Fix nomenclature

Author: Marko Mikulicic

src/ast.rs

@@ -25,16 +25,22 @@ use serde_json::Value;
 ///                / \
 ///               ^   \___ Union
 ///              / \            \
-///             /   \___ Union   \___ [Field("bar")]
+///             /   \___ Union   \___ [Name("bar")]
 ///            /              \
-///           ^                \___ [Number(1), Number(2)]
+///           ^                \___ [Index(1), Index(2)]
 ///          / \
 /// Root ___/   \___ DotName("foo")
 /// ```
 ///
 /// Selectors are left associative, thus `$.foo[1,2]["bar"]` behaves
 /// like (pseudocode) `(($.foo)[1,2])["bar"]`; thus the root of the resulting
 /// tree is actually the right-most selector (the last one to be applied).
+///
+/// The Path::Root AST node is called "root" because that's the
+/// name of the node in the JSONPath grammar. It represents the source of
+/// the json value stream which gets operated upon by Selector nodes.
+/// This is why despite being called "root", this node doesn't lie at the root
+/// of the AST tree.
 #[derive(Debug)]
 pub enum Path {
     Root,
@@ -43,15 +49,15 @@ pub enum Path {
 
 #[derive(Debug)]
 pub enum Selector {
-    Union(Vec<Index>),
+    Union(Vec<UnionElement>),
     DotName(String),
     DotWildcard,
 }
 
 #[derive(Debug)]
-pub enum Index {
-    Field(String),
-    Number(i64),
+pub enum UnionElement {
+    Name(String),
+    Index(i64),
 }
 
 type Iter<'a> = Box<dyn Iterator<Item = &'a Value> + 'a>;
@@ -79,11 +85,11 @@ impl Selector {
     }
 }
 
-impl Index {
+impl UnionElement {
     pub fn get<'a>(&self, v: &'a Value) -> Iter<'a> {
         match self {
-            Index::Field(name) => Box::new(v.get(name).into_iter()),
-            Index::Number(num) => Box::new(v.get(abs_index(*num, v)).into_iter()),
+            UnionElement::Name(name) => Box::new(v.get(name).into_iter()),
+            UnionElement::Index(num) => Box::new(v.get(abs_index(*num, v)).into_iter()),
         }
     }
 }
@@ -113,9 +119,9 @@ mod test {
         let a2 = Path::Sel(Box::new(a1), Selector::DotName("bar".to_owned()));
         let a3 = Path::Sel(
             Box::new(a2),
-            Selector::Union(vec![Index::Field("baz".to_owned())]),
+            Selector::Union(vec![UnionElement::Name("baz".to_owned())]),
         );
-        let a4 = Path::Sel(Box::new(a3), Selector::Union(vec![Index::Number(4)]));
+        let a4 = Path::Sel(Box::new(a3), Selector::Union(vec![UnionElement::Index(4)]));
 
         let j = json!({"foo":{"bar":{"baz":[10,20,30,40,50,60]}}});
         println!("j: {}", j);

src/grammar.pest

@@ -1,6 +1,6 @@
-selector = _{ SOI ~ rootSelector ~ jsonPath ~ EOI }
+selector = _{ SOI ~ rootSelector ~ matchers ~ EOI }
 
-jsonPath = ${ matcher* }
+matchers = ${ matcher* }
 rootSelector = { "$" }
 
 matcher = { dotChild | union }

src/parser.rs

@@ -45,7 +45,7 @@ fn parse_child_name(matcher_rule: pest::iterators::Pair<Rule>) -> String {
     }
 }
 
-fn parse_union_indices(matcher_rule: pest::iterators::Pair<Rule>) -> Vec<Index> {
+fn parse_union_indices(matcher_rule: pest::iterators::Pair<Rule>) -> Vec<UnionElement> {
     let mut res = Vec::new();
 
     for r in matcher_rule.into_inner() {
@@ -58,20 +58,20 @@ fn parse_union_indices(matcher_rule: pest::iterators::Pair<Rule>) -> Vec<Index>
     res
 }
 
-fn parse_union_child(matcher_rule: pest::iterators::Pair<Rule>) -> Vec<Index> {
+fn parse_union_child(matcher_rule: pest::iterators::Pair<Rule>) -> Vec<UnionElement> {
     matcher_rule
         .into_inner()
         .map(|r| match r.as_rule() {
-            Rule::doubleInner => Index::Field(unescape(r.as_str())),
-            Rule::singleInner => Index::Field(unescape_single(r.as_str())),
+            Rule::doubleInner => UnionElement::Name(unescape(r.as_str())),
+            Rule::singleInner => UnionElement::Name(unescape_single(r.as_str())),
             _ => panic!("invalid parse tree {:?}", r),
         })
         .collect()
 }
 
-fn parse_union_array_index(matcher_rule: pest::iterators::Pair<Rule>) -> Index {
+fn parse_union_array_index(matcher_rule: pest::iterators::Pair<Rule>) -> UnionElement {
     let i = matcher_rule.as_str().parse().unwrap();
-    Index::Number(i)
+    UnionElement::Index(i)
 }
 
 fn unescape(contents: &str) -> String {