

src/main.rs

@@ -0,0 +1,53 @@
+mod lexer;
+mod ast;
+mod parser;
+mod interpreter;
+mod error;
+
+use lexer::Lexer;
+use parser::Parser;
+use interpreter::Interpreter;
+use std::env;
+use std::fs;
+use std::io::{self, Read};
+
+fn main() {
+    let src = match env::args().len() {
+        1 => {
+            // 无参数：从 stdin 读取
+            let mut buf = String::new();
+            if let Err(e) = io::stdin().read_to_string(&mut buf) {
+                eprintln!("Failed to read stdin: {}", e);
+                std::process::exit(1);
+            }
+            buf
+        }
+        2 => {
+            // 一个参数：作为文件路径
+            let path = env::args().nth(1).unwrap();
+            match fs::read_to_string(&path) {
+                Ok(s) => s,
+                Err(e) => {
+                    eprintln!("Failed to read file '{}': {}", path, e);
+                    std::process::exit(1);
+                }
+            }
+        }
+        _ => {
+            eprintln!("Usage: aster [script_file]");
+            eprintln!("  aster          - run from stdin");
+            eprintln!("  aster <file>   - run script file");
+            std::process::exit(1);
+        }
+    };
+
+    let tokens = Lexer::new(&src).tokenize();
+    let mut parser = Parser::new(tokens);
+    let stmts = parser.parse();
+
+    let mut interpreter = Interpreter::new();
+    if let Err(e) = interpreter.interpret(stmts) {
+        eprintln!("{}", e);
+        std::process::exit(1);
+    }
+}