u/json: Add a lot more helper functions

src/xrt/auxiliary/util/u_json.c

@@ -9,41 +9,214 @@
  */
 
 #include "u_json.h"
+#include <assert.h>
 
+// This includes the c file completely.
 #include "cjson/cJSON.c"
 
+
+/*!
+ * Less typing.
+ */
+static inline const cJSON *
+get(const cJSON *json, const char *f)
+{
+	return cJSON_GetObjectItemCaseSensitive(json, f);
+}
+
+bool
+u_json_get_string_into_array(const cJSON *json, char *out_str, size_t max_size)
+{
+	assert(out_str != NULL);
+
+	if (!json) {
+		return false;
+	}
+	if (!cJSON_IsString(json)) {
+		return false;
+	}
+
+	int ret = snprintf(out_str, max_size, "%s", json->valuestring);
+	if (ret < 0) {
+		return false;
+	} else if ((size_t)ret < max_size) {
+		return true;
+	} else {
+		return false;
+	}
+}
+
+bool
+u_json_get_int(const cJSON *json, int *out_int)
+{
+	assert(out_int != NULL);
+
+	if (!json) {
+		return false;
+	}
+	if (!cJSON_IsNumber(json)) {
+		return false;
+	}
+
+	*out_int = json->valueint;
+
+	return true;
+}
+
+bool
+u_json_get_double(const cJSON *json, double *out_double)
+{
+	assert(out_double != NULL);
+
+	if (!json) {
+		return false;
+	}
+	if (!cJSON_IsNumber(json)) {
+		return false;
+	}
+	*out_double = json->valuedouble;
+	return true;
+}
+
+bool
+u_json_get_float(const cJSON *json, float *out_float)
+{
+	assert(out_float != NULL);
+
+	double d = 0;
+	if (!u_json_get_double(json, &d)) {
+		return false;
+	}
+
+	*out_float = (float)d;
+	return true;
+}
+
+bool
+u_json_get_vec3(const cJSON *json, struct xrt_vec3 *out_vec3)
+{
+	assert(out_vec3 != NULL);
+
+	if (!json) {
+		return false;
+	}
+	if (!cJSON_IsObject(json)) {
+		return false;
+	}
+
+	struct xrt_vec3 ret;
+	if (!u_json_get_float(get(json, "x"), &ret.x)) {
+		return false;
+	}
+	if (!u_json_get_float(get(json, "y"), &ret.y)) {
+		return false;
+	}
+	if (!u_json_get_float(get(json, "z"), &ret.z)) {
+		return false;
+	}
+
+	*out_vec3 = ret;
+
+	return true;
+}
+
+bool
+u_json_get_quat(const cJSON *json, struct xrt_quat *out_quat)
+{
+	assert(out_quat != NULL);
+
+	if (!json) {
+		return false;
+	}
+	if (!cJSON_IsObject(json)) {
+		return false;
+	}
+
+	struct xrt_quat ret;
+	if (!u_json_get_float(get(json, "w"), &ret.w)) {
+		return false;
+	}
+	if (!u_json_get_float(get(json, "x"), &ret.x)) {
+		return false;
+	}
+	if (!u_json_get_float(get(json, "y"), &ret.y)) {
+		return false;
+	}
+	if (!u_json_get_float(get(json, "z"), &ret.z)) {
+		return false;
+	}
+
+	*out_quat = ret;
+
+	return true;
+}
+
+size_t
+u_json_get_float_array(const cJSON *json_array,
+                       float *out_array,
+                       size_t max_size)
+{
+	assert(out_array != NULL);
+
+	if (!json_array) {
+		return 0;
+	}
+	if (!cJSON_IsArray(json_array)) {
+		return 0;
+	}
+
+	size_t i = 0;
+	const cJSON *elt;
+	cJSON_ArrayForEach(elt, json_array)
+	{
+		if (i >= max_size) {
+			break;
+		}
+
+		if (!u_json_get_float(elt, &out_array[i])) {
+			fprintf(stderr,
+			        "warning: u_json_get_float_array got a "
+			        "non-number in a numeric array");
+			return i;
+		}
+
+		i++;
+	}
+
+	return i;
+}
+
 size_t
 u_json_get_double_array(const cJSON *json_array,
                         double *out_array,
                         size_t max_size)
 {
+	assert(out_array != NULL);
+
 	if (!json_array) {
 		return 0;
 	}
-	if (!out_array) {
-		return 0;
-	}
 	if (!cJSON_IsArray(json_array)) {
 		return 0;
 	}
-	if (max_size == 0) {
-		return 0;
-	}
+
 	size_t i = 0;
 	const cJSON *elt;
 	cJSON_ArrayForEach(elt, json_array)
 	{
-		if (!cJSON_IsNumber(elt)) {
+		if (i >= max_size) {
+			break;
+		}
+
+		if (!u_json_get_double(elt, &out_array[i])) {
 			fprintf(stderr,
 			        "warning: u_json_get_double_array got a "
 			        "non-number in a numeric array");
 			return i;
 		}
-		out_array[i] = elt->valuedouble;
-		++i;
-		if (i == max_size) {
-			break;
-		}
+
+		i++;
 	}
+
 	return i;
 }

src/xrt/auxiliary/util/u_json.h

@@ -11,6 +11,7 @@
 #pragma once
 
 #include "xrt/xrt_compiler.h"
+#include "xrt/xrt_defines.h"
 
 #include "cjson/cJSON.h"
 
@@ -19,6 +20,66 @@
 extern "C" {
 #endif // __cplusplus
 
+
+/*!
+ * @brief Parse a string from a JSON object into a char array.
+ *
+ * @return true if successful, false if string does not fit in
+ *         array or any other error.
+ */
+bool
+u_json_get_string_into_array(const cJSON *json, char *out, size_t max_size);
+
+/*!
+ * @brief Parse an int from a JSON object.
+ *
+ * @return true if successful, false if not.
+ */
+bool
+u_json_get_int(const cJSON *json, int *out_int);
+
+/*!
+ * @brief Parse a float from a JSON object.
+ *
+ * @return true if successful, false if not.
+ */
+bool
+u_json_get_float(const cJSON *json, float *out_float);
+
+/*!
+ * @brief Parse a double from a JSON object.
+ *
+ * @return true if successful, false if not.
+ */
+bool
+u_json_get_double(const cJSON *json, double *out_double);
+
+/*!
+ * @brief Parse a vec3 from a JSON object.
+ *
+ * @return true if successful, false if not.
+ */
+bool
+u_json_get_vec3(const cJSON *json, struct xrt_vec3 *out_vec3);
+
+/*!
+ * @brief Parse a quaternion from a JSON object.
+ *
+ * @return true if successful, false if not.
+ */
+bool
+u_json_get_quat(const cJSON *json, struct xrt_quat *out_quat);
+
+/*!
+ * @brief Parse up to max_size floats from a JSON array.
+ *
+ * @return the number of elements set.
+ */
+size_t
+u_json_get_float_array(const cJSON *json_array,
+                       float *out_array,
+                       size_t max_size);
+
 /*!
  * @brief Parse up to max_size doubles from a JSON array.
  *
@@ -28,6 +89,8 @@ size_t
 u_json_get_double_array(const cJSON *json_array,
                         double *out_array,
                         size_t max_size);
+
+
 #ifdef __cplusplus
 } // extern "C"
 #endif // __cplusplus