sage/targets/mod.rs
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//! # Targets Module
//!
//! This module contains the code dealing with building the virtual
//! machine code to various targets, such as C source code.
//!
//! ## Current Structure
//!
//! Right now, this module is a bit empty, only implementing C (GCC only)
//! as a compiler target. This is due to the fact that it has been much
//! simpler to build the language on top of the virtual machine when there
//! are fewer implementations to change.
//!
//! ## Future Structure
//!
//! In the future, this module will be *much* more featured.
//! The frontend will use `Put` and `Get` to interact with the
//! virtual machine's I/O device, and this module will provide hooks
//! to add "system calls" to implement actual hardware-specific behaviors
//! using these instructions, **but with portability in mind**.
//!
//! Consider the `fork` system call on Unix systems. A backend might
//! implement a `fork` frontend for this virtual machine by executing
//! `fork` when a correct series of `Put` values are given to the I/O device.
//!
//! Other backends might not implement `fork` though, and so "catch all"
//! code can be implemented to *allow a backend to compile **as if** `fork`
//! is provided*. This might work by providing some frontend code which takes
//! two functions and runs them serially instead of in parallel, but still
//! accomplishing a simulated `fork`'s state.
//!
//! Other hardware specific instructions can be implemented this way very
//! nicely. Consider a VGA device which displays a screen. A hardware
//! specific implementation can be written for each supported target,
//! and a "catch all" implementation can work by trying to draw the screen
//! as ASCII/UNICODE with `PutChar. A hardware specific implementation may
//! also *choose* to fail under unsupported targets to prevent use where
//! not intended.
pub mod c;
pub use c::*;
pub mod sage_lisp;
pub use sage_lisp::*;
// pub mod sage_os;
// pub use sage_os::*;
// pub mod x86;
// pub use x86::*;
use log::info;
use crate::{
side_effects::{Input, Output},
vm::{self, *},
};
/// A trait for a target architecture to be compiled to.
pub trait Architecture {
/// The name of the target architecture.
fn name(&self) -> &str;
/// The version of the target architecture.
fn version(&self) -> &str;
/// Whether or not the target architecture supports floating point.
fn supports_floats(&self) -> bool;
/// Whether or not the target architecture supports the given input (mode + channel).
fn supports_input(&self, src: &Input) -> bool;
/// Whether or not the target architecture supports the given output (mode + channel).
fn supports_output(&self, dst: &Output) -> bool;
/// Get a value from the given input stream (mode + channel).
fn get(&mut self, src: &Input) -> Result<String, String>;
/// Put a value to the given output stream (mode + channel).
fn put(&mut self, dst: &Output) -> Result<String, String>;
/// Peek a value from the device connected to the program.
fn peek(&mut self) -> Result<String, String>;
/// Poke a value to the device connected to the program.
fn poke(&mut self) -> Result<String, String>;
/// The code before the program starts.
fn prelude(&self, _is_core: bool) -> Option<String> {
None
}
/// The code after each instruction.
fn postop(&self) -> Option<String> {
None
}
/// The code after the program ends.
fn postlude(&self, _is_core: bool) -> Option<String> {
None
}
/// The code before the function definitions.
fn pre_funs(&self, _funs: Vec<i32>) -> Option<String> {
None
}
/// The code after the function definitions.
fn post_funs(&self, _funs: Vec<i32>) -> Option<String> {
None
}
/// The string used for indentation.
fn indentation(&self) -> Option<String> {
Some("\t".to_string())
}
/// Compile the declaration of a procedure.
fn declare_proc(&mut self, label_id: usize) -> String;
/// Compile an `End` instruction (with the matching `If` or `While` or `Function`)
fn end(&mut self, matching: &CoreOp, fun: Option<usize>) -> String;
/// Compile a `CoreOp` instruction.
fn op(&mut self, op: &vm::CoreOp) -> String;
/// Compile a `StandardOp` instruction.
fn std_op(&mut self, op: &vm::StandardOp) -> Result<String, String>;
}
/// Implement a compiler for the given target.
pub trait CompiledTarget: Architecture {
fn build_op(
&mut self,
op: &vm::CoreOp,
matching_ops: &mut Vec<vm::CoreOp>,
matching_funs: &mut Vec<usize>,
current_fun: &mut usize,
indent: &mut usize,
) -> Result<String, String> {
Ok(match op {
CoreOp::Function => {
matching_ops.push(op.clone());
matching_funs.push(*current_fun);
let fun_header = self.declare_proc(*current_fun);
*current_fun += 1;
*indent += 1;
fun_header
}
CoreOp::While | CoreOp::If => {
matching_ops.push(op.clone());
*indent += 1;
self.op(op)
}
CoreOp::Else => {
if let Some(CoreOp::If) = matching_ops.pop() {
matching_ops.push(op.clone());
self.op(op)
} else {
return Err("Unexpected else".to_string());
}
}
CoreOp::End => {
*indent -= 1;
if let Some(op) = matching_ops.pop() {
self.end(
&op,
if let CoreOp::Function = op {
matching_funs.pop()
} else {
None
},
)
} else {
return Err("Unexpected end".to_string());
}
}
CoreOp::Get(src) => {
if !self.supports_input(src) {
return Err(format!(
"Input {:?} not supported on target {}",
src,
self.name()
));
}
self.get(src)?
}
CoreOp::Put(dst) => {
if !self.supports_output(dst) {
return Err(format!(
"Output {:?} not supported on target {}",
dst,
self.name()
));
}
self.put(dst)?
}
other => self.op(other),
})
}
fn build_std_op(
&mut self,
std_op: &vm::StandardOp,
matching_ops: &mut Vec<vm::CoreOp>,
matching_funs: &mut Vec<usize>,
current_fun: &mut usize,
indent: &mut usize,
) -> Result<String, String> {
match std_op {
StandardOp::CoreOp(op) => {
self.build_op(op, matching_ops, matching_funs, current_fun, indent)
}
other => self.std_op(other),
}
}
/// Compile the core variant of the machine code (must be implemented for every target).
fn build_core(&mut self, program: &vm::CoreProgram) -> Result<String, String> {
info!("Compiling core program for target {}", self.name());
let (main_ops, function_defs) = program.clone().get_main_and_functions();
let mut result = self.prelude(true).unwrap_or("".to_string());
let mut matching_ops = vec![];
let mut matching_funs = vec![];
let mut current_fun: usize = 0;
let tab = self.indentation().unwrap_or("".to_string());
let mut indent = 0;
result += &self
.pre_funs(function_defs.keys().cloned().collect())
.unwrap_or("".to_string());
for i in 0..function_defs.len() as i32 {
let f = &function_defs[&i];
for op in f {
result += &tab.repeat(indent);
result += &self.build_op(
op,
&mut matching_ops,
&mut matching_funs,
&mut current_fun,
&mut indent,
)?;
result += &self.postop().unwrap_or("".to_string());
}
}
result += &self
.post_funs(function_defs.keys().cloned().collect())
.unwrap_or("".to_string());
indent = 1;
for op in main_ops {
result += &tab.repeat(indent);
result += &self.build_op(
&op,
&mut matching_ops,
&mut matching_funs,
&mut current_fun,
&mut indent,
)?;
result += &self.postop().unwrap_or("".to_string());
}
info!("Finished compiling core program for target {}", self.name());
Ok(result + &tab + self.postlude(true).unwrap_or("".to_string()).as_str())
}
/// Compile the standard variant of the machine code (should be implemented for every target possible).
fn build_std(&mut self, program: &vm::StandardProgram) -> Result<String, String> {
info!("Compiling standard program for target {}", self.name());
let (main_ops, function_defs) = program.clone().get_main_and_functions();
let mut result = self.prelude(false).unwrap_or("".to_string());
let mut matching_ops = vec![];
let mut matching_funs = vec![];
let mut current_fun: usize = 0;
let tab = self.indentation().unwrap_or("".to_string());
let mut indent = 0;
result += &self
.pre_funs(function_defs.keys().cloned().collect())
.unwrap_or("".to_string());
for i in 0..function_defs.len() as i32 {
let f = &function_defs[&i];
for op in f {
result += &tab.repeat(indent);
result += &self.build_std_op(
op,
&mut matching_ops,
&mut matching_funs,
&mut current_fun,
&mut indent,
)?;
result += &self.postop().unwrap_or("".to_string());
}
}
result += &self
.post_funs(function_defs.keys().cloned().collect())
.unwrap_or("".to_string());
indent = 1;
for op in main_ops {
result += &tab.repeat(indent);
result += &self.build_std_op(
&op,
&mut matching_ops,
&mut matching_funs,
&mut current_fun,
&mut indent,
)?;
result += &self.postop().unwrap_or("".to_string());
}
info!(
"Finished compiling standard program for target {}",
self.name()
);
Ok(result + &tab + self.postlude(false).unwrap_or("".to_string()).as_str())
}
}