jsonpath/parser: add support for string scalars

This commit adds string scalars, enabling string comparisons within
jsonpath queries.

Epic: None
Release note (sql change): Support string comparisons within jsonpath
queries.

Author: normanchenn

pkg/sql/logictest/testdata/logic_test/jsonb_path_query

@@ -761,12 +761,30 @@ SELECT jsonb_path_query('{"a": "hello"}', '$.a / 2');
 statement error pgcode 22038 pq: right operand of jsonpath operator \+ is not a single numeric value
 SELECT jsonb_path_query('{"a": null}', '2 + $.a');
 
-# when string literals are supported
-# query T rowsort
-# SELECT jsonb_path_query('{"data": [{"val": "a", "num": 1}, {"val": "b", "num": 2}, {"val": "a", "num": 3}]}'::jsonb, '$.data ? (@.val == "a")'::jsonpath);
-# ----
-# {"num": 1, "val": "a"}
-# {"num": 3, "val": "a"}
+query T
+SELECT jsonb_path_query('{}', '"a" == "b"');
+----
+false
+
+query T
+SELECT jsonb_path_query('{}', '"a" < "b"');
+----
+true
+
+query T
+SELECT jsonb_path_query('{}', '"a" > "b"');
+----
+false
+
+statement error pgcode 22038 pq: left operand of jsonpath operator \+ is not a single numeric value
+SELECT jsonb_path_query('{}', '"a" + "b"');
+
+query T rowsort
+SELECT jsonb_path_query('{"data": [{"val": "a", "num": 1}, {"val": "b", "num": 2}, {"val": "a", "num": 3}]}', '$.data ? (@.val == "a")');
+----
+{"num": 1, "val": "a"}
+{"num": 3, "val": "a"}
+
 # select jsonb_path_query('[1, 2, 3, 4, 5]', '$[-1]');
 # select jsonb_path_query('[1, 2, 3, 4, 5]', 'strict $[-1]');
 

pkg/sql/scanner/jsonpath_scan.go

@@ -47,7 +47,7 @@ func (s *JSONPathScanner) Scan(lval ScanSymType) {
 	case identQuote:
 		// "[^"]"
 		if s.scanString(lval, identQuote, false /* allowEscapes */, true /* requireUTF8 */) {
-			lval.SetID(lexbase.IDENT)
+			lval.SetID(lexbase.STRING)
 		}
 		return
 	case '=':

pkg/util/jsonpath/parser/jsonpath.y

@@ -171,6 +171,8 @@ func unaryOp(op jsonpath.OperationType, left jsonpath.Path) jsonpath.Operation {
 
 %token <str> CURRENT
 
+%token <str> STRING
+
 %type <jsonpath.Jsonpath> jsonpath
 %type <jsonpath.Path> expr_or_predicate
 %type <jsonpath.Path> expr
@@ -447,20 +449,22 @@ scalar_value:
   {
     $$.val = jsonpath.Scalar{Type: jsonpath.ScalarBool, Value: json.FromBool(false)}
   }
-// TODO(normanchenn): support strings, null.
+| STRING
+  {
+    $$.val = jsonpath.Scalar{Type: jsonpath.ScalarString, Value: json.FromString($1)}
+  }
+// TODO(normanchenn): support null.
 ;
 
 any_identifier:
   IDENT
+| STRING
 | unreserved_keyword
 ;
 
 unreserved_keyword:
-  AND
-| FALSE
+  FALSE
 | LAX
-| NOT
-| OR
 | STRICT
 | TO
 | TRUE

pkg/util/jsonpath/parser/testdata/jsonpath

@@ -418,6 +418,24 @@ $.c[$.b - $.a to $.d - $.b]
 ----
 $."c"[($."b" - $."a") to ($."d" - $."b")] -- normalized!
 
+parse
+"hello" == "hello"
+----
+("hello" == "hello") -- normalized!
+
+parse
+$.a ? (@.b == "string")
+----
+$."a"?((@."b" == "string")) -- normalized!
+
+error
+"a" && "b"
+----
+at or near "&": syntax error
+DETAIL: source SQL:
+"a" && "b"
+    ^
+
 # postgres allows floats as array indexes
 # parse
 # $.abc[1.0]