[bugfix] Fix bug in parsing PathExpr steps (#162)

Without this change PathExpr steps only has the root and let step in
the steps. See the related issue for more details. The bug has surfaced after #152 merged.

Author: am357

partiql-parser/src/parse/mod.rs

@@ -283,6 +283,7 @@ mod tests {
             parse!(r#"@a.b[*]"#);
             parse!(r#"@"a".b[*]"#);
             parse!(r#"tables.items[*].product.*.nest"#);
+            parse!(r#"a.b.c['item']."d"[5].e['s'].f[1+2]"#);
         }
 
         #[test]
@@ -322,6 +323,33 @@ mod tests {
             parse!(r#"foo(x, y)[*].*.b[5]"#);
         }
 
+        #[test]
+        fn test_pathexpr_struct() {
+            let res = parse!(r#"a.b.c['item']."d"[5].e['s'].f[1+2]"#);
+
+            if let ast::ExprKind::Query(ast::AstNode {
+                node:
+                    ast::Query {
+                        set:
+                            ast::AstNode {
+                                node: ast::QuerySet::Expr(ref e),
+                                ..
+                            },
+                        ..
+                    },
+                ..
+            }) = res.kind
+            {
+                if let ast::ExprKind::Path(p) = &e.kind {
+                    assert_eq!(9, p.node.steps.len())
+                } else {
+                    panic!("PathExpr test failed!");
+                }
+            } else {
+                panic!("PathExpr test failed!");
+            }
+        }
+
         #[test]
         #[should_panic]
         fn erroneous() {

partiql-parser/src/parse/partiql.lalrpop

@@ -964,21 +964,21 @@ FunctionArgName: ast::SymbolPrimitive = {
 // See the path expression conformance tests under `partiql-tests` or parser unit-tests for more examples.
 PathSteps: Vec<ast::PathStep> = {
     <path:PathSteps> "." <v:PathExprVarRef> => {
-        vec![ast::PathStep::PathExpr( ast::PathExpr{ index: Box::new(v) })]
+        let mut steps = path;
+        steps.push(ast::PathStep::PathExpr( ast::PathExpr{ index: Box::new(v) }));
+        steps
     },
     <lo:@L> <path:PathSteps> "[" "*" "]" <hi:@R> => {
-        vec![ast::PathStep::PathWildCard]
+        let mut steps = path;
+        steps.push(ast::PathStep::PathWildCard);
+        steps
     },
     <lo:@L> <path:PathSteps>  "." "*" <hi:@R> => {
-         let step = ast::PathStep::PathUnpivot;
-
          let mut steps = path;
-         steps.push(step);
+         steps.push(ast::PathStep::PathUnpivot);
          steps
          // ast::Path{ root:path.root, steps }
     },
-    // TODO Add path expression with CAST E.g. {'attr': 1, 'b':2}[CAST('at' || 'tr' AS STRING)]
-    // once https://github.com/partiql/partiql-lang-rust/pull/122 is merged
     <lo:@L> <path:PathSteps> "[" <expr:ExprQuery> "]" <hi:@R> => {
         let step = ast::PathStep::PathExpr(
             ast::PathExpr{