// https://github.com/topojson/topojson-server v3.0.1 Copyright 2019 Mike Bostock
(function (global, factory) {
typeof exports === 'object' && typeof module !== 'undefined' ? factory(exports) :
typeof define === 'function' && define.amd ? define(['exports'], factory) :
(global = global || self, factory(global.topojson = global.topojson || {}));
}(this, function (exports) { 'use strict';

var hasOwnProperty = Object.prototype.hasOwnProperty;

// Computes the bounding box of the specified hash of GeoJSON objects.
function bounds(objects) {
  var x0 = Infinity,
      y0 = Infinity,
      x1 = -Infinity,
      y1 = -Infinity;

  function boundGeometry(geometry) {
    if (geometry != null && hasOwnProperty.call(boundGeometryType, geometry.type)) boundGeometryType[geometry.type](geometry);
  }

  var boundGeometryType = {
    GeometryCollection: function(o) { o.geometries.forEach(boundGeometry); },
    Point: function(o) { boundPoint(o.coordinates); },
    MultiPoint: function(o) { o.coordinates.forEach(boundPoint); },
    LineString: function(o) { boundLine(o.arcs); },
    MultiLineString: function(o) { o.arcs.forEach(boundLine); },
    Polygon: function(o) { o.arcs.forEach(boundLine); },
    MultiPolygon: function(o) { o.arcs.forEach(boundMultiLine); }
  };

  function boundPoint(coordinates) {
    var x = coordinates[0],
        y = coordinates[1];
    if (x < x0) x0 = x;
    if (x > x1) x1 = x;
    if (y < y0) y0 = y;
    if (y > y1) y1 = y;
  }

  function boundLine(coordinates) {
    coordinates.forEach(boundPoint);
  }

  function boundMultiLine(coordinates) {
    coordinates.forEach(boundLine);
  }

  for (var key in objects) {
    boundGeometry(objects[key]);
  }

  return x1 >= x0 && y1 >= y0 ? [x0, y0, x1, y1] : undefined;
}

function hashset(size, hash, equal, type, empty) {
  if (arguments.length === 3) {
    type = Array;
    empty = null;
  }

  var store = new type(size = 1 << Math.max(4, Math.ceil(Math.log(size) / Math.LN2))),
      mask = size - 1;

  for (var i = 0; i < size; ++i) {
    store[i] = empty;
  }

  function add(value) {
    var index = hash(value) & mask,
        match = store[index],
        collisions = 0;
    while (match != empty) {
      if (equal(match, value)) return true;
      if (++collisions >= size) throw new Error("full hashset");
      match = store[index = (index + 1) & mask];
    }
    store[index] = value;
    return true;
  }

  function has(value) {
    var index = hash(value) & mask,
        match = store[index],
        collisions = 0;
    while (match != empty) {
      if (equal(match, value)) return true;
      if (++collisions >= size) break;
      match = store[index = (index + 1) & mask];
    }
    return false;
  }

  function values() {
    var values = [];
    for (var i = 0, n = store.length; i < n; ++i) {
      var match = store[i];
      if (match != empty) values.push(match);
    }
    return values;
  }

  return {
    add: add,
    has: has,
    values: values
  };
}

function hashmap(size, hash, equal, keyType, keyEmpty, valueType) {
  if (arguments.length === 3) {
    keyType = valueType = Array;
    keyEmpty = null;
  }

  var keystore = new keyType(size = 1 << Math.max(4, Math.ceil(Math.log(size) / Math.LN2))),
      valstore = new valueType(size),
      mask = size - 1;

  for (var i = 0; i < size; ++i) {
    keystore[i] = keyEmpty;
  }

  function set(key, value) {
    var index = hash(key) & mask,
        matchKey = keystore[index],
        collisions = 0;
    while (matchKey != keyEmpty) {
      if (equal(matchKey, key)) return valstore[index] = value;
      if (++collisions >= size) throw new Error("full hashmap");
      matchKey = keystore[index = (index + 1) & mask];
    }
    keystore[index] = key;
    valstore[index] = value;
    return value;
  }

  function maybeSet(key, value) {
    var index = hash(key) & mask,
        matchKey = keystore[index],
        collisions = 0;
    while (matchKey != keyEmpty) {
      if (equal(matchKey, key)) return valstore[index];
      if (++collisions >= size) throw new Error("full hashmap");
      matchKey = keystore[index = (index + 1) & mask];
    }
    keystore[index] = key;
    valstore[index] = value;
    return value;
  }

  function get(key, missingValue) {
    var index = hash(key) & mask,
        matchKey = keystore[index],
        collisions = 0;
    while (matchKey != keyEmpty) {
      if (equal(matchKey, key)) return valstore[index];
      if (++collisions >= size) break;
      matchKey = keystore[index = (index + 1) & mask];
    }
    return missingValue;
  }

  function keys() {
    var keys = [];
    for (var i = 0, n = keystore.length; i < n; ++i) {
      var matchKey = keystore[i];
      if (matchKey != keyEmpty) keys.push(matchKey);
    }
    return keys;
  }

  return {
    set: set,
    maybeSet: maybeSet, // set if unset
    get: get,
    keys: keys
  };
}

function equalPoint(pointA, pointB) {
  return pointA[0] === pointB[0] && pointA[1] === pointB[1];
}

// TODO if quantized, use simpler Int32 hashing?

var buffer = new ArrayBuffer(16),
    floats = new Float64Array(buffer),
    uints = new Uint32Array(buffer);

function hashPoint(point) {
  floats[0] = point[0];
  floats[1] = point[1];
  var hash = uints[0] ^ uints[1];
  hash = hash << 5 ^ hash >> 7 ^ uints[2] ^ uints[3];
  return hash & 0x7fffffff;
}

// Given an extracted (pre-)topology, identifies all of the junctions. These are
// the points at which arcs (lines or rings) will need to be cut so that each
// arc is represented uniquely.
//
// A junction is a point where at least one arc deviates from another arc going
// through the same point. For example, consider the point B. If there is a arc
// through ABC and another arc through CBA, then B is not a junction because in
// both cases the adjacent point pairs are {A,C}. However, if there is an
// additional arc ABD, then {A,D} != {A,C}, and thus B becomes a junction.
//
// For a closed ring ABCA, the first point A’s adjacent points are the second
// and last point {B,C}. For a line, the first and last point are always
// considered junctions, even if the line is closed; this ensures that a closed
// line is never rotated.
function join(topology) {
  var coordinates = topology.coordinates,
      lines = topology.lines,
      rings = topology.rings,
      indexes = index(),
      visitedByIndex = new Int32Array(coordinates.length),
      leftByIndex = new Int32Array(coordinates.length),
      rightByIndex = new Int32Array(coordinates.length),
      junctionByIndex = new Int8Array(coordinates.length),
      junctionCount = 0, // upper bound on number of junctions
      i, n,
      previousIndex,
      currentIndex,
      nextIndex;

  for (i = 0, n = coordinates.length; i < n; ++i) {
    visitedByIndex[i] = leftByIndex[i] = rightByIndex[i] = -1;
  }

  for (i = 0, n = lines.length; i < n; ++i) {
    var line = lines[i],
        lineStart = line[0],
        lineEnd = line[1];
    currentIndex = indexes[lineStart];
    nextIndex = indexes[++lineStart];
    ++junctionCount, junctionByIndex[currentIndex] = 1; // start
    while (++lineStart <= lineEnd) {
      sequence(i, previousIndex = currentIndex, currentIndex = nextIndex, nextIndex = indexes[lineStart]);
    }
    ++junctionCount, junctionByIndex[nextIndex] = 1; // end
  }

  for (i = 0, n = coordinates.length; i < n; ++i) {
    visitedByIndex[i] = -1;
  }

  for (i = 0, n = rings.length; i < n; ++i) {
    var ring = rings[i],
        ringStart = ring[0] + 1,
        ringEnd = ring[1];
    previousIndex = indexes[ringEnd - 1];
    currentIndex = indexes[ringStart - 1];
    nextIndex = indexes[ringStart];
    sequence(i, previousIndex, currentIndex, nextIndex);
    while (++ringStart <= ringEnd) {
      sequence(i, previousIndex = currentIndex, currentIndex = nextIndex, nextIndex = indexes[ringStart]);
    }
  }

  function sequence(i, previousIndex, currentIndex, nextIndex) {
    if (visitedByIndex[currentIndex] === i) return; // ignore self-intersection
    visitedByIndex[currentIndex] = i;
    var leftIndex = leftByIndex[currentIndex];
    if (leftIndex >= 0) {
      var rightIndex = rightByIndex[currentIndex];
      if ((leftIndex !== previousIndex || rightIndex !== nextIndex)
        && (leftIndex !== nextIndex || rightIndex !== previousIndex)) {
        ++junctionCount, junctionByIndex[currentIndex] = 1;
      }
    } else {
      leftByIndex[currentIndex] = previousIndex;
      rightByIndex[currentIndex] = nextIndex;
    }
  }

  function index() {
    var indexByPoint = hashmap(coordinates.length * 1.4, hashIndex, equalIndex, Int32Array, -1, Int32Array),
        indexes = new Int32Array(coordinates.length);

    for (var i = 0, n = coordinates.length; i < n; ++i) {
      indexes[i] = indexByPoint.maybeSet(i, i);
    }

    return indexes;
  }

  function hashIndex(i) {
    return hashPoint(coordinates[i]);
  }

  function equalIndex(i, j) {
    return equalPoint(coordinates[i], coordinates[j]);
  }

  visitedByIndex = leftByIndex = rightByIndex = null;

  var junctionByPoint = hashset(junctionCount * 1.4, hashPoint, equalPoint), j;

  // Convert back to a standard hashset by point for caller convenience.
  for (i = 0, n = coordinates.length; i < n; ++i) {
    if (junctionByIndex[j = indexes[i]]) {
      junctionByPoint.add(coordinates[j]);
    }
  }

  return junctionByPoint;
}

// Given an extracted (pre-)topology, cuts (or rotates) arcs so that all shared
// point sequences are identified. The topology can then be subsequently deduped
// to remove exact duplicate arcs.
function cut(topology) {
  var junctions = join(topology),
      coordinates = topology.coordinates,
      lines = topology.lines,
      rings = topology.rings,
      next,
      i, n;

  for (i = 0, n = lines.length; i < n; ++i) {
    var line = lines[i],
        lineMid = line[0],
        lineEnd = line[1];
    while (++lineMid < lineEnd) {
      if (junctions.has(coordinates[lineMid])) {
        next = {0: lineMid, 1: line[1]};
        line[1] = lineMid;
        line = line.next = next;
      }
    }
  }

  for (i = 0, n = rings.length; i < n; ++i) {
    var ring = rings[i],
        ringStart = ring[0],
        ringMid = ringStart,
        ringEnd = ring[1],
        ringFixed = junctions.has(coordinates[ringStart]);
    while (++ringMid < ringEnd) {
      if (junctions.has(coordinates[ringMid])) {
        if (ringFixed) {
          next = {0: ringMid, 1: ring[1]};
          ring[1] = ringMid;
          ring = ring.next = next;
        } else { // For the first junction, we can rotate rather than cut.
          rotateArray(coordinates, ringStart, ringEnd, ringEnd - ringMid);
          coordinates[ringEnd] = coordinates[ringStart];
          ringFixed = true;
          ringMid = ringStart; // restart; we may have skipped junctions
        }
      }
    }
  }

  return topology;
}

function rotateArray(array, start, end, offset) {
  reverse(array, start, end);
  reverse(array, start, start + offset);
  reverse(array, start + offset, end);
}

function reverse(array, start, end) {
  for (var mid = start + ((end-- - start) >> 1), t; start < mid; ++start, --end) {
    t = array[start], array[start] = array[end], array[end] = t;
  }
}

// Given a cut topology, combines duplicate arcs.
function dedup(topology) {
  var coordinates = topology.coordinates,
      lines = topology.lines, line,
      rings = topology.rings, ring,
      arcCount = lines.length + rings.length,
      i, n;

  delete topology.lines;
  delete topology.rings;

  // Count the number of (non-unique) arcs to initialize the hashmap safely.
  for (i = 0, n = lines.length; i < n; ++i) {
    line = lines[i]; while (line = line.next) ++arcCount;
  }
  for (i = 0, n = rings.length; i < n; ++i) {
    ring = rings[i]; while (ring = ring.next) ++arcCount;
  }

  var arcsByEnd = hashmap(arcCount * 2 * 1.4, hashPoint, equalPoint),
      arcs = topology.arcs = [];

  for (i = 0, n = lines.length; i < n; ++i) {
    line = lines[i];
    do {
      dedupLine(line);
    } while (line = line.next);
  }

  for (i = 0, n = rings.length; i < n; ++i) {
    ring = rings[i];
    if (ring.next) { // arc is no longer closed
      do {
        dedupLine(ring);
      } while (ring = ring.next);
    } else {
      dedupRing(ring);
    }
  }

  function dedupLine(arc) {
    var startPoint,
        endPoint,
        startArcs, startArc,
        endArcs, endArc,
        i, n;

    // Does this arc match an existing arc in order?
    if (startArcs = arcsByEnd.get(startPoint = coordinates[arc[0]])) {
      for (i = 0, n = startArcs.length; i < n; ++i) {
        startArc = startArcs[i];
        if (equalLine(startArc, arc)) {
          arc[0] = startArc[0];
          arc[1] = startArc[1];
          return;
        }
      }
    }

    // Does this arc match an existing arc in reverse order?
    if (endArcs = arcsByEnd.get(endPoint = coordinates[arc[1]])) {
      for (i = 0, n = endArcs.length; i < n; ++i) {
        endArc = endArcs[i];
        if (reverseEqualLine(endArc, arc)) {
          arc[1] = endArc[0];
          arc[0] = endArc[1];
          return;
        }
      }
    }

    if (startArcs) startArcs.push(arc); else arcsByEnd.set(startPoint, [arc]);
    if (endArcs) endArcs.push(arc); else arcsByEnd.set(endPoint, [arc]);
    arcs.push(arc);
  }

  function dedupRing(arc) {
    var endPoint,
        endArcs,
        endArc,
        i, n;

    // Does this arc match an existing line in order, or reverse order?
    // Rings are closed, so their start point and end point is the same.
    if (endArcs = arcsByEnd.get(endPoint = coordinates[arc[0]])) {
      for (i = 0, n = endArcs.length; i < n; ++i) {
        endArc = endArcs[i];
        if (equalRing(endArc, arc)) {
          arc[0] = endArc[0];
          arc[1] = endArc[1];
          return;
        }
        if (reverseEqualRing(endArc, arc)) {
          arc[0] = endArc[1];
          arc[1] = endArc[0];
          return;
        }
      }
    }

    // Otherwise, does this arc match an existing ring in order, or reverse order?
    if (endArcs = arcsByEnd.get(endPoint = coordinates[arc[0] + findMinimumOffset(arc)])) {
      for (i = 0, n = endArcs.length; i < n; ++i) {
        endArc = endArcs[i];
        if (equalRing(endArc, arc)) {
          arc[0] = endArc[0];
          arc[1] = endArc[1];
          return;
        }
        if (reverseEqualRing(endArc, arc)) {
          arc[0] = endArc[1];
          arc[1] = endArc[0];
          return;
        }
      }
    }

    if (endArcs) endArcs.push(arc); else arcsByEnd.set(endPoint, [arc]);
    arcs.push(arc);
  }

  function equalLine(arcA, arcB) {
    var ia = arcA[0], ib = arcB[0],
        ja = arcA[1], jb = arcB[1];
    if (ia - ja !== ib - jb) return false;
    for (; ia <= ja; ++ia, ++ib) if (!equalPoint(coordinates[ia], coordinates[ib])) return false;
    return true;
  }

  function reverseEqualLine(arcA, arcB) {
    var ia = arcA[0], ib = arcB[0],
        ja = arcA[1], jb = arcB[1];
    if (ia - ja !== ib - jb) return false;
    for (; ia <= ja; ++ia, --jb) if (!equalPoint(coordinates[ia], coordinates[jb])) return false;
    return true;
  }

  function equalRing(arcA, arcB) {
    var ia = arcA[0], ib = arcB[0],
        ja = arcA[1], jb = arcB[1],
        n = ja - ia;
    if (n !== jb - ib) return false;
    var ka = findMinimumOffset(arcA),
        kb = findMinimumOffset(arcB);
    for (var i = 0; i < n; ++i) {
      if (!equalPoint(coordinates[ia + (i + ka) % n], coordinates[ib + (i + kb) % n])) return false;
    }
    return true;
  }

  function reverseEqualRing(arcA, arcB) {
    var ia = arcA[0], ib = arcB[0],
        ja = arcA[1], jb = arcB[1],
        n = ja - ia;
    if (n !== jb - ib) return false;
    var ka = findMinimumOffset(arcA),
        kb = n - findMinimumOffset(arcB);
    for (var i = 0; i < n; ++i) {
      if (!equalPoint(coordinates[ia + (i + ka) % n], coordinates[jb - (i + kb) % n])) return false;
    }
    return true;
  }

  // Rings are rotated to a consistent, but arbitrary, start point.
  // This is necessary to detect when a ring and a rotated copy are dupes.
  function findMinimumOffset(arc) {
    var start = arc[0],
        end = arc[1],
        mid = start,
        minimum = mid,
        minimumPoint = coordinates[mid];
    while (++mid < end) {
      var point = coordinates[mid];
      if (point[0] < minimumPoint[0] || point[0] === minimumPoint[0] && point[1] < minimumPoint[1]) {
        minimum = mid;
        minimumPoint = point;
      }
    }
    return minimum - start;
  }

  return topology;
}

// Given an array of arcs in absolute (but already quantized!) coordinates,
// converts to fixed-point delta encoding.
// This is a destructive operation that modifies the given arcs!
function delta(arcs) {
  var i = -1,
      n = arcs.length;

  while (++i < n) {
    var arc = arcs[i],
        j = 0,
        k = 1,
        m = arc.length,
        point = arc[0],
        x0 = point[0],
        y0 = point[1],
        x1,
        y1;

    while (++j < m) {
      point = arc[j], x1 = point[0], y1 = point[1];
      if (x1 !== x0 || y1 !== y0) arc[k++] = [x1 - x0, y1 - y0], x0 = x1, y0 = y1;
    }

    if (k === 1) arc[k++] = [0, 0]; // Each arc must be an array of two or more positions.

    arc.length = k;
  }

  return arcs;
}

// Extracts the lines and rings from the specified hash of geometry objects.
//
// Returns an object with three properties:
//
// * coordinates - shared buffer of [x, y] coordinates
// * lines - lines extracted from the hash, of the form [start, end]
// * rings - rings extracted from the hash, of the form [start, end]
//
// For each ring or line, start and end represent inclusive indexes into the
// coordinates buffer. For rings (and closed lines), coordinates[start] equals
// coordinates[end].
//
// For each line or polygon geometry in the input hash, including nested
// geometries as in geometry collections, the `coordinates` array is replaced
// with an equivalent `arcs` array that, for each line (for line string
// geometries) or ring (for polygon geometries), points to one of the above
// lines or rings.
function extract(objects) {
  var index = -1,
      lines = [],
      rings = [],
      coordinates = [];

  function extractGeometry(geometry) {
    if (geometry && hasOwnProperty.call(extractGeometryType, geometry.type)) extractGeometryType[geometry.type](geometry);
  }

  var extractGeometryType = {
    GeometryCollection: function(o) { o.geometries.forEach(extractGeometry); },
    LineString: function(o) { o.arcs = extractLine(o.arcs); },
    MultiLineString: function(o) { o.arcs = o.arcs.map(extractLine); },
    Polygon: function(o) { o.arcs = o.arcs.map(extractRing); },
    MultiPolygon: function(o) { o.arcs = o.arcs.map(extractMultiRing); }
  };

  function extractLine(line) {
    for (var i = 0, n = line.length; i < n; ++i) coordinates[++index] = line[i];
    var arc = {0: index - n + 1, 1: index};
    lines.push(arc);
    return arc;
  }

  function extractRing(ring) {
    for (var i = 0, n = ring.length; i < n; ++i) coordinates[++index] = ring[i];
    var arc = {0: index - n + 1, 1: index};
    rings.push(arc);
    return arc;
  }

  function extractMultiRing(rings) {
    return rings.map(extractRing);
  }

  for (var key in objects) {
    extractGeometry(objects[key]);
  }

  return {
    type: "Topology",
    coordinates: coordinates,
    lines: lines,
    rings: rings,
    objects: objects
  };
}

// Given a hash of GeoJSON objects, returns a hash of GeoJSON geometry objects.
// Any null input geometry objects are represented as {type: null} in the output.
// Any feature.{id,properties,bbox} are transferred to the output geometry object.
// Each output geometry object is a shallow copy of the input (e.g., properties, coordinates)!
function geometry(inputs) {
  var outputs = {}, key;
  for (key in inputs) outputs[key] = geomifyObject(inputs[key]);
  return outputs;
}

function geomifyObject(input) {
  return input == null ? {type: null}
      : (input.type === "FeatureCollection" ? geomifyFeatureCollection
      : input.type === "Feature" ? geomifyFeature
      : geomifyGeometry)(input);
}

function geomifyFeatureCollection(input) {
  var output = {type: "GeometryCollection", geometries: input.features.map(geomifyFeature)};
  if (input.bbox != null) output.bbox = input.bbox;
  return output;
}

function geomifyFeature(input) {
  var output = geomifyGeometry(input.geometry), key; // eslint-disable-line no-unused-vars
  if (input.id != null) output.id = input.id;
  if (input.bbox != null) output.bbox = input.bbox;
  for (key in input.properties) { output.properties = input.properties; break; }
  return output;
}

function geomifyGeometry(input) {
  if (input == null) return {type: null};
  var output = input.type === "GeometryCollection" ? {type: "GeometryCollection", geometries: input.geometries.map(geomifyGeometry)}
      : input.type === "Point" || input.type === "MultiPoint" ? {type: input.type, coordinates: input.coordinates}
      : {type: input.type, arcs: input.coordinates}; // TODO Check for unknown types?
  if (input.bbox != null) output.bbox = input.bbox;
  return output;
}

function prequantize(objects, bbox, n) {
  var x0 = bbox[0],
      y0 = bbox[1],
      x1 = bbox[2],
      y1 = bbox[3],
      kx = x1 - x0 ? (n - 1) / (x1 - x0) : 1,
      ky = y1 - y0 ? (n - 1) / (y1 - y0) : 1;

  function quantizePoint(input) {
    return [Math.round((input[0] - x0) * kx), Math.round((input[1] - y0) * ky)];
  }

  function quantizePoints(input, m) {
    var i = -1,
        j = 0,
        n = input.length,
        output = new Array(n), // pessimistic
        pi,
        px,
        py,
        x,
        y;

    while (++i < n) {
      pi = input[i];
      x = Math.round((pi[0] - x0) * kx);
      y = Math.round((pi[1] - y0) * ky);
      if (x !== px || y !== py) output[j++] = [px = x, py = y]; // non-coincident points
    }

    output.length = j;
    while (j < m) j = output.push([output[0][0], output[0][1]]);
    return output;
  }

  function quantizeLine(input) {
    return quantizePoints(input, 2);
  }

  function quantizeRing(input) {
    return quantizePoints(input, 4);
  }

  function quantizePolygon(input) {
    return input.map(quantizeRing);
  }

  function quantizeGeometry(o) {
    if (o != null && hasOwnProperty.call(quantizeGeometryType, o.type)) quantizeGeometryType[o.type](o);
  }

  var quantizeGeometryType = {
    GeometryCollection: function(o) { o.geometries.forEach(quantizeGeometry); },
    Point: function(o) { o.coordinates = quantizePoint(o.coordinates); },
    MultiPoint: function(o) { o.coordinates = o.coordinates.map(quantizePoint); },
    LineString: function(o) { o.arcs = quantizeLine(o.arcs); },
    MultiLineString: function(o) { o.arcs = o.arcs.map(quantizeLine); },
    Polygon: function(o) { o.arcs = quantizePolygon(o.arcs); },
    MultiPolygon: function(o) { o.arcs = o.arcs.map(quantizePolygon); }
  };

  for (var key in objects) {
    quantizeGeometry(objects[key]);
  }

  return {
    scale: [1 / kx, 1 / ky],
    translate: [x0, y0]
  };
}

// Constructs the TopoJSON Topology for the specified hash of features.
// Each object in the specified hash must be a GeoJSON object,
// meaning FeatureCollection, a Feature or a geometry object.
function topology(objects, quantization) {
  var bbox = bounds(objects = geometry(objects)),
      transform = quantization > 0 && bbox && prequantize(objects, bbox, quantization),
      topology = dedup(cut(extract(objects))),
      coordinates = topology.coordinates,
      indexByArc = hashmap(topology.arcs.length * 1.4, hashArc, equalArc);

  objects = topology.objects; // for garbage collection
  topology.bbox = bbox;
  topology.arcs = topology.arcs.map(function(arc, i) {
    indexByArc.set(arc, i);
    return coordinates.slice(arc[0], arc[1] + 1);
  });

  delete topology.coordinates;
  coordinates = null;

  function indexGeometry(geometry) {
    if (geometry && hasOwnProperty.call(indexGeometryType, geometry.type)) indexGeometryType[geometry.type](geometry);
  }

  var indexGeometryType = {
    GeometryCollection: function(o) { o.geometries.forEach(indexGeometry); },
    LineString: function(o) { o.arcs = indexArcs(o.arcs); },
    MultiLineString: function(o) { o.arcs = o.arcs.map(indexArcs); },
    Polygon: function(o) { o.arcs = o.arcs.map(indexArcs); },
    MultiPolygon: function(o) { o.arcs = o.arcs.map(indexMultiArcs); }
  };

  function indexArcs(arc) {
    var indexes = [];
    do {
      var index = indexByArc.get(arc);
      indexes.push(arc[0] < arc[1] ? index : ~index);
    } while (arc = arc.next);
    return indexes;
  }

  function indexMultiArcs(arcs) {
    return arcs.map(indexArcs);
  }

  for (var key in objects) {
    indexGeometry(objects[key]);
  }

  if (transform) {
    topology.transform = transform;
    topology.arcs = delta(topology.arcs);
  }

  return topology;
}

function hashArc(arc) {
  var i = arc[0], j = arc[1], t;
  if (j < i) t = i, i = j, j = t;
  return i + 31 * j;
}

function equalArc(arcA, arcB) {
  var ia = arcA[0], ja = arcA[1],
      ib = arcB[0], jb = arcB[1], t;
  if (ja < ia) t = ia, ia = ja, ja = t;
  if (jb < ib) t = ib, ib = jb, jb = t;
  return ia === ib && ja === jb;
}

exports.topology = topology;

Object.defineProperty(exports, '__esModule', { value: true });

}));