Add extra information to FormatException.

R=floitsch@google.com

Review URL: https://codereview.chromium.org//389603002

git-svn-id: https://dart.googlecode.com/svn/branches/bleeding_edge/dart@38181 260f80e4-7a28-3924-810f-c04153c831b5

pkg/json_rpc_2/test/server/parameters_test.dart

@@ -229,7 +229,8 @@ void main() {
     test("[].asDateTime fails for invalid date/times", () {
       expect(() => parameters['string'].asDateTime,
           throwsInvalidParams('Parameter "string" for method "foo" must be a '
-              'valid date/time, but was "zap".'));
+              'valid date/time, but was "zap".\n'
+              'Invalid date format'));
     });
 
     test("[].asUri returns URI parameters", () {
@@ -262,9 +263,7 @@ void main() {
       expect(() => parameters['invalid-uri'].asUri,
           throwsInvalidParams('Parameter "invalid-uri" for method "foo" must '
               'be a valid URI, but was "http://[::1".\n'
-              'Missing end `]` to match `[` in host at position 7.\n'
-              'http://[::1\n'
-              '       ^'));
+              'Missing end `]` to match `[` in host'));
     });
 
     group("with a nested parameter map", () {

runtime/lib/convert_patch.dart

@@ -33,8 +33,6 @@ abstract class _JsonListener {
   void beginArray() {}
   void arrayElement() {}
   void endArray() {}
-  /** Called on failure to parse [source]. */
-  void fail(String source, int position, String message) {}
 }
 
 /**
@@ -568,16 +566,7 @@ class _JsonParser {
 
   void fail(int position, [String message]) {
     if (message == null) message = "Unexpected character";
-    listener.fail(source, position, message);
-    // If the listener didn't throw, do it here.
-    String slice;
-    int sliceEnd = position + 20;
-    if (sliceEnd > source.length) {
-      slice = "'${source.substring(position)}'";
-    } else {
-      slice = "'${source.substring(position, sliceEnd)}...'";
-    }
-    throw new FormatException("Unexpected character at $position: $slice");
+    throw new FormatException(message, source, position);
   }
 }
 

runtime/lib/double_patch.dart

@@ -24,7 +24,7 @@ patch class double {
                                   [double onError(String str)]) {
     var result = _parse(str);
     if (result == null) {
-      if (onError == null) throw new FormatException(str);
+      if (onError == null) throw new FormatException("Invalid double", str);
       return onError(str);
     }
     return result;

runtime/lib/integers_patch.dart

@@ -67,8 +67,8 @@ patch class int {
 
   static int _native_parse(String str) native "Integer_parse";
 
-  static int _throwFormatException(String source) {
-    throw new FormatException(source);
+  static int _throwFormatException(String source, int position) {
+    throw new FormatException("", source, position);
   }
 
   /* patch */ static int parse(String source,
@@ -78,7 +78,7 @@ patch class int {
       int result = _parse(source);
       if (result == null) {
         if (onError == null) {
-          throw new FormatException(source);
+          throw new FormatException("", source);
         }
         return onError(source);
       }
@@ -97,12 +97,14 @@ patch class int {
     if (radix < 2 || radix > 36) {
       throw new RangeError("Radix $radix not in range 2..36");
     }
-    if (onError == null) {
-      onError = _throwFormatException;
-    }
     // Remove leading and trailing white space.
-    source = source.trim();
-    if (source.isEmpty) return onError(source);
+    int start = source._firstNonWhitespace();
+    int i = start;
+    if (onError == null) onError = (source) {
+      throw new FormatException("Invalid radix-$radix number", source, i);
+    };
+    if (start == source.length) return onError(source);
+    int end = source._lastNonWhitespace() + 1;
 
     bool negative = false;
     int result = 0;
@@ -118,12 +120,11 @@ patch class int {
       25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, NA, NA, NA, NA, NA,  // 0x70
     ];
 
-    int i = 0;
     int code = source.codeUnitAt(i);
     if (code == 0x2d || code == 0x2b) { // Starts with a plus or minus-sign.
       negative = (code == 0x2d);
-      if (source.length == 1) return onError(source);
-      i = 1;
+      i++;
+      if (i == end) return onError(source);
       code = source.codeUnitAt(i);
     }
     do {
@@ -132,7 +133,7 @@ patch class int {
       if (digit >= radix) return onError(source);
       result = result * radix + digit;
       i++;
-      if (i == source.length) break;
+      if (i == end) break;
       code = source.codeUnitAt(i);
     } while (true);
     return negative ? -result : result;

sdk/lib/core/date_time.dart

@@ -282,13 +282,13 @@ class DateTime implements Comparable {
       int millisecondsSinceEpoch = _brokenDownDateToMillisecondsSinceEpoch(
           years, month, day, hour, minute, second, millisecond, isUtc);
       if (millisecondsSinceEpoch == null) {
-        throw new FormatException(formattedString);
+        throw new FormatException("Time out of range", formattedString);
       }
       if (addOneMillisecond) millisecondsSinceEpoch++;
       return new DateTime.fromMillisecondsSinceEpoch(millisecondsSinceEpoch,
                                                      isUtc: isUtc);
     } else {
-      throw new FormatException(formattedString);
+      throw new FormatException("Invalid date format", formattedString);
     }
   }
 

sdk/lib/core/exceptions.dart

@@ -44,13 +44,122 @@ class FormatException implements Exception {
    * A message describing the format error.
    */
   final String message;
+  /**
+   * The source that caused the error.
+   *
+   * This is usually a [String], but can be other types too. If it is a string,
+   * parts of it may be included in the [toString] message.
+   *
+   * May also be `null` if omitted.
+   */
+  final source;
+  /**
+   * The position in source where the error was detected.
+   *
+   * May be omitted. If present, [source] should also be present.
+   */
+  final int position;
 
   /**
    * Creates a new FormatException with an optional error [message].
+   *
+   * Optionally also supply the [source] that had the incorrect format, and
+   * even the [position] in the format where this was detected.
    */
-  const FormatException([this.message = ""]);
+  const FormatException([this.message = "", this.source, this.position]);
 
-  String toString() => "FormatException: $message";
+  /**
+   * Returns a description of the format exception.
+   *
+   * The description always contains the [message].
+   * If [source] was provided, the description will contain (at least a part of)
+   * the source.
+   * If [position] is also provided, the part of the source included will
+   * contain that position, and the position will be marked.
+   *
+   * If the source contains a line break before position, only the line
+   * containing position will be included, and its line number will also be
+   * part of the description. Line and character offsets are 1-based.
+   */
+  String toString() {
+    String report = "FormatException";
+    if (message != null && message.isNotEmpty) {
+      report = "$report: $message";
+    }
+    int position = this.position;
+    if (source is! String) {
+      if (position != null) {
+        report += " (at position $position)";
+      }
+      return report;
+    }
+    if (position != null && (position < 0 || position > source.length)) {
+      position = null;
+    }
+    // Source is string and position is null or valid.
+    if (position == null) {
+      String source = this.source;
+      if (source.length > 78) {
+        source = source.substring(0, 75) + "...";
+      }
+      return "$report\n$source";
+    }
+    int lineNum = 1;
+    int lineStart = 0;
+    bool lastWasCR;
+    for (int i = 0; i < position; i++) {
+      int char = source.codeUnitAt(i);
+      if (char == 0x0a) {
+        if (lineStart != i || !lastWasCR) {
+          lineNum++;
+        }
+        lineStart = i + 1;
+        lastWasCR = false;
+      } else if (char == 0x0d) {
+        lineNum++;
+        lineStart = i + 1;
+        lastWasCR = true;
+      }
+    }
+    if (lineNum > 1) {
+      report += " (at line $lineNum, character ${position - lineStart + 1})\n";
+    } else {
+      report += " (at character ${position + 1})\n";
+    }
+    int lineEnd = source.length;
+    for (int i = position; i < source.length; i++) {
+      int char = source.codeUnitAt(i);
+      if (char == 0x0a || char == 0x0d) {
+        lineEnd = i;
+        break;
+      }
+    }
+    int length = lineEnd - lineStart;
+    int start = lineStart;
+    int end = lineEnd;
+    String prefix = "";
+    String postfix = "";
+    if (length > 78) {
+      // Can't show entire line. Try to anchor at the nearest end, if
+      // one is within reach.
+      int index = position - lineStart;
+      if (index < 75) {
+        end = start + 75;
+        postfix = "...";
+      } else if (end - position < 75) {
+        start = end - 75;
+        prefix = "...";
+      } else {
+        // Neither end is near, just pick an area around the position.
+        start = position - 36;
+        end = position + 36;
+        prefix = postfix = "...";
+      }
+    }
+    String slice = source.substring(start, end);
+    int markOffset = position - start + prefix.length;
+    return "$report$prefix$slice$postfix\n${" " * markOffset}^\n";
+  }
 }
 
 class IntegerDivisionByZeroException implements Exception {

sdk/lib/core/uri.dart

@@ -396,34 +396,7 @@ class Uri {
 
   // Report a parse failure.
   static void _fail(String uri, int index, String message) {
-    // TODO(lrn): Consider adding this to FormatException.
-    if (index == uri.length) {
-      message += " at end of input.";
-    } else {
-      message += " at position $index.\n";
-      // Pick a slice of uri containing index and, if
-      // necessary, truncate the ends to ensure the entire
-      // slice fits on one line.
-      int min = 0;
-      int max = uri.length;
-      String pre = "";
-      String post = "";
-      if (uri.length > 78) {
-        min = index - 10;
-        if (min < 0) min = 0;
-        int max = min + 72;
-        if (max > uri.length) {
-          max = uri.length;
-          min = max - 72;
-        }
-        if (min != 0) pre = "...";
-        if (max != uri.length) post = "...";
-      }
-      // Combine message, slice and a caret pointing to the error index.
-      message = "$message$pre${uri.substring(min, max)}$post\n"
-                "${' ' * (pre.length + index - min)}^";
-    }
-    throw new FormatException(message);
+    throw new FormatException(message, uri, index);
   }
 
   /// Internal non-verifying constructor. Only call with validated arguments.
@@ -608,13 +581,15 @@ class Uri {
           if (authority.codeUnitAt(hostEnd) == _RIGHT_BRACKET) break;
         }
         if (hostEnd == authority.length) {
-          throw new FormatException("Invalid IPv6 host entry.");
+          throw new FormatException("Invalid IPv6 host entry.",
+                                    authority, hostStart);
         }
         parseIPv6Address(authority, hostStart + 1, hostEnd);
         hostEnd++;  // Skip the closing bracket.
         if (hostEnd != authority.length &&
             authority.codeUnitAt(hostEnd) != _COLON) {
-          throw new FormatException("Invalid end of authority");
+          throw new FormatException("Invalid end of authority",
+                                    authority, hostEnd);
         }
       }
       // Split host and port.
@@ -1811,16 +1786,16 @@ class Uri {
     //  - One (and only one) wildcard (`::`) may be present, representing a fill
     //    of 0's. The IPv6 `::` is thus 16 bytes of `0`.
     //  - The last two parts may be replaced by an IPv4 address.
-    void error(String msg) {
-      throw new FormatException('Illegal IPv6 address, $msg');
+    void error(String msg, [position]) {
+      throw new FormatException('Illegal IPv6 address, $msg', host, position);
     }
     int parseHex(int start, int end) {
       if (end - start > 4) {
-        error('an IPv6 part can only contain a maximum of 4 hex digits');
+        error('an IPv6 part can only contain a maximum of 4 hex digits', start);
       }
       int value = int.parse(host.substring(start, end), radix: 16);
       if (value < 0 || value > (1 << 16) - 1) {
-        error('each part must be in the range of `0x0..0xFFFF`');
+        error('each part must be in the range of `0x0..0xFFFF`', start);
       }
       return value;
     }
@@ -1835,14 +1810,14 @@ class Uri {
           // If we see a `:` in the beginning, expect wildcard.
           i++;
           if (host.codeUnitAt(i) != _COLON) {
-            error('invalid start colon.');
+            error('invalid start colon.', i);
           }
           partStart = i;
         }
         if (i == partStart) {
           // Wildcard. We only allow one.
           if (wildcardSeen) {
-            error('only one wildcard `::` is allowed');
+            error('only one wildcard `::` is allowed', i);
           }
           wildcardSeen = true;
           parts.add(-1);
@@ -1857,7 +1832,7 @@ class Uri {
     bool atEnd = (partStart == end);
     bool isLastWildcard = (parts.last == -1);
     if (atEnd && !isLastWildcard) {
-      error('expected a part after last `:`');
+      error('expected a part after last `:`', end);
     }
     if (!atEnd) {
       try {
@@ -1869,7 +1844,7 @@ class Uri {
           parts.add(last[0] << 8 | last[1]);
           parts.add(last[2] << 8 | last[3]);
         } catch (e) {
-          error('invalid end of IPv6 address.');
+          error('invalid end of IPv6 address.', partStart);
         }
       }
     }

tests/corelib/format_exception_test.dart

@@ -0,0 +1,73 @@
+// Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+library format_exception_test;
+import "package:expect/expect.dart";
+
+test(exn, message, source, position, toString) {
+  Expect.equals(message, exn.message);
+  Expect.equals(source, exn.source);
+  Expect.equals(position, exn.position);
+  Expect.equals(toString, exn.toString());
+}
+
+main() {
+  var e;
+  e = new FormatException();
+  test(e, "", null, null, "FormatException");
+  e = new FormatException("");
+  test(e, "", null, null, "FormatException");
+  e = new FormatException(null);
+  test(e, null, null, null, "FormatException");
+
+  e = new FormatException("message");
+  test(e, "message", null, null, "FormatException: message");
+
+  e = new FormatException("message", "source");
+  test(e, "message", "source", null, "FormatException: message\nsource");
+
+  e = new FormatException("message", "source" * 25);
+  test(e, "message", "source" * 25, null, "FormatException: message\n" +
+                                          "source" * 12 + "sou...");
+  e = new FormatException("message", "source" * 25);
+  test(e, "message", "source" * 25, null, "FormatException: message\n" +
+                                          "source" * 12 + "sou...");
+  e = new FormatException("message", "s1\nsource\ns2");
+  test(e, "message", "s1\nsource\ns2", null, "FormatException: message\n" +
+                                             "s1\nsource\ns2");
+
+  var o = new Object();
+  e = new FormatException("message", o, 10);
+  test(e, "message", o, 10, "FormatException: message (at position 10)");
+
+  e = new FormatException("message", "source", 3);
+  test(e, "message", "source", 3,
+       "FormatException: message (at character 4)\nsource\n   ^\n");
+
+  e = new FormatException("message", "s1\nsource\ns2", 6);
+  test(e, "message", "s1\nsource\ns2", 6,
+       "FormatException: message (at line 2, character 4)\nsource\n   ^\n");
+
+  var longline = "watermelon cantaloupe " * 8 + "watermelon";  // Length > 160.
+  var longsource = (longline + "\n") * 25;
+  var line10 = (longline.length + 1) * 9;
+  e = new FormatException("message", longsource, line10);
+  test(e, "message", longsource, line10,
+       "FormatException: message (at line 10, character 1)\n"
+       "${longline.substring(0, 75)}...\n^\n");
+
+  e = new FormatException("message", longsource, line10 - 1);
+  test(e, "message", longsource, line10 - 1,
+       "FormatException: message (at line 9, "
+       "character ${longline.length + 1})\n"
+       "...${longline.substring(longline.length - 75)}\n"
+       "${' ' * 78}^\n");
+
+  var half = longline.length ~/ 2;
+  e = new FormatException("message", longsource, line10 + half);
+  test(e, "message", longsource, line10 + half,
+       "FormatException: message (at line 10, character ${half + 1})\n"
+       "...${longline.substring(half - 36, half + 36)}...\n"
+       "${' ' * 39}^\n");
+}