pkg/front_end/lib/src/fasta/command_line_reporting.dart

// Copyright (c) 2017, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

/// Provides a default implementation of the report and format methods of
/// [CompilerContext] that are suitable for command-line tools. The methods in
/// this library aren't intended to be called directly, instead, one should use
/// [CompilerContext].
library fasta.command_line_reporting;

import 'dart:math' show min;

import 'dart:typed_data' show Uint8List;

import 'package:_fe_analyzer_shared/src/messages/severity.dart'
    show Severity, severityPrefixes;

import 'package:_fe_analyzer_shared/src/scanner/characters.dart'
    show $CARET, $SPACE, $TAB;

import 'package:_fe_analyzer_shared/src/util/colors.dart'
    show enableColors, green, magenta, red;

import 'package:_fe_analyzer_shared/src/util/relativize.dart'
    show isWindows, relativizeUri;

import 'package:kernel/ast.dart' show Location, TreeNode;

import '../compute_platform_binaries_location.dart' show translateSdk;

import 'compiler_context.dart' show CompilerContext;

import 'crash.dart' show Crash, safeToString;

import 'fasta_codes.dart' show LocatedMessage;

import 'messages.dart' show getLocation, getSourceLine;

import 'problems.dart' show unhandled;

const bool hideWarnings = false;

/// Formats [message] as a string that is suitable for output from a
/// command-line tool. This includes source snippets and different colors based
/// on [severity].
String format(LocatedMessage message, Severity severity, {Location location}) {
  try {
    int length = message.length;
    if (length < 1) {
      // TODO(ahe): Throw in this situation. It is normally an error caused by
      // empty names.
      length = 1;
    }
    String prefix = severityPrefixes[severity];
    String messageText =
        prefix == null ? message.message : "$prefix: ${message.message}";
    if (message.tip != null) {
      messageText += "\n${message.tip}";
    }
    if (enableColors) {
      switch (severity) {
        case Severity.error:
        case Severity.internalProblem:
          messageText = red(messageText);
          break;

        case Severity.warning:
          messageText = magenta(messageText);
          break;

        case Severity.context:
          messageText = green(messageText);
          break;

        default:
          return unhandled("$severity", "format", -1, null);
      }
    }

    if (message.uri != null) {
      String path =
          relativizeUri(Uri.base, translateSdk(message.uri), isWindows);
      int offset = message.charOffset;
      location ??= (offset == -1 ? null : getLocation(message.uri, offset));
      if (location?.line == TreeNode.noOffset) {
        location = null;
      }
      String sourceLine = getSourceLine(location);
      return formatErrorMessage(
          sourceLine, location, length, path, messageText);
    } else {
      return messageText;
    }
  } catch (error, trace) {
    print("Crash when formatting: "
        "[${message.code.name}] ${safeToString(message.message)}\n"
        "${safeToString(error)}\n"
        "$trace");
    throw new Crash(message.uri, message.charOffset, error, trace);
  }
}

String formatErrorMessage(String sourceLine, Location location,
    int squigglyLength, String path, String messageText) {
  if (sourceLine == null) {
    sourceLine = "";
  } else if (sourceLine.isNotEmpty) {
    // TODO(askesc): Much more could be done to indent properly in the
    // presence of all sorts of unicode weirdness.
    // This handling covers the common case of single-width characters
    // indented with spaces and/or tabs, using no surrogates.
    int indentLength = location.column - 1;
    Uint8List indentation = new Uint8List(indentLength + squigglyLength)
      ..fillRange(0, indentLength, $SPACE)
      ..fillRange(indentLength, indentLength + squigglyLength, $CARET);
    int lengthInSourceLine = min(indentation.length, sourceLine.length);
    for (int i = 0; i < lengthInSourceLine; i++) {
      if (sourceLine.codeUnitAt(i) == $TAB) {
        indentation[i] = $TAB;
      }
    }
    String pointer = new String.fromCharCodes(indentation);
    if (pointer.length > sourceLine.length) {
      // Truncate the carets to handle messages that span multiple lines.
      int pointerLength = sourceLine.length;
      // Add one to cover the case of a parser error pointing to EOF when
      // the last line doesn't end with a newline. For messages spanning
      // multiple lines, this also provides a minor visual clue that can be
      // useful for debugging Fasta.
      pointerLength += 1;
      pointer = pointer.substring(0, pointerLength);
      pointer += "...";
    }
    sourceLine = "\n$sourceLine\n$pointer";
  }
  String position =
      location == null ? "" : ":${location.line}:${location.column}";
  return "$path$position: $messageText$sourceLine";
}

/// Are problems of [severity] suppressed?
bool isHidden(Severity severity) {
  switch (severity) {
    case Severity.error:
    case Severity.internalProblem:
    case Severity.context:
      return false;

    case Severity.warning:
      return hideWarnings;

    default:
      return unhandled("$severity", "isHidden", -1, null);
  }
}

/// Are problems of [severity] fatal? That is, should the compiler terminate
/// immediately?
bool shouldThrowOn(Severity severity) {
  switch (severity) {
    case Severity.error:
      return CompilerContext.current.options.throwOnErrorsForDebugging;

    case Severity.internalProblem:
      return true;

    case Severity.warning:
      return CompilerContext.current.options.throwOnWarningsForDebugging;

    case Severity.context:
      return false;

    default:
      return unhandled("$severity", "shouldThrowOn", -1, null);
  }
}

bool isCompileTimeError(Severity severity) {
  switch (severity) {
    case Severity.error:
    case Severity.internalProblem:
      return true;

    case Severity.warning:
    case Severity.context:
      return false;

    case Severity.ignored:
      break; // Fall-through to unhandled below.
  }
  return unhandled("$severity", "isCompileTimeError", -1, null);
}