Java tutorial
/* * Copyright (C) 2014 The Android Open Source Project * * 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.android.tools.idea.wizard; import com.android.tools.idea.templates.Parameter; import com.google.common.base.Objects; import com.google.common.collect.ImmutableMap; import com.google.common.collect.Iterables; import com.google.common.collect.Maps; import com.google.common.collect.Sets; import com.intellij.openapi.util.text.StringUtil; import org.jetbrains.annotations.NotNull; import org.jetbrains.annotations.Nullable; import java.util.HashMap; import java.util.Map; import java.util.Set; /** * Function for computing default parameter value based on current values of * other parameters. */ public final class ParameterDefaultValueComputer { private static final Deduplicator DO_NOTHING_DEDUPLICATOR = new Deduplicator() { @Nullable @Override public String deduplicate(@NotNull Parameter parameter, @Nullable String value) { return value; } }; @NotNull private final Set<Parameter> myComputedParameters = Sets.newHashSet(); @NotNull private final Set<Parameter> myStaticParameters = Sets.newHashSet(); @NotNull private final Deduplicator myDeduplicator; @NotNull private final StringEvaluator myStringEvaluator = new StringEvaluator(); @NotNull private final Map<Parameter, Object> myUserValues; @NotNull private final Map<String, Object> myImplicitParameters; @Nullable private static Object decodeInitialValue(Parameter input, @Nullable String initial) { if (initial != null && input.type == Parameter.Type.BOOLEAN) { return Boolean.valueOf(initial); } else { return initial; } } /** * Creates a new computer instance * * @param parameters list of parameters that need to be present in the map * @param userValues parameter values changed by the user. * @param implicitParameters parameters that were not declared by the template but are instead a part of our "runtime" * @param deduplicator a function that ensures uniqueness of the parameter value */ public ParameterDefaultValueComputer(@NotNull Iterable<Parameter> parameters, @NotNull Map<Parameter, Object> userValues, @NotNull Map<String, Object> implicitParameters, @Nullable Deduplicator deduplicator) { myUserValues = userValues; myImplicitParameters = implicitParameters; for (Parameter parameter : parameters) { if (parameter != null && !StringUtil.isEmptyOrSpaces(parameter.id)) { if (!StringUtil.isEmptyOrSpaces(parameter.suggest) && !userValues.containsKey(parameter)) { myComputedParameters.add(parameter); } else { myStaticParameters.add(parameter); } } } myDeduplicator = deduplicator == null ? DO_NOTHING_DEDUPLICATOR : deduplicator; } /** * Returns a map of parameter values * * @return mapping between paramaeter and its current value * @throws CircularParameterDependencyException if there is a circular dependecy between * parameters preventing us from computing the default values. */ public Map<Parameter, Object> getParameterValues() throws CircularParameterDependencyException { Map<String, Object> staticValues = getStaticParameterValues(myUserValues, myImplicitParameters); Map<String, Object> computedValues = computeParameterValues(staticValues); HashMap<Parameter, Object> allValues = Maps .newHashMapWithExpectedSize(computedValues.size() + staticValues.size()); for (Parameter parameter : Iterables.concat(myStaticParameters, myComputedParameters)) { allValues.put(parameter, computedValues.get(parameter.id)); } return allValues; } @Nullable private Object computeParameterValue(@NotNull Parameter computedParameter, @NotNull Map<String, Object> currentValues) { String suggest = computedParameter.suggest; assert !StringUtil.isEmptyOrSpaces(suggest); String value = myStringEvaluator.evaluate(suggest, currentValues); value = myDeduplicator.deduplicate(computedParameter, value); return decodeInitialValue(computedParameter, value); } private Map<String, Object> getStaticParameterValues(@NotNull Map<Parameter, Object> values, @NotNull Map<String, Object> implicitParameters) { final Map<String, Object> knownValues = Maps .newHashMapWithExpectedSize(myStaticParameters.size() + implicitParameters.size()); knownValues.putAll(implicitParameters); for (Parameter parameter : myStaticParameters) { Object value; if (values.containsKey(parameter)) { value = values.get(parameter); } else { String initial = parameter.initial; value = decodeInitialValue(parameter, initial); } knownValues.put(parameter.id, value); } return knownValues; } /** * <p>Computes values of the parameters with non-static default values.</p> * <p>These parameters may depend on other computable parameters. We do not have that information * (expressions are evaluated with FreeMarker), so we keep reevaluating the parameter values until * they stabilize.</p> * * @return a map of parameter ID to parameter values. * @throws CircularParameterDependencyException means it is not possible to stabilize parameter values * due to circular dependency */ private Map<String, Object> computeParameterValues(Map<String, Object> staticValues) throws CircularParameterDependencyException { Map<String, Object> computedValues = Maps .newHashMapWithExpectedSize(myComputedParameters.size() + staticValues.size()); computedValues.putAll(staticValues); for (Parameter parameter : myComputedParameters) { computedValues.put(parameter.id, ""); } // Limit the number of iterations before we recognize there's circular dependency. // The maximum depth of the parameter dependency tree would be a number of parameters, // hence this is our "worst case" number of iterations (note we'll need +1 iteration // to check the value is stable) we would need to compute the values. final int maxIterations = myComputedParameters.size(); Map<String, Object> updatedValues = ImmutableMap.of(); for (int i = 0; i <= maxIterations; i++) { updatedValues = computeUpdatedValues(computedValues); if (updatedValues.isEmpty()) { return computedValues; } else { computedValues.putAll(updatedValues); } } throw new CircularParameterDependencyException(updatedValues.keySet()); } @NotNull private Map<String, Object> computeUpdatedValues(@NotNull Map<String, Object> values) { Map<String, Object> updatedValues = Maps.newHashMapWithExpectedSize(myComputedParameters.size()); for (Parameter computedParameter : myComputedParameters) { Object value = computeParameterValue(computedParameter, values); String id = computedParameter.id; if (!Objects.equal(values.get(id), value)) { updatedValues.put(id, value); } } return updatedValues; } public interface Deduplicator { @Nullable String deduplicate(@NotNull Parameter parameter, @Nullable String value); } }