Migrate struct and Provider to the skylark build api

RELNOTES: None.
PiperOrigin-RevId: 195013604

1 files changed, 43 insertions, 0 deletions

diff --git a/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/ProviderApi.java b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/ProviderApi.java
new file mode 100644
index 0000000000..306cf97f01
--- /dev/null
+++ b/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/ProviderApi.java
@@ -0,0 +1,43 @@
+// Copyright 2017 The Bazel Authors. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+package com.google.devtools.build.lib.skylarkbuildapi;
+
+import com.google.devtools.build.lib.skylarkinterface.SkylarkModule;
+import com.google.devtools.build.lib.skylarkinterface.SkylarkValue;
+
+/** Interface for provider objects (constructors for {@link StructApi} objects). */
+@SkylarkModule(
+  name = "Provider",
+  doc =
+      "A constructor for simple value objects, known as provider instances."
+          + "<br>"
+          + "This value has a dual purpose:"
+          + "  <ul>"
+          + "     <li>It is a function that can be called to construct 'struct'-like values:"
+          + "<pre class=\"language-python\">DataInfo = provider()\n"
+          + "d = DataInfo(x = 2, y = 3)\n"
+          + "print(d.x + d.y) # prints 5</pre>"
+          + "     Note: Some providers, defined internally, do not allow instance creation"
+          + "     </li>"
+          + "     <li>It is a <i>key</i> to access a provider instance on a"
+          + "        <a href=\"Target.html\">Target</a>"
+          + "<pre class=\"language-python\">DataInfo = provider()\n"
+          + "def _rule_impl(ctx)\n"
+          + "  ... ctx.attr.dep[DataInfo]</pre>"
+          + "     </li>"
+          + "  </ul>"
+          + "Create a new <code>Provider</code> using the "
+          + "<a href=\"globals.html#provider\">provider</a> function."
+)
+public interface ProviderApi extends SkylarkValue {}