add a minimal GeoJSON parser

src/utils/geojson.cc

@@ -0,0 +1,126 @@
+/**
+ * This file is part of the "clip" project
+ *   Copyright (c) 2020 Paul Asmuth
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ *
+ * 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.
+ */
+#include "geojson.h"
+#include <iostream>
+#include <fstream>
+
+namespace clip {
+
+ReturnCode geojson_read_object(std::istream* input);
+ReturnCode geojson_read_objects(std::istream* input);
+
+ReturnCode geojson_read_object_data(
+    std::istream* input) {
+  std::string obj_type;
+
+  for (TokenType token = JSON_OBJECT_BEGIN; token != JSON_OBJECT_END; ) {
+    std::string token_data;
+    if (auto rc = json_parse(input, &token, &token_data); !rc) {
+      return rc;
+    }
+
+    switch (token) {
+      case JSON_STRING:
+        break;
+      case JSON_OBJECT_END:
+        continue;
+      default:
+        return {ERROR, "invalid GeoJSON"};
+    }
+
+    if (token_data == "type") {
+      if (auto rc = json_read_string(input, &obj_type); !rc) {
+        return rc;
+      }
+
+      continue;
+    }
+
+    if (token_data == "features") {
+      if (auto rc = geojson_read_objects(input); !rc) {
+        return rc;
+      }
+
+      continue;
+    }
+
+    if (token_data == "geometry") {
+      if (auto rc = geojson_read_object(input); !rc) {
+        return rc;
+      }
+
+      continue;
+    }
+
+    json_skip(input);
+  }
+
+  std::cerr << "read obj: " << obj_type << std::endl;
+  return OK;
+}
+
+ReturnCode geojson_read_objects(
+    std::istream* input) {
+  if (auto rc = json_read_array_begin(input); !rc) {
+    return rc;
+  }
+
+  for (TokenType token = JSON_ARRAY_BEGIN; token != JSON_ARRAY_END; ) {
+    std::string token_data;
+    if (auto rc = json_parse(input, &token, &token_data); !rc) {
+      return rc;
+    }
+
+    switch (token) {
+      case JSON_OBJECT_BEGIN:
+        if (auto rc = geojson_read_object_data(input); !rc) {
+          return rc;
+        }
+
+        continue;
+      case JSON_ARRAY_END:
+        continue;
+      default:
+        return {ERROR, "invalid GeoJSON"};
+    }
+  }
+
+  return OK;
+}
+
+ReturnCode geojson_read_object(
+    std::istream* input) {
+  if (auto rc = json_read_object_begin(input); !rc) {
+    return rc;
+  }
+
+  if (auto rc = geojson_read_object_data(input); !rc) {
+    return rc;
+  }
+
+  return OK;
+}
+
+ReturnCode geojson_parse_file(
+    const std::string& path) {
+  std::ifstream input(path, std::ios::binary);
+  if (!input) {
+    return errorf(ERROR, "unable to open file '{}': {}", path, std::strerror(errno));
+  }
+
+  return geojson_read_object(&input);
+}
+
+} // namespace clip
+

src/utils/geojson.h

@@ -0,0 +1,28 @@
+/**
+ * This file is part of the "clip" project
+ *   Copyright (c) 2020 Paul Asmuth
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ *
+ * 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.
+ */
+#pragma once
+#include <string>
+#include <vector>
+#include "return_code.h"
+#include "utils/json.h"
+
+namespace clip {
+
+// Parse a RFC7946 compliant GEOJSON file
+// https://tools.ietf.org/html/rfc4180
+ReturnCode geojson_parse_file(
+    const std::string& path);
+
+} // namespace clip
+