347 lines
8.2 KiB
Rust
347 lines
8.2 KiB
Rust
use std::collections::HashMap;
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use crate::{
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parser::types::{Field, FragmentDefinition, Selection, SelectionSet},
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Context, Name, Positioned, SelectionField,
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};
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/// A selection performed by a query.
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pub struct Lookahead<'a> {
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fragments: &'a HashMap<Name, Positioned<FragmentDefinition>>,
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fields: Vec<&'a Field>,
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context: &'a Context<'a>,
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}
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impl<'a> Lookahead<'a> {
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pub(crate) fn new(
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fragments: &'a HashMap<Name, Positioned<FragmentDefinition>>,
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field: &'a Field,
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context: &'a Context<'a>,
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) -> Self {
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Self {
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fragments,
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fields: vec![field],
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context,
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}
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}
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/// Get the field of the selection set with the specified name. This will
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/// ignore aliases.
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///
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/// For example, calling `.field("a")` on `{ a { b } }` will return a
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/// lookahead that represents `{ b }`.
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#[must_use]
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pub fn field(&self, name: &str) -> Self {
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let mut fields = Vec::new();
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for field in &self.fields {
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filter(&mut fields, self.fragments, &field.selection_set.node, name)
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}
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Self {
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fragments: self.fragments,
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fields,
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context: self.context,
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}
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}
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/// Returns true if field exists otherwise return false.
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#[inline]
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pub fn exists(&self) -> bool {
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!self.fields.is_empty()
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}
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/// Get the `SelectionField`s for each of the fields covered by this
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/// `Lookahead`.
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///
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/// There will be multiple fields in situations where the same field is
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/// queried twice.
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pub fn selection_fields(&self) -> Vec<SelectionField<'a>> {
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self.fields
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.iter()
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.map(|field| SelectionField {
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fragments: self.fragments,
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field,
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context: self.context,
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})
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.collect()
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}
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}
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impl<'a> From<SelectionField<'a>> for Lookahead<'a> {
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fn from(selection_field: SelectionField<'a>) -> Self {
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Lookahead {
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fragments: selection_field.fragments,
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fields: vec![selection_field.field],
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context: selection_field.context,
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}
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}
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}
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/// Convert a slice of `SelectionField`s to a `Lookahead`.
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/// Assumes all `SelectionField`s are from the same query and thus have the same
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/// fragments.
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///
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/// Fails if either no `SelectionField`s were provided.
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impl<'a> TryFrom<&[SelectionField<'a>]> for Lookahead<'a> {
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type Error = ();
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fn try_from(selection_fields: &[SelectionField<'a>]) -> Result<Self, Self::Error> {
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if selection_fields.is_empty() {
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Err(())
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} else {
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Ok(Lookahead {
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fragments: selection_fields[0].fragments,
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fields: selection_fields
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.iter()
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.map(|selection_field| selection_field.field)
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.collect(),
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context: selection_fields[0].context,
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})
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}
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}
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}
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fn filter<'a>(
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fields: &mut Vec<&'a Field>,
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fragments: &'a HashMap<Name, Positioned<FragmentDefinition>>,
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selection_set: &'a SelectionSet,
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name: &str,
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) {
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for item in &selection_set.items {
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match &item.node {
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Selection::Field(field) => {
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if field.node.name.node == name {
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fields.push(&field.node)
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}
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}
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Selection::InlineFragment(fragment) => {
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filter(fields, fragments, &fragment.node.selection_set.node, name)
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}
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Selection::FragmentSpread(spread) => {
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if let Some(fragment) = fragments.get(&spread.node.fragment_name.node) {
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filter(fields, fragments, &fragment.node.selection_set.node, name)
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}
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}
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}
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}
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}
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#[cfg(test)]
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mod tests {
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use crate::*;
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#[tokio::test]
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async fn test_look_ahead() {
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#[derive(SimpleObject)]
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#[graphql(internal)]
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struct Detail {
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c: i32,
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d: i32,
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}
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#[derive(SimpleObject)]
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#[graphql(internal)]
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struct MyObj {
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a: i32,
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b: i32,
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detail: Detail,
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}
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struct Query;
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#[Object(internal)]
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impl Query {
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async fn obj(&self, ctx: &Context<'_>, n: i32) -> MyObj {
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if ctx.look_ahead().field("a").exists() {
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// This is a query like `obj { a }`
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assert_eq!(n, 1);
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} else if ctx.look_ahead().field("detail").field("c").exists()
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&& ctx.look_ahead().field("detail").field("d").exists()
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{
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// This is a query like `obj { detail { c } }`
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assert_eq!(n, 2);
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} else if ctx.look_ahead().field("detail").field("c").exists() {
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// This is a query like `obj { detail { c } }`
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assert_eq!(n, 3);
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} else {
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// This query doesn't have `a`
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assert_eq!(n, 4);
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}
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MyObj {
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a: 0,
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b: 0,
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detail: Detail { c: 0, d: 0 },
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}
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}
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}
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let schema = Schema::new(Query, EmptyMutation, EmptySubscription);
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assert!(schema
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.execute(
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r#"{
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obj(n: 1) {
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a
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}
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 1) {
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k:a
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}
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 3) {
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detail {
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c
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}
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}
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 2) {
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detail {
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d
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}
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detail {
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c
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}
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}
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 4) {
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b
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}
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 1) {
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... {
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a
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}
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}
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 3) {
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... {
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detail {
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c
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}
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}
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}
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 2) {
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... {
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detail {
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d
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}
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detail {
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c
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}
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}
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}
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 1) {
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... A
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}
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}
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fragment A on MyObj {
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a
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 3) {
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... A
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}
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}
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fragment A on MyObj {
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detail {
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c
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}
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}"#,
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)
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.await
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.is_ok());
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assert!(schema
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.execute(
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r#"{
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obj(n: 2) {
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... A
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... B
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}
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}
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fragment A on MyObj {
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detail {
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d
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}
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}
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fragment B on MyObj {
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detail {
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c
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}
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}"#,
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)
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.await
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.is_ok());
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}
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}
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