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// Copyright 2016 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.syntax;
import com.google.common.collect.ImmutableList;
import com.google.devtools.build.lib.collect.nestedset.Order;
import com.google.devtools.build.lib.events.Location;
import com.google.devtools.build.lib.skylarkinterface.Param;
import com.google.devtools.build.lib.skylarkinterface.SkylarkSignature;
import java.util.List;
/**
* A helper class containing additional built in functions for Bazel (BUILD files and .bzl files).
*/
public class BazelLibrary {
@SkylarkSignature(
name = "type",
returnType = String.class,
doc =
"Returns the type name of its argument. This is useful for debugging and "
+ "type-checking. Examples:"
+ "<pre class=\"language-python\">"
+ "type(2) == \"int\"\n"
+ "type([1]) == \"list\"\n"
+ "type(struct(a = 2)) == \"struct\""
+ "</pre>"
+ "This function might change in the future. To write Python-compatible code and "
+ "be future-proof, use it only to compare return values: "
+ "<pre class=\"language-python\">"
+ "if type(x) == type([]): # if x is a list"
+ "</pre>",
parameters = {@Param(name = "x", doc = "The object to check type of.")}
)
private static final BuiltinFunction type =
new BuiltinFunction("type") {
public String invoke(Object object) {
// There is no 'type' type in Skylark, so we return a string with the type name.
return EvalUtils.getDataTypeName(object, false);
}
};
@SkylarkSignature(
name = "set",
returnType = SkylarkNestedSet.class,
doc =
"Creates a <a href=\"set.html\">set</a> from the <code>items</code>. "
+ "The set supports nesting other sets of the same element type in it. "
+ "A desired <a href=\"set.html\">iteration order</a> can also be specified.<br>"
+ "Examples:<br><pre class=\"language-python\">set([\"a\", \"b\"])\n"
+ "set([1, 2, 3], order=\"compile\")</pre>",
parameters = {
@Param(
name = "items",
type = Object.class,
defaultValue = "[]",
doc =
"The items to initialize the set with. May contain both standalone items "
+ "and other sets."
),
@Param(
name = "order",
type = String.class,
defaultValue = "\"stable\"",
doc =
"The ordering strategy for the set if it's nested, "
+ "possible values are: <code>stable</code> (default), <code>compile</code>, "
+ "<code>link</code> or <code>naive_link</code>. An explanation of the "
+ "values can be found <a href=\"set.html\">here</a>."
)
},
useLocation = true
)
private static final BuiltinFunction set =
new BuiltinFunction("set") {
public SkylarkNestedSet invoke(Object items, String order, Location loc)
throws EvalException {
try {
return new SkylarkNestedSet(Order.parse(order), items, loc);
} catch (IllegalArgumentException ex) {
throw new EvalException(loc, ex);
}
}
};
@SkylarkSignature(
name = "union",
objectType = SkylarkNestedSet.class,
returnType = SkylarkNestedSet.class,
doc =
"Creates a new <a href=\"set.html\">set</a> that contains both "
+ "the input set as well as all additional elements.",
parameters = {
@Param(name = "input", type = SkylarkNestedSet.class, doc = "The input set"),
@Param(name = "new_elements", type = Iterable.class, doc = "The elements to be added")
},
useLocation = true
)
private static final BuiltinFunction union =
new BuiltinFunction("union") {
@SuppressWarnings("unused")
public SkylarkNestedSet invoke(
SkylarkNestedSet input, Iterable<Object> newElements, Location loc)
throws EvalException {
return new SkylarkNestedSet(input, newElements, loc);
}
};
/**
* Returns a function-value implementing "select" (i.e. configurable attributes) in the specified
* package context.
*/
@SkylarkSignature(
name = "select",
doc = "Creates a SelectorValue from the dict parameter.",
parameters = {
@Param(name = "x", type = SkylarkDict.class, doc = "The parameter to convert."),
@Param(
name = "no_match_error",
type = String.class,
defaultValue = "''",
doc = "Optional custom error to report if no condition matches."
)
}
)
private static final BuiltinFunction select =
new BuiltinFunction("select") {
public Object invoke(SkylarkDict<?, ?> dict, String noMatchError) throws EvalException {
return SelectorList.of(new SelectorValue(dict, noMatchError));
}
};
private static Environment.Frame createGlobals() {
List<BaseFunction> bazelGlobalFunctions = ImmutableList.<BaseFunction>of(select, set, type);
try (Mutability mutability = Mutability.create("BUILD")) {
Environment env = Environment.builder(mutability).build();
Runtime.setupConstants(env);
Runtime.setupMethodEnvironment(env, MethodLibrary.defaultGlobalFunctions);
Runtime.setupMethodEnvironment(env, bazelGlobalFunctions);
return env.getGlobals();
}
}
public static final Environment.Frame GLOBALS = createGlobals();
static {
SkylarkSignatureProcessor.configureSkylarkFunctions(BazelLibrary.class);
}
}
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