Add surrounding source truncation for long lines

Author: LewisJEllis

lib/utils.js

@@ -162,6 +162,30 @@ function readSourceFiles(filenames, cb) {
   });
 }
 
+// This is basically just `trim_line` from https://github.com/getsentry/sentry/blob/master/src/sentry/lang/javascript/processor.py#L67
+function snipLine(line, colno) {
+  var ll = line.length;
+  if (ll <= 150) return line;
+  if (colno > ll) colno = ll;
+
+  var start = Math.max(colno - 60, 0);
+  if (start < 5) start = 0;
+
+  var end = Math.min(start + 140, ll);
+  if (end > ll - 5) end = ll;
+  if (end === ll) start = Math.max(end - 140, 0);
+
+  line = line.slice(start, end);
+  if (start > 0) line = '{snip} ' + line;
+  if (end < ll) line += ' {snip}';
+
+  return line;
+}
+
+function snipLine0(line) {
+  return snipLine(line, 0);
+}
+
 function parseStack(err, cb) {
   if (!err) return cb([]);
 
@@ -208,9 +232,9 @@ function parseStack(err, cb) {
       if (frame.filename && sourceFiles[frame.filename]) {
         var lines = sourceFiles[frame.filename];
         try {
-          frame.pre_context = lines.slice(Math.max(0, frame.lineno - (LINES_OF_CONTEXT + 1)), frame.lineno - 1);
-          frame.context_line = lines[frame.lineno - 1];
-          frame.post_context = lines.slice(frame.lineno, frame.lineno + LINES_OF_CONTEXT);
+          frame.pre_context = lines.slice(Math.max(0, frame.lineno - (LINES_OF_CONTEXT + 1)), frame.lineno - 1).map(snipLine0);
+          frame.context_line = snipLine(lines[frame.lineno - 1], frame.colno);
+          frame.post_context = lines.slice(frame.lineno, frame.lineno + LINES_OF_CONTEXT).map(snipLine0);
         } catch (e) {
           // anomaly, being defensive in case
           // unlikely to ever happen in practice but can definitely happen in theory