Support multiple occurrences of text in context

lib/src/span_with_context.dart

Index: lib/src/span_with_context.dart
diff --git a/lib/src/span_with_context.dart b/lib/src/span_with_context.dart
index edbb8b65ffe278f3084a4b8aa016c5b15df53a41..0a24e7171627bda34b6b3d9d2992cc635685f3c0 100644
--- a/lib/src/span_with_context.dart
+++ b/lib/src/span_with_context.dart
@@ -29,10 +29,20 @@ class SourceSpanWithContext extends SourceSpanBase {
           'The context line "$context" must contain "$text".');
     }
 
-    var beginningOfLine = context.lastIndexOf('\n', index) + 1;
-    if (start.column != index - beginningOfLine) {
-      throw new ArgumentError('The span text "$text" must start at '
-          'column ${start.column + 1} in a line within "$context".');
+    // Note: `text` can appear in multiple places within context, but we don't
+    // know which occurrance of `text` is the one in the right location.
+    while (index != -1) {
+      var beginningOfLine = context.lastIndexOf('\n', index) + 1;
+
+      // if the column matches, we are all set with validation.
+      if (start.column == index - beginningOfLine) return;
+
+      index = context.indexOf(text, index + 1);
     }

[nweiz, 2015/03/30 23:45:51]

Shouldn't you also do this logic when constructing the message?

[Siggi Cherem (dart-lang), 2015/03/31 01:07:49]

good point - fixed too.

+
+    // No match was found, means that all occurrences of `text` were not in the
+    // right place.
+    throw new ArgumentError('The span text "$text" must start at '
+        'column ${start.column + 1} in a line within "$context".');
   }
 }