add filter(String) convenience method

CHANGELOG.md

@@ -4,7 +4,8 @@ Changelog
 ## 0.6.0 SNAPSHOT (current master)
 
 * reorganize maven packages: rename group parent to ohsome-parent (version bump to 2.3), rename local parent to oshdb-parent, and change groupId to org.heigit.ohsome
-* compatibility fix to allow building of javadoc under Java 11 
+* compatibility fix to allow building of javadoc under Java 11.
+* integrate [ohsome filter](https://gitlab.gistools.geog.uni-heidelberg.de/giscience/big-data/ohsome/libs/ohsome-filter) functionality. #253
 
 ## 0.5.9
 

oshdb-api/src/main/java/org/heigit/bigspatialdata/oshdb/api/mapreducer/MapAggregator.java

@@ -826,6 +826,20 @@ public MapAggregator<U, X> filter(FilterExpression f) {
     return this.copyTransform(this.mapReducer.filter(f));
   }
 
+  /**
+   * Apply a custom "ohsome" filter to this query.
+   *
+   * <p>See https://gitlab.gistools.geog.uni-heidelberg.de/giscience/big-data/ohsome/libs/ohsome-filter#syntax
+   * for a description of the ohsome filter syntax.</p>
+   *
+   * @param f the ohsome filter string to apply to the mapAggregator
+   * @return a modified copy of this object (can be used to chain multiple commands together)
+   */
+  @Contract(pure = true)
+  public MapAggregator<U, X> filter(String f) {
+    return this.copyTransform(this.mapReducer.filter(f));
+  }
+
   // -----------------------------------------------------------------------------------------------
   // Exposed generic reduce.
   // Can be used by experienced users of the api to implement complex queries.

oshdb-api/src/main/java/org/heigit/bigspatialdata/oshdb/api/mapreducer/MapReducer.java

@@ -67,6 +67,7 @@
 import org.heigit.ohsome.filter.BinaryOperator;
 import org.heigit.ohsome.filter.Filter;
 import org.heigit.ohsome.filter.FilterExpression;
+import org.heigit.ohsome.filter.FilterParser;
 import org.heigit.ohsome.filter.GeometryTypeFilter;
 import org.heigit.ohsome.filter.TagFilterEquals;
 import org.heigit.ohsome.filter.TagFilterEqualsAny;
@@ -749,6 +750,20 @@ public MapReducer<X> filter(FilterExpression f) {
     return optimizeFilters(ret, f);
   }
 
+  /**
+   * Apply a custom "ohsome" filter to this query.
+   *
+   * <p>See https://gitlab.gistools.geog.uni-heidelberg.de/giscience/big-data/ohsome/libs/ohsome-filter#syntax
+   * for a description of the ohsome filter syntax.</p>
+   *
+   * @param f the ohsome filter string to apply to the mapReducer
+   * @return a modified copy of this mapReducer (can be used to chain multiple commands together)
+   */
+  @Contract(pure = true)
+  public MapReducer<X> filter(String f) {
+    return this.filter(new FilterParser(this.getTagTranslator()).parse(f));
+  }
+
   // -----------------------------------------------------------------------------------------------
   // Grouping and Aggregation
   // Sets how the input data is "grouped", or the output data is "aggregated" into separate chunks.