rigsql_rules/aliasing/
al04.rs

1use std::collections::HashMap;
2
3use rigsql_core::{Segment, SegmentType};
4
5use crate::rule::{CrawlType, Rule, RuleContext, RuleGroup};
6use crate::utils::extract_alias_name;
7use crate::violation::LintViolation;
8
9/// AL04: Table aliases should be unique within a statement.
10///
11/// Duplicate table aliases create ambiguity in column references.
12#[derive(Debug, Default)]
13pub struct RuleAL04;
14
15impl Rule for RuleAL04 {
16    fn code(&self) -> &'static str {
17        "AL04"
18    }
19    fn name(&self) -> &'static str {
20        "aliasing.unique.table"
21    }
22    fn description(&self) -> &'static str {
23        "Table aliases should be unique within a statement."
24    }
25    fn explanation(&self) -> &'static str {
26        "When the same alias is used for multiple tables in a single statement, \
27         column references become ambiguous. Each table alias must be unique within \
28         its containing statement."
29    }
30    fn groups(&self) -> &[RuleGroup] {
31        &[RuleGroup::Aliasing]
32    }
33    fn is_fixable(&self) -> bool {
34        false
35    }
36
37    fn crawl_type(&self) -> CrawlType {
38        CrawlType::Segment(vec![SegmentType::SelectStatement])
39    }
40
41    fn eval(&self, ctx: &RuleContext) -> Vec<LintViolation> {
42        let mut aliases: Vec<(String, rigsql_core::Span)> = Vec::new();
43        collect_table_aliases(ctx.segment, &mut aliases);
44
45        let mut violations = Vec::new();
46        let mut seen: HashMap<String, rigsql_core::Span> = HashMap::new();
47
48        for (name, span) in &aliases {
49            let lower = name.to_lowercase();
50            if let Some(first_span) = seen.get(&lower) {
51                violations.push(LintViolation::new(
52                    self.code(),
53                    format!(
54                        "Duplicate table alias '{}'. First used at offset {}.",
55                        name, first_span.start,
56                    ),
57                    *span,
58                ));
59            } else {
60                seen.insert(lower, *span);
61            }
62        }
63
64        violations
65    }
66}
67
68/// Collect alias names from FROM and JOIN clauses within a statement.
69fn collect_table_aliases(segment: &Segment, aliases: &mut Vec<(String, rigsql_core::Span)>) {
70    let st = segment.segment_type();
71
72    // Only look for aliases within FROM and JOIN clauses
73    if st == SegmentType::FromClause || st == SegmentType::JoinClause {
74        find_alias_names(segment, aliases);
75        return;
76    }
77
78    // Don't recurse into nested SelectStatements (subqueries have their own scope)
79    if st == SegmentType::SelectStatement || st == SegmentType::Subquery {
80        // Only recurse into top-level children for the current statement
81        // Skip nested selects
82        if st == SegmentType::Subquery {
83            return;
84        }
85    }
86
87    for child in segment.children() {
88        collect_table_aliases(child, aliases);
89    }
90}
91
92/// Find AliasExpression nodes and extract the alias name (last identifier).
93fn find_alias_names(segment: &Segment, aliases: &mut Vec<(String, rigsql_core::Span)>) {
94    if segment.segment_type() == SegmentType::AliasExpression {
95        if let Some(name) = extract_alias_name(segment.children()) {
96            aliases.push((name, segment.span()));
97        }
98        return;
99    }
100
101    // Don't recurse into subqueries
102    if segment.segment_type() == SegmentType::Subquery {
103        return;
104    }
105
106    for child in segment.children() {
107        find_alias_names(child, aliases);
108    }
109}
110
111#[cfg(test)]
112mod tests {
113    use super::*;
114    use crate::test_utils::lint_sql;
115
116    #[test]
117    fn test_al04_flags_duplicate_alias() {
118        let violations = lint_sql(
119            "SELECT * FROM t1 AS a JOIN t2 AS a ON t1.id = t2.id",
120            RuleAL04,
121        );
122        assert_eq!(violations.len(), 1);
123    }
124
125    #[test]
126    fn test_al04_accepts_unique_aliases() {
127        let violations = lint_sql(
128            "SELECT * FROM t1 AS a JOIN t2 AS b ON a.id = b.id",
129            RuleAL04,
130        );
131        assert_eq!(violations.len(), 0);
132    }
133}
rigsql_rules/aliasing/al04.rs

rigsql_rules/aliasing/
al04.rs
