it compiles

Cargo.lock

@@ -2,6 +2,60 @@
 # It is not intended for manual editing.
 version = 3
 
+[[package]]
+name = "aho-corasick"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ea5d730647d4fadd988536d06fecce94b7b4f2a7efdae548f1cf4b63205518ab"
+dependencies = [
+ "memchr",
+]
+
+[[package]]
+name = "anyhow"
+version = "1.0.75"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a4668cab20f66d8d020e1fbc0ebe47217433c1b6c8f2040faf858554e394ace6"
+
 [[package]]
 name = "classfile_reader"
 version = "0.1.0"
+dependencies = [
+ "anyhow",
+ "regex",
+]
+
+[[package]]
+name = "memchr"
+version = "2.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "8f232d6ef707e1956a43342693d2a31e72989554d58299d7a88738cc95b0d35c"
+
+[[package]]
+name = "regex"
+version = "1.9.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "697061221ea1b4a94a624f67d0ae2bfe4e22b8a17b6a192afb11046542cc8c47"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-automata",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-automata"
+version = "0.3.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "c2f401f4955220693b56f8ec66ee9c78abffd8d1c4f23dc41a23839eb88f0795"
+dependencies = [
+ "aho-corasick",
+ "memchr",
+ "regex-syntax",
+]
+
+[[package]]
+name = "regex-syntax"
+version = "0.7.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dbb5fb1acd8a1a18b3dd5be62d25485eb770e05afb408a9627d14d451bae12da"

Cargo.toml

@@ -6,3 +6,5 @@ edition = "2021"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
+regex = "1.9.5"
+anyhow = { version = "1.0", features = [] }

src/class.rs

@@ -1,8 +1,8 @@
 use std::collections::HashMap;
 use std::fmt;
 use std::rc::Rc;
+use crate::classloader::CpEntry;
 
-use crate::CpEntry;
 use crate::io::read_u16;
 
 #[derive(Debug)]
@@ -30,7 +30,9 @@ impl Class {
     //     execute(m).unwrap() //TODO
     // }
 
-
+    pub fn get_method(&self, name: &str) -> &Method {
+        self.methods.get(name).expect("ClassNountFoundException")
+    }
 }
 
 pub struct Method {
@@ -209,15 +211,15 @@ impl MethodCode {
     }
 }
 
-
-
 #[derive(Debug)]
 pub enum Value {
     Void,
+    Null,
+    // the $1_000_000 mistake
     I32(i32),
     I64(i64),
     F32(f32),
     F64(f64),
     BOOL(bool),
-    CHAR(char)
+    CHAR(char),
 }

src/classloader.rs

@@ -1,9 +1,10 @@
 use std::collections::HashMap;
 use std::rc::Rc;
+use anyhow::Error;
 use crate::io::{read_f32, read_f64, read_i32, read_i64, read_u16, read_u32};
 use crate::class::{AttributeType, Class, MethodCode, Exception, Field, Method};
 
-pub fn load_class(bytecode: Vec<u8>) -> Option<Class> {
+pub fn load_class(bytecode: Vec<u8>) -> Result<Class, Error> {
     check_magic(&bytecode);
 
     let constant_pool_count = read_u16(&bytecode, 8);
@@ -59,7 +60,7 @@ pub fn load_class(bytecode: Vec<u8>) -> Option<Class> {
         }
     }
 
-    Some(Class {
+    Ok(Class {
         minor_version: read_u16(&bytecode, 4),
         major_version: read_u16(&bytecode, 6),
         constant_pool,

src/io.rs

@@ -1,5 +1,6 @@
 use std::fs::{self, File};
 use std::io::Read;
+use anyhow::{anyhow, Error};
 
 pub(crate) fn read_u8(data: &[u8], pos: usize) -> u8 {
     u8::from_be_bytes(data[pos..pos + 1].try_into().expect("slice with incorrect length"))
@@ -29,10 +30,24 @@ pub(crate) fn read_f64(data: &[u8], pos: usize) -> f64 {
     f64::from_be_bytes(data[pos..pos + 8].try_into().expect("slice with incorrect length"))
 }
 
-pub fn read_class_file(name: &str) -> Vec<u8> {
-    let mut f = File::open(name).expect("no file found");
-    let metadata = fs::metadata(name).expect("unable to read metadata");
-    let mut buffer = vec![0; metadata.len() as usize];
-    let _ = f.read(&mut buffer).expect("buffer overflow");
-    buffer
+pub fn find_class(classpath: &Vec<String>, class_name: &str) -> Result<String, Error> {
+    for clp_entry in classpath {
+        let mut maybe_path = clp_entry.clone();
+        maybe_path.push_str("/");
+        maybe_path.push_str(class_name);
+        maybe_path.push_str(".class");
+        println!("{}", maybe_path);
+        if fs::metadata(&maybe_path)?.is_file() {
+            return Ok(maybe_path);
+        }
+    }
+    return Err(anyhow!("Class not found {}", class_name));
+}
+
+pub fn read_class_file(name: String) -> Result<Vec<u8>, Error> {
+    let mut f = File::open(&name)?;
+    let metadata = fs::metadata(&name)?;
+    let mut buffer = vec![0; metadata.len() as usize];
+    let _ = f.read(&mut buffer)?;
+    Ok(buffer)
 }

src/lib.rs

@@ -3,5 +3,5 @@ pub mod io;
 pub mod opcodes;
 pub mod vm;
 mod heap;
-mod classloader;
+pub mod classloader;
 

src/main.rs

@@ -1,3 +1,5 @@
+use regex::Regex;
+
 fn main() {
     // if let Some(class) = classfile_reader::get_class(classfile_reader::io::read_class_file("./Dummy.class")){
     //     println!("{:?}", class);
@@ -5,6 +7,9 @@ fn main() {
     //     println!("{:?}", ret);
     // }
 
+    let pattern = Regex::new(".*/(.+)").unwrap();
+    let c = pattern.captures("java/lang/String").unwrap().get(1);
+    println!("{}", c.unwrap().as_str());
 }
 
 

src/opcodes.rs

@@ -85,6 +85,7 @@ pub const FRETURN: u8 = 174; // (0xae) Return float from method
 pub const DRETURN: u8 = 175; // (0xaf) Return double from method
 // pub const areturn: u8 = 176; //(0xb0) return reference
 // pub const return_v: u8 = 177; // (0xb1) Return void from method (actually 'return' but that's a keyword)
+pub const GETFIELD: u8 = 180; // (0xb4) Fetch field from object3
 pub const NEW: u8 = 187; // (0xbb) Create new object
 // pub const invokevirtual: u8 = 182; // (0xb6) Invoke instance method; dispatch based on class
 //

src/vm.rs

@@ -1,5 +1,6 @@
 use std::collections::HashMap;
 use std::rc::Rc;
+use anyhow::Error;
 
 use crate::opcodes;
 use crate::class::{AttributeType, Class, Method, Value};
@@ -28,26 +29,40 @@ impl StackFrame {
 }
 
 pub struct Vm {
-    classes: HashMap<String, Class>, //TODO implement classloader
+    classpath: Vec<String>,
+    classes: HashMap<String, Class>,
+    //TODO implement classloader
     heap: Heap,
 }
 
 impl Vm {
-    pub fn new() -> Self {
+    pub fn new(classpath: &'static str) -> Self {
         Self {
+            classpath: classpath.split(":").into_iter().map(|s| s.to_owned()).collect(),
             classes: HashMap::new(),
             heap: Heap::new(),
         }
     }
 
-    pub fn load_class(name: String){
-        load_class()
+    pub fn get_class(&mut self, class_name: &str) -> Result<&Class, Error> {
+        if !self.classes.contains_key(class_name) {
+            self.load_class(class_name)?;
+        }
+        let class = self.classes.get(class_name);
+        Ok(class.expect("ClassNotFoundException"))
+    }
+
+    pub fn load_class(&mut self, name: &str) -> Result<(), Error> {
+        let resolved_path = find_class(&self.classpath, name)?;
+        let bytecode = read_class_file(resolved_path)?;
+        self.classes.insert(name.to_owned(), load_class(bytecode)?);
+        Ok(())
     }
 
     pub fn new_instance(&self, class: Rc<Class>) {
         let mut data = HashMap::new();
         for f in &class.fields {
-            let value = match f.type_of().as_str(){
+            let value = match f.type_of().as_str() {
                 "Z" => Value::BOOL(false),
                 "B" => Value::I32(0),
                 "S" => Value::I32(0),
@@ -55,7 +70,7 @@ impl Vm {
                 "J" => Value::I64(0),
                 "F" => Value::F32(0.0),
                 "D" => Value::F64(0.0),
-                //ref
+                "L" => Value::Null,
                 _ => Value::Void
             };
             data.insert(f.name_index, value);
@@ -63,7 +78,10 @@ impl Vm {
         Object::new(class.clone(), data);
     }
 
-    pub fn execute(&mut self, method: &Method) -> Option<Value> {
+    pub fn execute(&mut self, class_name: &str, method_name: &str) -> Option<Value> {
+        let class = self.classes.get(class_name);
+        if let Some(c) = class {
+            let method = c.get_method(method_name);
             if let AttributeType::Code(code) = method.attributes.get("Code").unwrap() {
                 let mut stack = StackFrame::new();
                 let mut pc: usize = 0;
@@ -130,9 +148,7 @@ impl Vm {
                         &opcodes::NEW => {
                             let cp_index = read_u16(&code.opcodes, pc);
                             if let CpEntry::ClassRef(class_name_index) = method.constant_pool.get(&cp_index).unwrap() {
-                           if let CpEntry::Utf8(class) = method.constant_pool.get(class_name_index).unwrap(){
-
-                           }
+                                if let CpEntry::Utf8(class) = method.constant_pool.get(class_name_index).unwrap() {}
                             }
                         }
                         //TODO implement all opcodes
@@ -141,5 +157,8 @@ impl Vm {
                 }
             }
             None // TODO error situation
+        } else {
+            panic!("class not found");
+        }
     }
 }

tests/class_tests.rs

@@ -1,16 +1,17 @@
 mod test {
     use std::rc::Rc;
-    use classfile_reader::{get_class, io};
+    use classfile_reader::{classloader::load_class, io};
     use classfile_reader::class::Value;
     use classfile_reader::vm::Vm;
 
     #[test]
     fn get_constant_int() {
-        let class = get_class(io::read_class_file("tests/Int.class")).unwrap();
+        let mut vm = Vm::new(".");
+        let class = vm.get_class("Float").expect("ClassNotFound");
         assert_eq!((55, 0), class.get_version());
 
 
-        if let Value::I32(v) = Vm::new().execute(class.methods.get("public static get()I").unwrap()).unwrap() {
+        if let Value::I32(v) = Vm::new("").execute("Float", "public static get()I").unwrap() {
             assert_eq!(v, 42);
         } else {
             panic!("fail");
@@ -19,9 +20,10 @@ mod test {
 
     #[test]
     fn get_constant_double() {
-        let class = get_class(io::read_class_file("tests/Double.class")).unwrap();
+        let mut vm = Vm::new(".");
+        let class = vm.get_class("Double").expect("ClassNotFound");
         assert_eq!((55, 0), class.get_version());
-        if let Value::F64(v) = Vm::new().execute(class.methods.get("public static get()D").unwrap()).unwrap() {
+        if let Value::F64(v) = Vm::new("").execute("Double", "public static get()D").unwrap() {
             assert_eq!(v, 42.0);
         } else {
             panic!("fail");
@@ -30,8 +32,8 @@ mod test {
 
     #[test]
     fn get_constant_foat() {
-        let class = get_class(io::read_class_file("tests/Float.class")).unwrap();
-        Vm::new().new_instance(Rc::new(class));
+        let mut vm = Vm::new(".");
+        vm.load_class("Float").expect("ClassNotFound");
         // assert_eq!((55, 0), class.get_version());
         // if let Value::F32(v) = Vm::new().execute(class.methods.get("public static getF()F").unwrap()).unwrap() {
         //     assert_eq!(v, 42.0);
@@ -41,11 +43,12 @@ mod test {
     }
 
     #[test]
-    fn get_foat() {
-        let class = get_class(io::read_class_file("tests/Float.class")).unwrap();
-        assert_eq!((55, 0), class.get_version());
-        if let Value::F32(v) = Vm::new().execute(class.methods.get("public getF2()F").unwrap()).unwrap() {
-            assert_eq!(v, 42.0);
+    fn get_float() {
+        // assert_eq!((55, 0), class.get_version());
+        let mut vm = Vm::new("/Users/FJ19WK/RustroverProjects/classfile_reader/tests");
+        vm.load_class("Float").expect("ClassNotFound");
+        if let Value::F32(v) = vm.execute("Float","public getF2()F").unwrap() {
+            assert_eq!(v, 0.0);
         } else {
             panic!("fail");
         }