json: support string minLength/maxLength

common/json-schema-to-grammar.cpp

@@ -93,10 +93,8 @@ std::unordered_map<std::string, BuiltinRule> PRIMITIVE_RULES = {
                 "\"-\" [0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] "
                 "\"-\" [0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] "
                 "\"-\" [0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F][0-9a-fA-F] \"\\\"\" space", {}}},
-    {"string", {" \"\\\"\" (\n"
+    {"char",   {"[^\"\\\\] | \"\\\\\" ([\"\\\\/bfnrt] | \"u\" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])", {}}},
-               "        [^\"\\\\] |\n"
+    {"string", {"\"\\\"\" char* \"\\\"\" space", {"char"}}},
-               "        \"\\\\\" ([\"\\\\/bfnrt] | \"u\" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])\n"
-               "      )* \"\\\"\" space", {}}},
     {"null", {"\"null\" space", {}}},
 };
 
@@ -720,6 +718,11 @@ public:
         } else if ((schema_type.is_null() || schema_type == "string") && STRING_FORMAT_RULES.find(schema_format + "-string") != STRING_FORMAT_RULES.end()) {
             auto prim_name = schema_format + "-string";
             return _add_rule(rule_name, _add_primitive(prim_name, STRING_FORMAT_RULES.at(prim_name)));
+        } else if (schema_type == "string" && (schema.contains("minLength") || schema.contains("maxLength"))) {
+            std::string char_rule = _add_primitive("char", PRIMITIVE_RULES.at("char"));
+            int min_len = schema.contains("minLength") ? schema["minLength"].get<int>() : 0;
+            int max_len = schema.contains("maxLength") ? schema["maxLength"].get<int>() : std::numeric_limits<int>::max();
+            return _add_rule(rule_name, "\"\\\"\" " + build_repetition(char_rule, min_len, max_len) + " \"\\\"\" space");
         } else if (schema.empty() || schema_type == "object") {
             return _add_rule(rule_name, _add_primitive("object", PRIMITIVE_RULES.at("object")));
         } else {

examples/json_schema_to_grammar.py

@@ -66,11 +66,9 @@ PRIMITIVE_RULES = {
     'value'        : BuiltinRule('object | array | string | number | boolean | null', ['object', 'array', 'string', 'number', 'boolean', 'null']),
     'object'       : BuiltinRule('"{" space ( string ":" space value ("," space string ":" space value)* )? "}" space', ['string', 'value']),
     'array'        : BuiltinRule('"[" space ( value ("," space value)* )? "]" space', ['value']),
-    'uuid'         : BuiltinRule('"\\"" ' + ' "-" '.join('[0-9a-fA-F]' * n for n in [8, 4, 4, 4, 12]) + ' "\\"" space', []),
+    'uuid'         : BuiltinRule(r'"\"" ' + ' "-" '.join('[0-9a-fA-F]' * n for n in [8, 4, 4, 4, 12]) + r' "\"" space', []),
-    'string'       : BuiltinRule(r''' "\"" (
+    'char'         : BuiltinRule(r'[^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])', []),
-        [^"\\] |
+    'string'       : BuiltinRule(r'"\"" char* "\"" space', ['char']),
-        "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-      )* "\"" space''', []),
     'null'         : BuiltinRule('"null" space', []),
 }
 
@@ -452,6 +450,13 @@ class SchemaConverter:
             prim_name = f'{schema_format}-string'
             return self._add_rule(rule_name, self._add_primitive(prim_name, STRING_FORMAT_RULES[prim_name]))
 
+        elif schema_type == 'string' and ('minLength' in schema or 'maxLength' in schema):
+            char_rule = self._add_primitive('char', PRIMITIVE_RULES['char'])
+            min_len = schema.get('minLength', 0)
+            max_len = schema.get('maxLength')
+
+            return self._add_rule(rule_name, r'"\"" ' + _build_repetition(char_rule, min_len, max_len) + r' "\"" space')
+
         elif (schema_type == 'object') or (len(schema) == 0):
             return self._add_rule(rule_name, self._add_primitive('object', PRIMITIVE_RULES['object']))
 

examples/server/public/json-schema-to-grammar.mjs

@@ -72,10 +72,8 @@ const PRIMITIVE_RULES = {
   object         : new BuiltinRule('"{" space ( string ":" space value ("," space string ":" space value)* )? "}" space', ['string', 'value']),
   array          : new BuiltinRule('"[" space ( value ("," space value)* )? "]" space', ['value']),
   uuid           : new BuiltinRule('"\\"" ' + [8, 4, 4, 4, 12].map(n => [...new Array(n)].map(_ => '[0-9a-fA-F]').join('')).join(' "-" ') + ' "\\"" space', []),
-  string         : new BuiltinRule(` "\\"" (
+  char           : new BuiltinRule(`[^"\\\\] | "\\\\" (["\\\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])`, []),
-        [^"\\\\] |
+  string         : new BuiltinRule(`"\\"" char* "\\"" space`, ['char']),
-        "\\\\" (["\\\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-      )* "\\"" space`, []),
   null           : new BuiltinRule('"null" space', []),
 };
 
@@ -463,6 +461,11 @@ export class SchemaConverter {
     } else if ((schemaType === undefined || schemaType === 'string') && `${schema.format}-string` in STRING_FORMAT_RULES) {
       const primName = `${schema.format}-string`
       return this._addRule(ruleName, this._addPrimitive(primName, STRING_FORMAT_RULES[primName]));
+    } else if (schemaType === 'string' && ('minLength' in schema || 'maxLength' in schema)) {
+      const charRuleName = this._addPrimitive('char', PRIMITIVE_RULES['char']);
+      const minLen = schema.minLength || 0;
+      const maxLen = schema.maxLength;
+      return this._addRule(ruleName, '"\\\"" ' + _buildRepetition(charRuleName, minLen, maxLen) + ' "\\\"" space');
     } else if ((schemaType === 'object') || (Object.keys(schema).length === 0)) {
       return this._addRule(ruleName, this._addPrimitive('object', PRIMITIVE_RULES['object']));
     } else {

tests/test-json-schema-to-grammar.cpp

@@ -104,6 +104,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
         R"""(
             array ::= "[" space ( value ("," space value)* )? "]" space
             boolean ::= ("true" | "false") space
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             decimal-part ::= [0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             integral-part ::= [0-9] | [1-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             null ::= "null" space
@@ -111,10 +112,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             object ::= "{" space ( string ":" space value ("," space string ":" space value)* )? "}" space
             root ::= object
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
             value ::= object | array | string | number | boolean | null
         )"""
     });
@@ -153,10 +151,65 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "type": "string"
         })""",
         R"""(
-            root ::=  "\"" (
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    [^"\\] |
+            root ::= "\"" char* "\"" space
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
+            space ::= " "?
-                    )* "\"" space
+        )"""
+    });
+
+    test({
+        SUCCESS,
+        "string w/ min length 1",
+        R"""({
+            "type": "string",
+            "minLength": 1
+        })""",
+        R"""(
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
+            root ::= "\"" char+ "\"" space
+            space ::= " "?
+        )"""
+    });
+
+    test({
+        SUCCESS,
+        "string w/ min length 3",
+        R"""({
+            "type": "string",
+            "minLength": 3
+        })""",
+        R"""(
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
+            root ::= "\"" char char char (char)* "\"" space
+            space ::= " "?
+        )"""
+    });
+
+    test({
+        SUCCESS,
+        "string w/ max length",
+        R"""({
+            "type": "string",
+            "maxLength": 3
+        })""",
+        R"""(
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
+            root ::= "\"" (char (char (char)?)?)? "\"" space
+            space ::= " "?
+        )"""
+    });
+
+    test({
+        SUCCESS,
+        "string w/ min & max length",
+        R"""({
+            "type": "string",
+            "minLength": 1,
+            "maxLength": 4
+        })""",
+        R"""(
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
+            root ::= "\"" char (char (char (char)?)?)? "\"" space
             space ::= " "?
         )"""
     });
@@ -229,12 +282,10 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "prefixItems": [{ "type": "string" }]
         })""",
         R"""(
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             root ::= "[" space string "]" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });
 
@@ -245,15 +296,13 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "prefixItems": [{ "type": "string" }, { "type": "number" }]
         })""",
         R"""(
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             decimal-part ::= [0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             integral-part ::= [0-9] | [1-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "[" space string "," space number "]" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });
 
@@ -416,12 +465,10 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             a-kv ::= "\"a\"" space ":" space string
             b-kv ::= "\"b\"" space ":" space string
             c-kv ::= "\"c\"" space ":" space string
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             root ::= "{" space b-kv "," space c-kv "," space a-kv "}" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });
 
@@ -438,12 +485,10 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
         })""",
         R"""(
             a-kv ::= "\"a\"" space ":" space string
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             root ::= "{" space  (a-kv )? "}" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });
 
@@ -464,12 +509,10 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             b-kv ::= "\"b\"" space ":" space string
             b-rest ::= ( "," space c-kv )?
             c-kv ::= "\"c\"" space ":" space string
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             root ::= "{" space  (a-kv a-rest | b-kv b-rest | c-kv )? "}" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });
 
@@ -490,14 +533,12 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             a-kv ::= "\"a\"" space ":" space string
             b-kv ::= "\"b\"" space ":" space string
             c-kv ::= "\"c\"" space ":" space string
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             d-kv ::= "\"d\"" space ":" space string
             d-rest ::= ( "," space c-kv )?
             root ::= "{" space b-kv "," space a-kv ( "," space ( d-kv d-rest | c-kv ) )? "}" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                )* "\"" space
         )"""
     });
 
@@ -512,15 +553,13 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             additional-kv ::= string ":" space additional-value
             additional-kvs ::= additional-kv ( "," space additional-kv )*
             additional-value ::= "[" space (number ("," space number)*)? "]" space
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             decimal-part ::= [0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             integral-part ::= [0-9] | [1-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "{" space  (additional-kvs )? "}" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });
 
@@ -534,6 +573,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
         R"""(
             array ::= "[" space ( value ("," space value)* )? "]" space
             boolean ::= ("true" | "false") space
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             decimal-part ::= [0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             integral-part ::= [0-9] | [1-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             null ::= "null" space
@@ -541,10 +581,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             object ::= "{" space ( string ":" space value ("," space string ":" space value)* )? "}" space
             root ::= object
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
             value ::= object | array | string | number | boolean | null
         )"""
     });
@@ -558,6 +595,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
         R"""(
             array ::= "[" space ( value ("," space value)* )? "]" space
             boolean ::= ("true" | "false") space
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             decimal-part ::= [0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             integral-part ::= [0-9] | [1-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             null ::= "null" space
@@ -565,10 +603,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             object ::= "{" space ( string ":" space value ("," space string ":" space value)* )? "}" space
             root ::= object
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
             value ::= object | array | string | number | boolean | null
         )"""
     });
@@ -601,15 +636,13 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             a-kv ::= "\"a\"" space ":" space number
             additional-kv ::= string ":" space string
             additional-kvs ::= additional-kv ( "," space additional-kv )*
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             decimal-part ::= [0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             integral-part ::= [0-9] | [1-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "{" space a-kv ( "," space ( additional-kvs ) )? "}" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });
 
@@ -628,15 +661,13 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             a-rest ::= additional-kvs
             additional-kv ::= string ":" space number
             additional-kvs ::= additional-kv ( "," space additional-kv )*
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             decimal-part ::= [0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             integral-part ::= [0-9] | [1-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "{" space  (a-kv a-rest | additional-kvs )? "}" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });
 
@@ -658,15 +689,13 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             additional-kvs ::= additional-kv ( "," space additional-kv )*
             b-kv ::= "\"b\"" space ":" space number
             b-rest ::= additional-kvs
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
             decimal-part ::= [0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             integral-part ::= [0-9] | [1-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9] ([0-9])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "{" space a-kv ( "," space ( b-kv b-rest | additional-kvs ) )? "}" space
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });
 
@@ -674,9 +703,9 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
         SUCCESS,
         "top-level $ref",
         R"""({
-            "$ref": "#/definitions/MyType",
+            "$ref": "#/definitions/foo",
             "definitions": {
-                "MyType": {
+                "foo": {
                     "type": "object",
                     "properties": {
                         "a": {
@@ -691,14 +720,12 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             }
         })""",
         R"""(
-            MyType ::= "{" space MyType-a-kv "}" space
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-            MyType-a-kv ::= "\"a\"" space ":" space string
+            foo ::= "{" space foo-a-kv "}" space
-            root ::= MyType
+            foo-a-kv ::= "\"a\"" space ":" space string
+            root ::= foo
             space ::= " "?
-            string ::=  "\"" (
+            string ::= "\"" char* "\"" space
-                    [^"\\] |
-                    "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
-                    )* "\"" space
         )"""
     });