src/main/java/com/google/devtools/build/lib/rules/platform/PlatformRule.java - bazel - Git at Google

 // 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.rules.platform;

 import static com.google.devtools.build.lib.packages.Attribute.attr;

 import com.google.devtools.build.lib.analysis.RuleDefinition;
 import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
 import com.google.devtools.build.lib.analysis.platform.ConstraintValueInfo;
 import com.google.devtools.build.lib.analysis.platform.PlatformInfo;
 import com.google.devtools.build.lib.packages.BuildType;
 import com.google.devtools.build.lib.packages.RuleClass;
 import com.google.devtools.build.lib.syntax.Type;
 import com.google.devtools.build.lib.util.FileTypeSet;

 /** Rule definition for {@link Platform}. */
 public class PlatformRule implements RuleDefinition {
   public static final String RULE_NAME = "platform";
   public static final String CONSTRAINT_VALUES_ATTR = "constraint_values";
   public static final String PARENTS_PLATFORM_ATTR = "parents";
   public static final String REMOTE_EXECUTION_PROPS_ATTR = "remote_execution_properties";
   static final String HOST_PLATFORM_ATTR = "host_platform";
   static final String TARGET_PLATFORM_ATTR = "target_platform";
   static final String CPU_CONSTRAINTS_ATTR = "cpu_constraints";
   static final String OS_CONSTRAINTS_ATTR = "os_constraints";

   @Override
   public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env) {
     /* <!-- #BLAZE_RULE(platform).NAME -->
     <!-- #END_BLAZE_RULE.NAME --> */
     return builder
         .advertiseProvider(PlatformInfo.class)

         /* <!-- #BLAZE_RULE(platform).ATTRIBUTE(constraint_values) -->
         The combination of constraint choices that this platform comprises. In order for a platform
         to apply to a given environment, the environment must have at least the values in this list.

         <p>Each <code>constraint_value</code> in this list must be for a different
         <code>constraint_setting</code>. For example, you cannot define a platform that requires the
         cpu architecture to be both <code>@platforms//cpu:x86_64</code> and
         <code>@bazel_tools//platforms:arm</code>.
         <!-- #END_BLAZE_RULE.ATTRIBUTE --> */
         .add(
             attr(CONSTRAINT_VALUES_ATTR, BuildType.LABEL_LIST)
                 .allowedFileTypes(FileTypeSet.NO_FILE)
                 .mandatoryProviders(ConstraintValueInfo.PROVIDER.id()))

         /* <!-- #BLAZE_RULE(platform).ATTRIBUTE(parents) -->
         The label of a <code>platform</code> target that this platform should inherit from. Although
         the attribute takes a list, there should be no more than one platform present. Any
         constraint_settings not set directly on this platform will be found in the parent platform.
         See the section on <a href="#platform_inheritance">Platform Inheritance</a> for details.
         <!-- #END_BLAZE_RULE.ATTRIBUTE --> */
         .add(
             attr(PARENTS_PLATFORM_ATTR, BuildType.LABEL_LIST)
                 .allowedFileTypes(FileTypeSet.NO_FILE)
                 .mandatoryProviders(PlatformInfo.PROVIDER.id()))

         /* <!-- #BLAZE_RULE(platform).ATTRIBUTE(remote_execution_properties) -->
         A string used to configure a remote execution platform. Actual builds make no attempt to
         interpret this, it is treated as opaque data that can be used by a specific SpawnRunner.
         This can include data from the parent platform's "remote_execution_properties" attribute,
         by using the macro "{PARENT_REMOTE_EXECUTION_PROPERTIES}". See the section on
         <a href="#platform_inheritance">Platform Inheritance</a> for details.
         <!-- #END_BLAZE_RULE.ATTRIBUTE --> */
         .add(attr(REMOTE_EXECUTION_PROPS_ATTR, Type.STRING))

         // Undocumented. Indicates that this platform should auto-configure the platform constraints
         // based on the current host OS and CPU settings.
         .add(
             attr(HOST_PLATFORM_ATTR, Type.BOOLEAN)
                 .value(false)
                 .undocumented("Should only be used by internal packages."))
         // Undocumented. Indicates that this platform should auto-configure the platform constraints
         // based on the current OS and CPU settings.
         .add(
             attr(TARGET_PLATFORM_ATTR, Type.BOOLEAN)
                 .value(false)
                 .undocumented("Should only be used by internal packages."))
         // Undocumented. Indicates to the rule which constraint_values to use for automatic CPU
         // mapping.
         .add(
             attr(CPU_CONSTRAINTS_ATTR, BuildType.LABEL_LIST)
                 .allowedFileTypes(FileTypeSet.NO_FILE)
                 .mandatoryProviders(ConstraintValueInfo.PROVIDER.id())
                 .undocumented("Should only be used by internal packages."))
         // Undocumented. Indicates to the rule which constraint_values to use for automatic CPU
         // mapping.
         .add(
             attr(OS_CONSTRAINTS_ATTR, BuildType.LABEL_LIST)
                 .allowedFileTypes(FileTypeSet.NO_FILE)
                 .mandatoryProviders(ConstraintValueInfo.PROVIDER.id())
                 .undocumented("Should only be used by internal packages."))
         .build();
   }

   @Override
   public Metadata getMetadata() {
     return Metadata.builder()
         .name(RULE_NAME)
         .ancestors(PlatformBaseRule.class)
         .factoryClass(Platform.class)
         .build();
   }
 }
 /*<!-- #BLAZE_RULE (NAME = platform, TYPE = OTHER, FAMILY = Platform)[GENERIC_RULE] -->

 <p>This rule defines a new platform -- a named collection of constraint choices (such as cpu
 architecture or compiler version) describing an environment in which part of the build may run.
 See the <a href="https://docs.bazel.build/versions/master/platforms.html">Platforms</a> page for
 more details.

 <h4 id="platform_examples">Example</h4>
 <p>
   This defines a platform that describes any environment running Linux on ARM.
 </p>
 <pre class="code">
 platform(
     name = "linux_arm",
     constraint_values = [
         "@platforms//os:linux",
         "@platforms//cpu:arm",
     ],
 )
 </pre>

 <h3 id="platform_inheritance">Platform Inheritance</h4>
 <p>
   Platforms may use the "parents" attribute to specify another platform that they will inherit
   constraint values from. Although the "parents" attribute takes a list, no more than a single value
   is currently supported, and specifying multiple parents is an error.
 </p>

 <p>
   When checking for the value of a constraint setting in a platform, first the values directly set
   (via the "constraint_values" attribute) are checked, and then the constraint values on the parent.
   This continues recursively up the chain of parent platforms. In this manner, any values set
   directly on a platform will override the values set on the parent.
 </p>

 <p>
   Platforms can also inherit the "remote_execution_properties" attribute from the parent platform.
   The logic for setting the "remote_execution_platform" is as follows when there is a parent
   platform:

   <ol>
     <li>
       If "remote_execution_property" is not set on the child platform, the parent's
       "remote_execution_properties" will be used.
     </li>
     <li>
       If "remote_execution_property" is set on the child platform, and contains the literal string
       "{PARENT_REMOTE_EXECUTION_PROPERTIES}", that macro will be replaced with the contents of the
       parent's "remote_execution_property" attribute.
     </li>
     <li>
       If "remote_execution_property" is set on the child platform, and does not contain the macro,
       the child's "remote_execution_property" will be used unchanged.
     </li>
   </ol>
 </p>

 <h4 id="platform_inheritance_examples">Example</h4>
 <pre class="code">
 platform(
     name = "parent",
     constraint_values = [
         "@platforms//os:linux",
         "@platforms//cpu:arm",
     ],
     remote_execution_properties = """
       parent properties
     """,
 )
 platform(
     name = "child_a",
     parents = [":parent"],
     constraint_values = [
         "@platforms//cpu:x86_64",
     ],
     remote_execution_properties = """
       child a properties
     """,
 )
 platform(
     name = "child_b",
     parents = [":parent"],
     remote_execution_properties = """
       child b properties
       {PARENT_REMOTE_EXECUTION_PROPERTIES}
       more child b properties
     """,
 )
 </pre>

 <p>
   In these examples, the child platforms have the following properties:

   <ul>
     <li>
       "child_a" has the constraint values "@platforms//os:linux" (inherited from the
       parent) and "@platforms//cpu:x86_64" (set directly on the platform). It has the
       "remote_execution_properties" set to "child a properties"
     </li>
     <li>
       "child_b" inherits all constraint values from the parent, and doesn't set any of its own.
       It has the "remote_execution_properties" set to:
 <pre>
 child b properties
 parent properties
 more child b properties
 </pre>
     </li>
   </ul>
 </p>
 <!-- #END_BLAZE_RULE -->*/
	// 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.rules.platform;

	import static com.google.devtools.build.lib.packages.Attribute.attr;

	import com.google.devtools.build.lib.analysis.RuleDefinition;
	import com.google.devtools.build.lib.analysis.RuleDefinitionEnvironment;
	import com.google.devtools.build.lib.analysis.platform.ConstraintValueInfo;
	import com.google.devtools.build.lib.analysis.platform.PlatformInfo;
	import com.google.devtools.build.lib.packages.BuildType;
	import com.google.devtools.build.lib.packages.RuleClass;
	import com.google.devtools.build.lib.syntax.Type;
	import com.google.devtools.build.lib.util.FileTypeSet;

	/** Rule definition for {@link Platform}. */
	public class PlatformRule implements RuleDefinition {
	public static final String RULE_NAME = "platform";
	public static final String CONSTRAINT_VALUES_ATTR = "constraint_values";
	public static final String PARENTS_PLATFORM_ATTR = "parents";
	public static final String REMOTE_EXECUTION_PROPS_ATTR = "remote_execution_properties";
	static final String HOST_PLATFORM_ATTR = "host_platform";
	static final String TARGET_PLATFORM_ATTR = "target_platform";
	static final String CPU_CONSTRAINTS_ATTR = "cpu_constraints";
	static final String OS_CONSTRAINTS_ATTR = "os_constraints";

	@Override
	public RuleClass build(RuleClass.Builder builder, RuleDefinitionEnvironment env) {
	/* <!-- #BLAZE_RULE(platform).NAME -->
	<!-- #END_BLAZE_RULE.NAME --> */
	return builder
	.advertiseProvider(PlatformInfo.class)

	/* <!-- #BLAZE_RULE(platform).ATTRIBUTE(constraint_values) -->
	The combination of constraint choices that this platform comprises. In order for a platform
	to apply to a given environment, the environment must have at least the values in this list.

	<p>Each <code>constraint_value</code> in this list must be for a different
	<code>constraint_setting</code>. For example, you cannot define a platform that requires the
	cpu architecture to be both <code>@platforms//cpu:x86_64</code> and
	<code>@bazel_tools//platforms:arm</code>.
	<!-- #END_BLAZE_RULE.ATTRIBUTE --> */
	.add(
	attr(CONSTRAINT_VALUES_ATTR, BuildType.LABEL_LIST)
	.allowedFileTypes(FileTypeSet.NO_FILE)
	.mandatoryProviders(ConstraintValueInfo.PROVIDER.id()))

	/* <!-- #BLAZE_RULE(platform).ATTRIBUTE(parents) -->
	The label of a <code>platform</code> target that this platform should inherit from. Although
	the attribute takes a list, there should be no more than one platform present. Any
	constraint_settings not set directly on this platform will be found in the parent platform.
	See the section on <a href="#platform_inheritance">Platform Inheritance</a> for details.
	<!-- #END_BLAZE_RULE.ATTRIBUTE --> */
	.add(
	attr(PARENTS_PLATFORM_ATTR, BuildType.LABEL_LIST)
	.allowedFileTypes(FileTypeSet.NO_FILE)
	.mandatoryProviders(PlatformInfo.PROVIDER.id()))

	/* <!-- #BLAZE_RULE(platform).ATTRIBUTE(remote_execution_properties) -->
	A string used to configure a remote execution platform. Actual builds make no attempt to
	interpret this, it is treated as opaque data that can be used by a specific SpawnRunner.
	This can include data from the parent platform's "remote_execution_properties" attribute,
	by using the macro "{PARENT_REMOTE_EXECUTION_PROPERTIES}". See the section on
	<a href="#platform_inheritance">Platform Inheritance</a> for details.
	<!-- #END_BLAZE_RULE.ATTRIBUTE --> */
	.add(attr(REMOTE_EXECUTION_PROPS_ATTR, Type.STRING))

	// Undocumented. Indicates that this platform should auto-configure the platform constraints
	// based on the current host OS and CPU settings.
	.add(
	attr(HOST_PLATFORM_ATTR, Type.BOOLEAN)
	.value(false)
	.undocumented("Should only be used by internal packages."))
	// Undocumented. Indicates that this platform should auto-configure the platform constraints
	// based on the current OS and CPU settings.
	.add(
	attr(TARGET_PLATFORM_ATTR, Type.BOOLEAN)
	.value(false)
	.undocumented("Should only be used by internal packages."))
	// Undocumented. Indicates to the rule which constraint_values to use for automatic CPU
	// mapping.
	.add(
	attr(CPU_CONSTRAINTS_ATTR, BuildType.LABEL_LIST)
	.allowedFileTypes(FileTypeSet.NO_FILE)
	.mandatoryProviders(ConstraintValueInfo.PROVIDER.id())
	.undocumented("Should only be used by internal packages."))
	// Undocumented. Indicates to the rule which constraint_values to use for automatic CPU
	// mapping.
	.add(
	attr(OS_CONSTRAINTS_ATTR, BuildType.LABEL_LIST)
	.allowedFileTypes(FileTypeSet.NO_FILE)
	.mandatoryProviders(ConstraintValueInfo.PROVIDER.id())
	.undocumented("Should only be used by internal packages."))
	.build();
	}

	@Override
	public Metadata getMetadata() {
	return Metadata.builder()
	.name(RULE_NAME)
	.ancestors(PlatformBaseRule.class)
	.factoryClass(Platform.class)
	.build();
	}
	}
	/*<!-- #BLAZE_RULE (NAME = platform, TYPE = OTHER, FAMILY = Platform)[GENERIC_RULE] -->

	<p>This rule defines a new platform -- a named collection of constraint choices (such as cpu
	architecture or compiler version) describing an environment in which part of the build may run.
	See the <a href="https://docs.bazel.build/versions/master/platforms.html">Platforms</a> page for
	more details.

	<h4 id="platform_examples">Example</h4>
	<p>
	This defines a platform that describes any environment running Linux on ARM.
	</p>
	<pre class="code">
	platform(
	name = "linux_arm",
	constraint_values = [
	"@platforms//os:linux",
	"@platforms//cpu:arm",
	],
	)
	</pre>

	<h3 id="platform_inheritance">Platform Inheritance</h4>
	<p>
	Platforms may use the "parents" attribute to specify another platform that they will inherit
	constraint values from. Although the "parents" attribute takes a list, no more than a single value
	is currently supported, and specifying multiple parents is an error.
	</p>

	<p>
	When checking for the value of a constraint setting in a platform, first the values directly set
	(via the "constraint_values" attribute) are checked, and then the constraint values on the parent.
	This continues recursively up the chain of parent platforms. In this manner, any values set
	directly on a platform will override the values set on the parent.
	</p>

	<p>
	Platforms can also inherit the "remote_execution_properties" attribute from the parent platform.
	The logic for setting the "remote_execution_platform" is as follows when there is a parent
	platform:

	<ol>
	<li>
	If "remote_execution_property" is not set on the child platform, the parent's
	"remote_execution_properties" will be used.
	</li>
	<li>
	If "remote_execution_property" is set on the child platform, and contains the literal string
	"{PARENT_REMOTE_EXECUTION_PROPERTIES}", that macro will be replaced with the contents of the
	parent's "remote_execution_property" attribute.
	</li>
	<li>
	If "remote_execution_property" is set on the child platform, and does not contain the macro,
	the child's "remote_execution_property" will be used unchanged.
	</li>
	</ol>
	</p>

	<h4 id="platform_inheritance_examples">Example</h4>
	<pre class="code">
	platform(
	name = "parent",
	constraint_values = [
	"@platforms//os:linux",
	"@platforms//cpu:arm",
	],
	remote_execution_properties = """
	parent properties
	""",
	)
	platform(
	name = "child_a",
	parents = [":parent"],
	constraint_values = [
	"@platforms//cpu:x86_64",
	],
	remote_execution_properties = """
	child a properties
	""",
	)
	platform(
	name = "child_b",
	parents = [":parent"],
	remote_execution_properties = """
	child b properties
	{PARENT_REMOTE_EXECUTION_PROPERTIES}
	more child b properties
	""",
	)
	</pre>

	<p>
	In these examples, the child platforms have the following properties:

	<ul>
	<li>
	"child_a" has the constraint values "@platforms//os:linux" (inherited from the
	parent) and "@platforms//cpu:x86_64" (set directly on the platform). It has the
	"remote_execution_properties" set to "child a properties"
	</li>
	<li>
	"child_b" inherits all constraint values from the parent, and doesn't set any of its own.
	It has the "remote_execution_properties" set to:
	<pre>
	child b properties
	parent properties
	more child b properties
	</pre>
	</li>
	</ul>
	</p>
	<!-- #END_BLAZE_RULE -->*/