Add common pathing code and SimplePathing module

src/main/java/com/replaymod/pathing/interpolation/AbstractInterpolator.java

@@ -0,0 +1,74 @@
+package com.replaymod.pathing.interpolation;
+
+import com.replaymod.pathing.path.PathSegment;
+import com.replaymod.pathing.property.Property;
+import com.replaymod.pathing.property.PropertyPart;
+
+import java.util.*;
+
+public abstract class AbstractInterpolator implements Interpolator {
+    private List<PathSegment> segments = new LinkedList<>();
+    private boolean dirty;
+    private final Set<Property> properties = new HashSet<>();
+
+    @Override
+    public Collection<Property> getKeyframeProperties() {
+        return Collections.unmodifiableCollection(properties);
+    }
+
+    public void registerProperty(Property property) {
+        properties.add(property);
+    }
+
+    @Override
+    public void addSegment(PathSegment segment) {
+        segments.add(segment);
+        dirty = true;
+    }
+
+    @Override
+    public void removeSegment(PathSegment segment) {
+        segments.remove(segment);
+        dirty = true;
+    }
+
+    @Override
+    public List<PathSegment> getSegments() {
+        return Collections.unmodifiableList(segments);
+    }
+
+    @Override
+    public Map<PropertyPart, InterpolationParameters> bake(Map<PropertyPart, InterpolationParameters> parameters) {
+        if (segments.isEmpty()) throw new IllegalStateException("No segments have been added yet.");
+        Collections.sort(segments, new Comparator<PathSegment>() {
+            @Override
+            public int compare(PathSegment s1, PathSegment s2) {
+                return Long.compare(s1.getStartKeyframe().getTime(), s2.getStartKeyframe().getTime());
+            }
+        });
+
+        // Check for continuity
+        Iterator<PathSegment> iter = segments.iterator();
+        PathSegment last = iter.next();
+        while (iter.hasNext()) {
+            if (last.getEndKeyframe() != (last = iter.next()).getStartKeyframe()) {
+                throw new IllegalStateException("Segments are not continuous.");
+            }
+        }
+
+        return bakeInterpolation(parameters);
+    }
+
+    /**
+     * Bake the interpolation of the current path segments with the specified parameters.
+     * Order of {@link #getSegments()} is guaranteed.
+     * @param parameters Map of parameters for some properties
+     * @return Map of parameters for the next interpolator
+     */
+    protected abstract Map<PropertyPart, InterpolationParameters> bakeInterpolation(Map<PropertyPart, InterpolationParameters> parameters);
+
+    @Override
+    public boolean isDirty() {
+        return dirty;
+    }
+}