Allow creation of a machine from string

src/ijvmreader.rs

@@ -20,6 +20,13 @@ impl IJVMReader {
             source: abc
         })
     }
+
+    pub fn new_from_string(source: String) -> IJVMReader {
+        IJVMReader {
+            pointer: 0,
+            source: source.into_bytes(),
+        }
+    }
 }
 
 impl BinReadable for IJVMReader {

src/machine.rs

@@ -52,8 +52,7 @@ impl Machine {
         }
     }
 
-    pub fn new_from_file(file: &str) -> Result<Machine> {
+    pub fn new_from_reader(mut reader: IJVMReader) -> Result<Machine> {
-        let mut reader = IJVMReader::new(file).unwrap();
         let magic = reader.read_u32()?;
         if magic != MAGIC_HEADER {
             return Err("Invalid magic header");
@@ -72,6 +71,16 @@ impl Machine {
         Ok(Machine::new(pool, text))
     }
 
+    pub fn new_from_file(file: &str) -> Result<Machine> {
+        let reader = IJVMReader::new(file).unwrap();
+        Machine::new_from_reader(reader)
+    }
+
+    pub fn new_from_string(source: String) -> Result<Machine> {
+        let reader = IJVMReader::new_from_string(source);
+        Machine::new_from_reader(reader)
+    }
+
     pub fn step(&mut self) -> Result<()> {
         match self.block.read_op() {
             Ok(Operation::Op(a, func)) => {