001// License: GPL. For details, see LICENSE file.
002package org.openstreetmap.josm.data.osm;
003
004import java.util.ArrayList;
005import java.util.Collection;
006import java.util.List;
007
008import org.openstreetmap.josm.actions.search.SearchAction.SearchMode;
009import org.openstreetmap.josm.actions.search.SearchCompiler;
010import org.openstreetmap.josm.actions.search.SearchCompiler.Match;
011import org.openstreetmap.josm.actions.search.SearchCompiler.Not;
012import org.openstreetmap.josm.actions.search.SearchCompiler.ParseError;
013import org.openstreetmap.josm.tools.SubclassFilteredCollection;
014
015/**
016 * Class that encapsulates the filter logic, i.e. applies a list of
017 * filters to a primitive.
018 *
019 * Uses {@link Match#match} to see if the filter expression matches,
020 * cares for "inverted-flag" of the filters and combines the results of all active
021 * filters.
022 *
023 * There are two major use cases:
024 *
025 * (1) Hide features that you don't like to edit but get in the way, e.g.
026 * <code>landuse</code> or power lines. It is expected, that the inverted flag
027 * if false for these kind of filters.
028 *
029 * (2) Highlight certain features, that are currently interesting and hide everything
030 * else. This can be thought of as an improved search (Ctrl-F), where you can
031 * continue editing and don't loose the current selection. It is expected that
032 * the inverted flag of the filter is true in this case.
033 *
034 * In addition to the formal application of filter rules, some magic is applied
035 * to (hopefully) match the expectations of the user:
036 *
037 * (1) non-inverted: When hiding a way, all its untagged nodes are hidden as well.
038 * This avoids a "cloud of nodes", that normally isn't useful without the
039 * corresponding way.
040 *
041 * (2) inverted: When displaying a way, we show all its nodes, although the
042 * individual nodes do not match the filter expression. The reason is, that a
043 * way without its nodes cannot be edited properly.
044 *
045 * Multipolygons and (untagged) member ways are handled in a similar way.
046 */
047public class FilterMatcher {
048
049    /**
050     * Describes quality of the filtering.
051     *
052     * Depending on the context, this can either refer to disabled or
053     * to hidden primitives.
054     *
055     * The distinction is necessary, because untagged nodes should only
056     * "inherit" their filter property from the parent way, when the
057     * parent way is hidden (or disabled) "explicitly" (i.e. by a non-inverted
058     * filter). This way, filters like
059     * <code>["child type:way", inverted, Add]</code> show the
060     * untagged way nodes, as intended.
061     *
062     * This information is only needed for ways and relations, so nodes are
063     * either <code>NOT_FILTERED</code> or <code>PASSIV</code>.
064     */
065    public enum FilterType {
066        /** no filter applies */
067        NOT_FILTERED,
068        /** at least one non-inverted filter applies */
069        EXPLICIT,
070        /** at least one filter applies, but they are all inverted filters */
071        PASSIV
072    }
073
074    private static class FilterInfo {
075        private final Match match;
076        private final boolean isDelete;
077        private final boolean isInverted;
078
079        FilterInfo(Filter filter) throws ParseError {
080            if (filter.mode == SearchMode.remove || filter.mode == SearchMode.in_selection) {
081                isDelete = true;
082            } else {
083                isDelete = false;
084            }
085
086            Match compiled = SearchCompiler.compile(filter);
087            this.match = filter.inverted ? new Not(compiled) : compiled;
088            this.isInverted = filter.inverted;
089        }
090    }
091
092    private final List<FilterInfo> hiddenFilters = new ArrayList<>();
093    private final List<FilterInfo> disabledFilters = new ArrayList<>();
094
095    /**
096     * Clears the current filters, and adds the given filters
097     * @param filters the filters to add
098     * @throws ParseError if the search expression in one of the filters cannot be parsed
099     */
100    public void update(Collection<Filter> filters) throws ParseError {
101        reset();
102        for (Filter filter : filters) {
103            add(filter);
104        }
105    }
106
107    /**
108     * Clears the filters in use.
109     */
110    public void reset() {
111        hiddenFilters.clear();
112        disabledFilters.clear();
113    }
114
115    /**
116     * Adds a filter to the currently used filters
117     * @param filter the filter to add
118     * @throws ParseError if the search expression in the filter cannot be parsed
119     */
120    public void add(final Filter filter) throws ParseError {
121        if (!filter.enable) {
122            return;
123        }
124
125        FilterInfo fi = new FilterInfo(filter);
126        if (fi.isDelete) {
127            if (filter.hiding) {
128                // Remove only hide flag
129                hiddenFilters.add(fi);
130            } else {
131                // Remove both flags
132                disabledFilters.add(fi);
133                hiddenFilters.add(fi);
134            }
135        } else {
136            if (filter.mode == SearchMode.replace) {
137                if (filter.hiding) {
138                    hiddenFilters.clear();
139                    disabledFilters.clear();
140                }
141            }
142
143            disabledFilters.add(fi);
144            if (filter.hiding) {
145                hiddenFilters.add(fi);
146            }
147        }
148    }
149
150    /**
151     * Check if primitive is filtered.
152     * @param primitive the primitive to check
153     * @param hidden the minimum level required for the primitive to count as filtered
154     * @return when hidden is true, returns whether the primitive is hidden
155     * when hidden is false, returns whether the primitive is disabled or hidden
156     */
157    private static boolean isFiltered(OsmPrimitive primitive, boolean hidden) {
158        return hidden ? primitive.isDisabledAndHidden() : primitive.isDisabled();
159    }
160
161    /**
162     * Check if primitive is hidden explicitly.
163     * Only used for ways and relations.
164     * @param primitive the primitive to check
165     * @param hidden the level where the check is performed
166     * @return true, if at least one non-inverted filter applies to the primitive
167     */
168    private static boolean isFilterExplicit(OsmPrimitive primitive, boolean hidden) {
169        return hidden ? primitive.getHiddenType() : primitive.getDisabledType();
170    }
171
172    /**
173     * Check if all parent ways are filtered.
174     * @param primitive the primitive to check
175     * @param hidden parameter that indicates the minimum level of filtering:
176     * true when objects need to be hidden to count as filtered and
177     * false when it suffices to be disabled to count as filtered
178     * @return true if (a) there is at least one parent way
179     * (b) all parent ways are filtered at least at the level indicated by the
180     * parameter <code>hidden</code> and
181     * (c) at least one of the parent ways is explicitly filtered
182     */
183    private static boolean allParentWaysFiltered(OsmPrimitive primitive, boolean hidden) {
184        List<OsmPrimitive> refs = primitive.getReferrers();
185        boolean isExplicit = false;
186        for (OsmPrimitive p: refs) {
187            if (p instanceof Way) {
188                if (!isFiltered(p, hidden))
189                    return false;
190                isExplicit |= isFilterExplicit(p, hidden);
191            }
192        }
193        return isExplicit;
194    }
195
196    private static boolean oneParentWayNotFiltered(OsmPrimitive primitive, boolean hidden) {
197        List<OsmPrimitive> refs = primitive.getReferrers();
198        for (OsmPrimitive p: refs) {
199            if (p instanceof Way && !isFiltered(p, hidden))
200                return true;
201        }
202
203        return false;
204    }
205
206    private static boolean allParentMultipolygonsFiltered(OsmPrimitive primitive, boolean hidden) {
207        boolean isExplicit = false;
208        for (Relation r : new SubclassFilteredCollection<OsmPrimitive, Relation>(
209                primitive.getReferrers(), OsmPrimitive::isMultipolygon)) {
210            if (!isFiltered(r, hidden))
211                return false;
212            isExplicit |= isFilterExplicit(r, hidden);
213        }
214        return isExplicit;
215    }
216
217    private static boolean oneParentMultipolygonNotFiltered(OsmPrimitive primitive, boolean hidden) {
218        for (Relation r : new SubclassFilteredCollection<OsmPrimitive, Relation>(
219                primitive.getReferrers(), OsmPrimitive::isMultipolygon)) {
220            if (!isFiltered(r, hidden))
221                return true;
222        }
223        return false;
224    }
225
226    private static FilterType test(List<FilterInfo> filters, OsmPrimitive primitive, boolean hidden) {
227
228        if (primitive.isIncomplete())
229            return FilterType.NOT_FILTERED;
230
231        boolean filtered = false;
232        // If the primitive is "explicitly" hidden by a non-inverted filter.
233        // Only interesting for nodes.
234        boolean explicitlyFiltered = false;
235
236        for (FilterInfo fi: filters) {
237            if (fi.isDelete) {
238                if (filtered && fi.match.match(primitive)) {
239                    filtered = false;
240                }
241            } else {
242                if ((!filtered || (!explicitlyFiltered && !fi.isInverted)) && fi.match.match(primitive)) {
243                    filtered = true;
244                    if (!fi.isInverted) {
245                        explicitlyFiltered = true;
246                    }
247                }
248            }
249        }
250
251        if (primitive instanceof Node) {
252            if (filtered) {
253                // If there is a parent way, that is not hidden, we  show the
254                // node anyway, unless there is no non-inverted filter that
255                // applies to the node directly.
256                if (explicitlyFiltered)
257                    return FilterType.PASSIV;
258                else {
259                    if (oneParentWayNotFiltered(primitive, hidden))
260                        return FilterType.NOT_FILTERED;
261                    else
262                        return FilterType.PASSIV;
263                }
264            } else {
265                if (!primitive.isTagged() && allParentWaysFiltered(primitive, hidden))
266                    // Technically not hidden by any filter, but we hide it anyway, if
267                    // it is untagged and all parent ways are hidden.
268                    return FilterType.PASSIV;
269                else
270                    return FilterType.NOT_FILTERED;
271            }
272        } else if (primitive instanceof Way) {
273            if (filtered) {
274                if (explicitlyFiltered)
275                    return FilterType.EXPLICIT;
276                else {
277                    if (oneParentMultipolygonNotFiltered(primitive, hidden))
278                        return FilterType.NOT_FILTERED;
279                    else
280                        return FilterType.PASSIV;
281                }
282            } else {
283                if (!primitive.isTagged() && allParentMultipolygonsFiltered(primitive, hidden))
284                    return FilterType.EXPLICIT;
285                else
286                    return FilterType.NOT_FILTERED;
287            }
288        } else {
289            if (filtered)
290                return explicitlyFiltered ? FilterType.EXPLICIT : FilterType.PASSIV;
291            else
292                return FilterType.NOT_FILTERED;
293        }
294
295    }
296
297    /**
298     * Check if primitive is hidden.
299     * The filter flags for all parent objects must be set correctly, when
300     * calling this method.
301     * @param primitive the primitive
302     * @return FilterType.NOT_FILTERED when primitive is not hidden;
303     * FilterType.EXPLICIT when primitive is hidden and there is a non-inverted
304     * filter that applies;
305     * FilterType.PASSIV when primitive is hidden and all filters that apply
306     * are inverted
307     */
308    public FilterType isHidden(OsmPrimitive primitive) {
309        return test(hiddenFilters, primitive, true);
310    }
311
312    /**
313     * Check if primitive is disabled.
314     * The filter flags for all parent objects must be set correctly, when
315     * calling this method.
316     * @param primitive the primitive
317     * @return FilterType.NOT_FILTERED when primitive is not disabled;
318     * FilterType.EXPLICIT when primitive is disabled and there is a non-inverted
319     * filter that applies;
320     * FilterType.PASSIV when primitive is disabled and all filters that apply
321     * are inverted
322     */
323    public FilterType isDisabled(OsmPrimitive primitive) {
324        return test(disabledFilters, primitive, false);
325    }
326
327}