266 lines
9.1 KiB
C
266 lines
9.1 KiB
C
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/*
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* Copyright (c) 2014, Matt Stancliff <matt@genges.com>.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are met:
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*
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* * Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* * Neither the name of Redis nor the names of its contributors may be used
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* to endorse or promote products derived from this software without
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* specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
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* LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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#include "geojson.h"
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#define L server.lua
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/* ====================================================================
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* The Encoder
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* ==================================================================== */
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static sds jsonEncode() {
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/* When entering this function, stack is: [1:[geojson table to encode]] */
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lua_getglobal(L, "cjson");
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lua_getfield(L, -1, "encode");
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/* Stack is now: [1:[geojson table], 2:'cjson', 3:'encode'] */
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/* Move current top ('encode') to bottom of stack */
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lua_insert(L, 1);
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/* Move current top ('cjson') to bottom of stack so we can 'cjson.encode' */
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lua_insert(L, 1);
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/* Stack is now: [1:'cjson', 2:'encode', 3:[table of geojson to encode]] */
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/* Call cjson.encode on the element above it on the stack;
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* obtain one return value */
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if (lua_pcall(L, 1, 1, 0) != 0)
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redisLog(REDIS_WARNING, "Could not encode geojson: %s",
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lua_tostring(L, -1));
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sds geojson = sdsnew(lua_tostring(L, -1));
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/* We're done. Remove entire stack. Drop mic. Walk away. */
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lua_pop(L, lua_gettop(L));
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/* Return sds the caller must sdsfree() on their own */
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return geojson;
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}
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/* ====================================================================
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* The Lua Helpers
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* ==================================================================== */
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static inline void luaCreateFieldFromPrevious(const char *field) {
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lua_setfield(L, -2, field);
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}
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static inline void luaCreateFieldStr(const char *field, const char *value) {
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lua_pushstring(L, value);
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luaCreateFieldFromPrevious(field);
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}
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/* Creates [Lat, Long] array attached to "coordinates" key */
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static void luaCreateCoordinates(const double x, const double y) {
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/* Create array table with two elements */
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lua_createtable(L, 2, 0);
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lua_pushnumber(L, x);
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lua_rawseti(L, -2, 1);
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lua_pushnumber(L, y);
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lua_rawseti(L, -2, 2);
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}
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static void luaCreatePropertyNull(void) {
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/* Create empty table and give it a name. This is a json {} value. */
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lua_createtable(L, 0, 0);
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luaCreateFieldFromPrevious("properties");
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}
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static void _luaCreateProperties(const char *k1, const char *v1, const char *k2,
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const char *v2, const int noclose) {
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/* we may add additional properties outside of here, so newtable instead of
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* fixed-size createtable */
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lua_newtable(L);
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luaCreateFieldStr(k1, v1);
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luaCreateFieldStr(k2, v2);
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if (!noclose)
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luaCreateFieldFromPrevious("properties");
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}
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static void luaCreateProperties(const char *k1, const char *v1, const char *k2,
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const char *v2) {
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_luaCreateProperties(k1, v1, k2, v2, 0);
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}
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/* ====================================================================
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* The Lua Aggregation Helpers
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* ==================================================================== */
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static void attachProperties(const char *set, const char *member) {
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if (member)
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luaCreateProperties("set", set, "member", member);
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else
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luaCreatePropertyNull();
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}
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static void attachPropertiesWithDist(const char *set, const char *member,
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double dist, const char *units) {
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if (member) {
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_luaCreateProperties("set", set, "member", member, 1);
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if (units) {
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/* Add units then distance. After encoding it comes
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* out as distance followed by units in the json. */
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lua_pushstring(L, units);
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luaCreateFieldFromPrevious("units");
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lua_pushnumber(L, dist);
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luaCreateFieldFromPrevious("distance");
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}
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/* We requested to leave the properties table open, but now we
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* are done and can close it. */
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luaCreateFieldFromPrevious("properties");
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} else {
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luaCreatePropertyNull();
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}
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}
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static void createGeometryPoint(const double x, const double y) {
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lua_createtable(L, 0, 2);
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/* coordinates = [x, y] */
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luaCreateCoordinates(x, y);
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luaCreateFieldFromPrevious("coordinates");
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/* type = Point */
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luaCreateFieldStr("type", "Point");
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/* geometry = (coordinates = [x, y]) */
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luaCreateFieldFromPrevious("geometry");
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}
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static void createGeometryBox(const double x1, const double y1, const double x2,
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const double y2) {
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lua_createtable(L, 0, 2);
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/* Result = [[[x1,y1],[x2,y1],[x2,y2],[x1,y2], [x1,y1]] */
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/* The end coord is the start coord to make a closed polygon */
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lua_createtable(L, 1, 0);
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lua_createtable(L, 5, 0);
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/* Bottom left */
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luaCreateCoordinates(x1, y1);
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lua_rawseti(L, -2, 1);
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/* Top Left */
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luaCreateCoordinates(x2, y1);
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lua_rawseti(L, -2, 2);
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/* Top Right */
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luaCreateCoordinates(x2, y2);
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lua_rawseti(L, -2, 3);
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/* Bottom Right */
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luaCreateCoordinates(x1, y2);
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lua_rawseti(L, -2, 4);
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/* Bottom Left (Again) */
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luaCreateCoordinates(x1, y1);
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lua_rawseti(L, -2, 5);
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/* Set the outer array of our inner array of the inner coords */
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lua_rawseti(L, -2, 1);
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/* Bundle those together in coordinates: [a, b, c, d] */
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luaCreateFieldFromPrevious("coordinates");
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/* Add type field */
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luaCreateFieldStr("type", "Polygon");
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luaCreateFieldFromPrevious("geometry");
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}
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static void createFeature() {
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/* Features have three fields: type, geometry, and properties */
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lua_createtable(L, 0, 3);
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luaCreateFieldStr("type", "Feature");
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/* You must call attachProperties on your own */
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}
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static void createCollection(size_t size) {
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/* FeatureCollections have two fields: type and features */
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lua_createtable(L, 0, 2);
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luaCreateFieldStr("type", "FeatureCollection");
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}
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static void pointsToCollection(const struct geojsonPoint *pts, const size_t len,
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const char *units) {
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createCollection(len);
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lua_createtable(L, len, 0);
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for (int i = 0; i < len; i++) {
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createFeature();
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createGeometryPoint(pts[i].longitude, pts[i].latitude); /* x, y */
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attachPropertiesWithDist(pts[i].set, pts[i].member, pts[i].dist, units);
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lua_rawseti(L, -2, i + 1); /* Attach this Feature to "features" array */
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}
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luaCreateFieldFromPrevious("features");
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}
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static void latLongToPointFeature(const double latitude,
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const double longitude) {
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createFeature();
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createGeometryPoint(longitude, latitude); /* geojson is: x,y */
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}
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static void squareToPolygonFeature(const double x1, const double y1,
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const double x2, const double y2) {
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createFeature();
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createGeometryBox(x1, y1, x2, y2);
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}
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/* ====================================================================
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* The Interface Functions
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* ==================================================================== */
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sds geojsonFeatureCollection(const struct geojsonPoint *pts, const size_t len,
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const char *units) {
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pointsToCollection(pts, len, units);
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return jsonEncode();
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}
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sds geojsonLatLongToPointFeature(const double latitude, const double longitude,
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const char *set, const char *member,
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const double dist, const char *units) {
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latLongToPointFeature(latitude, longitude);
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attachPropertiesWithDist(set, member, dist, units);
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return jsonEncode();
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}
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sds geojsonBoxToPolygonFeature(const double y1, const double x1,
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const double y2, const double x2,
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const char *set, const char *member) {
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squareToPolygonFeature(x1, y1, x2, y2);
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attachProperties(set, member);
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return jsonEncode();
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}
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