Add next_instruction helper and bump version

src/machine.rs

@@ -3,7 +3,7 @@ use std::sync::{Mutex, Arc};
 
 use Result;
 use block::Block;
-use ops::Operation;
+use ops::{Operation, Args, num_to_op};
 use ijvmreader::IJVMReader;
 use binread::{BinRead, BinReadable};
 use frame::Frame;
@@ -135,6 +135,45 @@ impl Machine {
         self.block[self.get_program_counter()]
     }
 
+    pub fn next_instruction(&mut self) -> Result<(String, Vec<i32>)> {
+        let checkpoint = self.block.cur();
+
+        let mut opcode = self.block.read_u8()?;
+        let mut params = Vec::new();
+        let mut wide = false;
+
+        // WIDE
+        if opcode == 0xC4 {
+            wide = true;
+            opcode = self.block.read_u8()?;
+        }
+
+        let (name, args) = match num_to_op(opcode) {
+            Operation::Invalid(_) => return Err("Invalid  operation"),
+            Operation::Op(name, _, args) => (name, args),
+        };
+
+        for arg in &args {
+            let v = match arg {
+                Args::Byte => self.block.read_i8()? as i32,
+                Args::Short => self.block.read_i16()? as i32,
+                Args::Var => {
+                    if wide {
+                        self.block.read_u16()? as i32
+                    } else {
+                        self.block.read_u8()? as i32
+                    }
+                },
+                Args::Label => self.block.read_i16()? as i32,
+                Args::Constant => self.block.read_u16()? as i32,
+            };
+            params.push(v);
+        }
+
+        self.block.seek(checkpoint).unwrap();
+        Ok((name.to_string(), params))
+    }
+
 //    pub fn get_stack_pointer(&self) -> usize {
 //        return self.frame.last().unwrap().stack.len();
 //    }