uqa_sql/
render.rs

1//
2// Unified Query Algebra
3//
4// Copyright (c) 2023-2026 Cognica, Inc.
5//
6
7//! Stable SQL rendering for compiler-owned statement trees.
8
9use std::fmt::Write as _;
10
11use uqa_core::{TemporalValue, Value};
12
13use crate::ast::{
14    CteBody, CteMaterialization, Expr, FrameBound, FrameMode, FromClause, JoinKind, LockWait,
15    NullsOrder, OrderBy, Projection, ReturningAliases, SelectStmt, SetOpKind, Statement,
16    TableFunction, WindowReferenceKind, WindowSpec, CTE,
17};
18use crate::SQLError;
19
20mod commands;
21use commands::{delete_sql, insert_sql, merge_sql, update_sql};
22
23/// Render one executable statement represented by UQA's durable SQL AST.
24pub fn statement_sql(statement: &Statement) -> Result<String, SQLError> {
25    match statement {
26        Statement::Select(select) => Ok(select_sql(select)),
27        Statement::Insert(insert) => Ok(insert_sql(insert)),
28        Statement::Update(update) => Ok(update_sql(update)),
29        Statement::Delete(delete) => Ok(delete_sql(delete)),
30        Statement::Merge(merge) => Ok(merge_sql(merge)),
31        Statement::Notify { channel, payload } => {
32            let payload = if payload.is_empty() {
33                String::new()
34            } else {
35                format!(", {}", string_literal(payload))
36            };
37            Ok(format!("NOTIFY {}{payload}", ident(channel)))
38        }
39        _ => Err(SQLError::Internal(
40            "durable rewrite-rule action has an unsupported statement kind".into(),
41        )),
42    }
43}
44
45/// Render one compiler-owned scalar expression without consulting runtime state.
46pub fn expression_sql(expression: &Expr) -> Result<String, SQLError> {
47    render_expr(expression)
48}
49
50fn select_sql(statement: &SelectStmt) -> String {
51    let mut rendered = with_sql(&statement.with);
52    if let Some(set) = statement.set_op.as_deref() {
53        let left = set
54            .left
55            .as_deref()
56            .map_or_else(|| select_body_sql(statement), select_sql);
57        rendered.push('(');
58        rendered.push_str(&left);
59        rendered.push_str(") ");
60        rendered.push_str(match set.kind {
61            SetOpKind::Union => "UNION",
62            SetOpKind::Intersect => "INTERSECT",
63            SetOpKind::Except => "EXCEPT",
64        });
65        if set.all {
66            rendered.push_str(" ALL");
67        }
68        rendered.push_str(" (");
69        rendered.push_str(&select_sql(&set.right));
70        rendered.push(')');
71        render_order_limit_offset(
72            &mut rendered,
73            &set.combined_order_by,
74            set.combined_limit.as_ref(),
75            set.combined_with_ties,
76            set.combined_offset.as_ref(),
77        );
78        return rendered;
79    }
80    rendered.push_str(&select_body_sql(statement));
81    rendered
82}
83
84fn select_body_sql(statement: &SelectStmt) -> String {
85    let mut rendered = String::new();
86    if statement.values.is_empty() {
87        rendered.push_str("SELECT");
88        if !statement.distinct_on.is_empty() {
89            rendered.push_str(" DISTINCT ON (");
90            rendered.push_str(&expr_list(&statement.distinct_on));
91            rendered.push(')');
92        } else if statement.distinct {
93            rendered.push_str(" DISTINCT");
94        }
95        rendered.push(' ');
96        rendered.push_str(&projections_sql(&statement.projections));
97        if let Some(source) = &statement.from {
98            rendered.push_str(" FROM ");
99            rendered.push_str(&from_sql(source));
100        }
101        if let Some(predicate) = &statement.r#where {
102            rendered.push_str(" WHERE ");
103            rendered.push_str(&expr_sql(predicate));
104        }
105        if !statement.grouping_sets.is_empty() {
106            rendered.push_str(" GROUP BY ");
107            if statement.group_distinct {
108                rendered.push_str("DISTINCT ");
109            }
110            rendered.push_str("GROUPING SETS (");
111            rendered.push_str(
112                &statement
113                    .grouping_sets
114                    .iter()
115                    .map(|set| format!("({})", expr_list(set)))
116                    .collect::<Vec<_>>()
117                    .join(", "),
118            );
119            rendered.push(')');
120        } else if !statement.group_by.is_empty() {
121            rendered.push_str(" GROUP BY ");
122            if statement.group_distinct {
123                rendered.push_str("DISTINCT ");
124            }
125            rendered.push_str(&expr_list(&statement.group_by));
126        }
127        if let Some(predicate) = &statement.having {
128            rendered.push_str(" HAVING ");
129            rendered.push_str(&expr_sql(predicate));
130        }
131    } else {
132        rendered.push_str("VALUES ");
133        rendered.push_str(&rows_sql(&statement.values));
134    }
135    render_order_limit_offset(
136        &mut rendered,
137        &statement.order_by,
138        statement.limit.as_ref(),
139        statement.with_ties,
140        statement.offset.as_ref(),
141    );
142    for locking in &statement.locking {
143        rendered.push(' ');
144        rendered.push_str(locking.strength.sql_name());
145        if !locking.relations.is_empty() {
146            rendered.push_str(" OF ");
147            rendered.push_str(&ident_list(&locking.relations));
148        }
149        rendered.push_str(match locking.wait {
150            LockWait::Block => "",
151            LockWait::SkipLocked => " SKIP LOCKED",
152            LockWait::NoWait => " NOWAIT",
153        });
154    }
155    rendered
156}
157
158#[expect(
159    clippy::too_many_lines,
160    reason = "exhaustive FROM rendering keeps each AST variant visibly complete"
161)]
162fn from_sql(source: &FromClause) -> String {
163    match source {
164        FromClause::Table {
165            name,
166            alias,
167            column_aliases,
168            include_descendants,
169            ..
170        } => {
171            let mut rendered = only_relation(name, *include_descendants);
172            render_relation_alias(&mut rendered, alias.as_deref(), column_aliases);
173            rendered
174        }
175        FromClause::Join {
176            left,
177            right,
178            kind,
179            on,
180            using,
181            natural,
182            alias,
183            column_aliases,
184            lateral,
185        } => {
186            let mut rendered = String::from("(");
187            rendered.push_str(&from_sql(left));
188            rendered.push(' ');
189            if *natural {
190                rendered.push_str("NATURAL ");
191            }
192            rendered.push_str(match kind {
193                JoinKind::Inner => "JOIN",
194                JoinKind::Left => "LEFT JOIN",
195                JoinKind::Right => "RIGHT JOIN",
196                JoinKind::Full => "FULL JOIN",
197                JoinKind::Cross => "CROSS JOIN",
198            });
199            rendered.push(' ');
200            if *lateral {
201                rendered.push_str("LATERAL ");
202            }
203            rendered.push_str(&from_sql(right));
204            if let Some(predicate) = on {
205                rendered.push_str(" ON ");
206                rendered.push_str(&expr_sql(predicate));
207            } else if let Some(using) = using {
208                rendered.push_str(" USING (");
209                rendered.push_str(&ident_list(&using.columns));
210                rendered.push(')');
211                if let Some(alias) = &using.alias {
212                    rendered.push_str(" AS ");
213                    rendered.push_str(&ident(alias));
214                }
215            }
216            rendered.push(')');
217            render_relation_alias(&mut rendered, alias.as_deref(), column_aliases);
218            rendered
219        }
220        FromClause::Values {
221            rows,
222            alias,
223            column_aliases,
224            ..
225        } => {
226            let mut rendered = format!("(VALUES {})", rows_sql(rows));
227            render_relation_alias(&mut rendered, alias.as_deref(), column_aliases);
228            rendered
229        }
230        FromClause::Function {
231            name,
232            output_name: _,
233            relations,
234            args,
235            alias,
236            column_aliases,
237            ordinality,
238            column_types,
239            ..
240        } => {
241            let mut arguments = args.iter().map(expr_sql).collect::<Vec<_>>();
242            if let Some(relations) = relations {
243                arguments.insert(0, relations.left.clone());
244                arguments.insert(2, relations.right.clone());
245            }
246            let mut rendered = format!("{name}({})", arguments.join(", "));
247            if *ordinality {
248                rendered.push_str(" WITH ORDINALITY");
249            }
250            render_function_alias(
251                &mut rendered,
252                alias.as_deref(),
253                column_aliases,
254                column_types,
255            );
256            rendered
257        }
258        FromClause::FunctionGroup {
259            functions,
260            alias,
261            column_aliases,
262            ordinality,
263        } => {
264            let mut rendered = format!(
265                "ROWS FROM ({})",
266                functions
267                    .iter()
268                    .map(table_function_sql)
269                    .collect::<Vec<_>>()
270                    .join(", ")
271            );
272            if *ordinality {
273                rendered.push_str(" WITH ORDINALITY");
274            }
275            render_relation_alias(&mut rendered, alias.as_deref(), column_aliases);
276            rendered
277        }
278        FromClause::Subquery {
279            body,
280            alias,
281            column_aliases,
282        } => {
283            let mut rendered = format!("({})", select_sql(body));
284            render_relation_alias(&mut rendered, alias.as_deref(), column_aliases);
285            rendered
286        }
287    }
288}
289
290fn table_function_sql(function: &TableFunction) -> String {
291    let mut arguments = function.args.iter().map(expr_sql).collect::<Vec<_>>();
292    if let Some(relations) = &function.relations {
293        arguments.insert(0, relations.left.clone());
294        arguments.insert(2, relations.right.clone());
295    }
296    let mut rendered = format!("{}({})", function.name, arguments.join(", "));
297    if !function.column_types.is_empty() {
298        rendered.push_str(" AS (");
299        rendered.push_str(
300            &function
301                .column_aliases
302                .iter()
303                .zip(&function.column_types)
304                .map(|(name, ty)| format!("{} {ty}", ident(name)))
305                .collect::<Vec<_>>()
306                .join(", "),
307        );
308        rendered.push(')');
309    }
310    rendered
311}
312
313#[expect(
314    clippy::too_many_lines,
315    reason = "exhaustive scalar rendering keeps every durable AST variant explicit"
316)]
317fn render_expr(expression: &Expr) -> Result<String, SQLError> {
318    Ok(match expression {
319        Expr::Star => "*".into(),
320        Expr::QualifiedStar(qualifier) => format!("{}.*", ident(qualifier)),
321        Expr::Default => "DEFAULT".into(),
322        Expr::Column(name) => ident(name),
323        Expr::QualifiedColumn { qualifier, column } => {
324            format!("{}.{}", ident(qualifier), ident(column))
325        }
326        Expr::InternalColumn(column) => {
327            return Err(SQLError::Internal(format!(
328                "executor-only column {column:?} reached durable SQL rendering"
329            )))
330        }
331        Expr::Literal(value) => value_sql(value),
332        Expr::TypedLiteral { value, ty } => format!("({})::{ty}", value_sql(value)),
333        Expr::Param(index) => format!("${index}"),
334        Expr::Func {
335            name,
336            args,
337            distinct,
338            order_by,
339            filter,
340            ..
341        } => {
342            let mut arguments = args.iter().map(expr_sql).collect::<Vec<_>>().join(", ");
343            if *distinct {
344                arguments = format!("DISTINCT {arguments}");
345            }
346            if !order_by.is_empty() {
347                if !arguments.is_empty() {
348                    arguments.push(' ');
349                }
350                arguments.push_str("ORDER BY ");
351                arguments.push_str(&order_by_sql(order_by));
352            }
353            let mut rendered = format!("{name}({arguments})");
354            if let Some(filter) = filter {
355                write!(&mut rendered, " FILTER (WHERE {})", expr_sql(filter))
356                    .expect("writing to a String cannot fail");
357            }
358            rendered
359        }
360        Expr::Array(items) => format!("ARRAY[{}]", expr_list(items)),
361        Expr::Row(items) => format!("ROW({})", expr_list(items)),
362        Expr::Binary { op, lhs, rhs } => format!(
363            "({} {} {})",
364            expr_sql(lhs),
365            binary_operator_sql(*op),
366            expr_sql(rhs)
367        ),
368        Expr::UnaryMinus(inner) => format!("(-{})", expr_sql(inner)),
369        Expr::Not(inner) => format!("(NOT {})", expr_sql(inner)),
370        Expr::And(items) => format!(
371            "({})",
372            items.iter().map(expr_sql).collect::<Vec<_>>().join(" AND ")
373        ),
374        Expr::Or(items) => format!(
375            "({})",
376            items.iter().map(expr_sql).collect::<Vec<_>>().join(" OR ")
377        ),
378        Expr::IsNull { expr, negated } => format!(
379            "({} IS {}NULL)",
380            expr_sql(expr),
381            if *negated { "NOT " } else { "" }
382        ),
383        Expr::Between { expr, low, high } => format!(
384            "({} BETWEEN {} AND {})",
385            expr_sql(expr),
386            expr_sql(low),
387            expr_sql(high)
388        ),
389        Expr::InList {
390            expr,
391            list,
392            negated,
393        } => format!(
394            "({} {}IN ({}))",
395            expr_sql(expr),
396            if *negated { "NOT " } else { "" },
397            expr_list(list)
398        ),
399        Expr::WindowCall { name, args, spec } => {
400            format!("{name}({}) OVER {}", expr_list(args), window_sql(spec))
401        }
402        Expr::Case {
403            base,
404            when,
405            else_branch,
406        } => {
407            let mut rendered = String::from("CASE");
408            if let Some(base) = base {
409                rendered.push(' ');
410                rendered.push_str(&expr_sql(base));
411            }
412            for (condition, result) in when {
413                write!(
414                    &mut rendered,
415                    " WHEN {} THEN {}",
416                    expr_sql(condition),
417                    expr_sql(result)
418                )
419                .expect("writing to a String cannot fail");
420            }
421            if let Some(branch) = else_branch {
422                rendered.push_str(" ELSE ");
423                rendered.push_str(&expr_sql(branch));
424            }
425            rendered.push_str(" END");
426            rendered
427        }
428        Expr::Cast { expr, ty } => format!("CAST({} AS {ty})", expr_sql(expr)),
429        Expr::ScalarSubquery(body) => format!("({})", select_sql(body)),
430        Expr::Exists { body, negated } => format!(
431            "{}EXISTS ({})",
432            if *negated { "NOT " } else { "" },
433            select_sql(body)
434        ),
435        Expr::InSubquery {
436            expr,
437            body,
438            negated,
439        } => format!(
440            "({} {}IN ({}))",
441            expr_sql(expr),
442            if *negated { "NOT " } else { "" },
443            select_sql(body)
444        ),
445    })
446}
447
448fn window_sql(spec: &WindowSpec) -> String {
449    if let Some(reference) = &spec.reference {
450        if reference.kind == WindowReferenceKind::Direct
451            && spec.partition_by.is_empty()
452            && spec.order_by.is_empty()
453            && spec.frame.is_none()
454        {
455            return ident(&reference.name);
456        }
457    }
458    let mut parts = Vec::new();
459    if let Some(reference) = &spec.reference {
460        parts.push(ident(&reference.name));
461    }
462    if !spec.partition_by.is_empty() {
463        parts.push(format!("PARTITION BY {}", expr_list(&spec.partition_by)));
464    }
465    if !spec.order_by.is_empty() {
466        parts.push(format!("ORDER BY {}", order_by_sql(&spec.order_by)));
467    }
468    if let Some(frame) = &spec.frame {
469        parts.push(format!(
470            "{} BETWEEN {} AND {}",
471            match frame.mode {
472                FrameMode::Rows => "ROWS",
473                FrameMode::Range => "RANGE",
474                FrameMode::Groups => "GROUPS",
475            },
476            frame_bound_sql(&frame.start),
477            frame_bound_sql(&frame.end)
478        ));
479    }
480    format!("({})", parts.join(" "))
481}
482
483const fn binary_operator_sql(operator: crate::ast::BinaryOp) -> &'static str {
484    match operator {
485        crate::ast::BinaryOp::Equal => "=",
486        crate::ast::BinaryOp::NotEqual => "<>",
487        crate::ast::BinaryOp::Less => "<",
488        crate::ast::BinaryOp::LessEqual => "<=",
489        crate::ast::BinaryOp::Greater => ">",
490        crate::ast::BinaryOp::GreaterEqual => ">=",
491        crate::ast::BinaryOp::Add => "+",
492        crate::ast::BinaryOp::Subtract => "-",
493        crate::ast::BinaryOp::Multiply => "*",
494        crate::ast::BinaryOp::Divide => "/",
495    }
496}
497
498fn frame_bound_sql(bound: &FrameBound) -> String {
499    match bound {
500        FrameBound::UnboundedPreceding => "UNBOUNDED PRECEDING".into(),
501        FrameBound::UnboundedFollowing => "UNBOUNDED FOLLOWING".into(),
502        FrameBound::CurrentRow => "CURRENT ROW".into(),
503        FrameBound::Preceding(expression) => format!("{} PRECEDING", expr_sql(expression)),
504        FrameBound::Following(expression) => format!("{} FOLLOWING", expr_sql(expression)),
505    }
506}
507
508fn with_sql(ctes: &[CTE]) -> String {
509    if ctes.is_empty() {
510        return String::new();
511    }
512    let recursive = ctes.iter().any(|cte| cte.recursive);
513    format!(
514        "WITH {}{} ",
515        if recursive { "RECURSIVE " } else { "" },
516        ctes.iter().map(cte_sql).collect::<Vec<_>>().join(", ")
517    )
518}
519
520fn cte_sql(cte: &CTE) -> String {
521    let mut rendered = ident(&cte.name);
522    if !cte.columns.is_empty() {
523        rendered.push_str(" (");
524        rendered.push_str(&ident_list(&cte.columns));
525        rendered.push(')');
526    }
527    rendered.push_str(" AS ");
528    rendered.push_str(match cte.materialization {
529        CteMaterialization::Default => "",
530        CteMaterialization::Materialized => "MATERIALIZED ",
531        CteMaterialization::NotMaterialized => "NOT MATERIALIZED ",
532    });
533    rendered.push('(');
534    rendered.push_str(&match &cte.body {
535        CteBody::Query(query) => select_sql(query),
536        CteBody::Insert(command) => insert_sql(command),
537        CteBody::Update(command) => update_sql(command),
538        CteBody::Delete(command) => delete_sql(command),
539        CteBody::Merge(command) => merge_sql(command),
540    });
541    rendered.push(')');
542    if let Some(search) = &cte.search {
543        write!(
544            &mut rendered,
545            " SEARCH {} FIRST BY {} SET {}",
546            if search.breadth_first {
547                "BREADTH"
548            } else {
549                "DEPTH"
550            },
551            ident_list(&search.columns),
552            ident(&search.sequence_column)
553        )
554        .expect("writing to a String cannot fail");
555    }
556    if let Some(cycle) = &cte.cycle {
557        write!(
558            &mut rendered,
559            " CYCLE {} SET {} TO {} DEFAULT {} USING {}",
560            ident_list(&cycle.columns),
561            ident(&cycle.mark_column),
562            expr_sql(&cycle.mark_value),
563            expr_sql(&cycle.mark_default),
564            ident(&cycle.path_column)
565        )
566        .expect("writing to a String cannot fail");
567    }
568    rendered
569}
570
571fn render_order_limit_offset(
572    rendered: &mut String,
573    order_by: &[OrderBy],
574    limit: Option<&Expr>,
575    with_ties: bool,
576    offset: Option<&Expr>,
577) {
578    if !order_by.is_empty() {
579        rendered.push_str(" ORDER BY ");
580        rendered.push_str(&order_by_sql(order_by));
581    }
582    if with_ties {
583        if let Some(offset) = offset {
584            rendered.push_str(" OFFSET ");
585            rendered.push_str(&expr_sql(offset));
586        }
587        if let Some(limit) = limit {
588            rendered.push_str(" FETCH FIRST ");
589            rendered.push_str(&expr_sql(limit));
590            rendered.push_str(" ROWS WITH TIES");
591        }
592    } else {
593        if let Some(limit) = limit {
594            rendered.push_str(" LIMIT ");
595            rendered.push_str(&expr_sql(limit));
596        }
597        if let Some(offset) = offset {
598            rendered.push_str(" OFFSET ");
599            rendered.push_str(&expr_sql(offset));
600        }
601    }
602}
603
604fn render_returning(rendered: &mut String, aliases: &ReturningAliases, projections: &[Projection]) {
605    if projections.is_empty() {
606        return;
607    }
608    rendered.push_str(" RETURNING ");
609    if aliases.old_explicit || aliases.new_explicit {
610        rendered.push_str("WITH (");
611        let mut names = Vec::new();
612        if aliases.old_explicit {
613            names.push(format!("OLD AS {}", ident(&aliases.old)));
614        }
615        if aliases.new_explicit {
616            names.push(format!("NEW AS {}", ident(&aliases.new)));
617        }
618        rendered.push_str(&names.join(", "));
619        rendered.push_str(") ");
620    }
621    rendered.push_str(&projections_sql(projections));
622}
623
624fn render_target_alias(rendered: &mut String, relation: &str, qualifier: &str) {
625    if relation_local_name(relation) != qualifier {
626        rendered.push_str(" AS ");
627        rendered.push_str(&ident(qualifier));
628    }
629}
630
631fn render_relation_alias(rendered: &mut String, alias: Option<&str>, columns: &[String]) {
632    if let Some(alias) = alias {
633        rendered.push_str(" AS ");
634        rendered.push_str(&ident(alias));
635        if !columns.is_empty() {
636            rendered.push('(');
637            rendered.push_str(&ident_list(columns));
638            rendered.push(')');
639        }
640    }
641}
642
643fn render_function_alias(
644    rendered: &mut String,
645    alias: Option<&str>,
646    columns: &[String],
647    types: &[String],
648) {
649    if let Some(alias) = alias {
650        rendered.push_str(" AS ");
651        rendered.push_str(&ident(alias));
652    } else if !types.is_empty() {
653        rendered.push_str(" AS");
654    }
655    if !types.is_empty() {
656        rendered.push_str(" (");
657        rendered.push_str(
658            &columns
659                .iter()
660                .zip(types)
661                .map(|(name, ty)| format!("{} {ty}", ident(name)))
662                .collect::<Vec<_>>()
663                .join(", "),
664        );
665        rendered.push(')');
666    } else if !columns.is_empty() {
667        rendered.push('(');
668        rendered.push_str(&ident_list(columns));
669        rendered.push(')');
670    }
671}
672
673fn assignments_sql(assignments: &[(String, Expr)]) -> String {
674    assignments
675        .iter()
676        .map(|(column, expression)| format!("{} = {}", ident(column), expr_sql(expression)))
677        .collect::<Vec<_>>()
678        .join(", ")
679}
680
681fn projections_sql(projections: &[Projection]) -> String {
682    projections
683        .iter()
684        .map(|projection| {
685            let mut rendered = expr_sql(&projection.expr);
686            if let Some(alias) = &projection.alias {
687                rendered.push_str(" AS ");
688                rendered.push_str(&ident(alias));
689            }
690            rendered
691        })
692        .collect::<Vec<_>>()
693        .join(", ")
694}
695
696fn order_by_sql(order_by: &[OrderBy]) -> String {
697    order_by
698        .iter()
699        .map(|order| {
700            let mut rendered = expr_sql(&order.expr);
701            if order.descending {
702                rendered.push_str(" DESC");
703            }
704            match order.nulls {
705                Some(NullsOrder::First) => rendered.push_str(" NULLS FIRST"),
706                Some(NullsOrder::Last) => rendered.push_str(" NULLS LAST"),
707                None => {}
708            }
709            rendered
710        })
711        .collect::<Vec<_>>()
712        .join(", ")
713}
714
715fn rows_sql(rows: &[Vec<Expr>]) -> String {
716    rows.iter()
717        .map(|row| format!("({})", expr_list(row)))
718        .collect::<Vec<_>>()
719        .join(", ")
720}
721
722fn expr_list(expressions: &[Expr]) -> String {
723    expressions
724        .iter()
725        .map(expr_sql)
726        .collect::<Vec<_>>()
727        .join(", ")
728}
729
730fn expr_sql(expression: &Expr) -> String {
731    render_expr(expression).expect("durable SQL AST cannot contain executor-only columns")
732}
733
734fn only_relation(name: &str, include_descendants: bool) -> String {
735    if include_descendants {
736        name.to_string()
737    } else {
738        format!("ONLY {name}")
739    }
740}
741
742fn ident_list(names: &[String]) -> String {
743    names
744        .iter()
745        .map(|name| ident(name))
746        .collect::<Vec<_>>()
747        .join(", ")
748}
749
750fn ident(name: &str) -> String {
751    crate::expr::quote_ident(name)
752}
753
754fn relation_local_name(name: &str) -> &str {
755    let mut quoted = false;
756    let mut last_dot = None;
757    let bytes = name.as_bytes();
758    let mut position = 0;
759    while position < bytes.len() {
760        match bytes[position] {
761            b'"' if quoted && bytes.get(position + 1) == Some(&b'"') => position += 2,
762            b'"' => {
763                quoted = !quoted;
764                position += 1;
765            }
766            b'.' if !quoted => {
767                last_dot = Some(position);
768                position += 1;
769            }
770            _ => position += 1,
771        }
772    }
773    let component = &name[last_dot.map_or(0, |dot| dot + 1)..];
774    component
775        .strip_prefix('"')
776        .and_then(|component| component.strip_suffix('"'))
777        .unwrap_or(component)
778}
779
780fn string_literal(value: &str) -> String {
781    format!("'{}'", value.replace('\'', "''"))
782}
783
784fn value_sql(value: &Value) -> String {
785    match value {
786        Value::Null => "NULL".into(),
787        Value::Void => "''::void".into(),
788        Value::Bool(value) => if *value { "true" } else { "false" }.into(),
789        Value::Int(value) => value.to_string(),
790        Value::Float(value) if value.is_finite() => value.to_string(),
791        Value::Float(value) => format!("{}::double precision", string_literal(&value.to_string())),
792        Value::Str(value) => string_literal(value),
793        Value::FixedChar(value) => format!("{}::character", string_literal(value)),
794        Value::Bytes(value) => {
795            let mut hex = String::new();
796            for byte in value {
797                write!(&mut hex, "{byte:02x}").expect("writing to a String cannot fail");
798            }
799            format!("{}::bytea", string_literal(&format!("\\x{hex}")))
800        }
801        Value::Temporal(value) => {
802            let ty = match value {
803                TemporalValue::Date { .. } => "date",
804                TemporalValue::Time { .. } => "time",
805                TemporalValue::TimeTz { .. } => "time with time zone",
806                TemporalValue::Timestamp { .. } => "timestamp",
807                TemporalValue::TimestampTz { .. } => "timestamp with time zone",
808                TemporalValue::Interval { .. } => "interval",
809            };
810            format!("{}::{ty}", string_literal(&value.to_sql_string()))
811        }
812        Value::Decimal(value) if value.is_nan() || value.is_infinite() => {
813            format!("{}::numeric", string_literal(&value.to_sql_string()))
814        }
815        Value::Decimal(value) => format!("{}::numeric", value.to_sql_string()),
816        Value::Json(value) => format!("{}::json", string_literal(value)),
817        Value::JsonB(value) => format!("{}::jsonb", string_literal(value)),
818        Value::Array(array) => format!(
819            "ARRAY[{}]",
820            array
821                .elements()
822                .iter()
823                .map(value_sql)
824                .collect::<Vec<_>>()
825                .join(", ")
826        ),
827        Value::List(values) => format!(
828            "ARRAY[{}]",
829            values.iter().map(value_sql).collect::<Vec<_>>().join(", ")
830        ),
831        Value::Row(values) => format!(
832            "ROW({})",
833            values.iter().map(value_sql).collect::<Vec<_>>().join(", ")
834        ),
835        Value::Record(fields) => format!(
836            "ROW({})",
837            fields
838                .iter()
839                .map(|(_, value)| value_sql(value))
840                .collect::<Vec<_>>()
841                .join(", ")
842        ),
843        Value::Map(value) => format!(
844            "{}::jsonb",
845            string_literal(
846                &serde_json::to_string(value)
847                    .expect("serializing an in-memory Value map cannot fail")
848            )
849        ),
850    }
851}
852
853#[cfg(test)]
854mod tests {
855    use super::statement_sql;
856
857    #[test]
858    fn rendered_rule_action_shapes_round_trip_stably() {
859        for sql in [
860            "SELECT source.key_value, row_number() OVER (ORDER BY source.key_value ROWS BETWEEN UNBOUNDED PRECEDING AND CURRENT ROW) AS sequence FROM left_table AS source(key_value, payload) JOIN right_table AS other USING (key_value) WHERE source.payload IS NOT NULL ORDER BY sequence LIMIT 2 OFFSET 1",
861            "WITH source(value) AS MATERIALIZED (SELECT 1) SELECT value FROM source UNION ALL SELECT 2 ORDER BY value",
862            "INSERT INTO target_table AS target(id, value) VALUES (1, 'one') ON CONFLICT (id) DO UPDATE SET value = excluded.value WHERE target.id = 1 RETURNING WITH (OLD AS before, NEW AS after) after.id",
863            "UPDATE target_table AS target SET value = source.value FROM source_table AS source(id, value) WHERE target.id = source.id RETURNING target.id",
864            "DELETE FROM target_table AS target USING source_table AS source(id) WHERE target.id = source.id RETURNING target.id",
865            "NOTIFY rule_channel, 'payload'",
866        ] {
867            let mut statements = crate::compile(sql).unwrap_or_else(|error| panic!("{sql}: {error}"));
868            let rendered = statement_sql(&statements.remove(0))
869                .unwrap_or_else(|error| panic!("render {sql}: {error}"));
870            let mut reparsed = crate::compile(&rendered)
871                .unwrap_or_else(|error| panic!("reparse `{rendered}` from `{sql}`: {error}"));
872            let rerendered = statement_sql(&reparsed.remove(0))
873                .unwrap_or_else(|error| panic!("rerender `{rendered}`: {error}"));
874            assert_eq!(rerendered, rendered, "unstable SQL rendering for `{sql}`");
875        }
876    }
877}
uqa_sql/render.rs

uqa_sql/
render.rs
