From 7dcea3c7213632e6ca86321c7429ac228853283c Mon Sep 17 00:00:00 2001
From: Oliver Cooper <oliver.cooper@me.com>
Date: Fri, 20 Aug 2021 10:49:20 +1200
Subject: [PATCH] Ignore items flagged @skip in SelectionField and Lookahead

---
 src/context.rs    | 19 ++++++++++++++++---
 src/look_ahead.rs | 41 ++++++++++++++++++++++++++++++++++++-----
 2 files changed, 52 insertions(+), 8 deletions(-)

diff --git a/src/context.rs b/src/context.rs
index 0fded9ff..be7bf5de 100644
--- a/src/context.rs
+++ b/src/context.rs
@@ -603,7 +603,7 @@ impl<'a> ContextBase<'a, &'a Positioned<Field>> {
     /// }
     /// ```
     pub fn look_ahead(&self) -> Lookahead {
-        Lookahead::new(&self.query_env.fragments, &self.item.node)
+        Lookahead::new(&self.query_env.fragments, &self.item.node, self)
     }
 
     /// Get the current field.
@@ -653,7 +653,7 @@ impl<'a> ContextBase<'a, &'a Positioned<Field>> {
 pub struct SelectionField<'a> {
     pub(crate) fragments: &'a HashMap<Name, Positioned<FragmentDefinition>>,
     pub(crate) field: &'a Field,
-    context: &'a Context<'a>,
+    pub(crate) context: &'a Context<'a>,
 }
 
 impl<'a> SelectionField<'a> {
@@ -727,7 +727,20 @@ impl<'a> Iterator for SelectionFieldsIter<'a> {
     fn next(&mut self) -> Option<Self::Item> {
         loop {
             let it = self.iter.last_mut()?;
-            match it.next() {
+            let item = it.next();
+            if let Some(item) = item {
+                // ignore any items that are skipped (i.e. @skip/@include)
+                if self
+                    .context
+                    .is_skip(&item.node.directives())
+                    .unwrap_or(false)
+                {
+                    // TODO: should we throw errors here? they will be caught later in execution and it'd cause major backwards compatibility issues
+                    continue;
+                }
+            }
+
+            match item {
                 Some(selection) => match &selection.node {
                     Selection::Field(field) => {
                         return Some(SelectionField {
diff --git a/src/look_ahead.rs b/src/look_ahead.rs
index 1dab6bf1..68e56637 100644
--- a/src/look_ahead.rs
+++ b/src/look_ahead.rs
@@ -2,22 +2,26 @@ use std::collections::HashMap;
 use std::convert::TryFrom;
 
 use crate::parser::types::{Field, FragmentDefinition, Selection, SelectionSet};
+use crate::Context;
 use crate::{Name, Positioned, SelectionField};
 
 /// A selection performed by a query.
 pub struct Lookahead<'a> {
     fragments: &'a HashMap<Name, Positioned<FragmentDefinition>>,
     fields: Vec<&'a Field>,
+    context: &'a Context<'a>,
 }
 
 impl<'a> Lookahead<'a> {
     pub(crate) fn new(
         fragments: &'a HashMap<Name, Positioned<FragmentDefinition>>,
         field: &'a Field,
+        context: &'a Context<'a>,
     ) -> Self {
         Self {
             fragments,
             fields: vec![field],
+            context,
         }
     }
 
@@ -29,12 +33,19 @@ impl<'a> Lookahead<'a> {
     pub fn field(&self, name: &str) -> Self {
         let mut fields = Vec::new();
         for field in &self.fields {
-            filter(&mut fields, self.fragments, &field.selection_set.node, name)
+            filter(
+                &mut fields,
+                self.fragments,
+                &field.selection_set.node,
+                name,
+                self.context,
+            )
         }
 
         Self {
             fragments: self.fragments,
             fields,
+            context: self.context,
         }
     }
 
@@ -50,6 +61,7 @@ impl<'a> From<SelectionField<'a>> for Lookahead<'a> {
         Lookahead {
             fragments: selection_field.fragments,
             fields: vec![selection_field.field],
+            context: selection_field.context,
         }
     }
 }
@@ -71,6 +83,7 @@ impl<'a> TryFrom<&[SelectionField<'a>]> for Lookahead<'a> {
                     .iter()
                     .map(|selection_field| selection_field.field)
                     .collect(),
+                context: selection_fields[0].context,
             })
         }
     }
@@ -81,22 +94,40 @@ fn filter<'a>(
     fragments: &'a HashMap<Name, Positioned<FragmentDefinition>>,
     selection_set: &'a SelectionSet,
     name: &str,
+    context: &'a Context<'a>,
 ) {
     for item in &selection_set.items {
         // doing this imperatively is a bit nasty, but using iterators would
         // require a boxed return type (I believe) as its recusive
+
+        // ignore any items that are skipped (i.e. @skip/@include)
+        if context.is_skip(&item.node.directives()).unwrap_or(false) {
+            // TODO: should we throw errors here? they will be caught later in execution and it'd cause major backwards compatibility issues
+            continue;
+        }
+
         match &item.node {
             Selection::Field(field) => {
                 if field.node.name.node == name {
                     fields.push(&field.node)
                 }
             }
-            Selection::InlineFragment(fragment) => {
-                filter(fields, fragments, &fragment.node.selection_set.node, name)
-            }
+            Selection::InlineFragment(fragment) => filter(
+                fields,
+                fragments,
+                &fragment.node.selection_set.node,
+                name,
+                context,
+            ),
             Selection::FragmentSpread(spread) => {
                 if let Some(fragment) = fragments.get(&spread.node.fragment_name.node) {
-                    filter(fields, fragments, &fragment.node.selection_set.node, name)
+                    filter(
+                        fields,
+                        fragments,
+                        &fragment.node.selection_set.node,
+                        name,
+                        context,
+                    )
                 }
             }
         }