actually commit the big new file
This commit is contained in:
Scott Richmond
parent
383f21fbd8
commit
f063d55404
575
src/context.rs
Normal file
575
src/context.rs
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@ -0,0 +1,575 @@
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use crate::base::*;
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use crate::parser::*;
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use crate::value::{Fn, Value};
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use imbl::HashMap;
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use imbl::Vector;
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use std::cell::RefCell;
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use std::rc::Rc;
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pub fn match_eq<T, U>(x: T, y: T, z: U) -> Option<U>
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where
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T: PartialEq,
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{
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if x == y {
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Some(z)
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} else {
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None
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}
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}
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pub struct LErr {
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pub msg: String,
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pub trace: Vec<String>,
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}
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impl LErr {
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pub fn new(msg: String) -> LErr {
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LErr {
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msg: msg.to_string(),
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trace: vec![],
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}
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}
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pub fn add_trace(mut self, fn_name: String) -> LErr {
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self.trace.push(fn_name);
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self
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}
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}
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type LResult<'src> = Result<Value<'src>, LErr>;
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pub struct Context<'src> {
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pub locals: Vec<(String, Value<'src>)>,
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pub prelude: Vec<(String, Value<'src>)>,
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pub prelude_ast: &'src Ast,
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pub ast: &'src Ast,
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}
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impl<'src> Context<'src> {
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pub fn resolve(&self, word: &String) -> LResult<'src> {
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let resolved_local = self.locals.iter().rev().find(|(name, _)| word == name);
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match resolved_local {
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Some((_, value)) => Ok(value.clone()),
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None => {
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let resolved_prelude = self.prelude.iter().rev().find(|(name, _)| word == name);
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match resolved_prelude {
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Some((_, value)) => Ok(value.clone()),
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None => Err(LErr::new(format!("unbound name {word}"))),
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}
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}
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}
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}
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pub fn bind(&mut self, word: String, value: &Value<'src>) {
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self.locals.push((word, value.clone()));
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}
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pub fn pop_to(&mut self, n: usize) {
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while self.locals.len() > n {
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self.locals.pop();
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}
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}
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pub fn match_eq<T>(&self, x: T, y: T) -> Option<&Context<'src>>
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where
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T: PartialEq,
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{
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if x == y {
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Some(&self)
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} else {
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None
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}
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}
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pub fn match_pattern(&mut self, patt: &Pattern, val: &Value<'src>) -> Option<&Context<'src>> {
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match (patt, val) {
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(Pattern::Nil, Value::Nil) => Some(self),
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(Pattern::Placeholder, _) => Some(self),
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(Pattern::Number(x), Value::Number(y)) => self.match_eq(x, y),
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(Pattern::Boolean(x), Value::Boolean(y)) => self.match_eq(x, y),
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(Pattern::Keyword(x), Value::Keyword(y)) => self.match_eq(x, y),
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(Pattern::String(x), Value::InternedString(y)) => self.match_eq(x, y),
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(Pattern::String(x), Value::AllocatedString(y)) => self.match_eq(&x.to_string(), y),
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(Pattern::Interpolated(_, StringMatcher(matcher)), Value::InternedString(y)) => {
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match matcher(y.to_string()) {
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Some(matches) => {
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let mut matches = matches
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.iter()
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.map(|(word, string)| {
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(
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word.clone(),
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Value::AllocatedString(Rc::new(string.clone())),
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)
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})
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.collect::<Vec<_>>();
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self.locals.append(&mut matches);
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Some(self)
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}
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None => None,
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}
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}
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(Pattern::Word(w), val) => {
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self.bind(w.to_string(), &val);
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Some(self)
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}
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(Pattern::As(word, type_str), value) => {
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let ludus_type = r#type(value);
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let type_kw = Value::Keyword(type_str);
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if type_kw == ludus_type {
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self.bind(word.to_string(), value);
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Some(self)
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} else {
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None
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}
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}
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(Pattern::Tuple(x), Value::Tuple(y)) => {
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let has_splat = x
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.iter()
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.any(|patt| matches!(patt, (Pattern::Splattern(_), _)));
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if x.len() > y.len() || (!has_splat && x.len() != y.len()) {
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return None;
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};
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let to = self.locals.len();
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for i in 0..x.len() {
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if let Pattern::Splattern(patt) = &x[i].0 {
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let mut list = Vector::new();
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for i in i..y.len() {
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list.push_back(y[i].clone())
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}
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let list = Value::List(list);
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self.match_pattern(&patt.0, &list);
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} else if self.match_pattern(&x[i].0, &y[i]).is_none() {
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self.pop_to(to);
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return None;
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}
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}
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Some(self)
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}
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(Pattern::List(x), Value::List(y)) => {
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let has_splat = x
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.iter()
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.any(|patt| matches!(patt, (Pattern::Splattern(_), _)));
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if x.len() > y.len() || (!has_splat && x.len() != y.len()) {
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return None;
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};
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let to = self.locals.len();
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for (i, (patt, _)) in x.iter().enumerate() {
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if let Pattern::Splattern(patt) = &patt {
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let list = Value::List(y.skip(i));
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self.match_pattern(&patt.0, &list);
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} else if self.match_pattern(patt, y.get(i).unwrap()).is_none() {
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self.pop_to(to);
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return None;
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}
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}
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Some(self)
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}
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// TODO: optimize this on several levels
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// - [ ] opportunistic mutation
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// - [ ] get rid of all the pointer indirection in word splats
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(Pattern::Dict(x), Value::Dict(y)) => {
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let has_splat = x
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.iter()
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.any(|patt| matches!(patt, (Pattern::Splattern(_), _)));
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if x.len() > y.len() || (!has_splat && x.len() != y.len()) {
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return None;
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};
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let to = self.locals.len();
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let mut matched = vec![];
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for (pattern, _) in x {
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match pattern {
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Pattern::Pair(key, patt) => {
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if let Some(val) = y.get(key) {
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if self.match_pattern(&patt.0, val).is_none() {
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self.pop_to(to);
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return None;
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} else {
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matched.push(key);
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}
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} else {
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return None;
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};
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}
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Pattern::Splattern(pattern) => match pattern.0 {
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Pattern::Word(w) => {
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// TODO: find a way to take ownership
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// this will ALWAYS make structural changes, because of this clone
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// we want opportunistic mutation if possible
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let mut unmatched = y.clone();
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for key in matched.iter() {
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unmatched.remove(*key);
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}
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self.bind(w.to_string(), &Value::Dict(unmatched));
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}
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Pattern::Placeholder => (),
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_ => unreachable!(),
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},
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_ => unreachable!(),
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}
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}
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Some(self)
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}
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_ => None,
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}
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}
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pub fn match_clauses(
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&mut self,
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value: &Value<'src>,
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clauses: &'src [MatchClause],
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) -> LResult<'src> {
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{
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let parent = self.ast;
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let to = self.locals.len();
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for MatchClause { patt, body, guard } in clauses.iter() {
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if let Some(_) = self.match_pattern(&patt.0, value) {
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let pass_guard = match guard {
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None => true,
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Some((ast, _)) => {
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self.ast = ast;
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let guard_res = self.eval();
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match &guard_res {
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Err(_) => return guard_res,
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Ok(val) => val.bool(),
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}
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}
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};
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if !pass_guard {
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self.pop_to(to);
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continue;
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}
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self.ast = &body.0;
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let res = self.eval();
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self.pop_to(to);
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self.ast = parent;
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return res;
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}
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}
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Err(LErr::new(format!("no match")))
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}
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}
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pub fn apply(&mut self, callee: Value<'src>, caller: Value<'src>) -> LResult<'src> {
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match (callee, caller) {
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(Value::Keyword(kw), Value::Dict(dict)) => {
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if let Some(val) = dict.get(kw) {
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Ok(val.clone())
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} else {
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Ok(Value::Nil)
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}
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}
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(Value::Dict(dict), Value::Keyword(kw)) => {
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if let Some(val) = dict.get(kw) {
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Ok(val.clone())
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} else {
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Ok(Value::Nil)
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}
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}
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(Value::Fn(f), Value::Tuple(args)) => {
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let args = Value::Tuple(args);
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self.match_clauses(&args, f.body)
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}
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(Value::Fn(_f), Value::Args(_args)) => todo!(),
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(_, Value::Keyword(_)) => Ok(Value::Nil),
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(_, Value::Args(_)) => Err(LErr::new(format!("you may only call a function"))),
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(Value::Base(f), Value::Tuple(args)) => match f {
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Base::Nullary(f) => {
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let num_args = args.len();
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if num_args != 0 {
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Err(LErr::new(format!(
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"wrong arity: expected 0 arguments, got {num_args}"
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)))
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} else {
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Ok(f())
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}
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}
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Base::Unary(f) => {
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let num_args = args.len();
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if num_args != 1 {
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Err(LErr::new(format!(
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"wrong arity: expected 1 argument, got {num_args}"
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)))
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} else {
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Ok(f(&args[0]))
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}
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}
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Base::Binary(r#fn) => {
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let num_args = args.len();
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if num_args != 2 {
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Err(LErr::new(format!(
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"wrong arity: expected 2 arguments, got {num_args}"
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)))
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} else {
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Ok(r#fn(&args[0], &args[1]))
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}
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}
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Base::Ternary(f) => {
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let num_args = args.len();
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if num_args != 3 {
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Err(LErr::new(format!(
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"wrong arity: expected 3 arguments, got {num_args}"
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)))
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} else {
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Ok(f(&args[0], &args[1], &args[2]))
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}
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}
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},
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_ => unreachable!(),
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}
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}
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pub fn eval(&mut self) -> LResult<'src> {
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let root = self.ast;
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let result = match self.ast {
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Ast::Nil => Ok(Value::Nil),
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Ast::Boolean(b) => Ok(Value::Boolean(*b)),
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Ast::Number(n) => Ok(Value::Number(*n)),
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Ast::Keyword(k) => Ok(Value::Keyword(k)),
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Ast::String(s) => Ok(Value::InternedString(s)),
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Ast::Interpolated(parts) => {
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let mut interpolated = String::new();
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for part in parts {
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match &part.0 {
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StringPart::Data(s) => interpolated.push_str(s.as_str()),
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StringPart::Word(w) => {
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let val = self.resolve(w)?;
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interpolated.push_str(val.interpolate().as_str())
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}
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StringPart::Inline(_) => unreachable!(),
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}
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}
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Ok(Value::AllocatedString(Rc::new(interpolated)))
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}
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Ast::Block(exprs) => {
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let parent = self.ast;
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let to = self.locals.len();
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let mut result = Value::Nil;
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for (expr, _) in exprs {
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self.ast = &expr;
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result = self.eval()?;
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}
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self.pop_to(to);
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self.ast = parent;
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Ok(result)
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}
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Ast::If(cond, if_true, if_false) => {
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let parent = self.ast;
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self.ast = &cond.0;
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let truthy = self.eval()?.bool();
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self.ast = if truthy { &if_true.0 } else { &if_false.0 };
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let result = self.eval();
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self.ast = parent;
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result
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}
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Ast::List(members) => {
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let parent = self.ast;
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let mut vect = Vector::new();
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for member in members {
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self.ast = &member.0;
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if let Ast::Splat(_) = self.ast {
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let to_splat = self.eval()?;
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match to_splat {
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Value::List(list) => vect.append(list),
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_ => {
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return Err(LErr::new(format!(
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"only lists may be splatted into lists"
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)))
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}
|
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}
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} else {
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vect.push_back(self.eval()?)
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}
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}
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self.ast = parent;
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Ok(Value::List(vect))
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}
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Ast::Tuple(members) => {
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let parent = self.ast;
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let mut vect = Vec::new();
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for member in members {
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self.ast = &member.0;
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vect.push(self.eval()?);
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}
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self.ast = parent;
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Ok(Value::Tuple(Rc::new(vect)))
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}
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Ast::Word(w) | Ast::Splat(w) => {
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let val = self.resolve(&w.to_string())?;
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Ok(val)
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}
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Ast::Let(patt, expr) => {
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let parent = self.ast;
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self.ast = &expr.0;
|
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let val = self.eval()?;
|
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let result = match self.match_pattern(&patt.0, &val) {
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Some(_) => Ok(val),
|
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None => Err(LErr::new(format!("no match"))),
|
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};
|
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self.ast = parent;
|
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result
|
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}
|
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Ast::Placeholder => Ok(Value::Placeholder),
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Ast::Error => unreachable!(),
|
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Ast::Arguments(a) => {
|
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let parent = self.ast;
|
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let mut args = vec![];
|
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for (arg, _) in a.iter() {
|
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self.ast = arg;
|
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let arg = self.eval()?;
|
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args.push(arg);
|
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}
|
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let result = if args.iter().any(|arg| matches!(arg, Value::Placeholder)) {
|
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Ok(Value::Args(Rc::new(args)))
|
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} else {
|
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Ok(Value::Tuple(Rc::new(args)))
|
||||
};
|
||||
self.ast = parent;
|
||||
result
|
||||
}
|
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Ast::Dict(terms) => {
|
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let parent = self.ast;
|
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let mut dict = HashMap::new();
|
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for term in terms {
|
||||
let (term, _) = term;
|
||||
match term {
|
||||
Ast::Pair(key, value) => {
|
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self.ast = &value.0;
|
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let value = self.eval()?;
|
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dict.insert(*key, value);
|
||||
}
|
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Ast::Splat(_) => {
|
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self.ast = term;
|
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let resolved = self.eval()?;
|
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let Value::Dict(to_splat) = resolved else {
|
||||
return Err(LErr::new(format!("cannot splat non-dict into dict")));
|
||||
};
|
||||
dict = to_splat.union(dict);
|
||||
}
|
||||
_ => unreachable!(),
|
||||
}
|
||||
}
|
||||
self.ast = parent;
|
||||
Ok(Value::Dict(dict))
|
||||
}
|
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Ast::Box(name, expr) => {
|
||||
let parent = self.ast;
|
||||
self.ast = &expr.0;
|
||||
let val = self.eval()?;
|
||||
let boxed = Value::Box(name, Rc::new(RefCell::new(val)));
|
||||
self.bind(name.to_string(), &boxed);
|
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self.ast = parent;
|
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Ok(boxed)
|
||||
}
|
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Ast::Synthetic(root, first, rest) => {
|
||||
let parent = self.ast;
|
||||
self.ast = &root.0;
|
||||
let root = self.eval()?;
|
||||
self.ast = &first.0;
|
||||
let first = self.eval()?;
|
||||
let mut curr = self.apply(root, first)?;
|
||||
for term in rest.iter() {
|
||||
self.ast = &term.0;
|
||||
let next = self.eval()?;
|
||||
curr = self.apply(curr, next)?;
|
||||
}
|
||||
self.ast = parent;
|
||||
Ok(curr)
|
||||
}
|
||||
Ast::When(clauses) => {
|
||||
let parent = self.ast;
|
||||
for clause in clauses.iter() {
|
||||
let WhenClause { cond, body } = &clause.0;
|
||||
self.ast = &cond.0;
|
||||
if self.eval()?.bool() {
|
||||
self.ast = &body.0;
|
||||
let result = self.eval();
|
||||
self.ast = parent;
|
||||
return result;
|
||||
};
|
||||
}
|
||||
Err(LErr::new(format!("no match")))
|
||||
}
|
||||
Ast::Match(value, clauses) => {
|
||||
let parent = self.ast;
|
||||
self.ast = &value.0;
|
||||
let value = self.eval()?;
|
||||
let result = self.match_clauses(&value, clauses);
|
||||
self.ast = parent;
|
||||
result
|
||||
}
|
||||
Ast::Fn(name, clauses, doc) => {
|
||||
let doc = doc.map(|s| s.to_string());
|
||||
let the_fn = Value::Fn::<'src>(Rc::new(Fn::<'src> {
|
||||
name: name.to_string(),
|
||||
body: clauses,
|
||||
doc,
|
||||
}));
|
||||
self.bind(name.to_string(), &the_fn);
|
||||
Ok(the_fn)
|
||||
}
|
||||
Ast::FnDeclaration(_name) => Ok(Value::Nil),
|
||||
Ast::Panic(msg) => {
|
||||
self.ast = &msg.0;
|
||||
let msg = self.eval()?;
|
||||
Err(LErr::new(format!("{msg}")))
|
||||
}
|
||||
Ast::Repeat(times, body) => {
|
||||
let parent = self.ast;
|
||||
self.ast = ×.0;
|
||||
let times_num = match self.eval() {
|
||||
Ok(Value::Number(n)) => n as usize,
|
||||
_ => return Err(LErr::new(format!("repeat may only take numbers"))),
|
||||
};
|
||||
self.ast = &body.0;
|
||||
for _ in 0..times_num {
|
||||
self.eval()?;
|
||||
}
|
||||
self.ast = parent;
|
||||
Ok(Value::Nil)
|
||||
}
|
||||
Ast::Do(terms) => {
|
||||
let parent = self.ast;
|
||||
self.ast = &terms[0].0;
|
||||
let mut result = self.eval()?;
|
||||
for (term, _) in terms.iter().skip(1) {
|
||||
self.ast = term;
|
||||
let next = self.eval()?;
|
||||
let arg = Value::Tuple(Rc::new(vec![result]));
|
||||
result = self.apply(next, arg)?;
|
||||
}
|
||||
self.ast = parent;
|
||||
Ok(result)
|
||||
}
|
||||
Ast::Pair(..) => {
|
||||
unreachable!()
|
||||
}
|
||||
Ast::Loop(init, clauses) => {
|
||||
let parent = self.ast;
|
||||
self.ast = &init.0;
|
||||
let mut args = self.eval()?;
|
||||
loop {
|
||||
let result = self.match_clauses(&args, clauses)?;
|
||||
if let Value::Recur(recur_args) = result {
|
||||
args = Value::Tuple(Rc::new(recur_args));
|
||||
} else {
|
||||
self.ast = parent;
|
||||
return Ok(result);
|
||||
}
|
||||
}
|
||||
}
|
||||
Ast::Recur(args) => {
|
||||
let parent = self.ast;
|
||||
let mut vect = Vec::new();
|
||||
for arg in args {
|
||||
self.ast = &arg.0;
|
||||
vect.push(self.eval()?);
|
||||
}
|
||||
self.ast = parent;
|
||||
Ok(Value::Recur(vect))
|
||||
}
|
||||
};
|
||||
self.ast = root;
|
||||
result
|
||||
}
|
||||
}
|
||||
Loading…
Reference in New Issue
Block a user