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Basic pattern matching working

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This commit is contained in:
greg 2018-08-14 21:17:43 -07:00
parent 6833bc4f00
commit 897c1181a9
2 changed files with 29 additions and 5 deletions
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25
schala-lang/src/eval.rs
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@ -1,3 +1,4 @@
use std::cell::RefCell;
use std::rc::Rc;
use std::fmt::Write;
@ -20,6 +21,7 @@ macro_rules! builtin_binding {
}
}
//TODO add a more concise way of getting a new frame
impl<'a> State<'a> {
pub fn new(symbol_table_handle: Rc<RefCell<SymbolTable>>) -> State<'a> {
let mut values = StateStack::new(Some(format!("global")));
@ -185,6 +187,7 @@ impl<'a> State<'a> {
other => return Err(format!("Tried to call {:?} which is not a function or data constructor", other)),
},
Val(v) => self.value(v),
Constructor { arity, ref name, tag, .. } if arity == 0 => Ok(Node::PrimObject { name: name.clone(), tag, items: vec![] }),
constructor @ Constructor { .. } => Ok(Node::Expr(constructor)),
func @ Func(_) => Ok(Node::Expr(func)),
Tuple(exprs) => {
@ -210,7 +213,27 @@ impl<'a> State<'a> {
Ok(Node::Expr(Expr::Unit))
},
Unit => Ok(Node::Expr(Unit)),
CaseMatch { cond, alternatives } => unimplemented!(),
CaseMatch { box cond, alternatives } => match self.expression(Node::Expr(cond))? {
Node::PrimObject { name, tag, items } => {
for alt in alternatives {
if alt.tag.map(|t| t == tag).unwrap_or(true) {
let mut inner_state = State {
values: self.values.new_frame(None),
symbol_table_handle: self.symbol_table_handle.clone(),
};
for (bound_var, val) in alt.bound_vars.iter().zip(items.iter()) {
if let Some(bv) = bound_var.as_ref() {
inner_state.values.insert(bv.clone(), ValueEntry::Binding { constant: true, val: val.clone() });
}
}
return inner_state.block(alt.item)
}
}
return Err(format!("No matches found"));
},
Node::PrimTuple { .. } => Err(format!("Tuples don't work")),
Node::Expr(e) => Err(format!("Exprs don't work {:?}", e))
},
UnimplementedSigilValue => Err(format!("Sigil value eval not implemented"))
}
}

9
schala-lang/src/reduced_ast.rs
View File

@ -57,9 +57,9 @@ pub enum Expr {
#[derive(Debug, Clone)]
pub struct Alternative {
tag: Option<usize>,
bound_vars: Vec<Rc<String>>,
item: Vec<Stmt>,
pub tag: Option<usize>,
pub bound_vars: Vec<Option<Rc<String>>>, //remember that order matters here
pub item: Vec<Stmt>,
}
#[derive(Debug, Clone)]
@ -160,8 +160,9 @@ fn reduce_if_expression(discriminator: &Discriminator, body: &IfExpressionBody,
SymbolSpec::DataConstructor { index, .. } => index.clone(),
_ => panic!("Bad symbol"),
};
let bound_vars = subpatterns.iter().flat_map(|p| match p {
let bound_vars = subpatterns.iter().map(|p| match p {
Pattern::Literal(PatternLiteral::VarPattern(var)) => Some(var.clone()),
Pattern::Ignored => None,
_ => None,
}).collect();
Alternative {