feat: unify record access syntax

README.md

@@ -64,12 +64,20 @@ Expressif distinguishes record fields from elements of ordered values:
 ```text
 .name       named field of the current record
 .0          positional field of the current record
+^.name      named field of the original immutable input record
+^.0         positional field of the original immutable input record
 $0          first element of the current tuple or array
 $1          second element of the current tuple or array
 $^0         last element of the current tuple or array
 $^1         second-to-last element of the current tuple or array
 ```
 
+Record access always uses `.` for navigation. A leading `^` changes the root
+from the current pipeline value to the original immutable input; it does not
+change how fields are selected. Access can be chained for nested records, for
+example `.customer.address` or `^.customer.0`. The former bracket forms
+`[name]` and `[0]` are replaced by `^.name` and `^.0` respectively.
+
 Element positions are zero-based. `$n` counts from the beginning and `$^n`
 counts from the end. The parser represents both tuple and array access with the
 same `positional_element_access` node; downstream binders decide whether the

grammar.js

@@ -52,8 +52,7 @@ export default grammar({
 
     value: ($) => choice(
       $.variable,
-      $.property_reference,
-      $.index_reference,
+      $.record_access,
       $.positional_element_access,
       $.numeric_literal,
       $.boolean_literal,
@@ -102,15 +101,43 @@ export default grammar({
       $.backtick_quoted_literal,
     ),
 
-    unquoted_record_field_name: (_) => /[A-Za-z]+(?:-[A-Za-z0-9]+)*/,
+    unquoted_record_field_name: (_) => /[A-Za-z][A-Za-z0-9]*(?:-[A-Za-z0-9]+)*/,
 
     numeric_literal: (_) => /-?(?:0|[1-9][0-9]*)(?:\.[0-9]+)?/,
 
     variable: (_) => /@[A-Za-z][A-Za-z0-9]*/,
 
-    property_reference: (_) => /\[[A-Za-z][A-Za-z0-9]*(?:-[A-Za-z0-9]+)*\]/,
+    record_access: ($) => seq(
+      choice(
+        field("field", $.record_field_selector),
+        seq(
+          field("root", $.original_input),
+          field("field", $.original_record_field_selector),
+        ),
+      ),
+      repeat(field("field", $.immediate_record_field_selector)),
+    ),
+
+    original_input: (_) => /\^\./,
+
+    record_field_selector: ($) => choice(
+      $.named_record_field,
+      $.positional_record_field,
+    ),
+
+    immediate_record_field_selector: ($) => choice(
+      alias(token.immediate(/\.[A-Za-z][A-Za-z0-9]*(?:-[A-Za-z0-9]+)*/), $.named_record_field),
+      alias(token.immediate(/\.(?:0|[1-9][0-9]*)/), $.positional_record_field),
+    ),
+
+    original_record_field_selector: ($) => choice(
+      alias(token.immediate(prec(-1, /[A-Za-z][A-Za-z0-9]*(?:-[A-Za-z0-9]+)*/)), $.named_record_field),
+      alias(token.immediate(prec(-1, /(?:0|[1-9][0-9]*)/)), $.positional_record_field),
+    ),
+
+    named_record_field: (_) => /\.[A-Za-z][A-Za-z0-9]*(?:-[A-Za-z0-9]+)*/,
 
-    index_reference: (_) => /\[(?:0|[1-9][0-9]*)\]/,
+    positional_record_field: (_) => /\.(?:0|[1-9][0-9]*)/,
 
     positional_element_access: (_) => /\$\^?(?:0|[1-9][0-9]*)/,