36 lines
886 B
Rust
36 lines
886 B
Rust
use crate::error::{Error, Result};
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use crate::expr::{self, Expr};
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use crate::{iter, token};
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use proc_macro::{Span, TokenStream};
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pub struct Args {
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pub condition: Expr,
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pub then: Then,
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}
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pub enum Then {
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Const(Span),
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Attribute(TokenStream),
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}
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pub fn parse(input: TokenStream) -> Result<Args> {
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let ref mut input = iter::new(input);
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let condition = expr::parse(input)?;
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token::parse_punct(input, ',')?;
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if input.peek().is_none() {
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return Err(Error::new(Span::call_site(), "expected one or more attrs"));
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}
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let const_span = token::parse_optional_keyword(input, "const");
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let then = if let Some(const_span) = const_span {
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token::parse_optional_punct(input, ',');
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token::parse_end(input)?;
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Then::Const(const_span)
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} else {
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Then::Attribute(input.collect())
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};
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Ok(Args { condition, then })
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}
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