Generalize parse_children and change its invocation

1 files changed, 94 insertions, 1 deletions

diff --git a/pest_consume/src/lib.rs b/pest_consume/src/lib.rs
index 6e4b2e3..70aee56 100644
--- a/pest_consume/src/lib.rs
+++ b/pest_consume/src/lib.rs
@@ -5,7 +5,7 @@ use pest::Span;
 pub use pest_consume_macros::{make_parser, parse_children};
 
 /// Carries a pest Pair alongside custom user data.
-#[derive(Debug, Clone)]
+#[derive(Debug)]
 pub struct ParseInput<'input, 'data, Rule, Data>
 where
     Rule: pest::RuleType,
@@ -14,6 +14,16 @@ where
     user_data: &'data Data,
 }
 
+/// Iterator over `ParseInput`s. It is created by `ParseInput::children`.
+#[derive(Debug)]
+pub struct ParseInputs<'input, 'data, Rule, Data>
+where
+    Rule: pest::RuleType,
+{
+    input: ParseInput<'input, 'data, Rule, Data>,
+    pairs: pest::iterators::Pairs<'input, Rule>,
+}
+
 impl<'input, 'data, Rule, Data> ParseInput<'input, 'data, Rule, Data>
 where
     Rule: pest::RuleType,
@@ -50,6 +60,15 @@ where
         }
         None
     }
+    /// Return an iterator over the children of this input
+    // Can't use `-> impl Iterator` because of weird lifetime limitations
+    // (see https://github.com/rust-lang/rust/issues/61997).
+    pub fn children(&self) -> ParseInputs<'input, 'data, Rule, Data> {
+        ParseInputs {
+            input: self.clone(),
+            pairs: self.as_pair().clone().into_inner(),
+        }
+    }
 
     pub fn user_data(&self) -> &'data Data {
         self.user_data
@@ -66,6 +85,28 @@ where
     pub fn as_rule(&self) -> Rule {
         self.pair.as_rule()
     }
+    pub fn as_rule_alias<T>(&self) -> String
+    where
+        T: PestConsumer<Rule = Rule>,
+    {
+        T::rule_alias(self.as_rule())
+    }
+}
+
+impl<'input, 'data, Rule, Data> ParseInputs<'input, 'data, Rule, Data>
+where
+    Rule: pest::RuleType,
+{
+    /// Create an error that points to the span of the input.
+    pub fn error(&self, message: String) -> Error<Rule> {
+        self.input.error(message)
+    }
+    pub fn aliased_rules<T>(&self) -> Vec<String>
+    where
+        T: PestConsumer<Rule = Rule>,
+    {
+        self.clone().map(|p| p.as_rule_alias::<T>()).collect()
+    }
 }
 
 /// Used by the macros.
@@ -121,3 +162,55 @@ fn debug_pair<Rule: pest::RuleType>(pair: Pair<Rule>) -> String {
     aux(&mut s, 0, "".into(), pair);
     s
 }
+
+impl<'input, 'data, Rule, Data> Iterator
+    for ParseInputs<'input, 'data, Rule, Data>
+where
+    Rule: pest::RuleType,
+{
+    type Item = ParseInput<'input, 'data, Rule, Data>;
+
+    fn next(&mut self) -> Option<Self::Item> {
+        let child_pair = self.pairs.next()?;
+        let child = self.input.with_pair(child_pair);
+        Some(child)
+    }
+}
+
+impl<'input, 'data, Rule, Data> DoubleEndedIterator
+    for ParseInputs<'input, 'data, Rule, Data>
+where
+    Rule: pest::RuleType,
+{
+    fn next_back(&mut self) -> Option<Self::Item> {
+        let child_pair = self.pairs.next_back()?;
+        let child = self.input.with_pair(child_pair);
+        Some(child)
+    }
+}
+
+// Manual impl to avoid stupid `Data: Clone` trait bound
+impl<'input, 'data, Rule, Data> Clone for ParseInput<'input, 'data, Rule, Data>
+where
+    Rule: pest::RuleType,
+{
+    fn clone(&self) -> Self {
+        ParseInput {
+            pair: self.pair.clone(),
+            user_data: self.user_data,
+        }
+    }
+}
+
+// Manual impl to avoid stupid `Data: Clone` trait bound
+impl<'input, 'data, Rule, Data> Clone for ParseInputs<'input, 'data, Rule, Data>
+where
+    Rule: pest::RuleType,
+{
+    fn clone(&self) -> Self {
+        ParseInputs {
+            input: self.input.clone(),
+            pairs: self.pairs.clone(),
+        }
+    }
+}