Add inference test functionality based on code point id.

tests/compiler/dart2js/annotated_code_helper.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.
+
+const int _LF = 0x0A;
+const int _CR = 0x0D;
+const int _LBRACE = 0x7B;
+
+class Annotation {
+  /// 1-based line number of the annotation.
+  final int lineNo;
+
+  /// 1-based column number of the annotation.
+  final int columnNo;
+
+  /// 0-based character offset  of the annotation within the source text.
+  final int offset;
+
+  /// The text in the annotation.
+  final String text;
+
+  Annotation(this.lineNo, this.columnNo, this.offset, this.text);
+}
+
+/// A source code text with annotated positions.
+///
+/// An [AnnotatedCode] can be created from a [String] of source code where
+/// annotated positions are embedded using the syntax `@{text}`. For instance
+///
+///     main() {
+///       @{foo-call}foo();
+///       bar@{bar-args}();
+///     }
+///
+///  the position of `foo` call will hold an annotation with text 'foo-call' and
+///  the position of `bar` arguments will hold an annotation with text
+///  'bar-args'.
+///
+///  Annotation text cannot span multiple lines and cannot contain '}'.
+class AnnotatedCode {
+  /// The source code without annotations.
+  final String sourceCode;
+
+  /// The annotations for the source code.
+  final List<Annotation> annotations;
+
+  AnnotatedCode.internal(this.sourceCode, this.annotations);
+
+  /// Creates an [AnnotatedCode] by processing [annotatedCode]. Annotation of
+  /// the form `@{...}` are converted into [Annotation]s and removed from the
+  /// [annotatedCode] to process the source code.
+  factory AnnotatedCode(String annotatedCode) {
+    StringBuffer codeBuffer = new StringBuffer();
+    List<Annotation> annotations = <Annotation>[];
+    int index = 0;
+    int offset = 0;
+    int lineNo = 1;
+    int columnNo = 1;
+    while (index < annotatedCode.length) {
+      int charCode = annotatedCode.codeUnitAt(index);
+      switch (charCode) {
+        case _LF:
+          codeBuffer.write('\n');
+          offset++;
+          lineNo++;
+          columnNo = 1;
+          break;
+        case _CR:
+          if (index + 1 < annotatedCode.length &&
+              annotatedCode.codeUnitAt(index + 1) == _LF) {
+            index++;
+          }
+          codeBuffer.write('\n');
+          offset++;
+          lineNo++;
+          columnNo = 1;
+          break;
+        case 0x40:
+          if (index + 1 < annotatedCode.length &&
+              annotatedCode.codeUnitAt(index + 1) == _LBRACE) {
+            int endIndex = annotatedCode.indexOf('}', index);
+            String text = annotatedCode.substring(index + 2, endIndex);
+            annotations.add(new Annotation(lineNo, columnNo, offset, text));
+            index = endIndex;
+          } else {
+            codeBuffer.writeCharCode(charCode);
+            offset++;
+            columnNo++;
+          }
+          break;
+        default:
+          codeBuffer.writeCharCode(charCode);
+          offset++;
+          columnNo++;
+      }
+      index++;
+    }
+    return new AnnotatedCode.internal(codeBuffer.toString(), annotations);
+  }
+}