454 lines
14 KiB
Rust
454 lines
14 KiB
Rust
use std::rc::Rc;
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use std::fmt::Write;
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use itertools::Itertools;
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use util::StateStack;
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use ast_reducing::{ReducedAST, Stmt, Expr, Lit, Func};
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pub struct State<'a> {
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values: StateStack<'a, Rc<String>, ValueEntry>
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}
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macro_rules! builtin_binding {
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($name:expr, $values:expr) => {
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$values.insert(Rc::new(format!($name)), ValueEntry::Binding { constant: true, val: Expr::Func(Func::BuiltIn(Rc::new(format!($name)))) });
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}
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}
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impl<'a> State<'a> {
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pub fn new() -> State<'a> {
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let mut values = StateStack::new(Some(format!("global")));
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builtin_binding!("print", values);
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builtin_binding!("println", values);
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State { values }
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}
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pub fn debug_print(&self) -> String {
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format!("Values: {:?}", self.values)
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}
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}
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#[derive(Debug)]
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enum ValueEntry {
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Binding {
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constant: bool,
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val: /*FullyEvaluatedExpr*/ Expr,
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}
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}
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type EvalResult<T> = Result<T, String>;
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/*
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#[derive(Debug, PartialEq, Clone)]
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enum FullyEvaluatedExpr {
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UnsignedInt(u64),
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SignedInt(i64),
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Float(f64),
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Str(String),
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Bool(bool),
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FuncLit(Rc<String>),
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Custom {
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string_rep: Rc<String>,
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},
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Tuple(Vec<FullyEvaluatedExpr>),
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List(Vec<FullyEvaluatedExpr>)
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}
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impl FullyEvaluatedExpr {
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fn to_string(&self) -> String {
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use self::FullyEvaluatedExpr::*;
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match self {
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&UnsignedInt(ref n) => format!("{}", n),
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&SignedInt(ref n) => format!("{}", n),
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&Float(ref f) => format!("{}", f),
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&Str(ref s) => format!("\"{}\"", s),
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&Bool(ref b) => format!("{}", b),
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&Custom { ref string_rep } => format!("{}", string_rep),
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&Tuple(ref items) => {
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let mut buf = String::new();
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write!(buf, "(").unwrap();
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for term in items.iter().map(|e| Some(e)).intersperse(None) {
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match term {
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Some(e) => write!(buf, "{}", e.to_string()).unwrap(),
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None => write!(buf, ", ").unwrap(),
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};
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}
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write!(buf, ")").unwrap();
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buf
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},
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&FuncLit(ref name) => format!("<function {}>", name),
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&List(ref items) => {
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let mut buf = String::new();
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write!(buf, "[").unwrap();
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for term in items.iter().map(|e| Some(e)).intersperse(None) {
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match term {
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Some(e) => write!(buf, "{}", e.to_string()).unwrap(),
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None => write!(buf, ", ").unwrap()
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}
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}
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write!(buf, "]").unwrap();
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buf
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}
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}
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}
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}
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*/
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/*
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pub fn new_with_parent(parent: &'a State<'a>) -> State<'a> {
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State { parent_frame: Some(parent), values: HashMap::new() }
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}
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pub fn evaluate(&mut self, ast: AST) -> Vec<Result<String, String>> {
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let mut acc = vec![];
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for statement in ast.0 {
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match self.eval_statement(statement) {
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Ok(output) => {
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if let Some(fully_evaluated) = output {
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acc.push(Ok(fully_evaluated.to_string()));
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}
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},
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Err(error) => {
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acc.push(Err(format!("Eval error: {}", error)));
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return acc;
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},
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}
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}
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acc
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}
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}
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impl<'a> State<'a> {
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fn eval_statement(&mut self, statement: Statement) -> EvalResult<Option<FullyEvaluatedExpr>> {
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Ok(match statement {
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Statement::ExpressionStatement(expr) => Some(self.eval_expr(expr)?),
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Statement::Declaration(decl) => { self.eval_decl(decl)?; None }
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})
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}
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fn eval_decl(&mut self, decl: Declaration) -> EvalResult<()> {
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use self::Declaration::*;
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use self::Variant::*;
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match decl {
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FuncDecl(signature, statements) => {
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let name = signature.name;
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let param_names: Vec<Rc<String>> = signature.params.iter().map(|fp| fp.0.clone()).collect();
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self.insert(name, ValueEntry::Function { body: statements.clone(), param_names });
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},
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TypeDecl(_name, body) => {
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for variant in body.0.iter() {
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match variant {
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&UnitStruct(ref name) => self.insert(name.clone(),
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ValueEntry::Binding { val: FullyEvaluatedExpr::Custom { string_rep: name.clone() } }),
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&TupleStruct(ref _name, ref _args) => unimplemented!(),
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&Record(ref _name, ref _fields) => unimplemented!(),
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};
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}
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},
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Binding { name, expr, ..} => {
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let val = self.eval_expr(expr)?;
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self.insert(name.clone(), ValueEntry::Binding { val });
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},
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_ => return Err(format!("Declaration evaluation not yet implemented"))
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}
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Ok(())
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}
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fn eval_expr(&mut self, expr: Expression) -> EvalResult<FullyEvaluatedExpr> {
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use self::ExpressionType::*;
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use self::FullyEvaluatedExpr::*;
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let expr_type = expr.0;
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match expr_type {
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IntLiteral(n) => Ok(UnsignedInt(n)),
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FloatLiteral(f) => Ok(Float(f)),
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StringLiteral(s) => Ok(Str(s.to_string())),
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BoolLiteral(b) => Ok(Bool(b)),
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PrefixExp(op, expr) => self.eval_prefix_exp(op, expr),
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BinExp(op, lhs, rhs) => self.eval_binexp(op, lhs, rhs),
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Value(name) => self.eval_value(name),
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TupleLiteral(expressions) => {
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let mut evals = Vec::new();
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for expr in expressions {
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match self.eval_expr(expr) {
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Ok(fully_evaluated) => evals.push(fully_evaluated),
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error => return error,
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}
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}
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Ok(Tuple(evals))
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}
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Call { f, arguments } => {
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let mut evaled_arguments = Vec::new();
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for arg in arguments.into_iter() {
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evaled_arguments.push(self.eval_expr(arg)?);
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}
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self.eval_application(*f, evaled_arguments)
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},
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Index { box indexee, indexers } => {
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let evaled = self.eval_expr(indexee)?;
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match evaled {
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Tuple(mut exprs) => {
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let len = indexers.len();
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if len == 1 {
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let idx = indexers.into_iter().nth(0).unwrap();
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match self.eval_expr(idx)? {
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UnsignedInt(n) if (n as usize) < exprs.len() => Ok(exprs.drain(n as usize..).next().unwrap()),
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UnsignedInt(n) => Err(format!("Index {} out of range", n)),
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other => Err(format!("{:?} is not an unsigned integer", other)),
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}
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} else {
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Err(format!("Tuple index must be one integer"))
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}
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},
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_ => Err(format!("Bad index expression"))
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}
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},
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ListLiteral(items) => Ok(List(items.into_iter().map(|item| self.eval_expr(item)).collect::<Result<Vec<_>,_>>()?)),
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x => Err(format!("Unimplemented thing {:?}", x)),
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}
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}
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fn eval_application(&mut self, f: Expression, arguments: Vec<FullyEvaluatedExpr>) -> EvalResult<FullyEvaluatedExpr> {
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use self::ExpressionType::*;
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match f {
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Expression(Value(ref identifier), _) if self.is_builtin(identifier) => self.eval_builtin(identifier, arguments),
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Expression(Value(identifier), _) => {
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match self.lookup(&identifier) {
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Some(&ValueEntry::Function { ref body, ref param_names }) => {
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if arguments.len() != param_names.len() {
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return Err(format!("Wrong number of arguments for the function"));
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}
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let mut new_state = State::new_with_parent(self);
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let sub_ast = body.clone();
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for (param, val) in param_names.iter().zip(arguments.into_iter()) {
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new_state.insert(param.clone(), ValueEntry::Binding { val });
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}
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let mut ret: Option<FullyEvaluatedExpr> = None;
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for statement in sub_ast.into_iter() {
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ret = new_state.eval_statement(statement)?;
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}
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Ok(ret.unwrap_or(FullyEvaluatedExpr::Custom { string_rep: Rc::new("()".to_string()) }))
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},
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_ => Err(format!("Function {} not found", identifier)),
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}
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},
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x => Err(format!("Trying to apply {:?} which is not a function", x)),
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}
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}
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fn is_builtin(&self, name: &Rc<String>) -> bool {
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match &name.as_ref()[..] {
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"print" | "println" => true,
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_ => false
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}
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}
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fn eval_builtin(&mut self, name: &Rc<String>, args: Vec<FullyEvaluatedExpr>) -> EvalResult<FullyEvaluatedExpr> {
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use self::FullyEvaluatedExpr::*;
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match &name.as_ref()[..] {
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"print" => {
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for arg in args {
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print!("{}", arg.to_string());
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}
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Ok(Tuple(vec![]))
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},
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"println" => {
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for arg in args {
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println!("{}", arg.to_string());
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}
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Ok(Tuple(vec![]))
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},
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_ => unreachable!()
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}
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}
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fn eval_value(&mut self, name: Rc<String>) -> EvalResult<FullyEvaluatedExpr> {
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use self::ValueEntry::*;
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match self.lookup(&name) {
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None => return Err(format!("Value {} not found", *name)),
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Some(lookup) => match lookup {
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&Binding { ref val } => Ok(val.clone()),
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&Function { .. } => Ok(FullyEvaluatedExpr::FuncLit(name.clone()))
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}
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}
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}
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}
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*/
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/* BELOW HERE NEW STUFF */
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impl Expr {
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fn to_repl(&self) -> String {
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use self::Lit::*;
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use self::Func::*;
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match self {
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Expr::Lit(ref l) => match l {
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Nat(n) => format!("{}", n),
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Int(i) => format!("{}", i),
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Float(f) => format!("{}", f),
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Bool(b) => format!("{}", b),
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StringLit(s) => format!("{}", s),
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},
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Expr::Func(f) => match f {
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BuiltIn(name) => format!("<built-in function {}>", name),
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UserDefined { name: None, .. } => format!("<function>"),
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UserDefined { name: Some(name), .. } => format!("<function {}>", name),
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},
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_ => format!("{:?}", self),
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}
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}
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}
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impl<'a> State<'a> {
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pub fn evaluate(&mut self, ast: ReducedAST, repl: bool) -> Vec<Result<String, String>> {
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use ast_reducing::*;
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let mut acc = vec![];
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for statement in ast.0 {
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match self.statement(statement) {
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Ok(Some(ref output)) if repl => acc.push(Ok(output.to_repl())),
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Ok(_) => (),
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Err(error) => {
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acc.push(Err(format!("Eval error: {}", error)));
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return acc;
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},
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}
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}
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acc
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}
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fn statement(&mut self, stmt: Stmt) -> EvalResult<Option<Expr>> {
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match stmt {
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Stmt::Binding { name, constant, expr } => {
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let val = self.expression(expr)?;
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self.values.insert(name.clone(), ValueEntry::Binding { constant, val });
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Ok(None)
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},
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Stmt::Expr(expr) => Ok(Some(self.expression(expr)?)),
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}
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}
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fn expression(&mut self, expr: Expr) -> EvalResult<Expr> {
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use self::Expr::*;
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match expr {
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literal @ Lit(_) => Ok(literal),
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Call { box f, args } => {
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let f = match self.expression(f)? {
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Func(f) => f,
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other => return Err(format!("Tried to call {:?} which is not a function", other)),
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};
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self.apply_function(f, args)
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},
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Val(v) => self.value(v),
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func @ Func(_) => Ok(func),
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e => Err(format!("Expr {:?} eval not implemented", e))
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}
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}
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fn apply_function(&mut self, f: Func, args: Vec<Expr>) -> EvalResult<Expr> {
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match f {
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Func::BuiltIn(sigil) => self.apply_builtin(sigil, args),
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Func::UserDefined { params, body, name } => {
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if params.len() != args.len() {
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return Err(format!("Runtime error: calling a {}-argument function with {} args", params.len(), args.len()))
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}
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let mut func_state = State { values: self.values.new_frame(name.map(|n| format!("{}", n))) };
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for (param, val) in params.into_iter().zip(args.into_iter()) {
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func_state.values.insert(param, ValueEntry::Binding { constant: true, val });
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}
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// TODO figure out function return semantics
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let mut ret = None;
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for stmt in body {
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ret = func_state.statement(stmt)?;
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}
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Ok(ret.unwrap_or(Expr::Unit))
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}
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}
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}
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fn apply_builtin(&mut self, name: Rc<String>, args: Vec<Expr>) -> EvalResult<Expr> {
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use self::Expr::*;
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use self::Lit::*;
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let evaled_args: Result<Vec<Expr>, String> = args.into_iter().map(|arg| self.expression(arg)).collect();
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let evaled_args = evaled_args?;
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Ok(match (name.as_str(), evaled_args.as_slice()) {
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/* binops */
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("+", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l + r)),
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("++", &[Lit(StringLit(ref s1)), Lit(StringLit(ref s2))]) => Lit(StringLit(Rc::new(format!("{}{}", s1, s2)))),
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("-", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l - r)),
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("*", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l * r)),
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("/", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Float((l as f64)/ (r as f64))),
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("//", &[Lit(Nat(l)), Lit(Nat(r))]) => if r == 0 {
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return Err(format!("Runtime error: divide by zero"));
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} else {
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Lit(Nat(l / r))
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},
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("%", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l % r)),
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("^", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l ^ r)),
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("&", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l & r)),
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("|", &[Lit(Nat(l)), Lit(Nat(r))]) => Lit(Nat(l | r)),
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/* prefix ops */
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("!", &[Lit(Bool(true))]) => Lit(Bool(false)),
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("!", &[Lit(Bool(false))]) => Lit(Bool(true)),
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("-", &[Lit(Nat(n))]) => Lit(Int(-1*(n as i64))),
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("-", &[Lit(Int(n))]) => Lit(Int(-1*(n as i64))),
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("+", &[Lit(Int(n))]) => Lit(Int(n)),
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("+", &[Lit(Nat(n))]) => Lit(Nat(n)),
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/* builtin functions */
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("print", &[ref anything]) => {
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print!("{}", anything.to_repl());
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Expr::Unit
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},
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("println", &[ref anything]) => {
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println!("{}", anything.to_repl());
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Expr::Unit
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},
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_ => return Err(format!("Runtime error: bad or unimplemented builtin")),
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})
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}
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fn value(&mut self, name: Rc<String>) -> EvalResult<Expr> {
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use self::ValueEntry::*;
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match self.values.lookup(&name) {
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None => return Err(format!("Value {} not found", *name)),
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Some(lookup) => match lookup {
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Binding { val, .. } => Ok(
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if let Expr::Func(Func::UserDefined { name: None, params, body }) = val {
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Expr::Func(Func::UserDefined { name: Some(name.clone()), params: params.clone(), body: body.clone() }) //TODO here is unnecessary cloning
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} else {
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val.clone()
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}),
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_ => Err(format!("Functions not done")),
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}
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}
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}
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}
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#[cfg(test)]
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mod eval_tests {
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use tokenizing::tokenize;
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use parsing::parse;
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use eval::State;
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macro_rules! fresh_env {
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($string:expr, $correct:expr) => {
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let mut state = State::new();
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let all_output = state.evaluate(parse(tokenize($string)).0.unwrap().reduce(), true);
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let ref output = all_output[0];
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assert_eq!(*output, Ok($correct.to_string()));
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}
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}
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#[test]
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fn test_basic_eval() {
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fresh_env!("1 + 2", "3");
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}
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}
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