com.google.javascript.jscomp.LightweightMessageFormatter Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of closure-compiler-unshaded Show documentation
Closure Compiler is a JavaScript optimizing compiler. It parses your JavaScript, analyzes it, removes dead code and rewrites and minimizes what's left. It also checks syntax, variable references, and types, and warns about common JavaScript pitfalls. It is used in many of Google's JavaScript apps, including Gmail, Google Web Search, Google Maps, and Google Docs.
The newest version!
/*
 * Copyright 2007 The Closure Compiler Authors.
 *
 * 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.javascript.jscomp;

import static com.google.common.base.Preconditions.checkNotNull;
import static com.google.common.base.Preconditions.checkState;
import static com.google.javascript.jscomp.SourceExcerptProvider.SourceExcerpt.FULL;
import static com.google.javascript.jscomp.SourceExcerptProvider.SourceExcerpt.LINE;
import static java.lang.Math.max;
import static java.lang.Math.min;

import com.google.common.base.Splitter;
import com.google.debugging.sourcemap.proto.Mapping.OriginalMapping;
import com.google.errorprone.annotations.CanIgnoreReturnValue;
import com.google.javascript.jscomp.SourceExcerptProvider.ExcerptFormatter;
import com.google.javascript.jscomp.SourceExcerptProvider.SourceExcerpt;
import com.google.javascript.rhino.Node;
import com.google.javascript.rhino.TokenUtil;
import java.util.List;
import org.jspecify.nullness.Nullable;

/**
 * Lightweight message formatter. The format of messages this formatter
 * produces is very compact and to the point.
 */
public final class LightweightMessageFormatter extends AbstractMessageFormatter {
  private final SourceExcerpt defaultFormat;
  private static final ExcerptFormatter excerptFormatter =
      new LineNumberingFormatter();
  private boolean includeLocation = true;
  private boolean includeLevel = true;
  private static final int MAX_MULTILINE_ERROR_LENGTH = 4; // must be even.

  /**
   * A constructor for when the client doesn't care about source information.
   */
  private LightweightMessageFormatter() {
    super(null);
    this.defaultFormat = LINE;
  }

  public LightweightMessageFormatter(SourceExcerptProvider source) {
    this(source, LINE);
  }

  public LightweightMessageFormatter(SourceExcerptProvider source, SourceExcerpt defaultFormat) {
    super(source);
    checkNotNull(source);
    this.defaultFormat = defaultFormat;
  }

  public static LightweightMessageFormatter withoutSource() {
    return new LightweightMessageFormatter();
  }

  @CanIgnoreReturnValue
  public LightweightMessageFormatter setIncludeLocation(boolean includeLocation) {
    this.includeLocation = includeLocation;
    return this;
  }

  @CanIgnoreReturnValue
  public LightweightMessageFormatter setIncludeLevel(boolean includeLevel) {
    this.includeLevel = includeLevel;
    return this;
  }

  @Override
  public String formatError(JSError error) {
    return format(error, false);
  }

  @Override
  public String formatWarning(JSError warning) {
    return format(warning, true);
  }

  private String format(JSError error, boolean warning) {
    SourceExcerptProvider source = getSource();
    String sourceName = error.getSourceName();
    int lineNumber = error.getLineNumber();
    int charno = error.getCharno();

    // Format the non-reverse-mapped position.
    StringBuilder b = new StringBuilder();
    StringBuilder boldLine = new StringBuilder();

    OriginalMapping mapping =
        source == null
            ? null
            : source.getSourceMapping(
                error.getSourceName(), error.getLineNumber(), error.getCharno());

    // Check if we can reverse-map the source.
    if (includeLocation) {
      if (mapping != null) {
        appendPosition(b, sourceName, lineNumber, charno);

        sourceName = mapping.getOriginalFile();
        lineNumber = mapping.getLineNumber();
        charno = mapping.getColumnPosition();

        b.append("\nOriginally at:\n");
      }

      appendPosition(boldLine, sourceName, lineNumber, charno);
    }

    if (includeLevel) {
      boldLine.append(getLevelName(warning ? CheckLevel.WARNING : CheckLevel.ERROR));
      boldLine.append(" - [");
      boldLine.append(error.getType().key);
      boldLine.append("] ");
    }

    boldLine.append(error.getDescription());

    b.append(maybeEmbolden(boldLine.toString()));
    b.append('\n');

    // For reverse-mapped sources, fall back to a single line excerpt because the excerpt length
    // cannot be reliably mapped.
    String sourceExcerptWithPosition =
        getExcerptWithPosition(
            error, sourceName, lineNumber, charno, mapping != null ? LINE : defaultFormat);

    if (sourceExcerptWithPosition != null) {
      b.append(sourceExcerptWithPosition);
    }

    return b.toString();
  }

  String getExcerptWithPosition(JSError error) {
    return getExcerptWithPosition(
        error, error.getSourceName(), error.getLineNumber(), error.getCharno(), defaultFormat);
  }

  private String getExcerptWithPosition(
      JSError error, String sourceName, int lineNumber, int charno, SourceExcerpt format) {
    StringBuilder b = new StringBuilder();

    SourceExcerptProvider source = getSource();
    int nodeLength = error.getNodeLength();
    int length = charno >= 0 && nodeLength >= 0 ? charno + nodeLength : -1;

    String sourceExcerpt =
        source == null
            ? null
            : format.get(source, sourceName, lineNumber, length, excerptFormatter);

    if (sourceExcerpt != null) {
      if (format.equals(FULL)) {
        if (0 <= charno) {
          padMultipleLines(error, charno, sourceExcerpt, b, error.getNode());
        } else {
          b.append(sourceExcerpt);
          b.append('\n');
        }
      } else {
        b.append(sourceExcerpt);
        b.append('\n');

        // charno == sourceExcerpt.length() means something is missing
        // at the end of the line
        if (format.equals(LINE) && 0 <= charno && charno <= sourceExcerpt.length()) {
          padLine(charno, sourceExcerpt, b, error.getNodeLength(), error.getNode());
        }
      }
    }
    return b.toString();
  }

  private static void appendPosition(
      StringBuilder b, String sourceName, int lineNumber, int charno) {
    if (sourceName != null) {
      b.append(sourceName);
      if (lineNumber > 0) {
        b.append(':').append(lineNumber);
        if (charno >= 0) {
          b.append(':').append(charno);
        }
      }
      b.append(": ");
    }
  }

  private void padLine(
      int charno, String sourceExcerpt, StringBuilder b, int errLength, Node errorNode) {
    // Append leading whitespace
    for (int i = 0; i < charno; i++) {
      char c = sourceExcerpt.charAt(i);
      if (TokenUtil.isWhitespace(c)) {
        b.append(c);
      } else {
        b.append(' ');
      }
    }
    if (errorNode == null) {
      b.append("^");
    } else {
      int length = max(1, min(errLength, sourceExcerpt.length() - charno));
      for (int i = 0; i < length; i++) {
        b.append("^");
      }
    }
    b.append("\n");
  }

  /**
   * Appends lines from the given excerpt, attempting to add "^^^^" highlighting to the parts of the
   * excerpt covered by the given error node.
   *
   * @param startCharno the (positive) charno representing the index into the first line.
   * @param sourceExcerpt the original source, possibly multiple lines separated by '\n'.
   */
  private void padMultipleLines(
      JSError error, int startCharno, String sourceExcerpt, StringBuilder b, Node errorNode) {
    if (errorNode == null) {
      b.append(sourceExcerpt);
      b.append("\n");
      int charWithLineNumberOffset = startCharno + sourceExcerpt.indexOf('|') + 2;
      checkState(
          charWithLineNumberOffset <= sourceExcerpt.length(),
          "Cannot format source excerpt; unexpected start character for error:\n %s",
          error);
      padLine(charWithLineNumberOffset, sourceExcerpt, b, -1, errorNode);
      return;
    }
    List lines = Splitter.on('\n').splitToList(sourceExcerpt);
    boolean requiresTruncation = lines.size() > MAX_MULTILINE_ERROR_LENGTH;
    int truncationStart = MAX_MULTILINE_ERROR_LENGTH / 2;
    int truncationEnd = lines.size() - MAX_MULTILINE_ERROR_LENGTH / 2;

    int remainingLength = errorNode.getLength();
    int charno = startCharno;
    for (int i = 0; i < lines.size(); i++) {
      String line = lines.get(i);
      if (requiresTruncation && i == truncationStart) {
        b.append("...\n");
      }
      boolean shouldPrintLine = !requiresTruncation || i < truncationStart || i >= truncationEnd;
      // The LineNumberingFormatter below will append "  5| " to the start of each line, so subtract
      // that from the source line length in order to match the actual error length.
      int charWithLineNumberOffset = charno + line.indexOf('|') + 2;

      if (shouldPrintLine) {
        b.append(line);
        b.append("\n");
        checkState(
            charWithLineNumberOffset <= sourceExcerpt.length(),
            "Cannot format source excerpt; unexpected start character for error\n%s",
            error);
        padLine(charWithLineNumberOffset, line, b, remainingLength, errorNode);
      }

      // add 1 to represent the newline; subtract the offset of the "  5| ".
      remainingLength -= (line.length() + 1 - charWithLineNumberOffset);
      charno = 0;
    }
  }

  /**
   * Formats a region by appending line numbers in front, e.g.
   *
   *    *    9| if (foo) {
   *   10|   alert('bar');
   *   11| }
   * 
   *
   * and return line excerpt without any modification.
   */
  static class LineNumberingFormatter implements ExcerptFormatter {
    @Override
    public String formatLine(String line, int lineNumber) {
      return line;
    }

    @Override
    public @Nullable String formatRegion(@Nullable Region region) {
      if (region == null) {
        return null;
      }
      String code = region.getSourceExcerpt();
      if (code.isEmpty()) {
        return null;
      }

      // max length of the number display
      int numberLength = Integer.toString(region.getEndingLineNumber())
          .length();

      // formatting
      StringBuilder builder = new StringBuilder(code.length() * 2);
      int start = 0;
      int end = code.indexOf('\n', start);
      int lineNumber = region.getBeginningLineNumber();
      while (start >= 0) {
        // line extraction
        String line;
        if (end < 0) {
          line = code.substring(start);
          if (line.isEmpty()) {
            return builder.substring(0, builder.length() - 1);
          }
        } else {
          line = code.substring(start, end);
        }
        builder.append("  ");

        // nice spaces for the line number
        int spaces = numberLength - Integer.toString(lineNumber).length();
        builder.append(" ".repeat(spaces));
        builder.append(lineNumber);
        builder.append("| ");

        // end & update
        if (end < 0) {
          builder.append(line);
          start = -1;
        } else {
          builder.append(line);
          builder.append('\n');
          start = end + 1;
          end = code.indexOf('\n', start);
          lineNumber++;
        }
      }
      return builder.toString();
    }
  }
}