1 files changed, 90 insertions, 0 deletions
diff --git a/testing/web-platform/tests/tools/wptserve/wptserve/ranges.py b/testing/web-platform/tests/tools/wptserve/wptserve/ranges.py
new file mode 100644
index 000000000..976cb1781
--- /dev/null
+++ b/testing/web-platform/tests/tools/wptserve/wptserve/ranges.py
@@ -0,0 +1,90 @@
+from .utils import HTTPException
+
+
+class RangeParser(object):
+    def __call__(self, header, file_size):
+        prefix = "bytes="
+        if not header.startswith(prefix):
+            raise HTTPException(416, message="Unrecognised range type %s" % (header,))
+
+        parts = header[len(prefix):].split(",")
+        ranges = []
+        for item in parts:
+            components = item.split("-")
+            if len(components) != 2:
+                raise HTTPException(416, "Bad range specifier %s" % (item))
+            data = []
+            for component in components:
+                if component == "":
+                    data.append(None)
+                else:
+                    try:
+                        data.append(int(component))
+                    except ValueError:
+                        raise HTTPException(416, "Bad range specifier %s" % (item))
+            try:
+                ranges.append(Range(data[0], data[1], file_size))
+            except ValueError:
+                raise HTTPException(416, "Bad range specifier %s" % (item))
+
+        return self.coalesce_ranges(ranges, file_size)
+
+    def coalesce_ranges(self, ranges, file_size):
+        rv = []
+        target = None
+        for current in reversed(sorted(ranges)):
+            if target is None:
+                target = current
+            else:
+                new = target.coalesce(current)
+                target = new[0]
+                if len(new) > 1:
+                    rv.append(new[1])
+        rv.append(target)
+
+        return rv[::-1]
+
+
+class Range(object):
+    def __init__(self, lower, upper, file_size):
+        self.file_size = file_size
+        self.lower, self.upper = self._abs(lower, upper)
+        if self.lower >= self.upper or self.lower >= self.file_size:
+            raise ValueError
+
+    def __repr__(self):
+        return "<Range %s-%s>" % (self.lower, self.upper)
+
+    def __lt__(self, other):
+        return self.lower < other.lower
+
+    def __gt__(self, other):
+        return self.lower > other.lower
+
+    def __eq__(self, other):
+        return self.lower == other.lower and self.upper == other.upper
+
+    def _abs(self, lower, upper):
+        if lower is None and upper is None:
+            lower, upper = 0, self.file_size
+        elif lower is None:
+            lower, upper = max(0, self.file_size - upper), self.file_size
+        elif upper is None:
+            lower, upper = lower, self.file_size
+        else:
+            lower, upper = lower, min(self.file_size, upper + 1)
+
+        return lower, upper
+
+    def coalesce(self, other):
+        assert self.file_size == other.file_size
+
+        if (self.upper < other.lower or self.lower > other.upper):
+            return sorted([self, other])
+        else:
+            return [Range(min(self.lower, other.lower),
+                          max(self.upper, other.upper) - 1,
+                          self.file_size)]
+
+    def header_value(self):
+        return "bytes %i-%i/%i" % (self.lower, self.upper - 1, self.file_size)