use std::collections::{HashMap, HashSet};
use ast::{Document, Fragment, FragmentSpread};
use validation::{RuleError, ValidatorContext, Visitor};
use parser::Spanning;
pub struct NoFragmentCycles<'a> {
current_fragment: Option<&'a str>,
spreads: HashMap<&'a str, Vec<Spanning<&'a str>>>,
fragment_order: Vec<&'a str>,
}
struct CycleDetector<'a> {
visited: HashSet<&'a str>,
spreads: &'a HashMap<&'a str, Vec<Spanning<&'a str>>>,
path_indices: HashMap<&'a str, usize>,
errors: Vec<RuleError>,
}
pub fn factory<'a>() -> NoFragmentCycles<'a> {
NoFragmentCycles {
current_fragment: None,
spreads: HashMap::new(),
fragment_order: Vec::new(),
}
}
impl<'a> Visitor<'a> for NoFragmentCycles<'a> {
fn exit_document(&mut self, ctx: &mut ValidatorContext<'a>, _: &'a Document) {
assert!(self.current_fragment.is_none());
let mut detector = CycleDetector {
visited: HashSet::new(),
spreads: &self.spreads,
path_indices: HashMap::new(),
errors: Vec::new(),
};
for frag in &self.fragment_order {
if !detector.visited.contains(frag) {
let mut path = Vec::new();
detector.detect_from(frag, &mut path);
}
}
ctx.append_errors(detector.errors);
}
fn enter_fragment_definition(
&mut self,
_: &mut ValidatorContext<'a>,
fragment: &'a Spanning<Fragment>,
) {
assert!(self.current_fragment.is_none());
let fragment_name = &fragment.item.name.item;
self.current_fragment = Some(fragment_name);
self.fragment_order.push(fragment_name);
}
fn exit_fragment_definition(
&mut self,
_: &mut ValidatorContext<'a>,
fragment: &'a Spanning<Fragment>,
) {
assert_eq!(Some(fragment.item.name.item), self.current_fragment);
self.current_fragment = None;
}
fn enter_fragment_spread(
&mut self,
_: &mut ValidatorContext<'a>,
spread: &'a Spanning<FragmentSpread>,
) {
if let Some(current_fragment) = self.current_fragment {
self.spreads
.entry(current_fragment)
.or_insert_with(Vec::new)
.push(Spanning::start_end(
&spread.start.clone(),
&spread.end.clone(),
spread.item.name.item,
));
}
}
}
impl<'a> CycleDetector<'a> {
fn detect_from(&mut self, from: &'a str, path: &mut Vec<&'a Spanning<&'a str>>) {
self.visited.insert(from);
if !self.spreads.contains_key(from) {
return;
}
self.path_indices.insert(from, path.len());
for node in &self.spreads[from] {
let name = &node.item;
let index = self.path_indices.get(name).cloned();
if let Some(index) = index {
let err_pos = if index < path.len() {
path[index]
} else {
node
};
self.errors.push(RuleError::new(
&error_message(name),
&[err_pos.start.clone()],
));
} else if !self.visited.contains(name) {
path.push(node);
self.detect_from(name, path);
path.pop();
}
}
self.path_indices.remove(from);
}
}
fn error_message(frag_name: &str) -> String {
format!(r#"Cannot spread fragment "{}""#, frag_name)
}
#[cfg(test)]
mod tests {
use super::{error_message, factory};
use parser::SourcePosition;
use validation::{expect_fails_rule, expect_passes_rule, RuleError};
#[test]
fn single_reference_is_valid() {
expect_passes_rule(
factory,
r#"
fragment fragA on Dog { ...fragB }
fragment fragB on Dog { name }
"#,
);
}
#[test]
fn spreading_twice_is_not_circular() {
expect_passes_rule(
factory,
r#"
fragment fragA on Dog { ...fragB, ...fragB }
fragment fragB on Dog { name }
"#,
);
}
#[test]
fn spreading_twice_indirectly_is_not_circular() {
expect_passes_rule(
factory,
r#"
fragment fragA on Dog { ...fragB, ...fragC }
fragment fragB on Dog { ...fragC }
fragment fragC on Dog { name }
"#,
);
}
#[test]
fn double_spread_within_abstract_types() {
expect_passes_rule(
factory,
r#"
fragment nameFragment on Pet {
... on Dog { name }
... on Cat { name }
}
fragment spreadsInAnon on Pet {
... on Dog { ...nameFragment }
... on Cat { ...nameFragment }
}
"#,
);
}
#[test]
fn does_not_false_positive_on_unknown_fragment() {
expect_passes_rule(
factory,
r#"
fragment nameFragment on Pet {
...UnknownFragment
}
"#,
);
}
#[test]
fn spreading_recursively_within_field_fails() {
expect_fails_rule(
factory,
r#"
fragment fragA on Human { relatives { ...fragA } },
"#,
&[
RuleError::new(&error_message("fragA"), &[SourcePosition::new(49, 1, 48)]),
],
);
}
#[test]
fn no_spreading_itself_directly() {
expect_fails_rule(
factory,
r#"
fragment fragA on Dog { ...fragA }
"#,
&[
RuleError::new(&error_message("fragA"), &[SourcePosition::new(35, 1, 34)]),
],
);
}
#[test]
fn no_spreading_itself_directly_within_inline_fragment() {
expect_fails_rule(
factory,
r#"
fragment fragA on Pet {
... on Dog {
...fragA
}
}
"#,
&[
RuleError::new(&error_message("fragA"), &[SourcePosition::new(74, 3, 14)]),
],
);
}
#[test]
fn no_spreading_itself_indirectly() {
expect_fails_rule(
factory,
r#"
fragment fragA on Dog { ...fragB }
fragment fragB on Dog { ...fragA }
"#,
&[
RuleError::new(&error_message("fragA"), &[SourcePosition::new(35, 1, 34)]),
],
);
}
#[test]
fn no_spreading_itself_indirectly_reports_opposite_order() {
expect_fails_rule(
factory,
r#"
fragment fragB on Dog { ...fragA }
fragment fragA on Dog { ...fragB }
"#,
&[
RuleError::new(&error_message("fragB"), &[SourcePosition::new(35, 1, 34)]),
],
);
}
#[test]
fn no_spreading_itself_indirectly_within_inline_fragment() {
expect_fails_rule(
factory,
r#"
fragment fragA on Pet {
... on Dog {
...fragB
}
}
fragment fragB on Pet {
... on Dog {
...fragA
}
}
"#,
&[
RuleError::new(&error_message("fragA"), &[SourcePosition::new(74, 3, 14)]),
],
);
}
#[test]
fn no_spreading_itself_deeply() {
expect_fails_rule(
factory,
r#"
fragment fragA on Dog { ...fragB }
fragment fragB on Dog { ...fragC }
fragment fragC on Dog { ...fragO }
fragment fragX on Dog { ...fragY }
fragment fragY on Dog { ...fragZ }
fragment fragZ on Dog { ...fragO }
fragment fragO on Dog { ...fragP }
fragment fragP on Dog { ...fragA, ...fragX }
"#,
&[
RuleError::new(&error_message("fragA"), &[SourcePosition::new(35, 1, 34)]),
RuleError::new(&error_message("fragO"), &[SourcePosition::new(305, 7, 34)]),
],
);
}
#[test]
fn no_spreading_itself_deeply_two_paths() {
expect_fails_rule(
factory,
r#"
fragment fragA on Dog { ...fragB, ...fragC }
fragment fragB on Dog { ...fragA }
fragment fragC on Dog { ...fragA }
"#,
&[
RuleError::new(&error_message("fragA"), &[SourcePosition::new(35, 1, 34)]),
RuleError::new(&error_message("fragA"), &[SourcePosition::new(45, 1, 44)]),
],
);
}
#[test]
fn no_spreading_itself_deeply_two_paths_alt_traversal_order() {
expect_fails_rule(
factory,
r#"
fragment fragA on Dog { ...fragC }
fragment fragB on Dog { ...fragC }
fragment fragC on Dog { ...fragA, ...fragB }
"#,
&[
RuleError::new(&error_message("fragA"), &[SourcePosition::new(35, 1, 34)]),
RuleError::new(&error_message("fragC"), &[SourcePosition::new(135, 3, 44)]),
],
);
}
#[test]
fn no_spreading_itself_deeply_and_immediately() {
expect_fails_rule(
factory,
r#"
fragment fragA on Dog { ...fragB }
fragment fragB on Dog { ...fragB, ...fragC }
fragment fragC on Dog { ...fragA, ...fragB }
"#,
&[
RuleError::new(&error_message("fragA"), &[SourcePosition::new(35, 1, 34)]),
RuleError::new(&error_message("fragB"), &[SourcePosition::new(80, 2, 34)]),
RuleError::new(&error_message("fragB"), &[SourcePosition::new(90, 2, 44)]),
],
);
}
}