Add stacktrace_test

tests/compiler/dart2js/sourcemaps/lazon.dart

+// Copyright (c) 2016, 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.
+
+/// Decode a lazy JSON encoded text, that is, JSON with Dart-like comments and
+/// trailing commas.
+///
+/// This is used together with `load.dart` and `save.dart` to allow for an easy
+/// editing of a human-readable source-map file.
+
+library lazon;

[Siggi Cherem (dart-lang), 2016/10/27 13:25:19]

funny name, but it might help to rename this library (and file) to some
descriptive name like "json_with_comments"or "commented_json"or "lazy_json".

I might prefer the former names, since lazy makes me think that the decoder
below is lazily loading code little by little, while in reality it's pretty
eager.

A crazy alternative: would it be possible to remove the comments with some
regexp and then use the standard json decoder?

[Johnni Winther, 2016/11/02 14:34:30]

How about lax_json (or laxon), it also supports trailing commas?

Regexp? Maybe, but in a later CL, maybe if we have to fix this implementation
for some reason.

+
+decode(String text) {
+  return new _Decoder(text)._decode();
+}
+
+class _Decoder {
+  static final int LF = '\n'.codeUnits.single;
+  static final int CR = '\r'.codeUnits.single;
+  static final int BACKSPACE = '\b'.codeUnits.single;
+  static final int FORMFEED = '\f'.codeUnits.single;
+  static final int TAB = '\t'.codeUnits.single;
+  static final int SPACE = ' '.codeUnits.single;
+  static final int SLASH = '/'.codeUnits.single;
+  static final int STAR = '*'.codeUnits.single;
+  static final int QUOTE = '"'.codeUnits.single;
+  static final int BACKSLASH = '\\'.codeUnits.single;
+  static final int COMMA = ','.codeUnits.single;
+  static final int COLON = ':'.codeUnits.single;
+  static final int LEFT_BRACE = '{'.codeUnits.single;
+  static final int RIGHT_BRACE = '}'.codeUnits.single;
+  static final int LEFT_BRACKET = '['.codeUnits.single;
+  static final int RIGHT_BRACKET = ']'.codeUnits.single;
+  static final int T = 't'.codeUnits.single;
+  static final List<int> TRUE = 'true'.codeUnits;
+  static final int F = 'f'.codeUnits.single;
+  static final List<int> FALSE = 'false'.codeUnits;
+  static final int N = 'n'.codeUnits.single;
+  static final List<int> NULL = 'null'.codeUnits;
+  static final int _0 = '0'.codeUnits.single;
+  static final int _9 = '9'.codeUnits.single;
+  static final int B = 'b'.codeUnits.single;
+  static final int R = 'r'.codeUnits.single;
+  static final int U = 'u'.codeUnits.single;
+
+  final List<int> codeUnits;
+  final int length;
+  int position = 0;
+
+  _Decoder(String text)
+      : codeUnits = text.codeUnits,
+        length = text.length;
+
+  _decode() {
+    var result = _decodeValue();
+    _trimWhitespace();
+    if (position != codeUnits.length) {
+      throw new ArgumentError("Unexpected trailing text: "
+          "'${new String.fromCharCodes(codeUnits, position)}'.");
+    }
+    return result;
+  }
+
+  _decodeValue() {
+    var result;
+    _trimWhitespace();
+    if (position < codeUnits.length) {
+      int codeUnit = codeUnits[position];
+      if (codeUnit == QUOTE) {
+        result = _decodeString();
+      } else if (codeUnit == LEFT_BRACE) {
+        result = _decodeMap();
+      } else if (codeUnit == LEFT_BRACKET) {
+        result = _decodeList();
+      } else if (codeUnit == T) {
+        result = _decodeTrue();
+      } else if (codeUnit == F) {
+        result = _decodeFalse();
+      } else if (codeUnit == N) {
+        result = _decodeNull();
+      } else {
+        result = _decodeNumber();
+      }
+    } else {
+      throw new ArgumentError("No value found in text: "
+          "'${new String.fromCharCodes(codeUnits, 0)}'.");
+    }
+    return result;
+  }
+
+  void _trimWhitespace() {
+    OUTER:
+    while (position < codeUnits.length) {
+      int codeUnit = codeUnits[position];
+      if (codeUnit == SLASH) {
+        if (position + 1 < codeUnits.length) {
+          int nextCodeUnit = codeUnits[position + 1];
+          if (nextCodeUnit == SLASH) {
+            position += 2;
+            while (position < codeUnits.length) {
+              codeUnit = codeUnits[position];
+              if (codeUnit == LF || codeUnit == CR) {
+                continue OUTER;
+              }
+              position++;
+            }
+          } else if (nextCodeUnit == STAR) {
+            position += 2;
+            while (position < codeUnits.length) {
+              codeUnit = codeUnits[position];
+              if (codeUnit == STAR &&
+                  position + 1 < codeUnits.length &&
+                  codeUnits[position + 1] == SLASH) {
+                position += 2;
+                continue OUTER;
+              }
+              position++;
+            }
+          }
+        }
+        break;
+      } else if (codeUnit == LF ||
+          codeUnit == CR ||
+          codeUnit == TAB ||
+          codeUnit == SPACE) {
+        position++;
+      } else {
+        break;
+      }
+    }
+  }
+
+  String _decodeString() {
+    int codeUnit = codeUnits[position];
+    if (codeUnit != QUOTE) {
+      _fail();
+    }
+    position++;
+    List<int> charCodes = <int>[];
+    while (position < length) {
+      codeUnit = codeUnits[position];
+      if (codeUnit == QUOTE) {
+        break;
+      } else if (codeUnit == BACKSLASH) {
+        if (position + 1 >= length) {
+          _fail();
+        }
+        codeUnit = codeUnits[++position];
+        if (codeUnit == B) {
+          codeUnit = BACKSPACE;
+        } else if (codeUnit == F) {
+          codeUnit = FORMFEED;
+        } else if (codeUnit == N) {
+          codeUnit = LF;
+        } else if (codeUnit == R) {
+          codeUnit = CR;
+        } else if (codeUnit == T) {
+          codeUnit = TAB;
+        } else if (codeUnit == U) {
+          throw new UnsupportedError('unicode escapes');
+        } else if (codeUnit == QUOTE ||
+            codeUnit == SLASH ||
+            codeUnit == BACKSLASH) {
+          // Ok.
+        } else {
+          _fail();
+        }
+      }
+      charCodes.add(codeUnit);
+      position++;
+    }
+    if (codeUnit != QUOTE) {
+      _fail();
+    }
+    position++;
+    return new String.fromCharCodes(charCodes);
+  }
+
+  Map _decodeMap() {
+    int codeUnit = codeUnits[position];
+    if (codeUnit != LEFT_BRACE) {
+      _fail();
+    }
+    position++;
+    _trimWhitespace();
+    Map result = {};
+    while (position < length) {
+      codeUnit = codeUnits[position];
+      if (codeUnit == RIGHT_BRACE) {
+        break;
+      }
+      String key = _decodeString();
+      _trimWhitespace();
+      if (position < length) {
+        codeUnit = codeUnits[position];
+        if (codeUnit == COLON) {
+          position++;
+          _trimWhitespace();
+        } else {
+          _fail();
+        }
+      } else {
+        _fail();
+      }
+      var value = _decodeValue();
+      result[key] = value;
+      _trimWhitespace();
+      if (position < length) {
+        codeUnit = codeUnits[position];
+        if (codeUnit == COMMA) {
+          position++;
+          _trimWhitespace();
+          continue;
+        } else {
+          break;
+        }
+      }
+    }
+
+    if (codeUnit != RIGHT_BRACE) {
+      _fail();
+    }
+    position++;
+    return result;
+  }
+
+  List _decodeList() {
+    int codeUnit = codeUnits[position];
+    if (codeUnit != LEFT_BRACKET) {
+      _fail();
+    }
+    position++;
+    _trimWhitespace();
+    List result = [];
+    while (position < length) {
+      codeUnit = codeUnits[position];
+      if (codeUnit == RIGHT_BRACKET) {
+        break;
+      }
+      result.add(_decodeValue());
+      _trimWhitespace();
+      if (position < length) {
+        codeUnit = codeUnits[position];
+        if (codeUnit == COMMA) {
+          position++;
+          _trimWhitespace();
+          continue;
+        } else {
+          break;
+        }
+      }
+    }
+
+    if (codeUnit != RIGHT_BRACKET) {
+      _fail();
+    }
+    position++;
+    return result;
+  }
+
+  bool _decodeTrue() {
+    match(TRUE);
+    return true;
+  }
+
+  bool _decodeFalse() {
+    match(FALSE);
+    return false;
+  }
+
+  Null _decodeNull() {
+    match(NULL);
+    return null;
+  }
+
+  void match(List<int> codes) {
+    if (position + codes.length > length) {
+      _fail();
+    }
+    for (int i = 0; i < codes.length; i++) {
+      if (codes[i] != codeUnits[position + i]) {
+        _fail();
+      }
+    }
+    position += codes.length;
+  }
+
+  num _decodeNumber() {
+    throw new UnsupportedError('_decodeNumber');
+  }
+
+  void _fail() {
+    throw new ArgumentError("Unexpected value: "
+        "'${new String.fromCharCodes(codeUnits, position)}'.");
+  }
+}