http://lucene.apache.org/lucene-parent/lucene-spatial-extras: Advanced Spatial Shape Strategies for Apache Lucene (The Apache Software Foundation) 
public class org.apache.lucene.spatial.prefix.tree.S2PrefixTree extends org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: org.apache.lucene.spatial.prefix.tree.S2PrefixTree
  super_class: org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree
{
  protected final org.apache.lucene.spatial.prefix.tree.S2ShapeFactory s2ShapeFactory;
    descriptor: Lorg/apache/lucene/spatial/prefix/tree/S2ShapeFactory;
    flags: (0x0014) ACC_PROTECTED, ACC_FINAL

  protected final int arity;
    descriptor: I
    flags: (0x0014) ACC_PROTECTED, ACC_FINAL

  public void <init>(org.locationtech.spatial4j.context.SpatialContext, int);
    descriptor: (Lorg/locationtech/spatial4j/context/SpatialContext;I)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=3, args_size=3
        start local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
        start local 1 // org.locationtech.spatial4j.context.SpatialContext ctx
        start local 2 // int maxLevels
         0: .line 76
            aload 0 /* this */
            aload 1 /* ctx */
            iload 2 /* maxLevels */
            iconst_1
            invokespecial org.apache.lucene.spatial.prefix.tree.S2PrefixTree.<init>:(Lorg/locationtech/spatial4j/context/SpatialContext;II)V
         1: .line 77
            return
        end local 2 // int maxLevels
        end local 1 // org.locationtech.spatial4j.context.SpatialContext ctx
        end local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    2     0       this  Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;
            0    2     1        ctx  Lorg/locationtech/spatial4j/context/SpatialContext;
            0    2     2  maxLevels  I
    MethodParameters:
           Name  Flags
      ctx        
      maxLevels  

  public void <init>(org.locationtech.spatial4j.context.SpatialContext, int, int);
    descriptor: (Lorg/locationtech/spatial4j/context/SpatialContext;II)V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=4, args_size=4
        start local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
        start local 1 // org.locationtech.spatial4j.context.SpatialContext ctx
        start local 2 // int maxLevels
        start local 3 // int arity
         0: .line 88
            aload 0 /* this */
            aload 1 /* ctx */
            iload 2 /* maxLevels */
            invokespecial org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree.<init>:(Lorg/locationtech/spatial4j/context/SpatialContext;I)V
         1: .line 89
            aload 1 /* ctx */
            invokevirtual org.locationtech.spatial4j.context.SpatialContext.getShapeFactory:()Lorg/locationtech/spatial4j/shape/ShapeFactory;
            instanceof org.apache.lucene.spatial.prefix.tree.S2ShapeFactory
            ifne 3
         2: .line 90
            new java.lang.IllegalArgumentException
            dup
            ldc "Spatial context does not support S2 spatial index."
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
         3: .line 92
      StackMap locals: org.apache.lucene.spatial.prefix.tree.S2PrefixTree org.locationtech.spatial4j.context.SpatialContext int int
      StackMap stack:
            aload 0 /* this */
            aload 1 /* ctx */
            invokevirtual org.locationtech.spatial4j.context.SpatialContext.getShapeFactory:()Lorg/locationtech/spatial4j/shape/ShapeFactory;
            checkcast org.apache.lucene.spatial.prefix.tree.S2ShapeFactory
            putfield org.apache.lucene.spatial.prefix.tree.S2PrefixTree.s2ShapeFactory:Lorg/apache/lucene/spatial/prefix/tree/S2ShapeFactory;
         4: .line 93
            iload 3 /* arity */
            iconst_1
            if_icmplt 5
            iload 3 /* arity */
            iconst_3
            if_icmple 6
         5: .line 94
      StackMap locals:
      StackMap stack:
            new java.lang.IllegalArgumentException
            dup
            new java.lang.StringBuilder
            dup
            ldc "Invalid value for S2 tree arity. Possible values are 1, 2 or 3. Provided value is "
            invokespecial java.lang.StringBuilder.<init>:(Ljava/lang/String;)V
            iload 3 /* arity */
            invokevirtual java.lang.StringBuilder.append:(I)Ljava/lang/StringBuilder;
            ldc "."
            invokevirtual java.lang.StringBuilder.append:(Ljava/lang/String;)Ljava/lang/StringBuilder;
            invokevirtual java.lang.StringBuilder.toString:()Ljava/lang/String;
            invokespecial java.lang.IllegalArgumentException.<init>:(Ljava/lang/String;)V
            athrow
         6: .line 96
      StackMap locals:
      StackMap stack:
            aload 0 /* this */
            iload 3 /* arity */
            putfield org.apache.lucene.spatial.prefix.tree.S2PrefixTree.arity:I
         7: .line 97
            return
        end local 3 // int arity
        end local 2 // int maxLevels
        end local 1 // org.locationtech.spatial4j.context.SpatialContext ctx
        end local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
      LocalVariableTable:
        Start  End  Slot       Name  Signature
            0    8     0       this  Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;
            0    8     1        ctx  Lorg/locationtech/spatial4j/context/SpatialContext;
            0    8     2  maxLevels  I
            0    8     3      arity  I
    MethodParameters:
           Name  Flags
      ctx        
      maxLevels  
      arity      

  public static int getMaxLevels(int);
    descriptor: (I)I
    flags: (0x0009) ACC_PUBLIC, ACC_STATIC
    Code:
      stack=2, locals=1, args_size=1
        start local 0 // int arity
         0: .line 106
            bipush 30
            iload 0 /* arity */
            idiv
            iconst_1
            iadd
            ireturn
        end local 0 // int arity
      LocalVariableTable:
        Start  End  Slot   Name  Signature
            0    1     0  arity  I
    MethodParameters:
       Name  Flags
      arity  

  public int getLevelForDistance(double);
    descriptor: (D)I
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=5, locals=5, args_size=2
        start local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
        start local 1 // double dist
         0: .line 111
            dload 1 /* dist */
            dconst_0
            dcmpl
            ifne 2
         1: .line 112
            aload 0 /* this */
            getfield org.apache.lucene.spatial.prefix.tree.S2PrefixTree.maxLevels:I
            ireturn
         2: .line 114
      StackMap locals:
      StackMap stack:
            getstatic com.google.common.geometry.S2Projections.MAX_WIDTH:Lcom/google/common/geometry/S2$Metric;
            dload 1 /* dist */
            ldc 0.017453292519943295
            dmul
            invokevirtual com.google.common.geometry.S2$Metric.getMinLevel:(D)I
            istore 3 /* level */
        start local 3 // int level
         3: .line 115
            iload 3 /* level */
            aload 0 /* this */
            getfield org.apache.lucene.spatial.prefix.tree.S2PrefixTree.arity:I
            irem
            ifeq 4
            iconst_1
            goto 5
      StackMap locals: int
      StackMap stack:
         4: iconst_0
      StackMap locals:
      StackMap stack: int
         5: istore 4 /* roundLevel */
        start local 4 // int roundLevel
         6: .line 116
            iload 3 /* level */
            aload 0 /* this */
            getfield org.apache.lucene.spatial.prefix.tree.S2PrefixTree.arity:I
            idiv
            iload 4 /* roundLevel */
            iadd
            istore 3 /* level */
         7: .line 117
            aload 0 /* this */
            getfield org.apache.lucene.spatial.prefix.tree.S2PrefixTree.maxLevels:I
            iload 3 /* level */
            iconst_1
            iadd
            invokestatic java.lang.Math.min:(II)I
            ireturn
        end local 4 // int roundLevel
        end local 3 // int level
        end local 1 // double dist
        end local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0    8     0        this  Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;
            0    8     1        dist  D
            3    8     3       level  I
            6    8     4  roundLevel  I
    MethodParameters:
      Name  Flags
      dist  

  public double getDistanceForLevel(int);
    descriptor: (I)D
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=2, args_size=2
        start local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
        start local 1 // int level
         0: .line 122
            iload 1 /* level */
            ifne 2
         1: .line 123
            ldc 180.0
            dreturn
         2: .line 125
      StackMap locals:
      StackMap stack:
            getstatic com.google.common.geometry.S2Projections.MAX_WIDTH:Lcom/google/common/geometry/S2$Metric;
            aload 0 /* this */
            getfield org.apache.lucene.spatial.prefix.tree.S2PrefixTree.arity:I
            iload 1 /* level */
            iconst_1
            isub
            imul
            invokevirtual com.google.common.geometry.S2$Metric.getValue:(I)D
            ldc 57.29577951308232
            dmul
            dreturn
        end local 1 // int level
        end local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
      LocalVariableTable:
        Start  End  Slot   Name  Signature
            0    3     0   this  Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;
            0    3     1  level  I
    MethodParameters:
       Name  Flags
      level  

  public org.apache.lucene.spatial.prefix.tree.Cell getWorldCell();
    descriptor: ()Lorg/apache/lucene/spatial/prefix/tree/Cell;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=4, locals=1, args_size=1
        start local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
         0: .line 130
            new org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell
            dup
            aload 0 /* this */
            aconst_null
            invokespecial org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell.<init>:(Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;Lcom/google/common/geometry/S2CellId;)V
            areturn
        end local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;

  public org.apache.lucene.spatial.prefix.tree.Cell readCell(org.apache.lucene.util.BytesRef, org.apache.lucene.spatial.prefix.tree.Cell);
    descriptor: (Lorg/apache/lucene/util/BytesRef;Lorg/apache/lucene/spatial/prefix/tree/Cell;)Lorg/apache/lucene/spatial/prefix/tree/Cell;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=3, locals=4, args_size=3
        start local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
        start local 1 // org.apache.lucene.util.BytesRef term
        start local 2 // org.apache.lucene.spatial.prefix.tree.Cell scratch
         0: .line 135
            aload 2 /* scratch */
            checkcast org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell
            astore 3 /* cell */
        start local 3 // org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell cell
         1: .line 136
            aload 3 /* cell */
            ifnonnull 3
         2: .line 137
            aload 0 /* this */
            invokevirtual org.apache.lucene.spatial.prefix.tree.S2PrefixTree.getWorldCell:()Lorg/apache/lucene/spatial/prefix/tree/Cell;
            checkcast org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell
            astore 3 /* cell */
         3: .line 139
      StackMap locals: org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell
      StackMap stack:
            aload 3 /* cell */
            aload 0 /* this */
            aload 1 /* term */
            invokevirtual org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell.readCell:(Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;Lorg/apache/lucene/util/BytesRef;)V
         4: .line 140
            aload 3 /* cell */
            areturn
        end local 3 // org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell cell
        end local 2 // org.apache.lucene.spatial.prefix.tree.Cell scratch
        end local 1 // org.apache.lucene.util.BytesRef term
        end local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
      LocalVariableTable:
        Start  End  Slot     Name  Signature
            0    5     0     this  Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;
            0    5     1     term  Lorg/apache/lucene/util/BytesRef;
            0    5     2  scratch  Lorg/apache/lucene/spatial/prefix/tree/Cell;
            1    5     3     cell  Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTreeCell;
    MethodParameters:
         Name  Flags
      term     
      scratch  

  public org.apache.lucene.spatial.prefix.tree.CellIterator getTreeCellIterator(org.locationtech.spatial4j.shape.Shape, int);
    descriptor: (Lorg/locationtech/spatial4j/shape/Shape;I)Lorg/apache/lucene/spatial/prefix/tree/CellIterator;
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=7, locals=7, args_size=3
        start local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
        start local 1 // org.locationtech.spatial4j.shape.Shape shape
        start local 2 // int detailLevel
         0: .line 145
            aload 1 /* shape */
            instanceof org.locationtech.spatial4j.shape.Point
            ifne 2
         1: .line 146
            aload 0 /* this */
            aload 1 /* shape */
            iload 2 /* detailLevel */
            invokespecial org.apache.lucene.spatial.prefix.tree.SpatialPrefixTree.getTreeCellIterator:(Lorg/locationtech/spatial4j/shape/Shape;I)Lorg/apache/lucene/spatial/prefix/tree/CellIterator;
            areturn
         2: .line 148
      StackMap locals:
      StackMap stack:
            aload 1 /* shape */
            checkcast org.locationtech.spatial4j.shape.Point
            astore 3 /* p */
        start local 3 // org.locationtech.spatial4j.shape.Point p
         3: .line 149
            aload 3 /* p */
            invokeinterface org.locationtech.spatial4j.shape.Point.getY:()D
            aload 3 /* p */
            invokeinterface org.locationtech.spatial4j.shape.Point.getX:()D
            invokestatic com.google.common.geometry.S2LatLng.fromDegrees:(DD)Lcom/google/common/geometry/S2LatLng;
            invokestatic com.google.common.geometry.S2CellId.fromLatLng:(Lcom/google/common/geometry/S2LatLng;)Lcom/google/common/geometry/S2CellId;
            aload 0 /* this */
            getfield org.apache.lucene.spatial.prefix.tree.S2PrefixTree.arity:I
            iload 2 /* detailLevel */
            iconst_1
            isub
            imul
            invokevirtual com.google.common.geometry.S2CellId.parent:(I)Lcom/google/common/geometry/S2CellId;
            astore 4 /* id */
        start local 4 // com.google.common.geometry.S2CellId id
         4: .line 150
            new java.util.ArrayList
            dup
            iload 2 /* detailLevel */
            invokespecial java.util.ArrayList.<init>:(I)V
            astore 5 /* cells */
        start local 5 // java.util.List cells
         5: .line 151
            iconst_0
            istore 6 /* i */
        start local 6 // int i
         6: goto 9
         7: .line 152
      StackMap locals: org.apache.lucene.spatial.prefix.tree.S2PrefixTree org.locationtech.spatial4j.shape.Shape int org.locationtech.spatial4j.shape.Point com.google.common.geometry.S2CellId java.util.List int
      StackMap stack:
            aload 5 /* cells */
            new org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell
            dup
            aload 0 /* this */
            aload 4 /* id */
            iload 6 /* i */
            aload 0 /* this */
            getfield org.apache.lucene.spatial.prefix.tree.S2PrefixTree.arity:I
            imul
            invokevirtual com.google.common.geometry.S2CellId.parent:(I)Lcom/google/common/geometry/S2CellId;
            invokespecial org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell.<init>:(Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;Lcom/google/common/geometry/S2CellId;)V
            invokeinterface java.util.List.add:(Ljava/lang/Object;)Z
            pop
         8: .line 151
            iinc 6 /* i */ 1
      StackMap locals:
      StackMap stack:
         9: iload 6 /* i */
            iload 2 /* detailLevel */
            iconst_1
            isub
            if_icmplt 7
        end local 6 // int i
        10: .line 154
            aload 5 /* cells */
            new org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell
            dup
            aload 0 /* this */
            aload 4 /* id */
            invokespecial org.apache.lucene.spatial.prefix.tree.S2PrefixTreeCell.<init>:(Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;Lcom/google/common/geometry/S2CellId;)V
            invokeinterface java.util.List.add:(Ljava/lang/Object;)Z
            pop
        11: .line 155
            new org.apache.lucene.spatial.prefix.tree.FilterCellIterator
            dup
            aload 5 /* cells */
            invokeinterface java.util.List.iterator:()Ljava/util/Iterator;
            aconst_null
            invokespecial org.apache.lucene.spatial.prefix.tree.FilterCellIterator.<init>:(Ljava/util/Iterator;Lorg/locationtech/spatial4j/shape/Shape;)V
            areturn
        end local 5 // java.util.List cells
        end local 4 // com.google.common.geometry.S2CellId id
        end local 3 // org.locationtech.spatial4j.shape.Point p
        end local 2 // int detailLevel
        end local 1 // org.locationtech.spatial4j.shape.Shape shape
        end local 0 // org.apache.lucene.spatial.prefix.tree.S2PrefixTree this
      LocalVariableTable:
        Start  End  Slot         Name  Signature
            0   12     0         this  Lorg/apache/lucene/spatial/prefix/tree/S2PrefixTree;
            0   12     1        shape  Lorg/locationtech/spatial4j/shape/Shape;
            0   12     2  detailLevel  I
            3   12     3            p  Lorg/locationtech/spatial4j/shape/Point;
            4   12     4           id  Lcom/google/common/geometry/S2CellId;
            5   12     5        cells  Ljava/util/List<Lorg/apache/lucene/spatial/prefix/tree/Cell;>;
            6   10     6            i  I
    MethodParameters:
             Name  Flags
      shape        
      detailLevel  
}
SourceFile: "S2PrefixTree.java"
NestMembers:
  org.apache.lucene.spatial.prefix.tree.S2PrefixTree$Factory
InnerClasses:
  public Metric = com.google.common.geometry.S2$Metric of com.google.common.geometry.S2
  protected Factory = org.apache.lucene.spatial.prefix.tree.S2PrefixTree$Factory of org.apache.lucene.spatial.prefix.tree.S2PrefixTree