com.google.template.soy.error.SnippetFormatter.java Source code

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Here is the source code for com.google.template.soy.error.SnippetFormatter.java

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/*
 * Copyright 2015 Google Inc.
 *
 * 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.template.soy.error;

import com.google.common.base.Optional;
import com.google.common.collect.ImmutableMap;
import com.google.common.collect.ImmutableMap.Builder;
import com.google.template.soy.base.SourceLocation;
import com.google.template.soy.base.internal.SoyFileSupplier;

import java.io.BufferedReader;
import java.io.IOException;
import java.util.List;

/**
 * Fetches a snippet of source code surrounding a given {@link SourceLocation}.
 * The snippet is just for human consumption and doesn't necessarily correspond to
 * any unit of Soy syntax.
 *
 * @author brndn@google.com (Brendan Linn)
 */
public final class SnippetFormatter {

    private final ImmutableMap<String, SoyFileSupplier> filePathsToSuppliers;

    public SnippetFormatter(List<SoyFileSupplier> suppliers) {
        ImmutableMap.Builder<String, SoyFileSupplier> builder = new Builder<>();
        for (SoyFileSupplier supplier : suppliers) {
            builder.put(supplier.getFilePath(), supplier);
        }
        filePathsToSuppliers = builder.build();
    }

    /**
     * Returns a snippet of source code surrounding the given {@link SourceLocation},
     * or {@link Optional#absent()} if source code is unavailable. (This happens, for example,
     * when anyone uses {@link SourceLocation#UNKNOWN}, which is why no one should use it.)
     */
    public Optional<String> getSnippet(SourceLocation sourceLocation) throws IOException {
        // Try to find a snippet of source code associated with the exception and print it.
        SoyFileSupplier supplier = filePathsToSuppliers.get(sourceLocation.getFilePath());
        if (supplier == null) {
            return Optional.absent();
        }
        String result;
        try (BufferedReader reader = new BufferedReader(supplier.open())) {
            // Line numbers are 1-indexed
            for (int linenum = 1; linenum < sourceLocation.getLineNumber(); ++linenum) {
                // Skip preceding lines
                reader.readLine();
            }
            result = reader.readLine();
        }
        return Optional.of(result);
    }
}