Fix handling of identifiers which start with numbers

src/grammar.pest

@@ -14,7 +14,7 @@ literal = { string_literal |
 
 null_literal = @{ "null" ~ !symbol_char }
 boolean_literal = @{ ("true"|"false") ~ !symbol_char }
-number_literal = @{ "-"? ~ ASCII_DIGIT+ ~ "."? ~ ASCII_DIGIT* ~ ("E" ~ "-"? ~ ASCII_DIGIT+)? }
+number_literal = @{ "-"? ~ ASCII_DIGIT+ ~ "."? ~ ASCII_DIGIT* ~ ("E" ~ "-"? ~ ASCII_DIGIT+)? ~ !symbol_char }
 json_char_double_quote = {
     !("\"" | "\\") ~ ANY
     | "\\" ~ ("\"" | "\\" | "/" | "b" | "f" | "n" | "r" | "t")

src/render.rs

@@ -1117,3 +1117,37 @@ fn test_zero_args_heler() {
         "Output name: first_name not resolved"
     );
 }
+
+#[test]
+fn test_identifiers_starting_with_numbers() {
+    let mut r = Registry::new();
+
+    assert!(r
+        .register_template_string("r1", "{{#if 0a}}true{{/if}}")
+        .is_ok());
+    let r1 = r.render("r1", &json!({"0a": true})).unwrap();
+    assert_eq!(r1, "true");
+
+    assert!(r.register_template_string("r2", "{{eq 1a 1}}").is_ok());
+    let r2 = r.render("r2", &json!({"1a": 2, "a": 1})).unwrap();
+    assert_eq!(r2, "false");
+
+    assert!(r
+        .register_template_string("r3", "0: {{0}} {{#if (eq 0 true)}}resolved from context{{/if}}\n1a: {{1a}} {{#if (eq 1a true)}}resolved from context{{/if}}\n2_2: {{2_2}} {{#if (eq 2_2 true)}}resolved from context{{/if}}") // YUP it is just eq that barfs! is if handled specially? maybe this test should go nearer to specific helpers that fail?
+        .is_ok());
+    let r3 = r
+        .render("r3", &json!({"0": true, "1a": true, "2_2": true}))
+        .unwrap();
+    assert_eq!(
+        r3,
+        "0: true \n1a: true resolved from context\n2_2: true resolved from context"
+    );
+
+    // these should all be errors:
+    assert!(r.register_template_string("r4", "{{eq 1}}").is_ok());
+    assert!(r.register_template_string("r5", "{{eq a1}}").is_ok());
+    assert!(r.register_template_string("r6", "{{eq 1a}}").is_ok());
+    assert!(r.render("r4", &()).is_err());
+    assert!(r.render("r5", &()).is_err());
+    assert!(r.render("r6", &()).is_err());
+}