| // Copyright 2014 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.skylarkinterface; |
| |
| import java.lang.annotation.ElementType; |
| import java.lang.annotation.Retention; |
| import java.lang.annotation.RetentionPolicy; |
| import java.lang.annotation.Target; |
| |
| /** |
| * A marker interface for Java methods which can be called from Skylark. |
| * |
| * <p>Methods annotated with this annotation are expected to meet certain requirements which are |
| * enforced by an annotation processor: |
| * |
| * <ul> |
| * <li>The method must be public. |
| * <li>If structField=true, there must be zero user-supplied parameters. |
| * <li>The underlying java method's parameters must be supplied in the following order: |
| * <pre>method([positionals]*[named args]*(extra positionals list)(extra kwargs) |
| * (Location)(FuncallExpression)(Envrionment)(SkylarkSemantics))</pre> |
| * where (extra positionals list) is a SkylarkList if extraPositionals is defined, (extra |
| * kwargs) is a SkylarkDict if extraKeywords is defined, and Location, FuncallExpression, |
| * Environment, and SkylarkSemantics are supplied by the interpreter if and only if |
| * useLocation, useAst, useEnvironment, and useSkylarkSemantics are specified, respectively. |
| * <li>The number of method parameters much match the number of annotation-declared parameters |
| * plus the number of interpreter-supplied parameters. |
| * </ul> |
| */ |
| @Target({ElementType.METHOD}) |
| @Retention(RetentionPolicy.RUNTIME) |
| public @interface SkylarkCallable { |
| |
| /** |
| * Name of the method, as exposed to Skylark. |
| */ |
| String name() default ""; |
| |
| /** |
| * The documentation text in Skylark. It can contain HTML tags for special formatting. |
| * |
| * <p>It is allowed to be empty only if {@link #documented()} is false. |
| */ |
| String doc() default ""; |
| |
| /** |
| * If true, the function will appear in the Skylark documentation. Set this to false if the |
| * function is experimental or an overloading and doesn't need to be documented. |
| */ |
| boolean documented() default true; |
| |
| /** |
| * If true, this method will be considered as a field of the enclosing Java object. E.g., if set |
| * to true on a method {@code foo}, then the callsites of this method will look like {@code |
| * bar.foo} instead of {@code bar.foo()}. The annotated method must be parameterless and {@link |
| * #parameters()} should be empty. |
| */ |
| boolean structField() default false; |
| |
| /** |
| * Number of parameters in the signature that are mandatory positional parameters. Any parameter |
| * after {@link #mandatoryPositionals()} must be specified in {@link #parameters()}. A negative |
| * value (default is {@code -1}), means that all arguments are mandatory positionals if {@link |
| * #parameters()} remains empty. If {@link #parameters()} is non empty, then a negative value for |
| * {@link #mandatoryPositionals()} is taken as 0. |
| */ |
| int mandatoryPositionals() default -1; |
| |
| /** |
| * List of parameters this function accept after the {@link #mandatoryPositionals()} parameters. |
| */ |
| Param[] parameters() default {}; |
| |
| /** |
| * Defines a catch-all list for additional unspecified positional parameters. |
| * |
| * <p>If this is left as default, it is an error for the caller to pass more positional arguments |
| * than are explicitly allowed by the method signature. If this is defined, all additional |
| * positional arguments are passed as elements of a {@link SkylarkList} to the method. |
| * |
| * <p>See python's <code>*args</code> (http://thepythonguru.com/python-args-and-kwargs/). |
| * |
| * <p>(If this is defined, the annotated method signature must contain a corresponding SkylarkList |
| * parameter. See the interface-level javadoc for details.) |
| */ |
| Param extraPositionals() default @Param(name = ""); |
| |
| /** |
| * Defines a catch-all dictionary for additional unspecified named parameters. |
| * |
| * <p>If this is left as default, it is an error for the caller to pass any named arguments not |
| * explicitly declared by the method signature. If this is defined, all additional named arguments |
| * are passed as elements of a {@link SkylarkDict} to the method. |
| * |
| * <p>See python's <code>**kwargs</code> (http://thepythonguru.com/python-args-and-kwargs/). |
| * |
| * <p>(If this is defined, the annotated method signature must contain a corresponding SkylarkDict |
| * parameter. See the interface-level javadoc for details.) |
| */ |
| Param extraKeywords() default @Param(name = ""); |
| |
| /** |
| * If true, indicates that the class containing the annotated method has the ability to be called |
| * from skylark (as if it were a function) and that the annotated method should be invoked when |
| * this occurs. |
| * |
| * <p>A class may only have one method with selfCall set to true.</p> |
| * |
| * <p>A method with selfCall=true must not be a structField, and must have name specified |
| * (used for descriptive errors if, for example, there are missing arguments).</p> |
| */ |
| boolean selfCall() default false; |
| |
| /** |
| * Set it to true if the Java method may return <code>null</code> (which will then be converted to |
| * <code>None</code>). If not set and the Java method returns null, an error will be raised. |
| */ |
| boolean allowReturnNones() default false; |
| |
| /** |
| * If true, the location of the call site will be passed as an argument of the annotated function. |
| * (Thus, the annotated method signature must contain Location as a parameter. See the |
| * interface-level javadoc for details.) |
| * |
| * <p>This is incompatible with structField=true. If structField is true, this must be false. |
| */ |
| boolean useLocation() default false; |
| |
| /** |
| * If true, the AST of the call site will be passed as an argument of the annotated function. |
| * (Thus, the annotated method signature must contain FuncallExpression as a parameter. See the |
| * interface-level javadoc for details.) |
| * |
| * <p>This is incompatible with structField=true. If structField is true, this must be false. |
| */ |
| boolean useAst() default false; |
| |
| /** |
| * If true, the Skylark Environment will be passed as an argument of the annotated function. |
| * (Thus, the annotated method signature must contain Environment as a parameter. See the |
| * interface-level javadoc for details.) |
| * |
| * <p>This is incompatible with structField=true. If structField is true, this must be false. |
| */ |
| boolean useEnvironment() default false; |
| |
| /** |
| * If true, the Skylark semantics will be passed as an argument of the annotated function. (Thus, |
| * the annotated method signature must contain SkylarkSemantics as a parameter. See the |
| * interface-level javadoc for details.) |
| */ |
| // TODO(cparsons): This field should work with structField=true. |
| boolean useSkylarkSemantics() default false; |
| } |