1 files changed, 28 insertions, 0 deletions
diff --git a/lib/util.js b/lib/util.js
index e8fc435..d25ecaf 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -141,3 +141,31 @@ u.escapeHTML = function (html) {
     .replace(/</g, '&lt;')
     .replace(/>/g, '&gt;')
 }
+
+u.pullSlice = function (start, end) {
+  if (end == null) end = Infinity
+  var offset = 0
+  return function (read) {
+    return function (abort, cb) {
+      if (abort) read(abort, cb)
+      else if (offset >= end) read(true, function (err) {
+        cb(err || true)
+      })
+      else if (offset < start) read(null, function next(err, data) {
+        if (err) return cb(err)
+        offset += data.length
+        if (offset <= start) read(null, next)
+        else if (offset < end) cb(null,
+          data.slice(data.length - (offset - start)))
+        else cb(null, data.slice(data.length - (offset - start),
+          data.length - (offset - end)))
+      })
+      else read(null, function (err, data) {
+        if (err) return cb(err)
+        offset += data.length
+        if (offset <= end) cb(null, data)
+          else cb(null, data.slice(0, data.length - (offset - end)))
+      })
+    }
+  }
+}