sort Linestring GeoJSON by tst

closes #52

LICENSE

@@ -251,3 +251,34 @@ OpenLDAP is a registered trademark of the OpenLDAP Foundation.
 Copyright 1999-2003 The OpenLDAP Foundation, Redwood City,
 California, USA.  All Rights Reserved.  Permission to copy and
 distribute verbatim copies of this document is granted.
+
+---------------------------------------------------------------------------
+
+## listsort
+http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.c
+
+/*
+ * This file is copyright 2001 Simon Tatham.
+ * 
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ * 
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL SIMON TATHAM BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+ * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+

Makefile

@@ -12,7 +12,8 @@ OTR_OBJS = json.o \
 	   base64.o \
 	   misc.o \
 	   util.o \
-	   storage.o
+	   storage.o \
+	   listsort.o
 
 CFLAGS += -DGHASHPREC=$(GHASHPREC)
 
@@ -78,8 +79,9 @@ http.o: http.c mongoose.h util.h http.h storage.h
 util.o: util.c util.h
 mongoose.o: mongoose.c mongoose.h
 ocat.o: ocat.c storage.h util.h version.h
-storage.o: storage.c storage.h util.h gcache.h
+storage.o: storage.c storage.h util.h gcache.h listsort.h
 hooks.o: hooks.c udata.h hooks.h util.h version.h gcache.h
+listsort.o: listsort.c listsort.h
 
 
 clean:

listsort.c

@@ -0,0 +1,226 @@
+#include <stdlib.h>
+#include <stdio.h>
+#include "listsort.h"
+
+/* from http://www.chiark.greenend.org.uk/~sgtatham/algorithms/listsort.c */
+
+/*
+ * This file is copyright 2001 Simon Tatham.
+ * 
+ * Permission is hereby granted, free of charge, to any person
+ * obtaining a copy of this software and associated documentation
+ * files (the "Software"), to deal in the Software without
+ * restriction, including without limitation the rights to use,
+ * copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following
+ * conditions:
+ * 
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ * 
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
+ * OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT.  IN NO EVENT SHALL SIMON TATHAM BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF
+ * CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ */
+
+static double cmp(JsonNode * a, JsonNode * b)
+{
+	JsonNode *ta = json_find_member(a, "tst");
+	JsonNode *tb = json_find_member(b, "tst");
+	//printf("a=%lf, b=%lf\n", ta->number_, tb->number_);
+
+	return ta->number_ - tb->number_;
+}
+
+/*
+ * This is the actual sort function. Notice that it returns the new head of
+ * the list. (It has to, because the head will not generally be the same
+ * element after the sort.) So unlike sorting an array, where you can do
+ * 
+ * sort(myarray);
+ * 
+ * you now have to do
+ * 
+ * list = listsort(mylist);
+ */
+JsonNode *listsort(JsonNode * list, int is_circular, int is_double)
+{
+	JsonNode *p, *q, *e, *tail, *oldhead;
+	int insize, nmerges, psize, qsize, i;
+
+	/*
+	 * Silly special case: if `list' was passed in as NULL, return NULL
+	 * immediately.
+	 */
+	if (!list)
+		return NULL;
+
+	insize = 1;
+
+	while (1) {
+		p = list;
+		oldhead = list;	/* only used for circular linkage */
+		list = NULL;
+		tail = NULL;
+
+		nmerges = 0;	/* count number of merges we do in this pass */
+
+		while (p) {
+			nmerges++;	/* there exists a merge to be done */
+			/* step `insize' places along from p */
+			q = p;
+			psize = 0;
+			for (i = 0; i < insize; i++) {
+				psize++;
+				if (is_circular)
+					q = (q->next == oldhead ? NULL : q->next);
+				else
+					q = q->next;
+				if (!q)
+					break;
+			}
+
+			/*
+			 * if q hasn't fallen off end, we have two lists to
+			 * merge
+			 */
+			qsize = insize;
+
+			/* now we have two lists; merge them */
+			while (psize > 0 || (qsize > 0 && q)) {
+
+				/*
+				 * decide whether next element of merge comes
+				 * from p or q
+				 */
+				if (psize == 0) {
+					/* p is empty; e must come from q. */
+					e = q;
+					q = q->next;
+					qsize--;
+					if (is_circular && q == oldhead)
+						q = NULL;
+				} else if (qsize == 0 || !q) {
+					/* q is empty; e must come from p. */
+					e = p;
+					p = p->next;
+					psize--;
+					if (is_circular && p == oldhead)
+						p = NULL;
+				} else if (cmp(p, q) <= 0) {
+					/*
+					 * First element of p is lower (or
+					 * same); e must come from p.
+					 */
+					e = p;
+					p = p->next;
+					psize--;
+					if (is_circular && p == oldhead)
+						p = NULL;
+				} else {
+					/*
+					 * First element of q is lower; e
+					 * must come from q.
+					 */
+					e = q;
+					q = q->next;
+					qsize--;
+					if (is_circular && q == oldhead)
+						q = NULL;
+				}
+
+				/* add the next element to the merged list */
+				if (tail) {
+					tail->next = e;
+				} else {
+					list = e;
+				}
+				if (is_double) {
+					/*
+					 * Maintain reverse pointers in a
+					 * doubly linked list.
+					 */
+					e->prev = tail;
+				}
+				tail = e;
+			}
+
+			/*
+			 * now p has stepped `insize' places along, and q has
+			 * too
+			 */
+			p = q;
+		}
+		if (is_circular) {
+			tail->next = list;
+			if (is_double)
+				list->prev = tail;
+		} else
+			tail->next = NULL;
+
+		/* If we have done only one merge, we're finished. */
+		if (nmerges <= 1)	/* allow for nmerges==0, the empty
+					 * list case */
+			return list;
+
+		/* Otherwise repeat, merging lists twice the size */
+		insize *= 2;
+	}
+}
+
+#ifdef TESTING
+int main()
+{
+	JsonNode *n, *sorted, *arr = json_mkarray();
+	JsonNode *o;
+
+	o = json_mkobject();
+	json_append_member(o, "tst", json_mknumber(2));
+	json_append_member(o, "desc", json_mkstring("dos"));
+	json_append_element(arr, o);
+
+	o = json_mkobject();
+	json_append_member(o, "tst", json_mknumber(69));
+	json_append_member(o, "desc", json_mkstring("sixtynine"));
+	json_append_element(arr, o);
+
+	o = json_mkobject();
+	json_append_member(o, "tst", json_mknumber(14));
+	json_append_member(o, "desc", json_mkstring("fourteen"));
+	json_append_element(arr, o);
+
+	o = json_mkobject();
+	json_append_member(o, "tst", json_mknumber(7));
+	json_append_member(o, "desc", json_mkstring("seven"));
+	json_append_element(arr, o);
+
+
+	json_foreach(n, arr) {
+		JsonNode *e = json_find_member(n, "tst");
+		JsonNode *d = json_find_member(n, "desc");
+		printf("%lf - %s\n", e->number_, d->string_);
+	}
+
+
+	listsort(NULL, 0, 0);
+	sorted = listsort(json_first_child(arr), 0, 0);
+	sorted = sorted->parent;
+	printf("------- %s\n", (sorted == arr) ? "SAME" : "different");
+
+	json_foreach(n, sorted) {
+		JsonNode *e = json_find_member(n, "tst");
+		JsonNode *d = json_find_member(n, "desc");
+		printf("%lf - %s\n", e->number_, d->string_);
+	}
+
+	json_delete(arr);
+
+	return 0;
+}
+#endif

listsort.h

@@ -0,0 +1,8 @@
+#ifndef _LISTSORT_INCL_
+# define _LISTSORT_INCL_
+
+#include "json.h"
+
+JsonNode *listsort(JsonNode *list, int is_circular, int is_double);
+
+#endif

storage.c

@@ -37,6 +37,7 @@
 #include "geohash.h"
 #include "util.h"
 #include "udata.h"
+#include "listsort.h"
 
 char STORAGEDIR[BUFSIZ] = STORAGEDEFAULT;
 
@@ -852,12 +853,19 @@ JsonNode *geo_json(JsonNode *location_array)
  */
 JsonNode *geo_linestring(JsonNode *location_array)
 {
-	JsonNode *top = json_mkobject();
+	JsonNode *top = json_mkobject(), *sorted;
 
 	json_append_member(top, "type", json_mkstring("Feature"));
 
 	JsonNode *c, *coords = json_mkarray();
-	json_foreach(c, location_array) {
+
+	sorted = listsort(json_first_child(location_array), 0, 0);
+	if (sorted && sorted->parent)
+		sorted = sorted->parent;
+	else
+		sorted = location_array;
+
+	json_foreach(c, sorted) {
 		JsonNode *lat, *lon;
 
 		if (((lat = json_find_member(c, "lat")) != NULL) &&