splitLimitR in standard library

Author: KetchupBomb

doc/_stdlib_gen/stdlib-content.jsonnet

@@ -382,6 +382,18 @@ local html = import 'html.libsonnet';
             },
           ],
         },
+        {
+          name: 'splitLimitR',
+          params: ['str', 'c', 'maxsplits'],
+          availableSince: 'upcoming',
+          description: 'As <code>std.splitLimit(str, c, maxsplits)</code> but will split from right to left.',
+          examples: [
+            {
+              input: @'std.splitLimitR("/_foo/_bar", "/_", 1)',
+              output: std.splitLimitR('/_foo/_bar', '/_', 1),
+            },
+          ],
+        },
         {
           name: 'strReplace',
           params: ['str', 'from', 'to'],

doc/ref/stdlib.html

@@ -833,6 +833,35 @@ <h4 id="splitLimit">
   </div>
 </div>
 
+<div class="hgroup">
+  <div class="hgroup-inline">
+    <div class="panel">
+      <h4 id="splitLimitR">
+        std.splitLimitR(str, c, maxsplits)
+      </h4>
+    </div>
+    <div style="clear: both"></div>
+  </div>
+</div>
+<div class="hgroup">
+  <div class="hgroup-inline">
+    <div class="panel">
+      <p>
+        <em>
+          Available in upcoming release.
+        </em>
+      </p>
+      <p>
+        As <code>std.splitLimit(str, c, maxsplits)</code> but will split from right to left.
+      </p>
+      <p>
+        Example: <code>std.splitLimitR("/_foo/_bar", "/_", 1)</code> yields <code>[ "/_foo", "bar" ]</code>.
+      </p>
+    </div>
+    <div style="clear: both"></div>
+  </div>
+</div>
+
 <div class="hgroup">
   <div class="hgroup-inline">
     <div class="panel">

stdlib/std.jsonnet

@@ -132,6 +132,17 @@ limitations under the License.
         aux(idx + 1, ret, val + str[idx]);
     aux(0, [], ''),
 
+  splitLimitR(str, c, maxsplits)::
+    assert std.isString(str) : 'str.splitLimitR first parameter must be a String, got ' + std.type(str);
+    assert std.isString(c) : 'str.splitLimitR second parameter must be a String, got ' + std.type(c);
+    assert std.length(c) >= 1 : 'std.splitLimitR second parameter must have length 1 or greater, got ' + std.length(c);
+    assert std.isNumber(maxsplits) : 'str.splitLimitR third parameter must be a Number, got ' + std.type(maxsplits);
+    if maxsplits == -1 then
+      std.splitLimit(str, c, -1)
+    else
+      local revStr(str) = std.join('', std.reverse(str));
+      std.map(function(e) revStr(e), std.reverse(std.splitLimit(revStr(str), revStr(c), maxsplits))),
+
   strReplace(str, from, to)::
     assert std.isString(str);
     assert std.isString(from);

test_suite/stdlib.jsonnet

@@ -488,6 +488,13 @@ std.assertEqual(std.splitLimit('/foo/', '/', 1), ['', 'foo/']) &&
 std.assertEqual(std.splitLimit('foo/_bar', '/_', 1), ['foo', 'bar']) &&
 std.assertEqual(std.splitLimit('/_foo/_', '/_', 1), ['', 'foo/_']) &&
 
+std.assertEqual(std.splitLimitR('foo/bar', '/', 1), ['foo', 'bar']) &&
+std.assertEqual(std.splitLimitR('/foo/', '/', 1), ['/foo', '']) &&
+std.assertEqual(std.splitLimitR('/foo/', '/', -1), ['', 'foo', '']) &&
+std.assertEqual(std.splitLimitR('foo/_bar', '/_', 1), ['foo', 'bar']) &&
+std.assertEqual(std.splitLimitR('/_foo/_', '/_', 1), ['/_foo', '']) &&
+std.assertEqual(std.splitLimitR('/_foo/_', '/_', -1), ['', 'foo', '']) &&
+
 local some_toml = {
   key: 'value',
   simple: { t: 5 },