sqruff_lib/rules/convention/
cv04.rs

use ahash::AHashMap;
use itertools::Itertools;
use sqruff_lib_core::dialects::syntax::{SyntaxKind, SyntaxSet};
use sqruff_lib_core::lint_fix::LintFix;
use sqruff_lib_core::parser::segments::base::{ErasedSegment, SegmentBuilder};

use crate::core::config::Value;
use crate::core::rules::base::{Erased, ErasedRule, LintResult, Rule, RuleGroups};
use crate::core::rules::context::RuleContext;
use crate::core::rules::crawlers::{Crawler, SegmentSeekerCrawler};
use crate::utils::functional::context::FunctionalContext;

#[derive(Debug, Default, Clone)]
pub struct RuleCV04 {
    pub prefer_count_1: bool,
    pub prefer_count_0: bool,
}

impl Rule for RuleCV04 {
    fn load_from_config(&self, _config: &AHashMap<String, Value>) -> Result<ErasedRule, String> {
        Ok(RuleCV04 {
            prefer_count_1: _config
                .get("prefer_count_1")
                .unwrap_or(&Value::Bool(false))
                .as_bool()
                .unwrap(),
            prefer_count_0: _config
                .get("prefer_count_0")
                .unwrap_or(&Value::Bool(false))
                .as_bool()
                .unwrap(),
        }
        .erased())
    }

    fn name(&self) -> &'static str {
        "convention.count_rows"
    }

    fn description(&self) -> &'static str {
        "Use consistent syntax to express \"count number of rows\"."
    }

    fn long_description(&self) -> &'static str {
        r#"
**Anti-pattern**

In this example, `count(1)` is used to count the number of rows in a table.

```sql
select
    count(1)
from table_a
```

**Best practice**

Use count(*) unless specified otherwise by config prefer_count_1, or prefer_count_0 as preferred.

```sql
select
    count(*)
from table_a
```
"#
    }

    fn groups(&self) -> &'static [RuleGroups] {
        &[RuleGroups::All, RuleGroups::Core, RuleGroups::Convention]
    }

    fn eval(&self, context: RuleContext) -> Vec<LintResult> {
        let Some(function_name) = context
            .segment
            .child(const { &SyntaxSet::new(&[SyntaxKind::FunctionName]) })
        else {
            return Vec::new();
        };

        if function_name.raw().eq_ignore_ascii_case("COUNT") {
            let f_content = FunctionalContext::new(context.clone())
                .segment()
                .children(Some(|it: &ErasedSegment| it.is_type(SyntaxKind::Bracketed)))
                .children(Some(|it: &ErasedSegment| {
                    !it.is_meta()
                        && !matches!(
                            it.get_type(),
                            SyntaxKind::StartBracket
                                | SyntaxKind::EndBracket
                                | SyntaxKind::Whitespace
                                | SyntaxKind::Newline
                        )
                }));

            if f_content.len() != 1 {
                return Vec::new();
            }

            let preferred = if self.prefer_count_1 {
                "1"
            } else if self.prefer_count_0 {
                "0"
            } else {
                "*"
            };

            if f_content[0].is_type(SyntaxKind::Star)
                && (self.prefer_count_0 || self.prefer_count_1)
            {
                let new_segment =
                    SegmentBuilder::token(context.tables.next_id(), preferred, SyntaxKind::Literal)
                        .finish();
                return vec![LintResult::new(
                    context.segment.into(),
                    vec![LintFix::replace(
                        f_content[0].clone(),
                        vec![new_segment],
                        None,
                    )],
                    None,
                    None,
                    None,
                )];
            }

            if f_content[0].is_type(SyntaxKind::Expression) {
                let expression_content = f_content[0]
                    .segments()
                    .iter()
                    .filter(|it| !it.is_meta())
                    .collect_vec();

                let raw = expression_content[0].raw();
                if expression_content.len() == 1
                    && matches!(
                        expression_content[0].get_type(),
                        SyntaxKind::NumericLiteral | SyntaxKind::Literal
                    )
                    && (raw == "0" || raw == "1")
                    && raw != preferred
                {
                    let first_expression = expression_content[0].clone();
                    let first_expression_raw = first_expression.raw();

                    return vec![LintResult::new(
                        context.segment.into(),
                        vec![LintFix::replace(
                            first_expression.clone(),
                            vec![first_expression.edit(
                                context.tables.next_id(),
                                first_expression
                                    .raw()
                                    .replace(first_expression_raw.as_str(), preferred)
                                    .into(),
                                None,
                            )],
                            None,
                        )],
                        None,
                        None,
                        None,
                    )];
                }
            }
        }

        Vec::new()
    }

    fn crawl_behaviour(&self) -> Crawler {
        SegmentSeekerCrawler::new(const { SyntaxSet::new(&[SyntaxKind::Function]) }).into()
    }
}
sqruff_lib/rules/convention/cv04.rs

sqruff_lib/rules/convention/
cv04.rs
