Add token field validation & support for numeral field names

Author: mvollmary

src/main/java/io/github/noncat_lang/Template.java

@@ -36,6 +36,9 @@ public Template withToken(@NonNull String field, @NonNull Token token) {
     if (field.isBlank()) {
       throw new IllegalArgumentException("Token field should not be blank/empty");
     }
+    if (!field.matches("[a-zA-Z0-9]+")) {
+      throw new IllegalArgumentException("Token field does not match pattern [a-zA-Z0-9]+");
+    }
     tokens.put(field, token);
     return this;
   }
@@ -82,7 +85,7 @@ private Map<String, String> decodeAllToken(Matcher matcher) {
   }
 
   private String decodeToken(Entry<String, Token> entry, Matcher matcher) {
-    return entry.getValue().decode(matcher.group(entry.getKey()));
+    return entry.getValue().decode(matcher.group("x" + entry.getKey()));
   }
 
   private String parseElement(ElementContext element) {
@@ -96,7 +99,7 @@ private String parseArg(ArgContext arg) {
     if (token == null) {
       throw new MissingTokenException(String.format("Token for field '%s' is missing", id));
     }
-    return String.format("(?<%s>%s)", id, token.getRegex());
+    return String.format("(?<x%s>%s)", id, token.getRegex());
   }
 
   private String getId(ArgContext arg) {

src/test/java/io/github/noncat_lang/TemplateTest.java

@@ -33,7 +33,8 @@ static Stream<Arguments> simpleParams() {
         Arguments.of("[a-zA-Z]+", "Hello ${world}!", "world", "LangSec", "Hello LangSec!"),
         Arguments.of("[a-zA-Z]+", "Hello {${world}}!", "world", "LangSec", "Hello {LangSec}!"),
         Arguments.of("[a-zA-Z]+", "Hello $${world}!", "world", "LangSec", "Hello $LangSec!"),
-        Arguments.of("[a-zA-Z]+", "Hello ${} ${world}!", "world", "LangSec", "Hello ${} LangSec!"));
+        Arguments.of("[a-zA-Z]+", "Hello ${} ${world}!", "world", "LangSec", "Hello ${} LangSec!"),
+        Arguments.of("[a-zA-Z]+", "Hello ${0}!", "0", "LangSec", "Hello LangSec!"));
   }
 
   @ParameterizedTest
@@ -144,28 +145,21 @@ void tokenNull() {
     assertThatThrownBy(() -> template.withToken("any", token)).isExactlyInstanceOf(NullPointerException.class);
   }
 
-  @Test
-  void tokenFieldNull() {
-    Template template = Template.of("any");
-    Token token = Token.of("any");
-    String field = null;
-    assertThatThrownBy(() -> template.withToken(field, token)).isExactlyInstanceOf(NullPointerException.class);
-  }
-
-  @Test
-  void tokenFieldEmpty() {
-    Template template = Template.of("any");
-    Token token = Token.of("any");
-    String field = "";
-    assertThatThrownBy(() -> template.withToken(field, token)).isExactlyInstanceOf(IllegalArgumentException.class);
+  static Stream<Arguments> invalidTokenFields() {
+    return Stream.of(
+        Arguments.of(null, NullPointerException.class, "field is marked non-null but is null"),
+        Arguments.of("", IllegalArgumentException.class, "Token field should not be blank/empty"),
+        Arguments.of(" ", IllegalArgumentException.class, "Token field should not be blank/empty"),
+        Arguments.of("#", IllegalArgumentException.class, "Token field does not match pattern [a-zA-Z0-9]+"));
   }
 
-  @Test
-  void tokenFieldBlank() {
+  @ParameterizedTest
+  @MethodSource("invalidTokenFields")
+  void tokenFieldEmpty(String field, Class<Exception> expectedException, String expectedMessage) {
     Template template = Template.of("any");
     Token token = Token.of("any");
-    String field = " ";
-    assertThatThrownBy(() -> template.withToken(field, token)).isExactlyInstanceOf(IllegalArgumentException.class);
+    assertThatThrownBy(() -> template.withToken(field, token)).isExactlyInstanceOf(expectedException)
+        .hasMessage(expectedMessage);
   }
 
 }