forked from Orchid/orchid
48 lines
1.4 KiB
Rust
48 lines
1.4 KiB
Rust
use std::fmt::Debug;
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use std::hash::Hash;
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use crate::external::assertion_error::AssertionError;
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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;
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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, c: Clause| {Ok(CharAt1{c})});
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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, PartialEq, Hash)]
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pub struct CharAt1{ c: Clause }
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atomic_redirect!(CharAt1, c);
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atomic_impl!(CharAt1);
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externfn_impl!(CharAt1, |this: &Self, c: Clause| {
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let s = if let Ok(Literal::Str(s)) = this.c.clone().try_into() {s}
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else {AssertionError::fail(this.c.clone(), "a string")?};
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Ok(CharAt0{ s, c })
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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, PartialEq, Hash)]
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pub struct CharAt0 { s: String, c: Clause }
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atomic_redirect!(CharAt0, c);
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atomic_impl!(CharAt0, |Self{ s, c }: &Self| {
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let i = if let Ok(Literal::Uint(i)) = c.clone().try_into() {i}
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else {AssertionError::fail(c.clone(), "an uint")?};
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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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