grammars: x{min,max} repetition operator (#6640)

* grammars: x{min,max} repetition operator + tweak +/*/? to avoid duplication of original over alternates

* grammars: handle `x{n}` and fix `x{n,n}`

* grammars: document new repetition operators

* grammars: uniform use of int for min & max

* grammars: refactor parser test

* grammar: parsing tests w/ natural pretty print of updated expectations

* grammars: much prettier print of expectations (+ TEST_GRAMMAR_PARSER_PRINT_ALL=1 to force all)

* grammars: improve test pretty print again

* grammars: pretty print rules and chars

* grammars: fix copy rule skipping

* grammars: disallow `a{,}` (not allowed in regexps)

* Update common/grammar-parser.cpp

Co-authored-by: Clint Herron <hanclinto@gmail.com>

* grammars: fix copy rule skipping (again) & display of expectations

* grammars: more test cases

* grammars: update reps parsing to bring ? / * / + closer to before

* json: use new GBNF repetitions{m,n} syntax

* grammars: update performance gotchas w/ repetition advice

* Update examples/json_schema_to_grammar.py

Co-authored-by: Clint Herron <hanclinto@gmail.com>

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

Co-authored-by: Clint Herron <hanclinto@gmail.com>

* grammars: comment on rule repetitions

* grammars: ensure unambiguous number alternatives

* grammar: nit typo switched error msgs

* grammar: nit numbering in comment

* json: update numeric rule to be unambiguous

* Apply suggestions from code review

Co-authored-by: Clint Herron <hanclinto@gmail.com>

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

Co-authored-by: Clint Herron <hanclinto@gmail.com>

* json: fix integral-part

* grammar: add repetition tests

---------

Co-authored-by: Clint Herron <hanclinto@gmail.com>

3 files changed, 555 insertions, 214 deletions

diff --git a/tests/test-grammar-integration.cpp b/tests/test-grammar-integration.cpp
index 01c5bb27..9bdab05a 100644
--- a/tests/test-grammar-integration.cpp
+++ b/tests/test-grammar-integration.cpp
@@ -292,6 +292,82 @@ static void test_quantifiers() {
             "catyyy",
         }
     );
+    test_grammar(
+        "simple exact repetition",
+        // Grammar
+        R"""(
+            root ::= [ab]{4}
+        )""",
+        // Passing strings
+        {
+            "aaaa",
+            "bbbb",
+            "abab",
+        },
+        // Failing strings
+        {
+            "a",
+            "b",
+            "aaaaa",
+        }
+    );
+    test_grammar(
+        "simple min repetition",
+        // Grammar
+        R"""(
+            root ::= [ab]{4,}
+        )""",
+        // Passing strings
+        {
+            "aaaa",
+            "aaaaab",
+            "bbbb",
+            "ababab",
+        },
+        // Failing strings
+        {
+            "",
+            "aba",
+        }
+    );
+    test_grammar(
+        "simple max repetition",
+        // Grammar
+        R"""(
+            root ::= [ab]{0,4}
+        )""",
+        // Passing strings
+        {
+            "",
+            "a",
+            "aa",
+            "aaa",
+            "aaab",
+        },
+        // Failing strings
+        {
+            "aaaaa",
+        }
+    );
+    test_grammar(
+        "min / max repetition",
+        // Grammar
+        R"""(
+            root ::= ("0x" [A-F0-9]{2} " "?){3,5}
+        )""",
+        // Passing strings
+        {
+            "0xFF 0x12 0xAB",
+            "0xFF 0x12 0xAB 0x00 0x00",
+        },
+        // Failing strings
+        {
+            "",
+            "0xFF",
+            "0xFF 0x12",
+            "0xFF 0x12 0xAB 0x00 0x00 0x00",
+        }
+    );
 }
 
 static void test_failure_missing_root() {
diff --git a/tests/test-grammar-parser.cpp b/tests/test-grammar-parser.cpp
index 91939e27..5df5abb2 100644
--- a/tests/test-grammar-parser.cpp
+++ b/tests/test-grammar-parser.cpp
@@ -7,28 +7,79 @@
 
 #include <cassert>
 
-int main()
-{
-    grammar_parser::parse_state parsed_grammar;
+static const char * type_str(llama_gretype type) {
+    switch (type) {
+        case LLAMA_GRETYPE_CHAR: return "LLAMA_GRETYPE_CHAR";
+        case LLAMA_GRETYPE_CHAR_NOT: return "LLAMA_GRETYPE_CHAR_NOT";
+        case LLAMA_GRETYPE_CHAR_ALT: return "LLAMA_GRETYPE_CHAR_ALT";
+        case LLAMA_GRETYPE_CHAR_RNG_UPPER: return "LLAMA_GRETYPE_CHAR_RNG_UPPER";
+        case LLAMA_GRETYPE_RULE_REF: return "LLAMA_GRETYPE_RULE_REF";
+        case LLAMA_GRETYPE_ALT: return "LLAMA_GRETYPE_ALT";
+        case LLAMA_GRETYPE_END: return "LLAMA_GRETYPE_END";
+        default: return "?";
+    }
+}
 
-    const char *grammar_bytes = R"""(root  ::= (expr "=" term "\n")+
-expr  ::= term ([-+*/] term)*
-term  ::= [0-9]+)""";
+static void verify_parsing(const char *grammar_bytes, const std::vector<std::pair<std::string, uint32_t>> expected, const std::vector<llama_grammar_element> &expected_rules) {
+    uint32_t index = 0;
+    grammar_parser::parse_state parsed_grammar = grammar_parser::parse(grammar_bytes);
 
-    parsed_grammar = grammar_parser::parse(grammar_bytes);
+    std::map<uint32_t, std::string> symbol_names;
+    for (auto it = parsed_grammar.symbol_ids.begin(); it != parsed_grammar.symbol_ids.end(); ++it) {
+        symbol_names[it->second] = it->first;
+    }
 
-    std::vector<std::pair<std::string, uint32_t>> expected = {
-        {"expr", 2},
-        {"expr_5", 5},
-        {"expr_6", 6},
-        {"root", 0},
-        {"root_1", 1},
-        {"root_4", 4},
-        {"term", 3},
-        {"term_7", 7},
+    auto print_all = [&]() {
+        fprintf(stderr, "    verify_parsing(R\"\"\"(%s)\"\"\", {\n", grammar_bytes);
+        for (auto it = parsed_grammar.symbol_ids.begin(); it != parsed_grammar.symbol_ids.end(); ++it) {
+            fprintf(stderr, "        {\"%s\", %u},\n", it->first.c_str(), it->second);
+        }
+        fprintf(stderr, "    }, {\n");
+        for (size_t i_rule = 0; i_rule < parsed_grammar.rules.size(); i_rule++) {
+            fprintf(stderr, "        // %s (index %zu)\n", symbol_names[i_rule].c_str(), i_rule);
+            auto & rule = parsed_grammar.rules[i_rule];
+            for (uint32_t i = 0; i < rule.size(); i++) {
+                std::string rule_str;
+                fprintf(stderr, "        {%s, ", type_str(rule[i].type));
+                if (rule[i].type == LLAMA_GRETYPE_CHAR || rule[i].type == LLAMA_GRETYPE_CHAR_ALT ||
+                    rule[i].type == LLAMA_GRETYPE_CHAR_NOT || rule[i].type == LLAMA_GRETYPE_CHAR_RNG_UPPER) {
+                    char c = rule[i].value;
+                    if (c == '\n') {
+                        fprintf(stderr, "'\\n'");
+                    } else if (c == '\t') {
+                        fprintf(stderr, "'\\t'");
+                    } else if (c == '\r') {
+                        fprintf(stderr, "'\\r'");
+                    } else if (c == '\0') {
+                        fprintf(stderr, "'\\0'");
+                    } else {
+                        fprintf(stderr, "'%c'", c);
+                    }
+                } else if (rule[i].type == LLAMA_GRETYPE_RULE_REF) {
+                    fprintf(stderr, "/* %s */ %u", symbol_names[rule[i].value].c_str(), rule[i].value);
+                } else {
+                    fprintf(stderr, "%u", rule[i].value);
+                }
+                fprintf(stderr, "},\n");
+            }
+        }
+        fprintf(stderr, "    });\n");
     };
 
-    uint32_t index = 0;
+    if (getenv("TEST_GRAMMAR_PARSER_PRINT_ALL")) {
+        print_all();
+        fprintf(stderr, "\n");
+        return;
+    }
+
+    fprintf(stderr, "Testing grammar:%s\n", grammar_bytes);
+
+    if (parsed_grammar.symbol_ids.size() != expected.size()) {
+        fprintf(stderr, "Code to update expectation (set TEST_GRAMMAR_PARSER_PRINT_ALL=1 to print all):\n");
+        print_all();
+        assert(parsed_grammar.symbol_ids.size() == expected.size());
+    }
+
     for (auto it = parsed_grammar.symbol_ids.begin(); it != parsed_grammar.symbol_ids.end(); ++it)
     {
         std::string key = it->first;
@@ -38,51 +89,18 @@ term  ::= [0-9]+)""";
         // pretty print error message before asserting
         if (expected_pair.first != key || expected_pair.second != value)
         {
+            fprintf(stderr, "index: %u\n", index);
             fprintf(stderr, "expected_pair: %s, %u\n", expected_pair.first.c_str(), expected_pair.second);
             fprintf(stderr, "actual_pair: %s, %u\n", key.c_str(), value);
             fprintf(stderr, "expected_pair != actual_pair\n");
+            fprintf(stderr, "Code to update expectation (set TEST_GRAMMAR_PARSER_PRINT_ALL=1 to print all):\n");
+            print_all();
         }
 
         assert(expected_pair.first == key && expected_pair.second == value);
 
         index++;
     }
-    std::vector<llama_grammar_element> expected_rules = {
-        {LLAMA_GRETYPE_RULE_REF, 4},
-        {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 2},
-        {LLAMA_GRETYPE_CHAR, 61},
-        {LLAMA_GRETYPE_RULE_REF, 3},
-        {LLAMA_GRETYPE_CHAR, 10},
-        {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 3},
-        {LLAMA_GRETYPE_RULE_REF, 6},
-        {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 7},
-        {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 1},
-        {LLAMA_GRETYPE_RULE_REF, 4},
-        {LLAMA_GRETYPE_ALT, 0},
-        {LLAMA_GRETYPE_RULE_REF, 1},
-        {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_CHAR, 45},
-        {LLAMA_GRETYPE_CHAR_ALT, 43},
-        {LLAMA_GRETYPE_CHAR_ALT, 42},
-        {LLAMA_GRETYPE_CHAR_ALT, 47},
-        {LLAMA_GRETYPE_RULE_REF, 3},
-        {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 5},
-        {LLAMA_GRETYPE_RULE_REF, 6},
-        {LLAMA_GRETYPE_ALT, 0},
-        {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_CHAR, 48},
-        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 57},
-        {LLAMA_GRETYPE_RULE_REF, 7},
-        {LLAMA_GRETYPE_ALT, 0},
-        {LLAMA_GRETYPE_CHAR, 48},
-        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 57},
-        {LLAMA_GRETYPE_END, 0},
-    };
 
     index = 0;
     for (auto rule : parsed_grammar.rules)
@@ -97,28 +115,306 @@ term  ::= [0-9]+)""";
             if (expected_element.type != element.type || expected_element.value != element.value)
             {
                 fprintf(stderr, "index: %u\n", index);
-                fprintf(stderr, "expected_element: %d, %u\n", expected_element.type, expected_element.value);
-                fprintf(stderr, "actual_element: %d, %u\n", element.type, element.value);
+                fprintf(stderr, "expected_element: %s, %u\n", type_str(expected_element.type), expected_element.value);
+                fprintf(stderr, "actual_element: %s, %u\n", type_str(element.type), element.value);
                 fprintf(stderr, "expected_element != actual_element\n");
+                fprintf(stderr, "all elements:\n");
+                fprintf(stderr, "Code to update expectation (set TEST_GRAMMAR_PARSER_PRINT_ALL=1 to print all):\n");
+                print_all();
             }
 
             assert(expected_element.type == element.type && expected_element.value == element.value);
             index++;
         }
     }
+}
+
+static void verify_failure(const char *grammar_bytes) {
+    fprintf(stderr, "Testing expected failure:%s\n", grammar_bytes);
+    auto result = grammar_parser::parse(grammar_bytes);
+    assert(result.rules.empty() && "should have failed");
+}
+
+int main()
+{
+    verify_failure(R"""(
+        root ::= "a"{,}"
+    )""");
+
+    verify_failure(R"""(
+        root ::= "a"{,10}"
+    )""");
 
-    const char *longer_grammar_bytes = R"""(
-    root  ::= (expr "=" ws term "\n")+
-    expr  ::= term ([-+*/] term)*
-    term  ::= ident | num | "(" ws expr ")" ws
-    ident ::= [a-z] [a-z0-9_]* ws
-    num   ::= [0-9]+ ws
-    ws    ::= [ \t\n]*
-    )""";
+    verify_parsing(R"""(
+        root  ::= "a"
+    )""", {
+        {"root", 0},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= "a" | [bdx-z] | [^1-3]
+    )""", {
+        {"root", 0},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_CHAR, 'b'},
+        {LLAMA_GRETYPE_CHAR_ALT, 'd'},
+        {LLAMA_GRETYPE_CHAR_ALT, 'x'},
+        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 'z'},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_CHAR_NOT, '1'},
+        {LLAMA_GRETYPE_CHAR_RNG_UPPER, '3'},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= a+
+        a     ::= "a"
+    )""", {
+        {"a", 1},
+        {"root", 0},
+        {"root_2", 2},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_RULE_REF, /* a */ 1},
+        {LLAMA_GRETYPE_RULE_REF, /* root_2 */ 2},
+        {LLAMA_GRETYPE_END, 0},
+        // a (index 1)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_END, 0},
+        // root_2 (index 2)
+        {LLAMA_GRETYPE_RULE_REF, /* a */ 1},
+        {LLAMA_GRETYPE_RULE_REF, /* root_2 */ 2},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= "a"+
+    )""", {
+        {"root", 0},
+        {"root_1", 1},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_END, 0},
+        // root_1 (index 1)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= a?
+        a     ::= "a"
+    )""", {
+        {"a", 1},
+        {"root", 0},
+        {"root_2", 2},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_RULE_REF, /* root_2 */ 2},
+        {LLAMA_GRETYPE_END, 0},
+        // a (index 1)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_END, 0},
+        // root_2 (index 2)
+        {LLAMA_GRETYPE_RULE_REF, /* a */ 1},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+    });
 
-    parsed_grammar = grammar_parser::parse(longer_grammar_bytes);
+    verify_parsing(R"""(
+        root  ::= "a"?
+    )""", {
+        {"root", 0},
+        {"root_1", 1},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_END, 0},
+        // root_1 (index 1)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= a*
+        a     ::= "a"
+    )""", {
+        {"a", 1},
+        {"root", 0},
+        {"root_2", 2},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_RULE_REF, /* root_2 */ 2},
+        {LLAMA_GRETYPE_END, 0},
+        // a (index 1)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_END, 0},
+        // root_2 (index 2)
+        {LLAMA_GRETYPE_RULE_REF, /* a */ 1},
+        {LLAMA_GRETYPE_RULE_REF, /* root_2 */ 2},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= "a"*
+    )""", {
+        {"root", 0},
+        {"root_1", 1},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_END, 0},
+        // root_1 (index 1)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+    });
 
-    expected = {
+    verify_parsing(R"""(
+        root  ::= "a"{2}
+    )""", {
+        {"root", 0},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= "a"{2,}
+    )""", {
+        {"root", 0},
+        {"root_1", 1},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_END, 0},
+        // root_1 (index 1)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= "a"{ 4}
+    )""", {
+        {"root", 0},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= "a"{2,4}
+    )""", {
+        {"root", 0},
+        {"root_1", 1},
+        {"root_2", 2},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_RULE_REF, /* root_2 */ 2},
+        {LLAMA_GRETYPE_END, 0},
+        // root_1 (index 1)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+        // root_2 (index 2)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= (expr "=" term "\n")+
+        expr  ::= term ([-+*/] term)*
+        term  ::= [0-9]+
+    )""", {
+        {"expr", 2},
+        {"expr_5", 5},
+        {"expr_6", 6},
+        {"root", 0},
+        {"root_1", 1},
+        {"root_4", 4},
+        {"term", 3},
+        {"term_7", 7},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_RULE_REF, /* root_4 */ 4},
+        {LLAMA_GRETYPE_END, 0},
+        // root_1 (index 1)
+        {LLAMA_GRETYPE_RULE_REF, /* expr */ 2},
+        {LLAMA_GRETYPE_CHAR, '='},
+        {LLAMA_GRETYPE_RULE_REF, /* term */ 3},
+        {LLAMA_GRETYPE_CHAR, '\n'},
+        {LLAMA_GRETYPE_END, 0},
+        // expr (index 2)
+        {LLAMA_GRETYPE_RULE_REF, /* term */ 3},
+        {LLAMA_GRETYPE_RULE_REF, /* expr_6 */ 6},
+        {LLAMA_GRETYPE_END, 0},
+        // term (index 3)
+        {LLAMA_GRETYPE_CHAR, '0'},
+        {LLAMA_GRETYPE_CHAR_RNG_UPPER, '9'},
+        {LLAMA_GRETYPE_RULE_REF, /* term_7 */ 7},
+        {LLAMA_GRETYPE_END, 0},
+        // root_4 (index 4)
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_RULE_REF, /* root_4 */ 4},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+        // expr_5 (index 5)
+        {LLAMA_GRETYPE_CHAR, '-'},
+        {LLAMA_GRETYPE_CHAR_ALT, '+'},
+        {LLAMA_GRETYPE_CHAR_ALT, '*'},
+        {LLAMA_GRETYPE_CHAR_ALT, '/'},
+        {LLAMA_GRETYPE_RULE_REF, /* term */ 3},
+        {LLAMA_GRETYPE_END, 0},
+        // expr_6 (index 6)
+        {LLAMA_GRETYPE_RULE_REF, /* expr_5 */ 5},
+        {LLAMA_GRETYPE_RULE_REF, /* expr_6 */ 6},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+        // term_7 (index 7)
+        {LLAMA_GRETYPE_CHAR, '0'},
+        {LLAMA_GRETYPE_CHAR_RNG_UPPER, '9'},
+        {LLAMA_GRETYPE_RULE_REF, /* term_7 */ 7},
+        {LLAMA_GRETYPE_ALT, 0},
+        {LLAMA_GRETYPE_END, 0},
+    });
+
+    verify_parsing(R"""(
+        root  ::= (expr "=" ws term "\n")+
+        expr  ::= term ([-+*/] term)*
+        term  ::= ident | num | "(" ws expr ")" ws
+        ident ::= [a-z] [a-z0-9_]* ws
+        num   ::= [0-9]+ ws
+        ws    ::= [ \t\n]*
+    )""", {
         {"expr", 2},
         {"expr_6", 6},
         {"expr_7", 7},
@@ -132,119 +428,88 @@ term  ::= [0-9]+)""";
         {"term", 4},
         {"ws", 3},
         {"ws_12", 12},
-    };
-
-    index = 0;
-    for (auto it = parsed_grammar.symbol_ids.begin(); it != parsed_grammar.symbol_ids.end(); ++it)
-    {
-        std::string key = it->first;
-        uint32_t value = it->second;
-        std::pair<std::string, uint32_t> expected_pair = expected[index];
-
-        // pretty print error message before asserting
-        if (expected_pair.first != key || expected_pair.second != value)
-        {
-            fprintf(stderr, "expected_pair: %s, %u\n", expected_pair.first.c_str(), expected_pair.second);
-            fprintf(stderr, "actual_pair: %s, %u\n", key.c_str(), value);
-            fprintf(stderr, "expected_pair != actual_pair\n");
-        }
-
-        assert(expected_pair.first == key && expected_pair.second == value);
-
-        index++;
-    }
-    expected_rules = {
-        {LLAMA_GRETYPE_RULE_REF, 5},
+    }, {
+        // root (index 0)
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_RULE_REF, /* root_5 */ 5},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 2},
-        {LLAMA_GRETYPE_CHAR, 61},
-        {LLAMA_GRETYPE_RULE_REF, 3},
-        {LLAMA_GRETYPE_RULE_REF, 4},
-        {LLAMA_GRETYPE_CHAR, 10},
+        // root_1 (index 1)
+        {LLAMA_GRETYPE_RULE_REF, /* expr */ 2},
+        {LLAMA_GRETYPE_CHAR, '='},
+        {LLAMA_GRETYPE_RULE_REF, /* ws */ 3},
+        {LLAMA_GRETYPE_RULE_REF, /* term */ 4},
+        {LLAMA_GRETYPE_CHAR, '\n'},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 4},
-        {LLAMA_GRETYPE_RULE_REF, 7},
+        // expr (index 2)
+        {LLAMA_GRETYPE_RULE_REF, /* term */ 4},
+        {LLAMA_GRETYPE_RULE_REF, /* expr_7 */ 7},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 12},
+        // ws (index 3)
+        {LLAMA_GRETYPE_RULE_REF, /* ws_12 */ 12},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 8},
+        // term (index 4)
+        {LLAMA_GRETYPE_RULE_REF, /* ident */ 8},
         {LLAMA_GRETYPE_ALT, 0},
-        {LLAMA_GRETYPE_RULE_REF, 9},
+        {LLAMA_GRETYPE_RULE_REF, /* num */ 9},
         {LLAMA_GRETYPE_ALT, 0},
-        {LLAMA_GRETYPE_CHAR, 40},
-        {LLAMA_GRETYPE_RULE_REF, 3},
-        {LLAMA_GRETYPE_RULE_REF, 2},
-        {LLAMA_GRETYPE_CHAR, 41},
-        {LLAMA_GRETYPE_RULE_REF, 3},
+        {LLAMA_GRETYPE_CHAR, '('},
+        {LLAMA_GRETYPE_RULE_REF, /* ws */ 3},
+        {LLAMA_GRETYPE_RULE_REF, /* expr */ 2},
+        {LLAMA_GRETYPE_CHAR, ')'},
+        {LLAMA_GRETYPE_RULE_REF, /* ws */ 3},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 1},
-        {LLAMA_GRETYPE_RULE_REF, 5},
+        // root_5 (index 5)
+        {LLAMA_GRETYPE_RULE_REF, /* root_1 */ 1},
+        {LLAMA_GRETYPE_RULE_REF, /* root_5 */ 5},
         {LLAMA_GRETYPE_ALT, 0},
-        {LLAMA_GRETYPE_RULE_REF, 1},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_CHAR, 45},
-        {LLAMA_GRETYPE_CHAR_ALT, 43},
-        {LLAMA_GRETYPE_CHAR_ALT, 42},
-        {LLAMA_GRETYPE_CHAR_ALT, 47},
-        {LLAMA_GRETYPE_RULE_REF, 4},
+        // expr_6 (index 6)
+        {LLAMA_GRETYPE_CHAR, '-'},
+        {LLAMA_GRETYPE_CHAR_ALT, '+'},
+        {LLAMA_GRETYPE_CHAR_ALT, '*'},
+        {LLAMA_GRETYPE_CHAR_ALT, '/'},
+        {LLAMA_GRETYPE_RULE_REF, /* term */ 4},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 6},
-        {LLAMA_GRETYPE_RULE_REF, 7},
+        // expr_7 (index 7)
+        {LLAMA_GRETYPE_RULE_REF, /* expr_6 */ 6},
+        {LLAMA_GRETYPE_RULE_REF, /* expr_7 */ 7},
         {LLAMA_GRETYPE_ALT, 0},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_CHAR, 97},
-        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 122},
-        {LLAMA_GRETYPE_RULE_REF, 10},
-        {LLAMA_GRETYPE_RULE_REF, 3},
+        // ident (index 8)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 'z'},
+        {LLAMA_GRETYPE_RULE_REF, /* ident_10 */ 10},
+        {LLAMA_GRETYPE_RULE_REF, /* ws */ 3},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_RULE_REF, 11},
-        {LLAMA_GRETYPE_RULE_REF, 3},
+        // num (index 9)
+        {LLAMA_GRETYPE_CHAR, '0'},
+        {LLAMA_GRETYPE_CHAR_RNG_UPPER, '9'},
+        {LLAMA_GRETYPE_RULE_REF, /* num_11 */ 11},
+        {LLAMA_GRETYPE_RULE_REF, /* ws */ 3},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_CHAR, 97},
-        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 122},
-        {LLAMA_GRETYPE_CHAR_ALT, 48},
-        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 57},
-        {LLAMA_GRETYPE_CHAR_ALT, 95},
-        {LLAMA_GRETYPE_RULE_REF, 10},
+        // ident_10 (index 10)
+        {LLAMA_GRETYPE_CHAR, 'a'},
+        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 'z'},
+        {LLAMA_GRETYPE_CHAR_ALT, '0'},
+        {LLAMA_GRETYPE_CHAR_RNG_UPPER, '9'},
+        {LLAMA_GRETYPE_CHAR_ALT, '_'},
+        {LLAMA_GRETYPE_RULE_REF, /* ident_10 */ 10},
         {LLAMA_GRETYPE_ALT, 0},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_CHAR, 48},
-        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 57},
-        {LLAMA_GRETYPE_RULE_REF, 11},
+        // num_11 (index 11)
+        {LLAMA_GRETYPE_CHAR, '0'},
+        {LLAMA_GRETYPE_CHAR_RNG_UPPER, '9'},
+        {LLAMA_GRETYPE_RULE_REF, /* num_11 */ 11},
         {LLAMA_GRETYPE_ALT, 0},
-        {LLAMA_GRETYPE_CHAR, 48},
-        {LLAMA_GRETYPE_CHAR_RNG_UPPER, 57},
         {LLAMA_GRETYPE_END, 0},
-        {LLAMA_GRETYPE_CHAR, 32},
-        {LLAMA_GRETYPE_CHAR_ALT, 9},
-        {LLAMA_GRETYPE_CHAR_ALT, 10},
-        {LLAMA_GRETYPE_RULE_REF, 12},
+        // ws_12 (index 12)
+        {LLAMA_GRETYPE_CHAR, ' '},
+        {LLAMA_GRETYPE_CHAR_ALT, '\t'},
+        {LLAMA_GRETYPE_CHAR_ALT, '\n'},
+        {LLAMA_GRETYPE_RULE_REF, /* ws_12 */ 12},
         {LLAMA_GRETYPE_ALT, 0},
         {LLAMA_GRETYPE_END, 0},
-    };
-
-    index = 0;
-    for (auto rule : parsed_grammar.rules)
-    {
-        // compare rule to expected rule
-        for (uint32_t i = 0; i < rule.size(); i++)
-        {
-            llama_grammar_element element = rule[i];
-            llama_grammar_element expected_element = expected_rules[index];
-
-            // pretty print error message before asserting
-            if (expected_element.type != element.type || expected_element.value != element.value)
-            {
-                fprintf(stderr, "index: %u\n", index);
-                fprintf(stderr, "expected_element: %d, %u\n", expected_element.type, expected_element.value);
-                fprintf(stderr, "actual_element: %d, %u\n", element.type, element.value);
-                fprintf(stderr, "expected_element != actual_element\n");
-            }
-
-            assert(expected_element.type == element.type && expected_element.value == element.value);
-            index++;
-        }
-    }
+    });
 
     return 0;
 }
diff --git a/tests/test-json-schema-to-grammar.cpp b/tests/test-json-schema-to-grammar.cpp
index c5361b5b..052c0807 100755
--- a/tests/test-json-schema-to-grammar.cpp
+++ b/tests/test-json-schema-to-grammar.cpp
@@ -105,9 +105,9 @@ 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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             null ::= "null" space
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             object ::= "{" space ( string ":" space value ("," space string ":" space value)* )? "}" space
@@ -130,18 +130,18 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             ]
         })""",
         R"""(
-            date ::= [0-9] [0-9] [0-9] [0-9] "-" ( "0" [1-9] | "1" [0-2] ) "-" ( "0" [1-9] | [1-2] [0-9] | "3" [0-1] )
+            date ::= [0-9]{4} "-" ( "0" [1-9] | "1" [0-2] ) "-" ( "0" [1-9] | [1-2] [0-9] | "3" [0-1] )
             date-string ::= "\"" date "\"" space
             date-time ::= date "T" time
             date-time-string ::= "\"" date-time "\"" space
             root ::= "[" space tuple-0 "," space uuid "," space tuple-2 "," space tuple-3 "]" space
             space ::= " "?
-            time ::= ([01] [0-9] | "2" [0-3]) ":" [0-5] [0-9] ":" [0-5] [0-9] ( "." [0-9] [0-9] [0-9] )? ( "Z" | ( "+" | "-" ) ( [01] [0-9] | "2" [0-3] ) ":" [0-5] [0-9] )
+            time ::= ([01] [0-9] | "2" [0-3]) ":" [0-5] [0-9] ":" [0-5] [0-9] ( "." [0-9]{3} )? ( "Z" | ( "+" | "-" ) ( [01] [0-9] | "2" [0-3] ) ":" [0-5] [0-9] )
             time-string ::= "\"" time "\"" space
             tuple-0 ::= date-string
             tuple-2 ::= time-string
             tuple-3 ::= date-time-string
-            uuid ::= "\"" [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] "-" [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
+            uuid ::= "\"" [0-9a-fA-F]{8} "-" [0-9a-fA-F]{4} "-" [0-9a-fA-F]{4} "-" [0-9a-fA-F]{4} "-" [0-9a-fA-F]{12} "\"" space
         )"""
     });
 
@@ -152,7 +152,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "type": "string"
         })""",
         R"""(
-            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
             root ::= "\"" char* "\"" space
             space ::= " "?
         )"""
@@ -166,7 +166,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "minLength": 1
         })""",
         R"""(
-            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
             root ::= "\"" char+ "\"" space
             space ::= " "?
         )"""
@@ -180,8 +180,8 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "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
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            root ::= "\"" char{3,} "\"" space
             space ::= " "?
         )"""
     });
@@ -194,8 +194,8 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "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
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            root ::= "\"" char{0,3} "\"" space
             space ::= " "?
         )"""
     });
@@ -209,8 +209,8 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "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
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            root ::= "\"" char{1,4} "\"" space
             space ::= " "?
         )"""
     });
@@ -234,7 +234,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "type": "integer"
         })""",
         R"""(
-            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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             root ::= ("-"? integral-part) space
             space ::= " "?
         )"""
@@ -283,7 +283,7 @@ 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])
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
             root ::= "[" space string "]" space
             space ::= " "?
             string ::= "\"" char* "\"" space
@@ -297,9 +297,9 @@ 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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "[" space string "," space number "]" space
             space ::= " "?
@@ -314,8 +314,8 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "type": "number"
         })""",
         R"""(
-            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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             root ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             space ::= " "?
         )"""
@@ -332,7 +332,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
         })""",
         R"""(
             boolean ::= ("true" | "false") space
-            root ::= "[" space boolean "," space boolean ("," space boolean)* "]" space
+            root ::= "[" space boolean ("," space boolean)+ "]" space
             space ::= " "?
         )"""
     });
@@ -348,7 +348,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
         })""",
         R"""(
             boolean ::= ("true" | "false") space
-            root ::= "[" space (boolean)? "]" space
+            root ::= "[" space boolean? "]" space
             space ::= " "?
         )"""
     });
@@ -380,12 +380,12 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "maxItems": 5
         })""",
         R"""(
-            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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            decimal-part ::= [0-9]{1,16}
             integer ::= ("-"? integral-part) space
-            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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             item ::= number | integer
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
-            root ::= "[" space item "," space item "," space item ("," space item ("," space item)?)? "]" space
+            root ::= "[" space item ("," space item){2,4} "]" space
             space ::= " "?
         )"""
     });
@@ -438,7 +438,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
         })""",
         R"""(
             dot ::= [^\x0A\x0D]
-            root ::= "\"" ("(" root-1 (root-1 (root-1)?)? ")")? root-1 root-1 root-1 "-" root-1 root-1 root-1 root-1 " " "aaa" ("a" ("a")?)? "nd" dot dot dot "\"" space
+            root ::= "\"" ("(" root-1{1,3} ")")? root-1{3,3} "-" root-1{4,4} " " "a"{3,5} "nd" dot dot dot "\"" space
             root-1 ::= [0-9]
             space ::= " "?
         )"""
@@ -466,7 +466,7 @@ 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])
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
             root ::= "{" space b-kv "," space c-kv "," space a-kv "}" space
             space ::= " "?
             string ::= "\"" char* "\"" space
@@ -486,7 +486,7 @@ 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])
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
             root ::= "{" space  (a-kv )? "}" space
             space ::= " "?
             string ::= "\"" char* "\"" space
@@ -510,7 +510,7 @@ 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])
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
             root ::= "{" space  (a-kv a-rest | b-kv b-rest | c-kv )? "}" space
             space ::= " "?
             string ::= "\"" char* "\"" space
@@ -534,7 +534,7 @@ 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])
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
             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
@@ -554,9 +554,9 @@ 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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "{" space  (additional-kvs )? "}" space
             space ::= " "?
@@ -574,9 +574,9 @@ 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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             null ::= "null" space
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             object ::= "{" space ( string ":" space value ("," space string ":" space value)* )? "}" space
@@ -596,9 +596,9 @@ 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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             null ::= "null" space
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             object ::= "{" space ( string ":" space value ("," space string ":" space value)* )? "}" space
@@ -637,9 +637,9 @@ 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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "{" space a-kv ( "," space ( additional-kvs ) )? "}" space
             space ::= " "?
@@ -662,9 +662,9 @@ 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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "{" space  (a-kv a-rest | additional-kvs )? "}" space
             space ::= " "?
@@ -690,9 +690,9 @@ 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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "{" space a-kv ( "," space ( b-kv b-rest | additional-kvs ) )? "}" space
             space ::= " "?
@@ -721,7 +721,7 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             }
         })""",
         R"""(
-            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F] [0-9a-fA-F])
+            char ::= [^"\\] | "\\" (["\\/bfnrt] | "u" [0-9a-fA-F]{4})
             foo ::= "{" space foo-a-kv "}" space
             foo-a-kv ::= "\"a\"" space ":" space string
             root ::= foo
@@ -753,10 +753,10 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             alternative-1 ::= bar
             bar ::= "{" space  (bar-b-kv )? "}" space
             bar-b-kv ::= "\"b\"" space ":" space number
-            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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            decimal-part ::= [0-9]{1,16}
             foo ::= "{" space  (foo-a-kv )? "}" space
             foo-a-kv ::= "\"a\"" space ":" space number
-            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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= alternative-0 | alternative-1
             space ::= " "?
@@ -799,8 +799,8 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             c-kv ::= "\"c\"" space ":" space number
             d-kv ::= "\"d\"" space ":" space number
             d-rest ::= ( "," space c-kv )?
-            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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             root ::= "{" space a-kv "," space b-kv ( "," space ( d-kv d-rest | c-kv ) )? "}" space
             space ::= " "?
@@ -842,8 +842,8 @@ static void test_all(const std::string & lang, std::function<void(const TestCase
             "definitions": {}
         })""",
         R"""(
-            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])?)?)?)?)?)?)?)?)?)?)?)?)?)?)?
+            decimal-part ::= [0-9]{1,16}
+            integral-part ::= [0] | [1-9] [0-9]{0,15}
             number ::= ("-"? integral-part) ("." decimal-part)? ([eE] [-+]? integral-part)? space
             number- ::= "{" space number-number-kv "}" space
             number-kv ::= "\"number\"" space ":" space number-