410 lines
14 KiB
Rust
410 lines
14 KiB
Rust
use crate::reduced_ir::{ReducedIR, Expression, Lookup, Callable, FunctionDefinition, Statement, Literal};
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use crate::symbol_table::{DefId};
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use crate::util::ScopeStack;
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use crate::builtin::Builtin;
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use crate::typechecking::TypeId;
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use std::fmt::Write;
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use std::rc::Rc;
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use std::convert::From;
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mod test;
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type EvalResult<T> = Result<T, RuntimeError>;
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#[derive(Debug)]
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pub struct State<'a> {
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environments: ScopeStack<'a, Memory, MemoryValue>,
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}
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//TODO - eh, I dunno, maybe it doesn't matter exactly how memory works in the tree-walking
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//evaluator
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#[derive(Debug, PartialEq, Eq, Hash, Clone)]
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enum Memory {
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Index(u32)
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}
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// This is for function param lookups, and is a hack
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impl From<u8> for Memory {
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fn from(n: u8) -> Self {
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Memory::Index(4_000_000 + (n as u32))
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}
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}
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impl From<&DefId> for Memory {
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fn from(id: &DefId) -> Self {
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Self::Index(id.as_u32())
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}
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}
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#[derive(Debug)]
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struct RuntimeError {
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msg: String
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}
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impl From<String> for RuntimeError {
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fn from(msg: String) -> Self {
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Self {
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msg
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}
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}
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}
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impl From<&str> for RuntimeError {
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fn from(msg: &str) -> Self {
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Self {
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msg: msg.to_string(),
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}
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}
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}
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impl RuntimeError {
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#[allow(dead_code)]
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fn get_msg(&self) -> String {
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format!("Runtime error: {}", self.msg)
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}
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}
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fn paren_wrapped(terms: impl Iterator<Item=String>) -> String {
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let mut buf = String::new();
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write!(buf, "(").unwrap();
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for term in terms.map(Some).intersperse(None) {
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match term {
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Some(e) => write!(buf, "{}", e).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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/// Anything that can be stored in memory; that is, a function definition, or a fully-evaluated
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/// program value.
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#[derive(Debug)]
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enum MemoryValue {
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Function(FunctionDefinition),
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Primitive(Primitive),
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}
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impl From<Primitive> for MemoryValue {
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fn from(prim: Primitive) -> Self {
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Self::Primitive(prim)
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}
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}
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impl MemoryValue {
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fn to_repl(&self) -> String {
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match self {
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MemoryValue::Primitive(ref prim) => prim.to_repl(),
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MemoryValue::Function(..) => "<function>".to_string(),
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}
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}
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}
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#[derive(Debug)]
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enum RuntimeValue {
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Expression(Expression),
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Evaluated(Primitive),
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}
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impl From<Expression> for RuntimeValue {
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fn from(expr: Expression) -> Self {
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Self::Expression(expr)
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}
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}
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impl From<Primitive> for RuntimeValue {
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fn from(prim: Primitive) -> Self {
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Self::Evaluated(prim)
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}
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}
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/// A fully-reduced value
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#[derive(Debug, Clone)]
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enum Primitive {
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Tuple(Vec<Primitive>),
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Literal(Literal),
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Callable(Callable),
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Object {
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type_id: TypeId,
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tag: u32,
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items: Vec<Primitive>
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},
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}
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impl Primitive {
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fn to_repl(&self) -> String {
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match self {
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Primitive::Object { type_id, items, .. } => {
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format!("{}{}", type_id.local_name(), paren_wrapped(items.iter().map(|item| item.to_repl())))
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},
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Primitive::Literal(lit) => match lit {
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Literal::Nat(n) => format!("{}", n),
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Literal::Int(i) => format!("{}", i),
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Literal::Float(f) => format!("{}", f),
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Literal::Bool(b) => format!("{}", b),
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Literal::StringLit(s) => format!("\"{}\"", s),
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}
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Primitive::Tuple(terms) => paren_wrapped(terms.iter().map(|x| x.to_repl())),
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Primitive::Callable(..) => "<some-callable>".to_string(),
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}
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}
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fn unit() -> Self {
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Primitive::Tuple(vec![])
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}
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}
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impl From<Literal> for Primitive {
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fn from(lit: Literal) -> Self {
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Primitive::Literal(lit)
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}
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}
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impl<'a> State<'a> {
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pub fn new() -> Self {
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Self {
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environments: ScopeStack::new(Some("global".to_string()))
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}
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}
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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.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 => {
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acc.push(Ok(output.to_repl()))
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},
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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 {
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ret
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} else {
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self.expression(Expression::unit())?
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})
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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.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(items.into_iter().map(|expr| self.expression(expr)).collect::<EvalResult<Vec<Primitive>>>()?),
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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.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.clone())),
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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.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.environments.lookup(&mem) {
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Some(MemoryValue::Primitive(expr)) => expr.clone(),
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_ => return Err(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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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.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(func) => Primitive::Callable(func),
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Expression::ReductionError(e) => return Err(e.into()),
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})
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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.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!("Lambda expression requries {} arguments, only {} provided", arity, args.len()).into());
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}
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let body = body.clone(); //TODO again ideally, no cloning here
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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!("Constructor expression requries {} arguments, only {} provided", arity, args.len()).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 {
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type_id,
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tag,
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items: evaluated_args
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})
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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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(Add, Lit(Nat(l)), Lit(Nat(r))) => Nat(l + r).into(),
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(Concatenate, Lit(StringLit(ref s1)), Lit(StringLit(ref s2))) => 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))) => 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) => 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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(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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}.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 {
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environments: self.environments.new_scope(None)
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};
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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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frame_state.environments.insert(mem, MemoryValue::Primitive(evaled));
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}
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frame_state.block(body)
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}
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}
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