46 lines
1.2 KiB
Rust
46 lines
1.2 KiB
Rust
use std::fmt::Debug;
|
|
|
|
use super::super::litconv::{with_str, with_uint};
|
|
use super::super::runtime_error::RuntimeError;
|
|
use crate::representations::interpreted::{Clause, ExprInst};
|
|
use crate::representations::{Literal, Primitive};
|
|
use crate::{atomic_impl, atomic_redirect, externfn_impl};
|
|
|
|
/// Takes an uint and a string, finds the char in a string at a 0-based index
|
|
///
|
|
/// Next state: [CharAt1]
|
|
#[derive(Clone)]
|
|
pub struct CharAt2;
|
|
externfn_impl!(CharAt2, |_: &Self, x: ExprInst| Ok(CharAt1 { x }));
|
|
|
|
/// Prev state: [CharAt2]; Next state: [CharAt0]
|
|
#[derive(Debug, Clone)]
|
|
pub struct CharAt1 {
|
|
x: ExprInst,
|
|
}
|
|
atomic_redirect!(CharAt1, x);
|
|
atomic_impl!(CharAt1);
|
|
externfn_impl!(CharAt1, |this: &Self, x: ExprInst| {
|
|
with_str(&this.x, |s| Ok(CharAt0 { s: s.clone(), x }))
|
|
});
|
|
|
|
/// Prev state: [CharAt1]
|
|
#[derive(Debug, Clone)]
|
|
pub struct CharAt0 {
|
|
s: String,
|
|
x: ExprInst,
|
|
}
|
|
atomic_redirect!(CharAt0, x);
|
|
atomic_impl!(CharAt0, |Self { s, x }: &Self, _| {
|
|
with_uint(x, |i| {
|
|
if let Some(c) = s.chars().nth(i as usize) {
|
|
Ok(Clause::P(Primitive::Literal(Literal::Char(c))))
|
|
} else {
|
|
RuntimeError::fail(
|
|
"Character index out of bounds".to_string(),
|
|
"indexing string",
|
|
)?
|
|
}
|
|
})
|
|
});
|