URLPattern: Implement compare() method.

This CL adds a prototype URLPattern.compare() to provide a natural
ordering to URLPattern objects.  This was based on feedback from routing
framework authors and there is some discussion in:

whatwg/urlpattern#61

The general algorithm is to compare the two URLPattern objects component
by component in order from hash through protocol.  Each component
pattern is then compared Part by Part.  The PartType, Modifier, and
text contents are then used to determine which Part is "more specific".

Bug: 1232795
Change-Id: I8474cd7d7689e657c9c74c552ad630cdcdd86c95

urlpattern/resources/urlpattern-compare-test-data.json

@@ -0,0 +1,132 @@
+[
+  {
+    "left": { "pathname": "/foo/a" },
+    "right": { "pathname": "/foo/b" },
+    "expected": -1
+  },
+  {
+    "left": { "pathname": "/foo/b" },
+    "right": { "pathname": "/foo/bar" },
+    "expected": -1
+  },
+  {
+    "left": { "pathname": "/foo/bar" },
+    "right": { "pathname": "/foo/:bar" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "/foo/" },
+    "right": { "pathname": "/foo/:bar" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "/foo/:bar" },
+    "right": { "pathname": "/foo/*" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "/foo/{bar}" },
+    "right": { "pathname": "/foo/(bar)" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "/foo/{bar}" },
+    "right": { "pathname": "/foo/{bar}+" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "/foo/{bar}+" },
+    "right": { "pathname": "/foo/{bar}?" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "/foo/{bar}?" },
+    "right": { "pathname": "/foo/{bar}*" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "/foo/(123)" },
+    "right": { "pathname": "/foo/(12)" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "/foo/:b" },
+    "right": { "pathname": "/foo/:a" },
+    "expected": 0
+  },
+  {
+    "left": { "pathname": "*/foo" },
+    "right": { "pathname": "*" },
+    "expected": 1
+  },
+  {
+    "left": { "protocol": "https", "pathname": "*/foo" },
+    "right": { "protocol": "https" },
+    "expected": 1
+  },
+  {
+    "left": { "protocol": "https" },
+    "right": { "protocol": "https", "pathname": "*" },
+    "expected": 0
+  },
+  {
+    "left": { "hash": "b", "search": "a" },
+    "right": { "hash": "a", "search": "b" },
+    "expected": 1
+  },
+  {
+    "left": { "search": "b", "pathname": "a" },
+    "right": { "search": "a", "pathname": "b" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "b", "port": "1" },
+    "right": { "pathname": "a", "port": "2" },
+    "expected": 1
+  },
+  {
+    "left": { "port": "2", "hostname": "a" },
+    "right": { "port": "1", "hostname": "b" },
+    "expected": 1
+  },
+  {
+    "left": { "hostname": "b", "password": "a" },
+    "right": { "hostname": "a", "password": "b" },
+    "expected": 1
+  },
+  {
+    "left": { "password": "b", "username": "a" },
+    "right": { "password": "a", "username": "b" },
+    "expected": 1
+  },
+  {
+    "left": { "username": "b", "protocol": "a" },
+    "right": { "username": "a", "protocol": "b" },
+    "expected": 1
+  },
+  {
+    "left": { "port": "9" },
+    "right": { "port": "100" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "foo/:bar?/baz" },
+    "right": { "pathname": "foo/{:bar}?/baz" },
+    "expected": -1
+  },
+  {
+    "left": { "pathname": "foo/:bar?/baz" },
+    "right": { "pathname": "foo{/:bar}?/baz" },
+    "expected": 0
+  },
+  {
+    "left": { "pathname": "foo/:bar?/baz" },
+    "right": { "pathname": "fo{o/:bar}?/baz" },
+    "expected": 1
+  },
+  {
+    "left": { "pathname": "foo/:bar?/baz" },
+    "right": { "pathname": "foo{/:bar/}?baz" },
+    "expected": -1
+  }
+]

urlpattern/resources/urlpattern-compare-tests.js

@@ -0,0 +1,25 @@
+function runTests(data) {
+  for (let entry of data) {
+    test(function() {
+      const left = new URLPattern(entry.left);
+      const right = new URLPattern(entry.right);
+
+      assert_equals(URLPattern.compare(left, right), entry.expected);
+
+      // We have to coerce to an integer here in order to avoid asserting
+      // that `+0` is `-0`.
+      const reverse_expected = ~~(entry.expected * -1);
+      assert_equals(URLPattern.compare(right, left), reverse_expected, "reverse order");
+
+      assert_equals(URLPattern.compare(left, left), 0, "left equality");
+      assert_equals(URLPattern.compare(right, right), 0, "right equality");
+    }, `Pattern: ${JSON.stringify(entry.left)} ` +
+       `Inputs: ${JSON.stringify(entry.right)}`);
+  }
+}
+
+promise_test(async function() {
+  const response = await fetch('resources/urlpattern-compare-test-data.json');
+  const data = await response.json();
+  runTests(data);
+}, 'Loading data...');

urlpattern/urlpattern-compare.any.js

@@ -0,0 +1,2 @@
+// META: global=window,worker
+// META: script=resources/urlpattern-compare-tests.js

urlpattern/urlpattern-compare.https.any.js

@@ -0,0 +1,2 @@
+// META: global=window,worker
+// META: script=resources/urlpattern-compare-tests.js