harper-core 2.0.0

The language checker for developers.
Documentation 
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use crate::expr::Expr;
use crate::expr::SequenceExpr;
use crate::{Token, TokenStringExt};

use crate::linting::expr_linter::Chunk;
use crate::linting::{ExprLinter, Lint, LintKind, Suggestion};

/// See also:
/// harper-core/src/linting/compound_nouns/implied_ownership_compound_nouns.rs
/// harper-core/src/linting/lets_confusion/mod.rs
/// harper-core/src/linting/lets_confusion/no_contraction_with_verb.rs
/// harper-core/src/linting/pronoun_contraction/should_contract.rs
pub struct LetUsRedundancy {
    expr: Box<dyn Expr>,
}

impl Default for LetUsRedundancy {
    fn default() -> Self {
        let pattern = SequenceExpr::aco("let's").then_whitespace().then_pronoun();

        Self {
            expr: Box::new(pattern),
        }
    }
}

impl ExprLinter for LetUsRedundancy {
    type Unit = Chunk;

    fn expr(&self) -> &dyn Expr {
        self.expr.as_ref()
    }

    fn match_to_lint(&self, matched_tokens: &[Token], source: &[char]) -> Option<Lint> {
        let template = matched_tokens.span()?.get_content(source);
        let pronoun = matched_tokens.last()?.get_str(source);

        Some(Lint {
            span: matched_tokens.span()?,
            lint_kind: LintKind::Repetition,
            suggestions: vec![
                Suggestion::replace_with_match_case(
                    format!("lets {pronoun}").chars().collect(),
                    template,
                ),
                Suggestion::replace_with_match_case(
                    "let's".to_string().chars().collect(),
                    template,
                ),
            ],
            message: "`let's` stands for `let us`, so including another pronoun is redundant."
                .to_owned(),
            priority: 31,
        })
    }

    fn description(&self) -> &'static str {
        "Many are not aware that the contraction `let's` is short for `let us`. As a result, many will incorrectly use it before a pronoun, such as in the phrase `let's us do`."
    }
}