add support for [*] syntax

Author: deifactor

src/ast/mod.rs

@@ -519,6 +519,10 @@ pub enum JsonPathElem {
     ///
     /// See <https://docs.snowflake.com/en/user-guide/querying-semistructured#bracket-notation>.
     Bracket { key: Expr },
+    /// Accesses all elements in the given (generally array) element. Used for constructs like `foo:bar[*].baz`.
+    ///
+    /// See <https://docs.databricks.com/aws/en/sql/language-manual/sql-ref-json-path-expression#extract-values-from-arrays>
+    AllElements,
 }
 
 /// A JSON path.
@@ -552,6 +556,9 @@ impl fmt::Display for JsonPath {
                 JsonPathElem::Bracket { key } => {
                     write!(f, "[{key}]")?;
                 }
+                JsonPathElem::AllElements => {
+                    write!(f, "[*]")?;
+                }
             }
         }
         Ok(())

src/ast/spans.rs

@@ -1725,11 +1725,13 @@ impl Spanned for JsonPath {
 ///
 /// Missing spans:
 /// - [JsonPathElem::Dot]
+/// - [JsonPathElem::AllElements]
 impl Spanned for JsonPathElem {
     fn span(&self) -> Span {
         match self {
             JsonPathElem::Dot { .. } => Span::empty(),
             JsonPathElem::Bracket { key } => key.span(),
+            JsonPathElem::AllElements => Span::empty(),
         }
     }
 }

src/dialect/databricks.rs

@@ -49,6 +49,10 @@ impl Dialect for DatabricksDialect {
         }
     }
 
+    fn supports_semi_structured_array_all_elements(&self) -> bool {
+        true
+    }
+
     fn supports_filter_during_aggregation(&self) -> bool {
         true
     }

src/dialect/mod.rs

@@ -876,6 +876,11 @@ pub trait Dialect: Debug + Any {
         false
     }
 
+    /// Returns true if the dialect supports writing `[*]` to select all elements in a JSON array.
+    fn supports_semi_structured_array_all_elements(&self) -> bool {
+        false
+    }
+
     /// Returns true if the specified keyword is reserved and cannot be
     /// used as an identifier without special handling like quoting.
     fn is_reserved_for_identifier(&self, kw: Keyword) -> bool {

src/parser/mod.rs

@@ -3726,10 +3726,17 @@ impl<'a> Parser<'a> {
                     path.push(self.parse_json_path_object_key()?);
                 }
                 Token::LBracket => {
-                    let key = self.parse_expr()?;
-                    self.expect_token(&Token::RBracket)?;
+                    if self.peek_token_ref().token == Token::Mul
+                        && self.dialect.supports_semi_structured_array_all_elements()
+                    {
+                        self.expect_token(&Token::Mul)?;
+                        path.push(JsonPathElem::AllElements);
+                    } else {
+                        let key = self.parse_expr()?;
+                        path.push(JsonPathElem::Bracket { key });
+                    }
 
-                    path.push(JsonPathElem::Bracket { key });
+                    self.expect_token(&Token::RBracket)?;
                 }
                 _ => {
                     self.prev_token();