forked from Orchid/orchid
43 lines
1.2 KiB
Rust
43 lines
1.2 KiB
Rust
use std::fmt::Debug;
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use crate::external::litconv::{with_str, with_uint};
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use crate::external::runtime_error::RuntimeError;
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use crate::representations::{Literal, Primitive};
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use crate::{atomic_impl, atomic_redirect, externfn_impl};
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use crate::representations::interpreted::{Clause, ExprInst};
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/// CharAt function
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///
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/// Next state: [CharAt1]
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#[derive(Clone)]
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pub struct CharAt2;
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externfn_impl!(CharAt2, |_: &Self, x: ExprInst| Ok(CharAt1{x}));
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/// Partially applied CharAt function
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///
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/// Prev state: [CharAt2]; Next state: [CharAt0]
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#[derive(Debug, Clone)]
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pub struct CharAt1{ x: ExprInst }
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atomic_redirect!(CharAt1, x);
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atomic_impl!(CharAt1);
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externfn_impl!(CharAt1, |this: &Self, x: ExprInst| {
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with_str(&this.x, |s| Ok(CharAt0{ s: s.clone(), x }))
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});
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/// Fully applied CharAt function.
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///
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/// Prev state: [CharAt1]
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#[derive(Debug, Clone)]
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pub struct CharAt0 { s: String, x: ExprInst }
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atomic_redirect!(CharAt0, x);
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atomic_impl!(CharAt0, |Self{ s, x }: &Self, _| {
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with_uint(x, |i| if let Some(c) = s.chars().nth(i as usize) {
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Ok(Clause::P(Primitive::Literal(Literal::Char(c))))
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} else {
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RuntimeError::fail("Character index out of bounds".to_string(), "indexing string")?
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})
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});
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