1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
use std::collections::HashSet;
use anyhow::{bail, Result};
use itertools::Itertools;
use crate::ast::ast_fold::*;
use crate::error::{Error, Reason, Span, WithErrorInfo};
use crate::{ast::*, split_var_name, Declaration};
use super::complexity::determine_complexity;
use super::frame::extract_sorts;
use super::transforms;
use super::Context;
pub fn resolve_names(nodes: Vec<Node>, context: Option<Context>) -> Result<(Vec<Node>, Context)> {
let context = context.unwrap_or_else(init_context);
let mut resolver = NameResolver::new(context);
let nodes = resolver.fold_nodes(nodes)?;
let nodes = determine_complexity(nodes, &resolver.context);
Ok((nodes, resolver.context))
}
pub struct NameResolver {
pub context: Context,
within_group: Vec<usize>,
within_window: Option<(WindowKind, Range)>,
within_aggregate: bool,
sorted: Vec<ColumnSort<usize>>,
}
impl NameResolver {
fn new(context: Context) -> Self {
NameResolver {
context,
within_group: vec![],
within_window: None,
within_aggregate: false,
sorted: vec![],
}
}
}
impl AstFold for NameResolver {
fn fold_nodes(&mut self, items: Vec<Node>) -> Result<Vec<Node>> {
items
.into_iter()
.map(|node| {
Ok(match node.item {
Item::FuncDef(mut func_def) => {
for (param, _) in &mut func_def.named_params {
param.declared_at = Some(self.context.declare_func_param(param));
}
for (param, _) in &mut func_def.positional_params {
param.declared_at = Some(self.context.declare_func_param(param));
}
func_def.body = Box::new(self.fold_node(*func_def.body)?);
self.context.scope.clear();
self.context.declare_func(func_def);
None
}
_ => Some(self.fold_node(node)?),
})
})
.filter_map(|x| x.transpose())
.try_collect()
}
fn fold_node(&mut self, mut node: Node) -> Result<Node> {
let r = match node.item {
Item::FuncCall(ref func_call) => {
node.declared_at = Some(
self.lookup_variable(&func_call.name, node.span)
.map_err(|e| Error::new(Reason::Simple(e)).with_span(node.span))?,
);
self.fold_function_call(node)?
}
Item::Ident(ref ident) => {
node.declared_at = Some(
(self.lookup_variable(ident, node.span))
.map_err(|e| Error::new(Reason::Simple(e)).with_span(node.span))?,
);
let decl = &self.context.declarations.0[node.declared_at.unwrap()].0;
if matches!(decl, Declaration::Function(_)) {
node.item = Item::FuncCall(FuncCall {
name: ident.clone(),
args: vec![],
named_args: Default::default(),
});
self.fold_function_call(node)?
} else {
node
}
}
item => {
node.item = fold_item(self, item)?;
node
}
};
Ok(r)
}
fn fold_transform(&mut self, t: Transform) -> Result<Transform> {
let mut t = match t {
Transform::From(mut t) => {
self.sorted.clear();
self.context.scope.clear();
self.context.declare_table(&mut t);
Transform::From(t)
}
Transform::Select(assigns) => {
let assigns = self.fold_assigns(assigns)?;
self.context.scope.clear();
Transform::Select(assigns)
}
Transform::Derive(assigns) => {
let assigns = self.fold_assigns(assigns)?;
Transform::Derive(assigns)
}
Transform::Group { by, pipeline } => {
let by = self.fold_nodes(by)?;
self.within_group = by.iter().filter_map(|n| n.declared_at).collect();
self.sorted.clear();
let pipeline = Box::new(self.fold_node(*pipeline)?);
self.within_group.clear();
self.sorted.clear();
Transform::Group { by, pipeline }
}
Transform::Aggregate { assigns, by } => {
self.within_aggregate = true;
let assigns = self.fold_assigns(assigns)?;
self.within_aggregate = false;
self.context.scope.clear();
Transform::Aggregate { assigns, by }
}
Transform::Join {
side,
mut with,
filter,
} => {
self.context.declare_table(&mut with);
Transform::Join {
side,
with,
filter: self.fold_join_filter(filter)?,
}
}
Transform::Sort(sorts) => {
let sorts = self.fold_column_sorts(sorts)?;
self.sorted = extract_sorts(&sorts)?;
Transform::Sort(sorts)
}
Transform::Window {
range,
kind,
pipeline,
} => {
self.within_window = Some((kind.clone(), range.clone()));
let pipeline = Box::new(self.fold_node(*pipeline)?);
self.within_window = None;
Transform::Window {
range,
kind,
pipeline,
}
}
t => fold_transform(self, t)?,
};
if !self.within_group.is_empty() {
self.apply_group(&mut t)?;
}
if self.within_window.is_some() {
self.apply_window(&mut t)?;
}
Ok(t)
}
fn fold_join_filter(&mut self, filter: JoinFilter) -> Result<JoinFilter> {
Ok(match filter {
JoinFilter::On(nodes) => JoinFilter::On(self.fold_nodes(nodes)?),
JoinFilter::Using(mut nodes) => {
for node in &mut nodes {
let ident = node.item.as_ident().unwrap();
let namespaces = self.lookup_namespaces_of(ident);
match namespaces.len() {
0 => Err(format!("Unknown variable `{ident}`")),
1 => Err("join using a column name must belong to both tables".to_string()),
_ => Ok(()),
}
.map_err(|e| Error::new(Reason::Simple(e)).with_span(node.span))?;
let decl = Declaration::ExternRef {
table: None,
variable: ident.to_string(),
};
let id = self.context.declare(decl, node.span);
self.context.scope.add(ident.clone(), id);
node.declared_at = Some(id);
}
JoinFilter::Using(nodes)
}
})
}
fn fold_table(&mut self, mut table: Table) -> Result<Table> {
table.pipeline = Box::new(self.fold_node(*table.pipeline)?);
let decl = Declaration::Table(table.name.clone());
table.id = Some(self.context.declare(decl, None));
Ok(table)
}
}
impl NameResolver {
fn fold_assigns(&mut self, nodes: Vec<Node>) -> Result<Vec<Node>> {
nodes
.into_iter()
.map(|mut node| {
Ok(match node.item {
Item::Assign(NamedExpr { name, expr }) => {
let expr = self.fold_assign_expr(*expr)?;
let id = expr.declared_at.unwrap();
self.context.scope.add(name.clone(), id);
node.item = Item::Ident(name);
node.declared_at = Some(id);
node
}
_ => {
self.fold_assign_expr(node)?
}
})
})
.try_collect()
}
fn fold_assign_expr(&mut self, node: Node) -> Result<Node> {
let node = self.fold_node(node)?;
Ok(match node.item {
Item::Ident(_) => {
node
}
_ => {
let span = node.span;
let decl = Declaration::Expression(Box::from(node));
let id = self.context.declare(decl, span);
let mut placeholder: Node = Item::Ident("<unnamed>".to_string()).into();
placeholder.declared_at = Some(id);
placeholder
}
})
}
fn fold_function_call(&mut self, mut node: Node) -> Result<Node> {
let func_call = node.item.into_func_call().unwrap();
let (func_call, func_def) = self
.validate_function_call(node.declared_at, func_call)
.with_span(node.span)?;
let return_type = func_def.return_type.as_ref();
if Some(&Ty::frame()) <= return_type {
let transform = transforms::cast_transform(func_call, node.span)?;
node.item = Item::Transform(self.fold_transform(transform)?)
} else {
let func_call = Item::FuncCall(self.fold_func_call(func_call)?);
if !self.within_aggregate && Some(&Ty::column()) <= return_type {
node.item = self.wrap_into_windowed(func_call, node.declared_at);
node.declared_at = None;
} else {
node.item = func_call;
}
}
Ok(node)
}
fn wrap_into_windowed(&self, func_call: Item, declared_at: Option<usize>) -> Item {
const REF: &str = "<ref>";
let mut expr: Node = func_call.into();
expr.declared_at = declared_at;
let frame = self
.within_window
.clone()
.unwrap_or((WindowKind::Rows, Range::unbounded()));
let mut window = Windowed::new(expr, frame);
if !self.within_group.is_empty() {
window.group = (self.within_group)
.iter()
.map(|id| Node::new_ident(REF, *id))
.collect();
}
if !self.sorted.is_empty() {
window.sort = (self.sorted)
.iter()
.map(|s| ColumnSort {
column: Node::new_ident(REF, s.column),
direction: s.direction.clone(),
})
.collect();
}
Item::Windowed(window)
}
fn apply_group(&mut self, t: &mut Transform) -> Result<()> {
match t {
Transform::Select(_)
| Transform::Derive(_)
| Transform::Sort(_)
| Transform::Window { .. } => {
}
Transform::Aggregate { by, .. } => {
*by = (self.within_group)
.iter()
.map(|id| Node::new_ident("<ref>", *id))
.collect();
}
Transform::Take { by, sort, .. } => {
*by = (self.within_group)
.iter()
.map(|id| Node::new_ident("<ref>", *id))
.collect();
*sort = (self.sorted)
.iter()
.map(|s| ColumnSort {
column: Node::new_ident("<ref>", s.column),
direction: s.direction.clone(),
})
.collect();
}
_ => {
bail!(Error::new(Reason::Simple(format!(
"transform `{}` is not allowed within group context",
t.as_ref()
))))
}
}
Ok(())
}
fn apply_window(&mut self, t: &mut Transform) -> Result<()> {
if !matches!(t, Transform::Select(_) | Transform::Derive(_)) {
bail!(Error::new(Reason::Simple(format!(
"transform `{}` is not allowed within window context",
t.as_ref()
))))
}
Ok(())
}
fn validate_function_call(
&self,
declared_at: Option<usize>,
mut func_call: FuncCall,
) -> Result<(FuncCall, FuncDef), Error> {
if declared_at.is_none() {
return Err(Error::new(Reason::NotFound {
name: func_call.name,
namespace: "function".to_string(),
}));
}
let func_dec = declared_at.unwrap();
let func_dec = &self.context.declarations.0[func_dec].0;
let func_def = func_dec
.as_function()
.ok_or_else(|| {
Error::new(Reason::NotFound {
name: func_call.name.clone(),
namespace: "function".to_string(),
})
})?
.clone();
let named_params: HashSet<_> = (func_def.named_params)
.iter()
.map(|param| ¶m.0.item.as_named_arg().unwrap().name)
.collect();
let (named, positional) = func_call
.args
.into_iter()
.partition(|arg| matches!(&arg.item, Item::NamedArg(_)));
func_call.args = positional;
for node in named {
let arg = node.item.into_named_arg().unwrap();
if !named_params.contains(&arg.name) {
return Err(Error::new(Reason::Unexpected {
found: format!("argument named `{}`", arg.name),
})
.with_span(node.span));
}
func_call.named_args.insert(arg.name, arg.expr);
}
let expected_len = func_def.positional_params.len();
let passed_len = func_call.args.len();
if expected_len < passed_len {
let mut err = Error::new(Reason::Expected {
who: Some(func_call.name.clone()),
expected: format!("{} arguments", expected_len),
found: format!("{}", passed_len),
});
if passed_len > expected_len && passed_len >= 2 {
err = err.with_help(format!(
"If you are calling a function, you may want to add parentheses `{} [{:?} {:?}]`",
func_call.name, func_call.args[0], func_call.args[1]
));
}
return Err(err);
}
Ok((func_call, func_def))
}
pub fn lookup_variable(&mut self, ident: &str, span: Option<Span>) -> Result<usize, String> {
let (namespace, variable) = split_var_name(ident);
if let Some(decls) = self.context.scope.variables.get(ident) {
match decls.len() {
0 => unreachable!("inverse index contains empty lists?"),
1 => Ok(decls.iter().next().cloned().unwrap()),
_ => {
let decls = decls
.iter()
.map(|d| self.context.declarations.get(*d))
.map(|d| format!("`{d}`"))
.join(", ");
Err(format!(
"Ambiguous reference. Could be from either of {decls}"
))
}
}
} else {
let all = if namespace.is_empty() {
"*".to_string()
} else {
format!("{namespace}.*")
};
if let Some(decls) = self.context.scope.variables.get(&all) {
match decls.len() {
0 => unreachable!("inverse index contains empty lists?"),
1 => {
let table_id = decls.iter().next().unwrap();
let decl = Declaration::ExternRef {
table: Some(*table_id),
variable: variable.to_string(),
};
let id = self.context.declare(decl, span);
self.context.scope.add(ident.to_string(), id);
Ok(id)
}
_ => {
let decl = Declaration::ExternRef {
table: None,
variable: ident.to_string(),
};
let id = self.context.declare(decl, span);
Ok(id)
}
}
} else {
Err(format!("Unknown variable `{ident}`"))
}
}
}
pub fn lookup_namespaces_of(&mut self, variable: &str) -> HashSet<usize> {
let mut r = HashSet::new();
if let Some(ns) = self.context.scope.variables.get(variable) {
r.extend(ns.clone());
}
if let Some(ns) = self.context.scope.variables.get("*") {
r.extend(ns.clone());
}
r
}
}
pub fn init_context() -> Context {
use crate::parse;
let transforms = include_str!("./transforms.prql");
let transforms = parse(transforms).unwrap().nodes;
let (_, context) = resolve_names(transforms, Some(Context::default())).unwrap();
context
}
#[cfg(test)]
mod tests {
use insta::assert_snapshot;
use serde_yaml::from_str;
use crate::{parse, resolve_and_translate};
use super::*;
#[test]
fn test_scopes_during_from() {
let context = init_context();
let mut resolver = NameResolver::new(context);
let pipeline: Node = from_str(
r##"
Pipeline:
nodes:
- FuncCall:
name: from
args:
- Ident: employees
named_args: {}
"##,
)
.unwrap();
resolver.fold_node(pipeline).unwrap();
assert!(resolver.context.scope.variables["employees.*"].len() == 1);
}
#[test]
fn test_scopes_during_select() {
let context = init_context();
let mut resolver = NameResolver::new(context);
let pipeline: Node = from_str(
r##"
Pipeline:
nodes:
- FuncCall:
name: from
args:
- Ident: employees
named_args: {}
- FuncCall:
name: select
args:
- List:
- Assign:
name: salary_1
expr:
Ident: salary
- Assign:
name: salary_2
expr:
Binary:
left:
Ident: salary_1
op: Add
right:
Literal:
Integer: 1
- Ident: age
named_args: {}
"##,
)
.unwrap();
resolver.fold_node(pipeline).unwrap();
assert!(resolver.context.scope.variables.contains_key("salary_1"));
assert!(resolver.context.scope.variables.contains_key("salary_2"));
assert!(resolver.context.scope.variables.contains_key("age"));
}
#[test]
fn test_variable_scoping() {
let prql = r#"
from employees
select first_name
select last_name
"#;
let result = parse(prql).and_then(|x| resolve_names(x.nodes, None));
assert!(result.is_err());
let prql = r#"
from employees
select [salary1 = salary, salary2 = salary1 + 1, age]
"#;
let result: String = parse(prql).and_then(resolve_and_translate).unwrap();
assert_snapshot!(result, @r###"
SELECT
salary AS salary1,
salary + 1 AS salary2,
age
FROM
employees
"###);
}
#[test]
fn test_join_using_two_tables() {
let prql = r#"
from employees
select [first_name, emp_no]
join salaries [emp_no]
select [first_name, salaries.salary]
"#;
let result = parse(prql).and_then(|x| resolve_names(x.nodes, None));
result.unwrap();
let prql = r#"
from employees
select first_name
join salaries [emp_no]
select [first_name, salaries.salary]
"#;
let result = parse(prql).and_then(|x| resolve_names(x.nodes, None));
assert!(result.is_err());
}
#[test]
fn test_ambiguous_resolve() {
let prql = r#"
from employees
join salaries [emp_no]
select first_name # this could belong to either table!
"#;
let result = parse(prql).and_then(resolve_and_translate).unwrap();
assert_snapshot!(result, @r###"
SELECT
first_name
FROM
employees
JOIN salaries USING(emp_no)
"###);
let prql = r#"
from employees
select first_name # this can only be from employees
"#;
let result = parse(prql).and_then(resolve_and_translate).unwrap();
assert_snapshot!(result, @r###"
SELECT
first_name
FROM
employees
"###);
let prql = r#"
from employees
select [first_name, emp_no]
join salaries [emp_no]
select [first_name, emp_no, salary]
"#;
let result = parse(prql).and_then(resolve_and_translate).unwrap();
assert_snapshot!(result, @r###"
SELECT
employees.first_name,
emp_no,
salaries.salary
FROM
employees
JOIN salaries USING(emp_no)
"###);
}
#[test]
fn test_applying_group_context() {
assert_snapshot!(parse(r#"
from employees
group last_name (
sort first_name
take 1
)
"#).and_then(resolve_and_translate).unwrap(), @r###"
WITH table_0 AS (
SELECT
employees.*,
ROW_NUMBER() OVER (
PARTITION BY last_name
ORDER BY
first_name
) AS _rn
FROM
employees
)
SELECT
table_0.*
FROM
table_0
WHERE
_rn <= 1
"###);
let res = parse(
r#"
from employees
group last_name (
group last_name ( aaa )
)
"#,
)
.and_then(resolve_and_translate);
assert!(res.is_err());
assert_snapshot!(parse(r#"
from employees
group last_name (
select first_name
)
"#).and_then(resolve_and_translate).unwrap(), @r###"
SELECT
first_name
FROM
employees
"###);
assert_snapshot!(parse(r#"
from employees
group last_name (
aggregate count
)
"#).and_then(resolve_and_translate).unwrap(), @r###"
SELECT
last_name,
COUNT(*)
FROM
employees
GROUP BY
last_name
"###);
}
}