not-python-rust/src/disassemble.rs

use crate::obj::{ObjP, UserFunctionInst};
use crate::vm::{Chunk, JumpOpArg, Op};

type Row = (String, String, &'static str, String, String);

fn disassemble_chunk(chunk: &Chunk, constants: &Vec<ObjP>, globals: &Vec<String>) {
    let mut rows: Vec<Row> = vec![(
        "ADDR".into(),
        "LINE".into(),
        "OP".into(),
        "ARG".into(),
        "INFO".into(),
    )];

    for (index, op) in chunk.code.iter().enumerate() {
        let (start_line, end_line) = chunk.lines[index];

        let addr: String = index.to_string();
        let line = if start_line == end_line {
            start_line.to_string()
        } else {
            format!("{start_line}-{end_line}")
        };
        let op_str: &'static str;
        let arg: String;
        let info: String;

        match op {
            Op::Pop => {
                op_str = "POP";
                arg = String::new();
                info = String::new();
            }
            Op::PushConstant(constant_id) => {
                op_str = "PUSH_CONSTANT";
                arg = format!("{}", &constants[*constant_id as usize]);
                info = format!("(constant ID {constant_id})");
            }
            Op::GetLocal(local_id) => {
                op_str = "GET_LOCAL";
                let local = &chunk.locals[*local_id as usize];
                arg = local.name.to_string();
                info = format!("(slot {}, local ID {})", local.slot, local.index);
            }
            Op::SetLocal(local_id) => {
                op_str = "SET_LOCAL";
                let local = &chunk.locals[*local_id as usize];
                arg = local.name.to_string();
                info = format!("(slot {}, local ID {})", local.slot, local.index);
            }
            Op::GetGlobal(global_id) => {
                op_str = "GET_GLOBAL";
                arg = globals[*global_id as usize].clone();
                info = format!("(global ID {global_id})");
            }
            Op::SetGlobal(global_id) => {
                op_str = "SET_GLOBAL";
                arg = globals[*global_id as usize].clone();
                info = format!("(global ID {global_id})");
            }
            Op::GetAttr(constant_id) => {
                op_str = "GET_ATTR";
                arg = format!("{}", &constants[*constant_id as usize]);
                info = format!("(constant ID {constant_id})");
            }
            Op::SetAttr(constant_id) => {
                op_str = "SET_ATTR";
                arg = format!("{}", &constants[*constant_id as usize]);
                info = format!("(constant ID {constant_id})");
            }
            Op::Jump(jump_offset) => {
                op_str = "JUMP";
                arg = format!("{}", jump_offset);
                info = format!("(address {})", (index as JumpOpArg) + *jump_offset);
            }
            Op::JumpFalse(jump_offset) => {
                op_str = "JUMP_FALSE";
                arg = format!("{}", jump_offset);
                info = format!("(address {})", (index as JumpOpArg) + *jump_offset);
            }
            Op::JumpTrue(jump_offset) => {
                op_str = "JUMP_FALSE";
                arg = format!("{}", jump_offset);
                info = format!("(address {})", (index as JumpOpArg) + *jump_offset);
            }
            Op::Call(argc) => {
                op_str = "CALL";
                arg = format!("argc {argc}");
                info = String::new();
            }
            Op::Return => {
                op_str = "RETURN";
                arg = String::new();
                info = String::new();
            }
            Op::CloseOver { depth, slot } => {
                op_str = "CLOSE_OVER";
                arg = format!("{depth}");
                info = format!("slot {slot} (name unknown)");
            }
            Op::Halt => {
                op_str = "HALT";
                arg = String::new();
                info = String::new();
            }
        }

        rows.push((addr, line, op_str, arg, info));
    }

    display_rows(&rows);
}

fn display_rows(rows: &Vec<Row>) {
    // get the longest width of each row
    let mut addr_width = 0;
    let mut line_width = 0;
    let mut op_width = 0;
    let mut arg_width = 0;
    let mut info_width = 0;
    for (addr, line, op, arg, info) in rows {
        addr_width = addr_width.max(addr.len());
        line_width = line_width.max(line.len());
        op_width = op_width.max(op.len());
        arg_width = arg_width.max(arg.len());
        info_width = info_width.max(info.len());
    }

    addr_width += 2;
    line_width += 2;
    op_width += 2;
    arg_width += 2;
    info_width += 2;

    for (addr, line, op, arg, info) in rows {
        println!(
            "{addr:>addr_width$} {line:>line_width$} {op:>op_width$} {arg:arg_width$} {info:info_width$}"
        );
    }
}

pub fn disassemble(chunk: &Chunk, constants: &Vec<ObjP>, globals: &Vec<String>) {
    println!("== main chunk");
    println!();
    disassemble_chunk(chunk, constants, globals);

    for constant in constants {
        if let Some(fun) = constant.as_any().downcast_ref::<UserFunctionInst>() {
            println!();
            println!(
                "== {} starting on line {}",
                fun.name(),
                fun.chunk().lines[0].0
            );
            println!();
            disassemble_chunk(fun.chunk(), constants, globals);
        }
    }
}