339 lines
15 KiB
Rust
339 lines
15 KiB
Rust
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use std::rc::Rc;
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use super::{EvalResult, Memory, MemoryValue, Primitive, State};
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use crate::{
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builtin::Builtin,
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reduced_ir::{
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Alternative, Callable, Expression, FunctionDefinition, Literal, Lookup, Pattern, ReducedIR, Statement,
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},
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type_inference::TypeContext,
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util::ScopeStack,
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};
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pub struct Evaluator<'a, 'b> {
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pub type_context: &'b TypeContext,
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pub state: &'b mut State<'a>,
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}
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impl<'a, 'b> Evaluator<'a, 'b> {
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pub fn evaluate(&mut self, reduced: ReducedIR, repl: bool) -> Vec<Result<String, String>> {
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let mut acc = vec![];
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for (def_id, function) in reduced.functions.into_iter() {
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let mem = (&def_id).into();
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self.state.environments.insert(mem, MemoryValue::Function(function));
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}
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for statement in reduced.entrypoint.into_iter() {
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match self.statement(statement) {
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Ok(Some(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(error.msg));
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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 block(&mut self, statements: Vec<Statement>) -> EvalResult<Primitive> {
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//TODO need to handle breaks, returns, etc.
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let mut ret = None;
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for stmt in statements.into_iter() {
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if let Some(MemoryValue::Primitive(prim)) = self.statement(stmt)? {
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ret = Some(prim);
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}
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}
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Ok(if let Some(ret) = ret { ret } else { self.expression(Expression::unit())? })
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}
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fn statement(&mut self, stmt: Statement) -> EvalResult<Option<MemoryValue>> {
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match stmt {
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Statement::Binding { ref id, expr, constant: _ } => {
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println!("eval() binding id: {}", id);
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let evaluated = self.expression(expr)?;
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self.state.environments.insert(id.into(), evaluated.into());
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Ok(None)
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}
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Statement::Expression(expr) => {
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let evaluated = self.expression(expr)?;
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Ok(Some(evaluated.into()))
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}
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}
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}
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fn expression(&mut self, expression: Expression) -> EvalResult<Primitive> {
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Ok(match expression {
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Expression::Literal(lit) => Primitive::Literal(lit),
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Expression::Tuple(items) => Primitive::Tuple(
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items
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.into_iter()
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.map(|expr| self.expression(expr))
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.collect::<EvalResult<Vec<Primitive>>>()?,
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),
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Expression::Lookup(kind) => match kind {
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Lookup::Function(ref id) => {
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let mem = id.into();
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match self.state.environments.lookup(&mem) {
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// This just checks that the function exists in "memory" by ID, we don't
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// actually retrieve it until `apply_function()`
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Some(MemoryValue::Function(_)) => Primitive::Callable(Callable::UserDefined(*id)),
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x => return Err(format!("Function not found for id: {} : {:?}", id, x).into()),
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}
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}
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Lookup::Param(n) => {
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let mem = n.into();
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match self.state.environments.lookup(&mem) {
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Some(MemoryValue::Primitive(prim)) => prim.clone(),
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e => return Err(format!("Param lookup error, got {:?}", e).into()),
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}
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}
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Lookup::LocalVar(ref id) | Lookup::GlobalVar(ref id) => {
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let mem = id.into();
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match self.state.environments.lookup(&mem) {
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Some(MemoryValue::Primitive(expr)) => expr.clone(),
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_ =>
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return Err(
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format!("Nothing found for local/gloval variable lookup {}", id).into()
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),
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}
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}
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},
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Expression::Assign { ref lval, box rval } => {
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let mem = lval.into();
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let evaluated = self.expression(rval)?;
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self.state.environments.insert(mem, MemoryValue::Primitive(evaluated));
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Primitive::unit()
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}
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Expression::Call { box f, args } => self.call_expression(f, args)?,
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Expression::Callable(Callable::DataConstructor { type_id, arity, tag }) if arity == 0 =>
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Primitive::Object { type_id, tag, items: vec![] },
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Expression::Callable(func) => Primitive::Callable(func),
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Expression::Conditional { box cond, then_clause, else_clause } => {
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let cond = self.expression(cond)?;
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match cond {
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Primitive::Literal(Literal::Bool(true)) => self.block(then_clause)?,
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Primitive::Literal(Literal::Bool(false)) => self.block(else_clause)?,
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v => return Err(format!("Non-boolean value {:?} in if-statement", v).into()),
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}
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}
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Expression::CaseMatch { box cond, alternatives } =>
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self.case_match_expression(cond, alternatives)?,
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Expression::ReductionError(e) => return Err(e.into()),
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})
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}
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fn case_match_expression(
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&mut self,
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cond: Expression,
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alternatives: Vec<Alternative>,
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) -> EvalResult<Primitive> {
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fn matches(scrut: &Primitive, pat: &Pattern, scope: &mut ScopeStack<Memory, MemoryValue>) -> bool {
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match pat {
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Pattern::Ignored => true,
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Pattern::Binding(ref def_id) => {
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let mem = def_id.into();
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scope.insert(mem, MemoryValue::Primitive(scrut.clone())); //TODO make sure this doesn't cause problems with nesting
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true
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}
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Pattern::Literal(pat_literal) =>
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if let Primitive::Literal(scrut_literal) = scrut {
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pat_literal == scrut_literal
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} else {
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false
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},
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Pattern::Tuple { subpatterns, tag } => match tag {
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None => match scrut {
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Primitive::Tuple(items) if items.len() == subpatterns.len() => items
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.iter()
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.zip(subpatterns.iter())
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.all(|(item, subpat)| matches(item, subpat, scope)),
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_ => false, //TODO should be a type error
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},
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Some(pattern_tag) => match scrut {
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//TODO should test type_ids for runtime type checking, once those work
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Primitive::Object { tag, items, .. }
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if tag == pattern_tag && items.len() == subpatterns.len() =>
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items
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.iter()
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.zip(subpatterns.iter())
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.all(|(item, subpat)| matches(item, subpat, scope)),
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_ => false,
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},
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},
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}
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}
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let cond = self.expression(cond)?;
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for alt in alternatives.into_iter() {
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let mut new_scope = self.state.environments.new_scope(None);
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if matches(&cond, &alt.pattern, &mut new_scope) {
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let mut new_state = State { environments: new_scope };
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let mut evaluator = Evaluator { state: &mut new_state, type_context: self.type_context };
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return evaluator.block(alt.item);
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}
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}
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Err("No valid match in match expression".into())
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}
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fn call_expression(&mut self, f: Expression, args: Vec<Expression>) -> EvalResult<Primitive> {
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let func = match self.expression(f)? {
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Primitive::Callable(func) => func,
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other => return Err(format!("Trying to call non-function value: {:?}", other).into()),
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};
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match func {
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Callable::Builtin(builtin) => self.apply_builtin(builtin, args),
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Callable::UserDefined(def_id) => {
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let mem = (&def_id).into();
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match self.state.environments.lookup(&mem) {
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Some(MemoryValue::Function(FunctionDefinition { body })) => {
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let body = body.clone(); //TODO ideally this clone would not happen
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self.apply_function(body, args)
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}
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e => Err(format!("Error looking up function with id {}: {:?}", def_id, e).into()),
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}
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}
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Callable::Lambda { arity, body } => {
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if arity as usize != args.len() {
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return Err(format!(
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"Lambda expression requries {} arguments, only {} provided",
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arity,
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args.len()
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)
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.into());
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}
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self.apply_function(body, args)
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}
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Callable::DataConstructor { type_id, arity, tag } => {
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if arity as usize != args.len() {
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return Err(format!(
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"Constructor expression requries {} arguments, only {} provided",
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arity,
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args.len()
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)
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.into());
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}
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let mut evaluated_args: Vec<Primitive> = vec![];
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for arg in args.into_iter() {
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evaluated_args.push(self.expression(arg)?);
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}
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Ok(Primitive::Object { type_id, tag, items: evaluated_args })
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}
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Callable::RecordConstructor { type_id: _, tag: _ } => {
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unimplemented!()
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}
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}
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}
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fn apply_builtin(&mut self, builtin: Builtin, args: Vec<Expression>) -> EvalResult<Primitive> {
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use Builtin::*;
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use Literal::*;
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use Primitive::Literal as Lit;
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let evaled_args: EvalResult<Vec<Primitive>> =
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args.into_iter().map(|arg| self.expression(arg)).collect();
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let evaled_args = evaled_args?;
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Ok(match (builtin, evaled_args.as_slice()) {
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(FieldAccess, /*&[Node::PrimObject { .. }]*/ _) => {
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return Err("Field access unimplemented".into());
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}
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/* builtin functions */
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(IOPrint, &[ref anything]) => {
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print!("{}", anything.to_repl());
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Primitive::Tuple(vec![])
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}
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(IOPrintLn, &[ref anything]) => {
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print!("{}", anything.to_repl());
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Primitive::Tuple(vec![])
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}
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(IOGetLine, &[]) => {
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let mut buf = String::new();
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std::io::stdin().read_line(&mut buf).expect("Error readling line in 'getline'");
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StringLit(Rc::new(buf.trim().to_string())).into()
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}
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/* Binops */
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(binop, &[ref lhs, ref rhs]) => match (binop, lhs, rhs) {
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// TODO need a better way of handling these literals
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(Add, Lit(Nat(l)), Lit(Nat(r))) => Nat(l + r).into(),
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(Add, Lit(Int(l)), Lit(Int(r))) => Int(l + r).into(),
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(Add, Lit(Nat(l)), Lit(Int(r))) => Int((*l as i64) + (*r as i64)).into(),
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(Add, Lit(Int(l)), Lit(Nat(r))) => Int((*l as i64) + (*r as i64)).into(),
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(Concatenate, Lit(StringLit(ref s1)), Lit(StringLit(ref s2))) =>
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StringLit(Rc::new(format!("{}{}", s1, s2))).into(),
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(Subtract, Lit(Nat(l)), Lit(Nat(r))) => Nat(l - r).into(),
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(Multiply, Lit(Nat(l)), Lit(Nat(r))) => Nat(l * r).into(),
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(Divide, Lit(Nat(l)), Lit(Nat(r))) => Float((*l as f64) / (*r as f64)).into(),
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(Quotient, Lit(Nat(l)), Lit(Nat(r))) =>
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if *r == 0 {
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return Err("Divide-by-zero error".into());
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} else {
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Nat(l / r).into()
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},
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(Modulo, Lit(Nat(l)), Lit(Nat(r))) => Nat(l % r).into(),
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(Exponentiation, Lit(Nat(l)), Lit(Nat(r))) => Nat(l ^ r).into(),
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(BitwiseAnd, Lit(Nat(l)), Lit(Nat(r))) => Nat(l & r).into(),
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(BitwiseOr, Lit(Nat(l)), Lit(Nat(r))) => Nat(l | r).into(),
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/* comparisons */
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(Equality, Lit(Nat(l)), Lit(Nat(r))) => Bool(l == r).into(),
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(Equality, Lit(Int(l)), Lit(Int(r))) => Bool(l == r).into(),
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(Equality, Lit(Float(l)), Lit(Float(r))) => Bool(l == r).into(),
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(Equality, Lit(Bool(l)), Lit(Bool(r))) => Bool(l == r).into(),
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(Equality, Lit(StringLit(ref l)), Lit(StringLit(ref r))) => Bool(l == r).into(),
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(LessThan, Lit(Nat(l)), Lit(Nat(r))) => Bool(l < r).into(),
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(LessThan, Lit(Int(l)), Lit(Int(r))) => Bool(l < r).into(),
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(LessThan, Lit(Float(l)), Lit(Float(r))) => Bool(l < r).into(),
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(LessThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Bool(l <= r).into(),
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(LessThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Bool(l <= r).into(),
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(LessThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Bool(l <= r).into(),
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(GreaterThan, Lit(Nat(l)), Lit(Nat(r))) => Bool(l > r).into(),
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(GreaterThan, Lit(Int(l)), Lit(Int(r))) => Bool(l > r).into(),
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(GreaterThan, Lit(Float(l)), Lit(Float(r))) => Bool(l > r).into(),
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(GreaterThanOrEqual, Lit(Nat(l)), Lit(Nat(r))) => Bool(l >= r).into(),
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(GreaterThanOrEqual, Lit(Int(l)), Lit(Int(r))) => Bool(l >= r).into(),
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(GreaterThanOrEqual, Lit(Float(l)), Lit(Float(r))) => Bool(l >= r).into(),
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(binop, lhs, rhs) =>
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return Err(format!("Invalid binop expression {:?} {:?} {:?}", lhs, binop, rhs).into()),
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},
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(prefix, &[ref arg]) => match (prefix, arg) {
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(BooleanNot, Lit(Bool(true))) => Bool(false),
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(BooleanNot, Lit(Bool(false))) => Bool(true),
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(Negate, Lit(Nat(n))) => Int(-(*n as i64)),
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(Negate, Lit(Int(n))) => Int(-(*n as i64)),
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(Negate, Lit(Float(f))) => Float(-(*f as f64)),
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(Increment, Lit(Int(n))) => Int(*n),
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(Increment, Lit(Nat(n))) => Nat(*n),
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_ => return Err("No valid prefix op".into()),
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}
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.into(),
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(x, args) => return Err(format!("bad or unimplemented builtin {:?} | {:?}", x, args).into()),
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})
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}
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fn apply_function(&mut self, body: Vec<Statement>, args: Vec<Expression>) -> EvalResult<Primitive> {
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let mut evaluated_args: Vec<Primitive> = vec![];
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for arg in args.into_iter() {
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evaluated_args.push(self.expression(arg)?);
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}
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let mut frame_state = State { environments: self.state.environments.new_scope(None) };
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let mut evaluator = Evaluator { state: &mut frame_state, type_context: self.type_context };
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for (n, evaled) in evaluated_args.into_iter().enumerate() {
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let n = n as u8;
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let mem = n.into();
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evaluator.state.environments.insert(mem, MemoryValue::Primitive(evaled));
|
||
|
|
}
|
||
|
|
|
||
|
|
evaluator.block(body)
|
||
|
|
}
|
||
|
|
}
|