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|
use super::ast;
use super::runtime::{advance_v, Term, Value};
use std::fmt;
use std::rc::Rc;
#[derive(Debug, Clone, PartialEq)]
pub struct Builtin {
pub identifier: &'static str,
pub repr_name: &'static str,
pub arguments: Vec<Value>,
}
impl Builtin {
pub fn new(identifier: &'static str) -> Builtin {
Builtin {
identifier: identifier,
repr_name: identifier,
arguments: vec![],
}
}
// pub fn bind_arg(self: &Builtin, arg: &Value) -> Builtin {
// let mut new_args = self.arguments.clone();
// new_args.push(arg.clone());
// Builtin {
// identifier: new_identifier,
// repr_name: self.repr_name,
// arguments: new_args,
// }
// }
}
impl fmt::Display for Builtin {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut arg_str = String::new();
for argument in &self.arguments {
arg_str.push_str(format!(" {}", argument).as_str());
}
write!(f, "Builtin({}){}", self.repr_name, arg_str)
}
}
fn argument_error(builtin_id: &'static str, arg: &Value) -> Result<(Rc<Term>, usize), String> {
Err(format!(
"[runtime] cannot apply builtin {} to argument {}",
builtin_id, arg
))
}
pub const B_INTEGER_EQ: &str = "int.eq?";
pub const B_INTEGER_EQ_1: &str = "##int.eq?_1";
pub const B_INTEGER_INCREMENT: &str = "int.increment";
pub const B_INTEGER_ADD: &str = "int.add";
pub const B_INTEGER_ADD_1: &str = "##int.add_1";
pub fn make_boolean_true_function() -> Term {
let x = advance_v();
let y = advance_v();
Term::Abstraction(x, Rc::new(Term::Abstraction(y, Rc::new(Term::Variable(x)))))
}
pub fn make_boolean_false_function() -> Term {
let x = advance_v();
let y = advance_v();
Term::Abstraction(x, Rc::new(Term::Abstraction(y, Rc::new(Term::Variable(y)))))
}
pub fn make_identity_function() -> Term {
let v = advance_v();
Term::Abstraction(v, Rc::new(Term::Variable(v)))
}
pub fn try_ast_symbol_to_builtin_term(symbol: &ast::Symbol) -> Option<Term> {
let builtin = match symbol.as_str() {
"true" => return Some(make_boolean_true_function()),
"false" => return Some(make_boolean_false_function()),
"id" => return Some(make_identity_function()),
B_INTEGER_EQ => Builtin::new(B_INTEGER_EQ),
B_INTEGER_INCREMENT => Builtin::new(B_INTEGER_INCREMENT),
B_INTEGER_ADD => Builtin::new(B_INTEGER_ADD),
_ => return None,
};
Some(Term::Builtin(builtin))
}
pub fn evaluate_builtin(builtin: &Builtin, rhs: Rc<Term>) -> Result<(Rc<Term>, usize), String> {
let result_term = match builtin.identifier {
B_INTEGER_EQ => match &*rhs {
Term::Primitive(primitive) => match primitive {
Value::Integer(_) => {
let new_builtin = Builtin {
identifier: B_INTEGER_EQ_1,
repr_name: builtin.identifier,
arguments: vec![primitive.clone()],
};
Term::Builtin(new_builtin)
}
other => return argument_error(builtin.identifier, other),
},
_ => return Ok((Rc::new(Term::Builtin(builtin.clone())), 0)),
},
B_INTEGER_EQ_1 => match &*rhs {
Term::Primitive(primitive) => match primitive {
Value::Integer(value) => {
assert_eq!(builtin.arguments.len(), 1);
let other = &builtin.arguments[0];
match other {
Value::Integer(other_value) => {
if value == other_value {
make_boolean_true_function()
} else {
make_boolean_false_function()
}
}
other => return argument_error(builtin.identifier, other),
}
}
other => return argument_error(builtin.identifier, other),
},
_ => return Ok((Rc::new(Term::Builtin(builtin.clone())), 0)),
},
B_INTEGER_INCREMENT => match &*rhs {
Term::Primitive(primitive) => match primitive {
Value::Integer(value) => Term::Primitive(Value::Integer(value + 1)),
other => return argument_error(builtin.identifier, other),
},
_ => return Ok((Rc::new(Term::Builtin(builtin.clone())), 0)),
},
B_INTEGER_ADD => match &*rhs {
Term::Primitive(primitive) => match primitive {
Value::Integer(_) => {
let new_builtin = Builtin {
identifier: B_INTEGER_ADD_1,
repr_name: builtin.identifier,
arguments: vec![primitive.clone()],
};
Term::Builtin(new_builtin)
}
other => return argument_error(builtin.identifier, other),
},
_ => return Ok((Rc::new(Term::Builtin(builtin.clone())), 0)),
},
B_INTEGER_ADD_1 => match &*rhs {
Term::Primitive(primitive) => match primitive {
Value::Integer(value) => {
assert_eq!(builtin.arguments.len(), 1);
let summand = &builtin.arguments[0];
match summand {
Value::Integer(summand_value) => {
Term::Primitive(Value::Integer(summand_value + value))
}
other => return argument_error(builtin.identifier, other),
}
}
other => return argument_error(builtin.identifier, other),
},
_ => return Ok((Rc::new(Term::Builtin(builtin.clone())), 0)),
},
_ => {
return Err(format!(
"[runtime] invalid builtin evaluated: {}",
builtin.identifier
))
}
};
Ok((Rc::new(result_term), 1))
}
|
