uber · dfellis · Jul 16, 2021 · Jun 18, 2021 · Jun 18, 2021 · Jul 8, 2021
diff --git a/CMakeLists.txt b/CMakeLists.txt
@@ -156,6 +156,7 @@ set(EXAMPLE_SOURCE_FILES
     examples/compactCells.c
     examples/edge.c)
 set(OTHER_SOURCE_FILES
+    src/apps/filters/h3.c
     src/apps/filters/cellToLatLng.c
     src/apps/filters/h3ToLocalIj.c
     src/apps/filters/localIjToH3.c
@@ -380,6 +381,8 @@ if(BUILD_FILTERS)
         list(APPEND INSTALL_TARGETS ${name})
     endmacro()
 
+    add_h3_filter(h3_bin src/apps/filters/h3.c ${APP_SOURCE_FILES})
+    set_target_properties(h3_bin PROPERTIES OUTPUT_NAME h3) # Special logic for the `h3` executable
     add_h3_filter(latLngToCell src/apps/filters/latLngToCell.c ${APP_SOURCE_FILES})
     add_h3_filter(h3ToComponents src/apps/filters/h3ToComponents.c ${APP_SOURCE_FILES})
     add_h3_filter(cellToLatLng src/apps/filters/cellToLatLng.c ${APP_SOURCE_FILES})

diff --git a/src/apps/applib/include/args.h b/src/apps/applib/include/args.h
@@ -100,6 +100,14 @@ int _parseArgsList(int argc, char *argv[], int numArgs, Arg *args[],
         .value = &varName,                 \
         .helpText =                        \
             "Index, or not specified to read indexes from standard input."}
+#define DEFINE_CELL_ARG(varName, argName)     \
+    H3Index varName = 0;                      \
+    Arg argName = {.names = {"-c", "--cell"}, \
+                   .required = true,          \
+                   .scanFormat = "%" PRIx64,  \
+                   .valueName = "index",      \
+                   .value = &varName,         \
+                   .helpText = "H3 Cell"}
 #define ARG_KML \
     { .names = {"-k", "--kml"}, .helpText = "Print output in KML format." }
 #define DEFINE_KML_NAME_ARG(varName, argName)      \

diff --git a/src/apps/applib/lib/args.c b/src/apps/applib/lib/args.c
@@ -24,6 +24,16 @@
 #include <stdlib.h>
 #include <string.h>
 
+#ifdef _WIN32
+
+#define strcasecmp _stricmp
+
+#else
+
+#include <strings.h>
+
+#endif
+
 #include "h3api.h"
 
 /*
@@ -113,7 +123,7 @@ int _parseArgsList(int argc, char *argv[], int numArgs, Arg *args[],
             for (int k = 0; k < NUM_ARG_NAMES; k++) {
                 if (args[j]->names[k] == NULL) continue;
 
-                if (strcmp(argv[i], args[j]->names[k]) == 0) {
+                if (strcasecmp(argv[i], args[j]->names[k]) == 0) {
                     argName = args[j]->names[k];
                     break;
                 }

diff --git a/src/apps/filters/h3.c b/src/apps/filters/h3.c
@@ -0,0 +1,148 @@
+/*
+ * Copyright 2021 Uber Technologies, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *         http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+/** @file
+ * @brief cli app that exposes most of the H3 C library for scripting
+ *
+ *  See `h3 --help` for usage.
+ */
+
+#include <string.h>
+
+#ifdef _WIN32
+
+#define strcasecmp _stricmp
+
+#else
+
+#include <strings.h>
+
+#endif
+
+#include "args.h"
+#include "h3Index.h"
+#include "utility.h"
+
+bool has(char *subcommand, int level, char *argv[]) {
+    return strcasecmp(subcommand, argv[level]) == 0;
+}
+
+bool cellToLatLngCmd(int argc, char *argv[]) {
+    Arg cellToLatLngArg = {
+        .names = {"cellToLatLng"},
+        .required = true,
+        .helpText = "Convert an H3 cell to a latitude/longitude coordinate",
+    };
+    Arg helpArg = ARG_HELP;
+    DEFINE_CELL_ARG(cell, cellArg);
+    Arg *args[] = {&cellToLatLngArg, &helpArg, &cellArg};
+    if (parseArgs(argc, argv, 3, args, &helpArg,
+                  "Convert an H3 cell to a latitude/longitude coordinate")) {
+        return helpArg.found;
+    }
+    LatLng ll;
+    H3_EXPORT(cellToLatLng)(cell, &ll);
+    printf("%.10lf, %.10lf\n", H3_EXPORT(radsToDegs)(ll.lat),
+           H3_EXPORT(radsToDegs)(ll.lng));
+    return true;
+}
+
+bool latLngToCellCmd(int argc, char *argv[]) {
+    int res = 0;
+    double lat = 0;
+    double lng = 0;
+
+    Arg latLngToCellArg = {
+        .names = {"latLngToCell"},
+        .required = true,
+        .helpText =
+            "Convert degrees latitude/longitude coordinate to an H3 cell.",
+    };
+    Arg helpArg = ARG_HELP;
+    Arg resArg = {.names = {"-r", "--resolution"},
+                  .required = true,
+                  .scanFormat = "%d",
+                  .valueName = "res",
+                  .value = &res,
+                  .helpText = "Resolution, 0-15 inclusive."};
+    Arg latArg = {.names = {"--lat", "--latitude"},
+                  .required = true,
+                  .scanFormat = "%lf",
+                  .valueName = "lat",
+                  .value = &lat,
+                  .helpText = "Latitude in degrees."};
+    Arg lngArg = {.names = {"--lng", "--longitude"},
+                  .required = true,
+                  .scanFormat = "%lf",
+                  .valueName = "lng",
+                  .value = &lng,
+                  .helpText = "Longitude in degrees."};
+
+    Arg *args[] = {&latLngToCellArg, &helpArg, &resArg, &latArg, &lngArg};
+    if (parseArgs(
+            argc, argv, 5, args, &helpArg,
+            "Convert degrees latitude/longitude coordinate to an H3 cell.")) {
+        return helpArg.found;
+    }
+    LatLng ll = {.lat = H3_EXPORT(degsToRads)(lat),
+                 .lng = H3_EXPORT(degsToRads)(lng)};
+
+    H3Index c;
+    H3Error e = H3_EXPORT(latLngToCell)(&ll, res, &c);
+
+    if (e == E_SUCCESS) {
+        h3Println(c);
+    } else {
+        h3Println(H3_NULL);
+    }
+    return true;
+}
+
+bool generalHelp(int argc, char *argv[]) {
+    Arg helpArg = ARG_HELP;
+    Arg cellToLatLngArg = {
+        .names = {"cellToLatLng"},
+        .helpText = "Convert an H3 cell to a latitude/longitude coordinate",
+    };
+    Arg latLngToCellArg = {
+        .names = {"latLngToCell"},
+        .helpText =
+            "Convert degrees latitude/longitude coordinate to an H3 cell.",
+    };
+    Arg *args[] = {&helpArg, &cellToLatLngArg, &latLngToCellArg};
+    const char *helpText =
+        "Please use one of the subcommands listed to perform an H3 "
+        "calculation. Use h3 <SUBCOMMAND> --help for details on the usage of "
+        "any subcommand.";
+    return parseArgs(argc, argv, 3, args, &helpArg, helpText);
+}
+
+int main(int argc, char *argv[]) {
+    if (argc <= 1) {
+        printf("Please use h3 --help to see how to use this command.\n");
+        return 1;
+    }
+    if (has("cellToLatLng", 1, argv) && cellToLatLngCmd(argc, argv)) {
+        return 0;
+    }
+    if (has("latLngToCell", 1, argv) && latLngToCellCmd(argc, argv)) {
+        return 0;
+    }
+    if (generalHelp(argc, argv)) {
+        return 0;
+    }
+    printf("Please use h3 --help to see how to use this command.\n");
+    return 1;
+}