com.google.devtools.build.lib.syntax.LoadStatement.java Source code

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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.syntax;

import com.google.common.base.Joiner;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.ImmutableMap;
import java.util.Map;

/**
 * Syntax node for an import statement.
 */
public final class LoadStatement extends Statement {

    private final ImmutableMap<Identifier, String> symbols;
    private final ImmutableList<Identifier> cachedSymbols; // to save time
    private final StringLiteral imp;

    /**
     * Constructs an import statement.
     *
     * <p>{@code symbols} maps a symbol to the original name under which it was defined in
     * the bzl file that should be loaded. If aliasing is used, the value differs from its key's
     * {@code symbol.getName()}. Otherwise, both values are identical.
     */
    LoadStatement(StringLiteral imp, Map<Identifier, String> symbols) {
        this.imp = imp;
        this.symbols = ImmutableMap.copyOf(symbols);
        this.cachedSymbols = ImmutableList.copyOf(symbols.keySet());
    }

    public ImmutableList<Identifier> getSymbols() {
        return cachedSymbols;
    }

    public StringLiteral getImport() {
        return imp;
    }

    @Override
    public String toString() {
        return String.format("load(\"%s\", %s)", imp.getValue(), Joiner.on(", ").join(cachedSymbols));
    }

    @Override
    void doExec(Environment env) throws EvalException, InterruptedException {
        for (Map.Entry<Identifier, String> entry : symbols.entrySet()) {
            try {
                Identifier name = entry.getKey();
                Identifier declared = new Identifier(entry.getValue());

                if (declared.isPrivate()) {
                    throw new EvalException(getLocation(),
                            "symbol '" + declared.getName() + "' is private and cannot be imported.");
                }
                // The key is the original name that was used to define the symbol
                // in the loaded bzl file.
                env.importSymbol(imp.getValue(), name, declared.getName());
            } catch (Environment.LoadFailedException e) {
                throw new EvalException(getLocation(), e.getMessage());
            }
        }
    }

    @Override
    public void accept(SyntaxTreeVisitor visitor) {
        visitor.visit(this);
    }

    @Override
    void validate(ValidationEnvironment env) throws EvalException {
        for (Identifier symbol : cachedSymbols) {
            env.declare(symbol.getName(), getLocation());
        }
    }
}