Add array index support to expression grammar

Author: SteveL-MSFT

tree-sitter-dscexpression/corpus/valid_expressions.txt

@@ -114,3 +114,121 @@ Quotes float input
           (functionName)
           (arguments
               (string)))))
+
+=====
+Array index
+=====
+[myFunction('argString')[0]]
+---
+
+    (statement
+      (expression
+        (memberAccess
+          (function
+            (functionName)
+            (arguments
+              (string)))
+          (index))))
+
+=====
+Multiple array indexes
+=====
+[myFunction('argString')[0][1][2]]
+---
+
+    (statement
+      (expression
+        (memberAccess
+          (memberAccess
+            (memberAccess
+              (function
+                (functionName)
+                (arguments
+                  (string)))
+              (index))
+            (index))
+          (index))))
+
+=====
+Array index with function
+=====
+[myFunction('argString')[myFunction2(1)]]
+---
+
+    (statement
+      (expression
+        (memberAccess
+          (function
+            (functionName)
+            (arguments
+              (string)))
+          (function
+            (functionName)
+            (arguments
+              (number))))))
+
+=====
+Array index with function and dot-notation
+=====
+[myFunction('argString')[myFunction2(1)].prop1]
+---
+
+    (statement
+      (expression
+        (memberAccess
+          (memberAccess
+            (function
+              (functionName)
+              (arguments
+                (string)))
+            (function
+              (functionName)
+              (arguments
+                (number))))
+          (memberName)))
+
+=====
+Array index with function and nested dot-notation
+=====
+[myFunction('argString')[myFunction2(1).prop1.prop2].prop3]
+---
+
+    (statement
+      (expression
+        (memberAccess
+          (memberAccess
+            (function
+              (functionName)
+              (arguments
+                (string)))
+            (memberAccess
+              (function
+                (functionName)
+                (arguments
+                  (number)))
+              (memberName)
+              (memberName))
+            (memberName))))
+
+=====
+Array index with function and nested dot-notation with index
+=====
+[myFunction('argString')[myFunction2(1).prop1.prop2][0]]
+---
+
+    (statement
+      (expression
+        (memberAccess
+          (memberAccess
+            (function
+              (functionName)
+              (arguments
+                (string)))
+            (memberAccess
+              (function
+                (functionName)
+                (arguments
+                  (number)))
+              (memberName)
+              (memberName))
+            (index))))

tree-sitter-dscexpression/grammar.js

@@ -18,7 +18,7 @@ module.exports = grammar({
     escapedStringLiteral: $ => token(prec(PREC.ESCAPEDSTRING, seq('[[', /.*?/))),
     bracketInStringLiteral: $ => token(prec(PREC.BRACKETINSTRING, seq('[', /.*?/, ']', /.+?/))),
     _expressionString: $ => prec(PREC.EXPRESSIONSTRING, seq('[', $.expression, ']')),
-    expression: $ => seq(field('function', $.function), field('members', optional($.memberAccess))),
+    expression: $ => seq(field('function', $.function), optional($.accessor)),
     stringLiteral: $ => token(prec(PREC.STRINGLITERAL, /[^\[].*?/)),
 
     function: $ => seq(field('name', $.functionName), '(', field('args', optional($.arguments)), ')'),
@@ -27,13 +27,17 @@ module.exports = grammar({
     _argument: $ => choice($.expression, $._quotedString, $.number, $.boolean),
 
     _quotedString: $ => seq('\'', $.string, '\''),
-    // ARM strings do not allow to contain single-quote characters
+    // ARM strings are allowed to contain single-quote characters
     string: $ => /[^']*/,
     number: $ => /-?\d+/,
     boolean: $ => choice('true', 'false'),
 
-    memberAccess: $ => seq('.', $.memberName, repeat(seq('.', $.memberName))),
+    accessor: $ => choice(field('members', $.memberAccess), field('index', $.arrayIndex)),
+
+    memberAccess: $ => seq('.', $.memberName, optional($.accessor)),
     memberName: $ => /[a-zA-Z0-9_-]+/,
+
+    arrayIndex: $ => seq('[', $.expression, ']'),
   }
 
 });