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|
use crate::{
app::AppState,
lisp::{
error::LispError,
expr::{LispExpr, LispFunction},
number::LispNumber,
Environment,
},
primitive,
};
use std::collections::HashMap;
use log::{error, info};
pub fn with_prelude() -> Environment {
let mut env = Environment::new();
primitive!(env, Some(2), "+", |args, _| {
if args.iter().any(|arg| !matches!(arg, LispExpr::Number(_))) {
Err(LispError::EvalError)
} else {
Ok(LispExpr::Number(
args.iter()
.map(|arg| unwrap_number(arg))
.fold(LispNumber::Integer(0), |acc, x| acc + *x),
))
}
});
primitive!(env, Some(2), "-", |args, _| {
if args.iter().any(|arg| !matches!(arg, LispExpr::Number(_))) {
Err(LispError::EvalError)
} else {
let mut acc = unwrap_number(&args[0]).clone();
for arg in args.into_iter().skip(1) {
acc = acc - *unwrap_number(&arg);
}
Ok(LispExpr::Number(acc))
}
});
primitive!(env, Some(2), "*", |args, _| {
if args.iter().any(|arg| !matches!(arg, LispExpr::Number(_))) {
Err(LispError::EvalError)
} else {
Ok(LispExpr::Number(
args.iter()
.map(|arg| unwrap_number(arg))
.fold(LispNumber::Integer(1), |acc, x| acc * *x),
))
}
});
primitive!(env, Some(0), "toggle-grid", |_, app| {
app.toggle_grid();
Ok(LispExpr::Unit)
});
primitive!(env, Some(3), "if", |args, _| {
match args {
[predicate, then, else_] => {
if matches!(predicate, LispExpr::BoolLit(false)) {
Ok(else_.clone())
} else {
Ok(then.clone())
}
}
_ => {
error!("invalid args for `if` primitive");
Err(LispError::EvalError)
}
}
});
primitive!(env, Some(1), "and", |args, _| {
if args
.iter()
.any(|arg| matches!(arg, LispExpr::BoolLit(false)))
{
Ok(LispExpr::BoolLit(false))
} else {
Ok(LispExpr::BoolLit(true))
}
});
env
}
pub fn eval(
expr: &LispExpr,
app: &mut AppState,
extra_env: Option<&Environment>,
) -> Result<LispExpr, LispError> {
match expr {
LispExpr::Unit => Ok(expr.clone()),
LispExpr::StringLit(_) => Ok(expr.clone()),
LispExpr::Number(_) => Ok(expr.clone()),
LispExpr::BoolLit(_) => Ok(expr.clone()),
LispExpr::Ident(ref id) => {
lookup_extended(extra_env.unwrap_or(&Environment::new()), &app.lisp_env, id)
}
LispExpr::List(li) => {
let func_expr = &li[0];
match func_expr {
LispExpr::Ident(s) => match s.as_ref() {
"define" => define_var(&li[1..], app),
"set!" => set_var(&li[1..], app),
"lambda" => create_lambda(&li[1..]),
_ => {
let func_expr = eval(&func_expr, app, extra_env)?;
match func_expr {
LispExpr::PrimitiveFunc(f) => {
let mut args = Vec::new();
for item in li[1..].iter() {
args.push(eval(item, app, extra_env)?);
}
f.call(&args, app)
}
LispExpr::Function(f) => {
info!("eval custom func");
let mut args = Vec::new();
for item in li[1..].iter() {
args.push(eval(item, app, extra_env)?);
}
if f.params.len() != args.len() {
info!("too many or too little number of args");
Err(LispError::EvalError) // too many or too little number of args
} else {
let mut local_env: Environment =
f.params.into_iter().zip(args).collect();
local_env.extend(app.lisp_env.clone());
if let Some(env) = extra_env {
local_env.extend(env.clone());
}
if f.body.is_empty() {
return Ok(LispExpr::Unit);
} else {
eval(&LispExpr::List(f.body), app, Some(&local_env))
}
}
}
_ => Err(LispError::EvalError),
}
}
},
_ => Err(LispError::EvalError),
}
}
_ => Err(LispError::ParseError),
}
}
pub fn define_var(args: &[LispExpr], app: &mut AppState) -> Result<LispExpr, LispError> {
if args.len() != 2 {
error!("Invalid arity for `define`");
return Err(LispError::EvalError);
}
match args {
[LispExpr::Ident(id), expr] => {
let value = eval(&expr, app, None)?;
app.lisp_env.insert(id.into(), value);
return Ok(LispExpr::Unit);
}
_ => {
error!("Invalid usage of `define`");
return Err(LispError::EvalError);
}
}
}
pub fn set_var(args: &[LispExpr], app: &mut AppState) -> Result<LispExpr, LispError> {
if args.len() != 2 {
error!("Invalid arity for `define`");
return Err(LispError::EvalError);
}
match args {
[LispExpr::Ident(id), expr] => {
let value = eval(&expr, app, None)?;
return app
.lisp_env
.insert(id.into(), value)
.ok_or(LispError::EvalError);
}
_ => {
error!("Invalid usage of `define`");
return Err(LispError::EvalError);
}
}
}
pub fn create_lambda(cdr: &[LispExpr]) -> Result<LispExpr, LispError> {
if cdr.len() != 2 {
// needs params and body
error!("needs params and body");
return Err(LispError::EvalError);
}
info!("creating lambda");
match cdr {
[LispExpr::List(params), LispExpr::List(body)]
if params.iter().all(|p| matches!(p, LispExpr::Ident(_))) =>
{
return Ok(LispExpr::Function(LispFunction {
params: params
.into_iter()
.map(|p| unwrap_ident(p.clone()))
.collect::<Vec<_>>(),
body: body.clone(),
}));
}
_ => {
error!("Invalid usage of `define`");
return Err(LispError::EvalError);
}
}
}
pub fn lookup_extended(
local: &Environment,
super_: &Environment,
key: &str,
) -> Result<LispExpr, LispError> {
if let Some(e) = local.get(key) {
Ok(e.clone())
} else if let Some(e) = super_.get(key) {
Ok(e.clone())
} else {
Err(LispError::EvalError)
}
}
pub fn unwrap_number(n: &LispExpr) -> &LispNumber {
match n {
LispExpr::Number(i) => i,
_ => panic!("unwrap_number expected number"),
}
}
pub fn unwrap_ident(i: LispExpr) -> String {
match i {
LispExpr::Ident(i) => i,
_ => panic!("unwrap_ident expected string"),
}
}
|
