com.google.devtools.build.lib.analysis.actions.CommandLine.java Source code

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Here is the source code for com.google.devtools.build.lib.analysis.actions.CommandLine.java

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// 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.analysis.actions;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterables;
import com.google.devtools.build.lib.actions.Artifact.ArtifactExpander;
import com.google.devtools.build.lib.collect.CollectionUtils;
import com.google.devtools.build.lib.util.Preconditions;

/**
 * A representation of a command line to be executed by a SpawnAction.
 */
public abstract class CommandLine {
    /**
     * Returns the command line.
     */
    public abstract Iterable<String> arguments();

    /**
     * Returns the evaluated command line with enclosed artifacts expanded by {@code artifactExpander}
     * at execution time.
     *
     * <p>By default, this method just delegates to {@link #arguments()}, without performing any
     * artifact expansion. Subclasses should override this method if they contain TreeArtifacts and
     * need to expand them for proper argument evaluation.
     */
    public Iterable<String> arguments(ArtifactExpander artifactExpander) {
        return arguments();
    }

    /**
     * Returns whether the command line represents a shell command with the given shell executable.
     * This is used to give better error messages.
     *
     * <p>By default, this method returns false.
     */
    public boolean isShellCommand() {
        return false;
    }

    /**
     * Returns the {@link ParameterFileWriteAction} that generates the parameter file used in this
     * command line, or null if no parameter file is used.
     */
    @VisibleForTesting
    public ParameterFileWriteAction parameterFileWriteAction() {
        return null;
    }

    /** A default implementation of a command line backed by a copy of the given list of arguments. */
    static CommandLine ofInternal(Iterable<String> arguments, final boolean isShellCommand,
            final ParameterFileWriteAction paramFileWriteAction) {
        final Iterable<String> immutableArguments = CollectionUtils.makeImmutable(arguments);
        return new CommandLine() {
            @Override
            public Iterable<String> arguments() {
                return immutableArguments;
            }

            @Override
            public boolean isShellCommand() {
                return isShellCommand;
            }

            @Override
            public ParameterFileWriteAction parameterFileWriteAction() {
                return paramFileWriteAction;
            }
        };
    }

    /**
     * Returns a {@link CommandLine} backed by a copy of the given list of arguments.
     */
    public static CommandLine of(Iterable<String> arguments, final boolean isShellCommand) {
        final Iterable<String> immutableArguments = CollectionUtils.makeImmutable(arguments);
        return new CommandLine() {
            @Override
            public Iterable<String> arguments() {
                return immutableArguments;
            }

            @Override
            public boolean isShellCommand() {
                return isShellCommand;
            }
        };
    }

    /**
     * Returns a {@link CommandLine} that is constructed by prepending the {@code executableArgs} to
     * {@code commandLine}.
     */
    static CommandLine ofMixed(final ImmutableList<String> executableArgs, final CommandLine commandLine,
            final boolean isShellCommand) {
        Preconditions.checkState(!executableArgs.isEmpty());
        return new CommandLine() {
            @Override
            public Iterable<String> arguments() {
                return Iterables.concat(executableArgs, commandLine.arguments());
            }

            @Override
            public Iterable<String> arguments(ArtifactExpander artifactExpander) {
                return Iterables.concat(executableArgs, commandLine.arguments(artifactExpander));
            }

            @Override
            public boolean isShellCommand() {
                return isShellCommand;
            }
        };
    }

    /**
     * Returns a {@link CommandLine} with {@link CharSequence} arguments. This can be useful to create
     * memory efficient command lines with {@link com.google.devtools.build.lib.util.LazyString}s.
     */
    public static CommandLine ofCharSequences(final ImmutableList<CharSequence> arguments) {
        return new CommandLine() {
            @Override
            public Iterable<String> arguments() {
                ImmutableList.Builder<String> builder = ImmutableList.builder();
                for (CharSequence arg : arguments) {
                    builder.add(arg.toString());
                }
                return builder.build();
            }
        };
    }

    /**
     * This helps when debugging Blaze code that uses {@link CommandLine}s, as you can see their
     * content directly in the variable inspector.
     */
    @Override
    public String toString() {
        return Joiner.on(' ').join(arguments());
    }
}