1 files changed, 53 insertions, 1 deletions
diff --git a/java/src/main/java/com/google/protobuf/TextFormat.java b/java/src/main/java/com/google/protobuf/TextFormat.java
index 44d036c1..c99b5285 100644
--- a/java/src/main/java/com/google/protobuf/TextFormat.java
+++ b/java/src/main/java/com/google/protobuf/TextFormat.java
@@ -1074,6 +1074,18 @@ public final class TextFormat {
     private ParseException floatParseException(final NumberFormatException e) {
       return parseException("Couldn't parse number: " + e.getMessage());
     }
+    
+    /**
+     * Returns a {@link UnknownFieldParseException} with the line and column
+     * numbers of the previous token in the description, and the unknown field
+     * name, suitable for throwing.
+     */
+    public UnknownFieldParseException unknownFieldParseExceptionPreviousToken(
+        final String unknownField, final String description) {
+      // Note:  People generally prefer one-based line and column numbers.
+      return new UnknownFieldParseException(
+        previousLine + 1, previousColumn + 1, unknownField, description);
+    }
   }
 
   /** Thrown when parsing an invalid text format message. */
@@ -1121,6 +1133,45 @@ public final class TextFormat {
       return column;
     }
   }
+  
+  /**
+   * Thrown when encountering an unknown field while parsing
+   * a text format message.
+   */
+  public static class UnknownFieldParseException extends ParseException {
+    private final String unknownField;
+
+    /**
+     * Create a new instance, with -1 as the line and column numbers, and an
+     * empty unknown field name.
+     */
+    public UnknownFieldParseException(final String message) {
+      this(-1, -1, "", message);
+    }
+
+    /**
+     * Create a new instance
+     *
+     * @param line the line number where the parse error occurred,
+     * using 1-offset.
+     * @param column the column number where the parser error occurred,
+     * using 1-offset.
+     * @param unknownField the name of the unknown field found while parsing.
+     */
+    public UnknownFieldParseException(final int line, final int column,
+        final String unknownField, final String message) {
+      super(line, column, message);
+      this.unknownField = unknownField;
+    }
+
+    /**
+     * Return the name of the unknown field encountered while parsing the
+     * protocol buffer string.
+     */
+    public String getUnknownField() {
+      return unknownField;
+    }
+  }
 
   private static final Parser PARSER = Parser.newBuilder().build();
 
@@ -1388,7 +1439,8 @@ public final class TextFormat {
 
         if (field == null) {
           if (!allowUnknownFields) {
-            throw tokenizer.parseExceptionPreviousToken(
+            throw tokenizer.unknownFieldParseExceptionPreviousToken(
+              name,
               "Message type \"" + type.getFullName()
               + "\" has no field named \"" + name + "\".");
           } else {