path: root/src/main/java/com/google/devtools/build/lib/skylarkbuildapi/SkylarkRuleFunctionsApi.java

// Copyright 2018 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.cmdline.Label;
import com.google.devtools.build.lib.events.Location;
import com.google.devtools.build.lib.skylarkinterface.Param;
import com.google.devtools.build.lib.skylarkinterface.ParamType;
import com.google.devtools.build.lib.skylarkinterface.SkylarkCallable;
import com.google.devtools.build.lib.skylarkinterface.SkylarkConstructor;
import com.google.devtools.build.lib.skylarkinterface.SkylarkGlobalLibrary;
import com.google.devtools.build.lib.syntax.BaseFunction;
import com.google.devtools.build.lib.syntax.Environment;
import com.google.devtools.build.lib.syntax.EvalException;
import com.google.devtools.build.lib.syntax.FuncallExpression;
import com.google.devtools.build.lib.syntax.SkylarkDict;
import com.google.devtools.build.lib.syntax.SkylarkList;

/**
 * Interface for a global Skylark library containing rule-related helper and registration functions.
 */
@SkylarkGlobalLibrary
public interface SkylarkRuleFunctionsApi<FileApiT extends FileApi> {

  @SkylarkCallable(
    name = "provider",
    doc =
        "Creates a declared provider 'constructor'. The return value of this "
            + "function can be used to create \"struct-like\" values. Example:<br>"
            + "<pre class=\"language-python\">data = provider()\n"
            + "d = data(x = 2, y = 3)\n"
            + "print(d.x + d.y) # prints 5</pre>",
    parameters = {
      @Param(
        name = "doc",
        type = String.class,
        legacyNamed = true,
        defaultValue = "''",
        doc =
            "A description of the provider that can be extracted by documentation generating tools."
      ),
      @Param(
        name = "fields",
        doc = "If specified, restricts the set of allowed fields. <br>"
            + "Possible values are:"
            + "<ul>"
            + "  <li> list of fields:<br>"
            + "       <pre class=\"language-python\">provider(fields = ['a', 'b'])</pre><p>"
            + "  <li> dictionary field name -> documentation:<br>"
            + "       <pre class=\"language-python\">provider(\n"
            + "       fields = { 'a' : 'Documentation for a', 'b' : 'Documentation for b' })</pre>"
            + "</ul>"
            + "All fields are optional.",
        allowedTypes = {
            @ParamType(type = SkylarkList.class, generic1 = String.class),
            @ParamType(type = SkylarkDict.class)
        },
        noneable = true,
        named = true,
        positional = false,
        defaultValue = "None"
      )
    },
    useLocation = true
  )
  public ProviderApi provider(String doc, Object fields, Location location) throws EvalException;

  @SkylarkCallable(
    name = "rule",
    doc =
        "Creates a new rule, which can be called from a BUILD file or a macro to create targets."
            + "<p>Rules must be assigned to global variables in a .bzl file; the name of the "
            + "global variable is the rule's name."
            + "<p>Test rules are required to have a name ending in <code>_test</code>, while all "
            + "other rules must not have this suffix. (This restriction applies only to rules, not "
            + "to their targets.)",
    parameters = {
      @Param(
        name = "implementation",
        type = BaseFunction.class,
        legacyNamed = true,
        doc =
            "the function implementing this rule, must have exactly one parameter: "
                + "<a href=\"ctx.html\">ctx</a>. The function is called during the analysis "
                + "phase for each instance of the rule. It can access the attributes "
                + "provided by the user. It must create actions to generate all the declared "
                + "outputs."
      ),
      @Param(
        name = "test",
        type = Boolean.class,
        legacyNamed = true,
        defaultValue = "False",
        doc =
            "Whether this rule is a test rule, that is, whether it may be the subject of a "
                + "<code>blaze test</code> command. All test rules are automatically considered "
                + "<a href='#rule.executable'>executable</a>; it is unnecessary (and discouraged) "
                + "to explicitly set <code>executable = True</code> for a test rule. See the "
                + "<a href='../rules.$DOC_EXT#executable-rules-and-test-rules'>Rules page</a> for "
                + "more information."
      ),
      @Param(
        name = "attrs",
        type = SkylarkDict.class,
        legacyNamed = true,
        noneable = true,
        defaultValue = "None",
        doc =
            "dictionary to declare all the attributes of the rule. It maps from an attribute "
                + "name to an attribute object (see <a href=\"attr.html\">attr</a> module). "
                + "Attributes starting with <code>_</code> are private, and can be used to "
                + "add an implicit dependency on a label. The attribute <code>name</code> is "
                + "implicitly added and must not be specified. Attributes "
                + "<code>visibility</code>, <code>deprecation</code>, <code>tags</code>, "
                + "<code>testonly</code>, and <code>features</code> are implicitly added and "
                + "cannot be overridden."
      ),
      // TODO(bazel-team): need to give the types of these builtin attributes
      @Param(
        name = "outputs",
        type = SkylarkDict.class,
        legacyNamed = true,
        callbackEnabled = true,
        noneable = true,
        defaultValue = "None",
        doc =
            "<b>Experimental:</b> This API is in the process of being redesigned."
                + "<p>A schema for defining predeclared outputs. Unlike <a href='attr.html#output'>"
                + "<code>output</code></a> and <a href='attr.html#output_list'><code>output_list"
                + "</code></a> attributes, the user does not specify the labels for these files. "
                + "See the <a href='../rules.$DOC_EXT#files'>Rules page</a> for more on "
                + "predeclared outputs."
                + "<p>The value of this argument is either a dictionary or a callback function "
                + "that produces a dictionary. The callback works similar to computed dependency "
                + "attributes: The function's parameter names are matched against the rule's "
                + "attributes, so for example if you pass <code>outputs = _my_func</code> with the "
                + "definition <code>def _my_func(srcs, deps): ...</code>, the function has access "
                + "to the attributes <code>srcs</code> and <code>deps</code>. Whether the "
                + "dictionary is specified directly or via a function, it is interpreted as "
                + "follows."
                + "<p>Each entry in the dictionary creates a predeclared output where the key is "
                + "an identifier and the value is a string template that determines the output's "
                + "label. In the rule's implementation function, the identifier becomes the field "
                + "name used to access the output's <a href='File.html'><code>File</code></a> in "
                + "<a href='ctx.html#outputs'><code>ctx.outputs</code></a>. The output's label has "
                + "the same package as the rule, and the part after the package is produced by "
                + "substituting each placeholder of the form <code>\"%{ATTR}\"</code> with a "
                + "string formed from the value of the attribute <code>ATTR</code>:"
                + "<ul>"
                + "<li>String-typed attributes are substituted verbatim."
                + "<li>Label-typed attributes become the part of the label after the package, "
                + "minus the file extension. For example, the label <code>\"//pkg:a/b.c\"</code> "
                + "becomes <code>\"a/b\"</code>."
                + "<li>Output-typed attributes become the part of the label after the package, "
                + "including the file extension (for the above example, <code>\"a/b.c\"</code>)."
                + "<li>All list-typed attributes (for example, <code>attr.label_list</code>) used "
                + "in placeholders are required to have <i>exactly one element</i>. Their "
                + "conversion is the same as their non-list version (<code>attr.label</code>)."
                + "<li>Other attribute types may not appear in placeholders."
                + "<li>The special non-attribute placeholders <code>%{dirname}</code> and <code>"
                + "%{basename}</code> expand to those parts of the rule's label, excluding its "
                + "package. For example, in <code>\"//pkg:a/b.c\"</code>, the dirname is <code>"
                + "a</code> and the basename is <code>b.c</code>."
                + "</ul>"
                + "<p>In practice, the most common substitution placeholder is "
                + "<code>\"%{name}\"</code>. For example, for a target named \"foo\", the outputs "
                + "dict <code>{\"bin\": \"%{name}.exe\"}</code> predeclares an output named "
                + "<code>foo.exe</code> that is accessible in the implementation function as "
                + "<code>ctx.outputs.bin</code>."
      ),
      @Param(
        name = "executable",
        type = Boolean.class,
        legacyNamed = true,
        defaultValue = "False",
        doc =
            "Whether this rule is considered executable, that is, whether it may be the subject of "
                + "a <code>blaze run</code> command. See the "
                + "<a href='../rules.$DOC_EXT#executable-rules-and-test-rules'>Rules page</a> for "
                + "more information."
      ),
      @Param(
        name = "output_to_genfiles",
        type = Boolean.class,
        legacyNamed = true,
        defaultValue = "False",
        doc =
            "If true, the files will be generated in the genfiles directory instead of the "
                + "bin directory. Unless you need it for compatibility with existing rules "
                + "(e.g. when generating header files for C++), do not set this flag."
      ),
      @Param(
        name = "fragments",
        type = SkylarkList.class,
        legacyNamed = true,
        generic1 = String.class,
        defaultValue = "[]",
        doc =
            "List of names of configuration fragments that the rule requires "
                + "in target configuration."
      ),
      @Param(
        name = "host_fragments",
        type = SkylarkList.class,
        legacyNamed = true,
        generic1 = String.class,
        defaultValue = "[]",
        doc =
            "List of names of configuration fragments that the rule requires "
                + "in host configuration."
      ),
      @Param(
        name = "_skylark_testable",
        type = Boolean.class,
        legacyNamed = true,
        defaultValue = "False",
        doc =
            "<i>(Experimental)</i><br/><br/>"
                + "If true, this rule will expose its actions for inspection by rules that "
                + "depend on it via an <a href=\"globals.html#Actions\">Actions</a> "
                + "provider. The provider is also available to the rule itself by calling "
                + "<a href=\"ctx.html#created_actions\">ctx.created_actions()</a>."
                + "<br/><br/>"
                + "This should only be used for testing the analysis-time behavior of "
                + "Skylark rules. This flag may be removed in the future."
      ),
      @Param(
        name = "toolchains",
        type = SkylarkList.class,
        legacyNamed = true,
        generic1 = String.class,
        defaultValue = "[]",
        doc =
            "<i>(Experimental)</i><br/><br/>"
                + "If set, the set of toolchains this rule requires. Toolchains will be "
                + "found by checking the current platform, and provided to the rule "
                + "implementation via <code>ctx.toolchain</code>."
      ),
      @Param(
        name = "doc",
        type = String.class,
        legacyNamed = true,
        defaultValue = "''",
        doc = "A description of the rule that can be extracted by documentation generating tools."
      ),
      @Param(
        name = "provides",
        type = SkylarkList.class,
        named = true,
        positional = false,
        defaultValue = "[]",
        doc =
            "A list of providers this rule is guaranteed to provide. "
                + "It is an error if a provider is listed here and the rule "
                + "implementation function does not return it."
      ),
      @Param(
        name = "execution_platform_constraints_allowed",
        type = Boolean.class,
        named = true,
        positional = false,
        defaultValue = "False",
        doc =
            "If true, a special attribute named <code>exec_compatible_with</code> of "
                + "label-list type is added, which must not already exist in "
                + "<code>attrs</code>. Targets may use this attribute to specify additional "
                + "constraints on the execution platform beyond those given in the "
                + "<code>exec_compatible_with</code> argument to <code>rule()</code>."
      ),
      @Param(
        name = "exec_compatible_with",
        type = SkylarkList.class,
        generic1 = String.class,
        named = true,
        positional = false,
        defaultValue = "[]",
        doc =
            "A list of constraints on the execution platform that apply to all targets of "
                + "this rule type."
      )
    },
    useAst = true,
    useEnvironment = true
  )
  public BaseFunction rule(
      BaseFunction implementation,
      Boolean test,
      Object attrs,
      Object implicitOutputs,
      Boolean executable,
      Boolean outputToGenfiles,
      SkylarkList<?> fragments,
      SkylarkList<?> hostFragments,
      Boolean skylarkTestable,
      SkylarkList<?> toolchains,
      String doc,
      SkylarkList<?> providesArg,
      Boolean executionPlatformConstraintsAllowed,
      SkylarkList<?> execCompatibleWith,
      FuncallExpression ast,
      Environment funcallEnv)
      throws EvalException;

  @SkylarkCallable(
      name = "aspect",
      doc =
          "Creates a new aspect. The result of this function must be stored in a global value. "
              + "Please see the <a href=\"../aspects.md\">introduction to Aspects</a> for more "
              + "details.",
      parameters = {
          @Param(
              name = "implementation",
              type = BaseFunction.class,
              legacyNamed = true,
              doc =
                  "the function implementing this aspect. Must have two parameters: "
                      + "<a href=\"Target.html\">Target</a> (the target to which the aspect is "
                      + "applied) and <a href=\"ctx.html\">ctx</a>. Attributes of the target are "
                      + "available via ctx.rule field. The function is called during the analysis "
                      + "phase for each application of an aspect to a target."
          ),
          @Param(
              name = "attr_aspects",
              type = SkylarkList.class,
              legacyNamed = true,
              generic1 = String.class,
              defaultValue = "[]",
              doc = "List of attribute names.  The aspect propagates along dependencies specified "
                  + "by attributes of a target with this name. The list can also contain a single "
                  + "string '*': in that case aspect propagates along all dependencies of a target."
          ),
          @Param(
              name = "attrs",
              type = SkylarkDict.class,
              legacyNamed = true,
              noneable = true,
              defaultValue = "None",
              doc = "dictionary to declare all the attributes of the aspect.  "
                  + "It maps from an attribute name to an attribute object "
                  + "(see <a href=\"attr.html\">attr</a> module). "
                  + "Aspect attributes are available to implementation function as fields of ctx "
                  + "parameter. Implicit attributes starting with <code>_</code> must have default "
                  + "values, and have type <code>label</code> or <code>label_list</code>. "
                  + "Explicit attributes must have type <code>string</code>, and must use the "
                  + "<code>values</code> restriction. If explicit attributes are present, the "
                  + "aspect can only be used with rules that have attributes of the same name and "
                  + "type, with valid values."
          ),
          @Param(
              name = "required_aspect_providers",
              type = SkylarkList.class,
              legacyNamed = true,
              defaultValue = "[]",
              doc = "Allow the aspect to inspect other aspects. If the aspect propagates along "
                  + "a dependency, and the underlying rule sends a different aspect along that "
                  + "dependency, and that aspect provides one of the providers listed here, this "
                  + "aspect will see the providers provided by that aspect. "
                  + "<p>The value should be either a list of providers, or a "
                  + "list of lists of providers. This aspect will 'see'  the underlying aspects "
                  + "that provide  ALL providers from at least ONE of these lists. A single list "
                  + "of providers will be automatically converted to a list containing one list of "
                  + "providers."
          ),
          @Param(
              name = "provides",
              type = SkylarkList.class,
              legacyNamed = true,
              defaultValue = "[]",
              doc =
                  "A list of providers this aspect is guaranteed to provide. "
                      + "It is an error if a provider is listed here and the aspect "
                      + "implementation function does not return it."
          ),
          @Param(
              name = "fragments",
              type = SkylarkList.class,
              legacyNamed = true,
              generic1 = String.class,
              defaultValue = "[]",
              doc =
                  "List of names of configuration fragments that the aspect requires "
                      + "in target configuration."
          ),
          @Param(
              name = "host_fragments",
              type = SkylarkList.class,
              legacyNamed = true,
              generic1 = String.class,
              defaultValue = "[]",
              doc =
                  "List of names of configuration fragments that the aspect requires "
                      + "in host configuration."
          ),
          @Param(
              name = "toolchains",
              type = SkylarkList.class,
              legacyNamed = true,
              generic1 = String.class,
              defaultValue = "[]",
              doc =
                  "<i>(Experimental)</i><br/><br/>"
                      + "If set, the set of toolchains this rule requires. Toolchains will be "
                      + "found by checking the current platform, and provided to the rule "
                      + "implementation via <code>ctx.toolchain</code>."
          ),
          @Param(
              name = "doc",
              type = String.class,
              legacyNamed = true,
              defaultValue = "''",
              doc = "A description of the aspect that can be extracted by documentation generating "
                  + "tools."
          )
      },
      useEnvironment = true,
      useAst = true
  )
  public SkylarkAspectApi aspect(
      BaseFunction implementation,
      SkylarkList<?> attributeAspects,
      Object attrs,
      SkylarkList<?> requiredAspectProvidersArg,
      SkylarkList<?> providesArg,
      SkylarkList<?> fragments,
      SkylarkList<?> hostFragments,
      SkylarkList<?> toolchains,
      String doc,
      FuncallExpression ast,
      Environment funcallEnv)
      throws EvalException;

  @SkylarkCallable(
      name = "Label",
      doc = "Creates a Label referring to a BUILD target. Use "
          + "this function only when you want to give a default value for the label attributes. "
          + "The argument must refer to an absolute label. "
          + "Example: <br><pre class=language-python>Label(\"//tools:default\")</pre>",
      parameters = {
          @Param(name = "label_string", type = String.class, legacyNamed = true,
              doc = "the label string."),
          @Param(
              name = "relative_to_caller_repository",
              type = Boolean.class,
              defaultValue = "False",
              named = true,
              positional = false,
              doc = "Deprecated. Do not use. "
                  + "When relative_to_caller_repository is True and the calling thread is a rule's "
                  + "implementation function, then a repo-relative label //foo:bar is resolved "
                  + "relative to the rule's repository.  For calls to Label from any other "
                  + "thread, or calls in which the relative_to_caller_repository flag is False, "
                  + "a repo-relative label is resolved relative to the file in which the "
                  + "Label() call appears."
          )
      },
      useLocation = true,
      useEnvironment = true
  )
  @SkylarkConstructor(objectType = Label.class)
  public Label label(
      String labelString, Boolean relativeToCallerRepository, Location loc, Environment env)
      throws EvalException;

  @SkylarkCallable(
      name = "FileType",
      doc =
          "Deprecated. Creates a file filter from a list of strings. For example, to match "
              + "files ending with .cc or .cpp, use: "
              + "<pre class=language-python>FileType([\".cc\", \".cpp\"])</pre>",
      parameters = {
          @Param(
              name = "types",
              type = SkylarkList.class,
              legacyNamed = true,
              generic1 = String.class,
              defaultValue = "[]",
              doc = "a list of the accepted file extensions."
          )
      },
      useLocation = true,
      useEnvironment = true
  )
  @SkylarkConstructor(objectType = FileTypeApi.class)
  public FileTypeApi<FileApiT> fileType(SkylarkList<?> types, Location loc, Environment env)
     throws EvalException;
}