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

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Here is the source code for com.google.template.soy.error.ErrorPrettyPrinter.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.Strings;
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.SoySyntaxException;
import com.google.template.soy.base.internal.SoyFileSupplier;

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

/**
 * Displays {@link SoySyntaxException}s in a useful way, with a snippet of Soy source code
 * containing the error and a caret pointing at the exact place where the error was found.
 *
 * @author brndn@google.com (Brendan Linn)
 */
public final class ErrorPrettyPrinter {

    private final ImmutableMap<String, SoyFileSupplier> filePathsToSuppliers;

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

    /**
     * Displays {@code e} on the given {@link java.io.PrintStream} in a useful way, with a snippet
     * of Soy source code containing the error and a caret pointing at the exact place where the error
     * was found.
     */
    public void print(SoySyntaxException e, PrintStream err) {
        // Start by printing the actual text of the exception.
        err.println(e.getMessage());

        // Try to find a snippet of source code associated with the exception and print it.
        SourceLocation sourceLocation = e.getSourceLocation();
        SoyFileSupplier supplier = filePathsToSuppliers.get(sourceLocation.getFilePath());
        if (supplier == null) {
            // TODO(user): this is a result of calling SoySyntaxException#createWithoutMetaInfo,
            // which occurs almost 100 times. Clean them up.
            return;
        }
        String snippet;
        try {
            snippet = getSnippet(supplier, sourceLocation);
        } catch (IOException ioe) {
            return;
        }

        err.println(snippet);
        // Print a caret below the error.
        // TODO(brndn): SourceLocation.beginColumn is occasionally -1. Review all SoySyntaxException
        // instantiations and ensure the SourceLocation is well-formed.
        int beginColumn = Math.max(e.getSourceLocation().getBeginColumn(), 1);
        String caretLine = Strings.repeat(" ", beginColumn - 1) + "^";
        err.println(caretLine);
    }

    private String getSnippet(SoyFileSupplier supplier, SourceLocation sourceLocation) throws IOException {
        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();
            }
            return reader.readLine();
        }
    }
}