src/main/java/com/google/devtools/common/options/OptionsParserImpl.java

// 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.common.options;

import static java.util.Comparator.comparing;
import static java.util.stream.Collectors.toCollection;

import com.google.common.base.Joiner;
import com.google.common.base.Preconditions;
import com.google.common.collect.ImmutableList;
import com.google.common.collect.Iterators;
import com.google.common.collect.LinkedHashMultimap;
import com.google.common.collect.Multimap;
import com.google.devtools.common.options.OptionsParser.OptionDescription;
import java.lang.reflect.Constructor;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.HashMap;
import java.util.Iterator;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;
import java.util.function.Function;
import javax.annotation.Nullable;

/**
 * The implementation of the options parser. This is intentionally package
 * private for full flexibility. Use {@link OptionsParser} or {@link Options}
 * if you're a consumer.
 */
class OptionsParserImpl {

  private final OptionsData optionsData;

  /**
   * We store the results of option parsing in here - since there can only be one value per option
   * field, this is where the different instances of an option have been combined and the final
   * value is tracked. It'll look like
   *
   * <pre>
   *   OptionDefinition("--host") -> "www.google.com"
   *   OptionDefinition("--port") -> 80
   * </pre>
   *
   * This map is modified by repeated calls to {@link #parse(OptionPriority,Function,List)}.
   */
  private final Map<OptionDefinition, OptionValueDescription> optionValues = new HashMap<>();

  /**
   * Explicit option tracking, tracking each option as it was provided, after they have been parsed.
   *
   * <p>The value is unconverted, still the string as it was read from the input, or partially
   * altered in cases where the flag was set by non {@code --flag=value} forms; e.g. {@code --nofoo}
   * becomes {@code --foo=0}.
   */
  private final List<ParsedOptionDescription> parsedOptions = new ArrayList<>();

  /**
   * The options for use with the canonicalize command are stored separately from parsedOptions so
   * that invocation policy can modify the values for canonicalization (e.g. override user-specified
   * values with default values) without corrupting the data used to represent the user's original
   * invocation for {@link #asListOfExplicitOptions()} and {@link #asCompleteListOfParsedOptions()}.
   * A LinkedHashMultimap is used so that canonicalization happens in the correct order and multiple
   * values can be stored for flags that allow multiple values.
   */
  private final Multimap<OptionDefinition, ParsedOptionDescription> canonicalizeValues =
      LinkedHashMultimap.create();

  private final List<String> warnings = new ArrayList<>();

  private boolean allowSingleDashLongOptions = false;

  private ArgsPreProcessor argsPreProcessor =
      new ArgsPreProcessor() {
        @Override
        public List<String> preProcess(List<String> args) throws OptionsParsingException {
          return args;
        }
      };

  /** Create a new parser object. Do not accept a null OptionsData object. */
  OptionsParserImpl(OptionsData optionsData) {
    Preconditions.checkNotNull(optionsData);
    this.optionsData = optionsData;
  }

  OptionsData getOptionsData() {
    return optionsData;
  }

  /**
   * Indicates whether or not the parser will allow long options with a
   * single-dash, instead of the usual double-dash, too, eg. -example instead of just --example.
   */
  void setAllowSingleDashLongOptions(boolean allowSingleDashLongOptions) {
    this.allowSingleDashLongOptions = allowSingleDashLongOptions;
  }

  /** Sets the ArgsPreProcessor for manipulations of the options before parsing. */
  void setArgsPreProcessor(ArgsPreProcessor preProcessor) {
    this.argsPreProcessor = Preconditions.checkNotNull(preProcessor);
  }

  /** Implements {@link OptionsParser#asCompleteListOfParsedOptions()}. */
  List<ParsedOptionDescription> asCompleteListOfParsedOptions() {
    return parsedOptions
        .stream()
        // It is vital that this sort is stable so that options on the same priority are not
        // reordered.
        .sorted(comparing(ParsedOptionDescription::getPriority))
        .collect(toCollection(ArrayList::new));
  }

  /** Implements {@link OptionsParser#asListOfExplicitOptions()}. */
  List<ParsedOptionDescription> asListOfExplicitOptions() {
    return parsedOptions
        .stream()
        .filter(ParsedOptionDescription::isExplicit)
        // It is vital that this sort is stable so that options on the same priority are not
        // reordered.
        .sorted(comparing(ParsedOptionDescription::getPriority))
        .collect(toCollection(ArrayList::new));
  }

  /**
   * Implements {@link OptionsParser#canonicalize}.
   */
  List<String> asCanonicalizedList() {
    return canonicalizeValues
        .values()
        .stream()
        // Sort implicit requirement options to the end, keeping their existing order, and sort
        // the other options alphabetically.
        .sorted(
            (v1, v2) -> {
              if (v1.getOptionDefinition().hasImplicitRequirements()) {
                return v2.getOptionDefinition().hasImplicitRequirements() ? 0 : 1;
              }
              if (v2.getOptionDefinition().hasImplicitRequirements()) {
                return -1;
              }
              return v1.getOptionDefinition()
                  .getOptionName()
                  .compareTo(v2.getOptionDefinition().getOptionName());
            })
        // Ignore expansion options.
        .filter(value -> !value.getOptionDefinition().isExpansionOption())
        .map(ParsedOptionDescription::getDeprecatedCanonicalForm)
        .collect(toCollection(ArrayList::new));
  }

  /**
   * Implements {@link OptionsParser#asListOfEffectiveOptions()}.
   */
  List<OptionValueDescription> asListOfEffectiveOptions() {
    List<OptionValueDescription> result = new ArrayList<>();
    for (Map.Entry<String, OptionDefinition> mapEntry : optionsData.getAllOptionDefinitions()) {
      OptionDefinition optionDefinition = mapEntry.getValue();
      OptionValueDescription optionValue = optionValues.get(optionDefinition);
      if (optionValue == null) {
        result.add(OptionValueDescription.getDefaultOptionValue(optionDefinition));
      } else {
        result.add(optionValue);
      }
    }
    return result;
  }

  private void maybeAddDeprecationWarning(OptionDefinition optionDefinition) {
    // Continue to support the old behavior for @Deprecated options.
    String warning = optionDefinition.getDeprecationWarning();
    if (!warning.isEmpty() || (optionDefinition.getField().isAnnotationPresent(Deprecated.class))) {
      addDeprecationWarning(optionDefinition.getOptionName(), warning);
    }
  }

  private void addDeprecationWarning(String optionName, String warning) {
    warnings.add("Option '" + optionName + "' is deprecated"
        + (warning.isEmpty() ? "" : ": " + warning));
  }


  OptionValueDescription clearValue(OptionDefinition optionDefinition)
      throws OptionsParsingException {
    // Actually remove the value from various lists tracking effective options.
    canonicalizeValues.removeAll(optionDefinition);
    return optionValues.remove(optionDefinition);
  }

  OptionValueDescription getOptionValueDescription(String name) {
    OptionDefinition optionDefinition = optionsData.getOptionDefinitionFromName(name);
    if (optionDefinition == null) {
      throw new IllegalArgumentException("No such option '" + name + "'");
    }
    return optionValues.get(optionDefinition);
  }

  OptionDescription getOptionDescription(String name, OptionPriority priority, String source)
      throws OptionsParsingException {
    OptionDefinition optionDefinition = optionsData.getOptionDefinitionFromName(name);
    if (optionDefinition == null) {
      return null;
    }

    return new OptionDescription(
        optionDefinition,
        optionsData.getExpansionDataForField(optionDefinition),
        getImplicitDependentDescriptions(
            ImmutableList.copyOf(optionDefinition.getImplicitRequirements()),
            optionDefinition,
            priority,
            source));
  }

  /** @return A list of the descriptions corresponding to the implicit dependent flags passed in. */
  private ImmutableList<ParsedOptionDescription> getImplicitDependentDescriptions(
      ImmutableList<String> options,
      OptionDefinition implicitDependent,
      OptionPriority priority,
      String source)
      throws OptionsParsingException {
    ImmutableList.Builder<ParsedOptionDescription> builder = ImmutableList.builder();
    Iterator<String> optionsIterator = options.iterator();

    Function<OptionDefinition, String> sourceFunction =
        o ->
            String.format(
                "implicitely required for option %s (source: %s)",
                implicitDependent.getOptionName(), source);
    while (optionsIterator.hasNext()) {
      String unparsedFlagExpression = optionsIterator.next();
      ParsedOptionDescription parsedOption =
          identifyOptionAndPossibleArgument(
              unparsedFlagExpression,
              optionsIterator,
              priority,
              sourceFunction,
              implicitDependent,
              null);
      builder.add(parsedOption);
    }
    return builder.build();
  }

  /**
   * @return A list of the descriptions corresponding to options expanded from the flag for the
   *     given value. The value itself is a string, no conversion has taken place.
   */
  ImmutableList<ParsedOptionDescription> getExpansionOptionValueDescriptions(
      OptionDefinition expansionFlag,
      @Nullable String flagValue,
      OptionPriority priority,
      String source)
      throws OptionsParsingException {
    ImmutableList.Builder<ParsedOptionDescription> builder = ImmutableList.builder();

    ImmutableList<String> options = optionsData.getEvaluatedExpansion(expansionFlag, flagValue);
    Iterator<String> optionsIterator = options.iterator();
    Function<OptionDefinition, String> sourceFunction =
        o -> String.format("expanded from %s (source: %s)", expansionFlag.getOptionName(), source);
    while (optionsIterator.hasNext()) {
      String unparsedFlagExpression = optionsIterator.next();
      ParsedOptionDescription parsedOption =
          identifyOptionAndPossibleArgument(
              unparsedFlagExpression,
              optionsIterator,
              priority,
              sourceFunction,
              null,
              expansionFlag);
      builder.add(parsedOption);
    }
    return builder.build();
  }

  boolean containsExplicitOption(String name) {
    OptionDefinition optionDefinition = optionsData.getOptionDefinitionFromName(name);
    if (optionDefinition == null) {
      throw new IllegalArgumentException("No such option '" + name + "'");
    }
    return optionValues.get(optionDefinition) != null;
  }

  /**
   * Parses the args, and returns what it doesn't parse. May be called multiple times, and may be
   * called recursively. In each call, there may be no duplicates, but separate calls may contain
   * intersecting sets of options; in that case, the arg seen last takes precedence.
   */
  List<String> parse(
      OptionPriority priority, Function<OptionDefinition, String> sourceFunction, List<String> args)
      throws OptionsParsingException {
    return parse(priority, sourceFunction, null, null, args);
  }

  /**
   * Parses the args, and returns what it doesn't parse. May be called multiple times, and may be
   * called recursively. Calls may contain intersecting sets of options; in that case, the arg seen
   * last takes precedence.
   *
   * <p>The method uses the invariant that if an option has neither an implicit dependent nor an
   * expanded from value, then it must have been explicitly set.
   */
  private List<String> parse(
      OptionPriority priority,
      Function<OptionDefinition, String> sourceFunction,
      OptionDefinition implicitDependent,
      OptionDefinition expandedFrom,
      List<String> args)
      throws OptionsParsingException {
    List<String> unparsedArgs = new ArrayList<>();
    LinkedHashMap<OptionDefinition, List<String>> implicitRequirements = new LinkedHashMap<>();

    Iterator<String> argsIterator = argsPreProcessor.preProcess(args).iterator();
    while (argsIterator.hasNext()) {
      String arg = argsIterator.next();

      if (!arg.startsWith("-")) {
        unparsedArgs.add(arg);
        continue;  // not an option arg
      }

      if (arg.equals("--")) {  // "--" means all remaining args aren't options
        Iterators.addAll(unparsedArgs, argsIterator);
        break;
      }

      ParsedOptionDescription parsedOption =
          identifyOptionAndPossibleArgument(
              arg, argsIterator, priority, sourceFunction, implicitDependent, expandedFrom);
      OptionDefinition optionDefinition = parsedOption.getOptionDefinition();
      // All options can be deprecated; check and warn before doing any option-type specific work.
      maybeAddDeprecationWarning(optionDefinition);

      // Track the value, before any remaining option-type specific work that is done outside of
      // the OptionValueDescription.
      OptionValueDescription entry =
          optionValues.computeIfAbsent(
              optionDefinition, OptionValueDescription::createOptionValueDescription);
      entry.addOptionInstance(parsedOption, warnings);

      @Nullable String unconvertedValue = parsedOption.getUnconvertedValue();
      if (optionDefinition.isWrapperOption()) {
        if (unconvertedValue.startsWith("-")) {
          String sourceMessage =
              "Unwrapped from wrapper option --" + optionDefinition.getOptionName();
          List<String> unparsed =
              parse(
                  priority,
                  o -> sourceMessage,
                  null, // implicitDependent
                  null, // expandedFrom
                  ImmutableList.of(unconvertedValue));

          if (!unparsed.isEmpty()) {
            throw new OptionsParsingException(
                "Unparsed options remain after unwrapping "
                    + arg
                    + ": "
                    + Joiner.on(' ').join(unparsed));
          }

          // Don't process implicitRequirements or expansions for wrapper options. In particular,
          // don't record this option in parsedOptions, so that only the wrapped option shows
          // up in canonicalized options.
          continue;

        } else {
          throw new OptionsParsingException(
              "Invalid --"
                  + optionDefinition.getOptionName()
                  + " value format. "
                  + "You may have meant --"
                  + optionDefinition.getOptionName()
                  + "=--"
                  + unconvertedValue);
        }
      }

      if (implicitDependent == null) {
        // Log explicit options and expanded options in the order they are parsed (can be sorted
        // later). Also remember whether they were expanded or not. This information is needed to
        // correctly canonicalize flags.
        parsedOptions.add(parsedOption);
        if (optionDefinition.allowsMultiple()) {
          canonicalizeValues.put(optionDefinition, parsedOption);
        } else {
          canonicalizeValues.replaceValues(optionDefinition, ImmutableList.of(parsedOption));
        }
      }

      // Handle expansion options.
      if (optionDefinition.isExpansionOption()) {
        ImmutableList<String> expansion =
            optionsData.getEvaluatedExpansion(optionDefinition, unconvertedValue);

        String sourceFunctionApplication = sourceFunction.apply(optionDefinition);
        String sourceMessage =
            (sourceFunctionApplication == null)
                ? String.format("expanded from option --%s", optionDefinition.getOptionName())
                : String.format(
                    "expanded from option --%s from %s",
                    optionDefinition.getOptionName(), sourceFunctionApplication);
        Function<OptionDefinition, String> expansionSourceFunction = o -> sourceMessage;
        List<String> unparsed =
            parse(priority, expansionSourceFunction, null, optionDefinition, expansion);
        if (!unparsed.isEmpty()) {
          // Throw an assertion, because this indicates an error in the definition of this
          // option's expansion, not with the input as provided by the user.
          throw new AssertionError(
              "Unparsed options remain after parsing expansion of "
                  + arg
                  + ": "
                  + Joiner.on(' ').join(unparsed));
        }
      }

      // Collect any implicit requirements.
      if (optionDefinition.hasImplicitRequirements()) {
        implicitRequirements.put(
            optionDefinition, Arrays.asList(optionDefinition.getImplicitRequirements()));
      }
    }

    // Now parse any implicit requirements that were collected.
    // TODO(bazel-team): this should happen when the option is encountered.
    if (!implicitRequirements.isEmpty()) {
      for (Map.Entry<OptionDefinition, List<String>> entry : implicitRequirements.entrySet()) {
        OptionDefinition optionDefinition = entry.getKey();
        String sourceFunctionApplication = sourceFunction.apply(optionDefinition);
        String sourceMessage =
            (sourceFunctionApplication == null)
                ? String.format(
                    "implicit requirement of option --%s", optionDefinition.getOptionName())
                : String.format(
                    "implicit requirement of option --%s from %s",
                    optionDefinition.getOptionName(), sourceFunctionApplication);
        Function<OptionDefinition, String> requirementSourceFunction = o -> sourceMessage;

        List<String> unparsed = parse(priority, requirementSourceFunction, entry.getKey(), null,
            entry.getValue());
        if (!unparsed.isEmpty()) {
          // Throw an assertion, because this indicates an error in the code that specified in the
          // implicit requirements for the option(s).
          throw new AssertionError("Unparsed options remain after parsing implicit options: "
              + Joiner.on(' ').join(unparsed));
        }
      }
    }

    // Go through the final values and make sure they are valid values for their option. Unlike any
    // checks that happened above, this also checks that flags that were not set have a valid
    // default value. getValue() will throw if the value is invalid.
    for (OptionValueDescription valueDescription : asListOfEffectiveOptions()) {
      valueDescription.getValue();
    }

    return unparsedArgs;
  }

  private ParsedOptionDescription identifyOptionAndPossibleArgument(
      String arg,
      Iterator<String> nextArgs,
      OptionPriority priority,
      Function<OptionDefinition, String> sourceFunction,
      OptionDefinition implicitDependent,
      OptionDefinition expandedFrom)
      throws OptionsParsingException {

    // Store the way this option was parsed on the command line.
    StringBuilder commandLineForm = new StringBuilder();
    commandLineForm.append(arg);
    String unconvertedValue = null;
    OptionDefinition optionDefinition;
    boolean booleanValue = true;

    if (arg.length() == 2) { // -l  (may be nullary or unary)
      optionDefinition = optionsData.getFieldForAbbrev(arg.charAt(1));
      booleanValue = true;

    } else if (arg.length() == 3 && arg.charAt(2) == '-') { // -l-  (boolean)
      optionDefinition = optionsData.getFieldForAbbrev(arg.charAt(1));
      booleanValue = false;

    } else if (allowSingleDashLongOptions // -long_option
        || arg.startsWith("--")) { // or --long_option

      int equalsAt = arg.indexOf('=');
      int nameStartsAt = arg.startsWith("--") ? 2 : 1;
      String name =
          equalsAt == -1 ? arg.substring(nameStartsAt) : arg.substring(nameStartsAt, equalsAt);
      if (name.trim().isEmpty()) {
        throw new OptionsParsingException("Invalid options syntax: " + arg, arg);
      }
      unconvertedValue = equalsAt == -1 ? null : arg.substring(equalsAt + 1);
      optionDefinition = optionsData.getOptionDefinitionFromName(name);

      // Look for a "no"-prefixed option name: "no<optionName>".
      if (optionDefinition == null && name.startsWith("no")) {
        name = name.substring(2);
        optionDefinition = optionsData.getOptionDefinitionFromName(name);
        booleanValue = false;
        if (optionDefinition != null) {
          // TODO(bazel-team): Add tests for these cases.
          if (!optionDefinition.usesBooleanValueSyntax()) {
            throw new OptionsParsingException(
                "Illegal use of 'no' prefix on non-boolean option: " + arg, arg);
          }
          if (unconvertedValue != null) {
            throw new OptionsParsingException(
                "Unexpected value after boolean option: " + arg, arg);
          }
          // "no<optionname>" signifies a boolean option w/ false value
          unconvertedValue = "0";
        }
      }
    } else {
      throw new OptionsParsingException("Invalid options syntax: " + arg, arg);
    }

    if (optionDefinition == null
        || ImmutableList.copyOf(optionDefinition.getOptionMetadataTags())
            .contains(OptionMetadataTag.INTERNAL)) {
      // Do not recognize internal options, which are treated as if they did not exist.
      throw new OptionsParsingException("Unrecognized option: " + arg, arg);
    }

    if (unconvertedValue == null) {
      // Special-case boolean to supply value based on presence of "no" prefix.
      if (optionDefinition.usesBooleanValueSyntax()) {
        unconvertedValue = booleanValue ? "1" : "0";
      } else if (optionDefinition.getType().equals(Void.class)
          && !optionDefinition.isWrapperOption()) {
        // This is expected, Void type options have no args (unless they're wrapper options).
      } else if (nextArgs.hasNext()) {
        // "--flag value" form
        unconvertedValue = nextArgs.next();
        commandLineForm.append(" ").append(unconvertedValue);
      } else {
        throw new OptionsParsingException("Expected value after " + arg);
      }
    }

    return new ParsedOptionDescription(
        optionDefinition,
        commandLineForm.toString(),
        unconvertedValue,
        new OptionInstanceOrigin(
            priority, sourceFunction.apply(optionDefinition), implicitDependent, expandedFrom));
  }

  /**
   * Gets the result of parsing the options.
   */
  <O extends OptionsBase> O getParsedOptions(Class<O> optionsClass) {
    // Create the instance:
    O optionsInstance;
    try {
      Constructor<O> constructor = optionsData.getConstructor(optionsClass);
      if (constructor == null) {
        return null;
      }
      optionsInstance = constructor.newInstance();
    } catch (ReflectiveOperationException e) {
      throw new IllegalStateException("Error while instantiating options class", e);
    }

    // Set the fields
    for (OptionDefinition optionDefinition :
        OptionsData.getAllOptionDefinitionsForClass(optionsClass)) {
      Object value;
      OptionValueDescription optionValue = optionValues.get(optionDefinition);
      if (optionValue == null) {
        value = optionDefinition.getDefaultValue();
      } else {
        value = optionValue.getValue();
      }
      try {
        optionDefinition.getField().set(optionsInstance, value);
      } catch (IllegalArgumentException e) {
        throw new IllegalStateException(
            String.format(
                "Unable to set option '%s' to value '%s'.",
                optionDefinition.getOptionName(), value),
            e);
      } catch (IllegalAccessException e) {
        throw new IllegalStateException(
            "Could not set the field due to access issues. This is impossible, as the "
                + "OptionProcessor checks that all options are non-final public fields.",
            e);
      }
    }
    return optionsInstance;
  }

  List<String> getWarnings() {
    return ImmutableList.copyOf(warnings);
  }
}