Add proj_get_units_from_database() (fixes #2004)

data/sql/customizations.sql

@@ -135,3 +135,35 @@ INSERT INTO "alias_name" VALUES('geodetic_datum','EPSG','6312','hermannskogel','
 INSERT INTO "alias_name" VALUES('geodetic_datum','EPSG','6299','ire65','PROJ');
 INSERT INTO "alias_name" VALUES('geodetic_datum','EPSG','6272','nzgd49','PROJ');
 INSERT INTO "alias_name" VALUES('geodetic_datum','EPSG','6277','OSGB36','PROJ');
+
+---- PROJ unit short names -----
+
+-- Linear units
+UPDATE unit_of_measure SET proj_short_name = 'mm'        WHERE auth_name = 'EPSG' AND code = '1025';
+UPDATE unit_of_measure SET proj_short_name = 'cm'        WHERE auth_name = 'EPSG' AND code = '1033';
+UPDATE unit_of_measure SET proj_short_name = 'm'         WHERE auth_name = 'EPSG' AND code = '9001';
+UPDATE unit_of_measure SET proj_short_name = 'ft'        WHERE auth_name = 'EPSG' AND code = '9002';
+UPDATE unit_of_measure SET proj_short_name = 'us-ft'     WHERE auth_name = 'EPSG' AND code = '9003';
+UPDATE unit_of_measure SET proj_short_name = 'fath'      WHERE auth_name = 'EPSG' AND code = '9014';
+UPDATE unit_of_measure SET proj_short_name = 'kmi'       WHERE auth_name = 'EPSG' AND code = '9030';
+UPDATE unit_of_measure SET proj_short_name = 'us-ch'     WHERE auth_name = 'EPSG' AND code = '9033';
+UPDATE unit_of_measure SET proj_short_name = 'us-mi'     WHERE auth_name = 'EPSG' AND code = '9035';
+UPDATE unit_of_measure SET proj_short_name = 'km'        WHERE auth_name = 'EPSG' AND code = '9036';
+UPDATE unit_of_measure SET proj_short_name = 'ind-ft'    WHERE auth_name = 'EPSG' AND code = '9081';
+UPDATE unit_of_measure SET proj_short_name = 'ind-yd'    WHERE auth_name = 'EPSG' AND code = '9085';
+UPDATE unit_of_measure SET proj_short_name = 'mi'        WHERE auth_name = 'EPSG' AND code = '9093';
+UPDATE unit_of_measure SET proj_short_name = 'yd'        WHERE auth_name = 'EPSG' AND code = '9096';
+UPDATE unit_of_measure SET proj_short_name = 'ch'        WHERE auth_name = 'EPSG' AND code = '9097';
+UPDATE unit_of_measure SET proj_short_name = 'link'      WHERE auth_name = 'EPSG' AND code = '9098';
+
+-- Angular units
+UPDATE unit_of_measure SET proj_short_name = 'rad'       WHERE auth_name = 'EPSG' AND code = '9101';
+UPDATE unit_of_measure SET proj_short_name = 'deg'       WHERE auth_name = 'EPSG' AND code = '9102';
+UPDATE unit_of_measure SET proj_short_name = 'grad'      WHERE auth_name = 'EPSG' AND code = '9105';
+
+-- PROJ specific units
+INSERT INTO "unit_of_measure" VALUES('PROJ','DM','decimeter','length',0.01,'dm',0);
+INSERT INTO "unit_of_measure" VALUES('PROJ','IN','inch','length',0.0254,'in',0);
+INSERT INTO "unit_of_measure" VALUES('PROJ','US_IN','US survey inch','length',0.025400050800101,'us-in',0);
+INSERT INTO "unit_of_measure" VALUES('PROJ','US_YD','US survey yard','length',0.914401828803658,'us-yd',0);
+INSERT INTO "unit_of_measure" VALUES('PROJ','IND_CH','Indian chain','length',20.11669506,'ind-ch',0);

data/sql/proj_db_table_defs.sql

@@ -14,6 +14,7 @@ CREATE TABLE unit_of_measure(
     name TEXT NOT NULL CHECK (length(name) >= 2),
     type TEXT NOT NULL CHECK (type IN ('length', 'angle', 'scale', 'time')),
     conv_factor FLOAT,
+    proj_short_name TEXT, -- PROJ string name, like 'm', 'ft'. Might be NULL
     deprecated BOOLEAN NOT NULL CHECK (deprecated IN (0, 1)),
     CONSTRAINT pk_unit_of_measure PRIMARY KEY (auth_name, code)
 );

docs/source/development/reference/functions.rst

@@ -521,6 +521,9 @@ Lists
     entry of the returned array is a NULL-entry. The array is statically
     allocated and does not need to be freed after use.
 
+    Note: starting with PROJ 7.1, this function is deprecated by
+    :cpp:func:`proj_get_units_from_database`
+
     :returns: :c:type:`PJ_UNITS*`
 
 .. c:function:: const PJ_PRIME_MERIDIANS* proj_list_prime_meridians(void)

include/proj/io.hpp

@@ -1013,6 +1013,8 @@ class PROJ_GCC_DLL AuthorityFactory {
 
     PROJ_DLL std::string getDescriptionText(const std::string &code) const;
 
+    // non-standard
+
     /** CRS information */
     struct CRSInfo {
         /** Authority name */
@@ -1049,7 +1051,33 @@ class PROJ_GCC_DLL AuthorityFactory {
 
     PROJ_DLL std::list<CRSInfo> getCRSInfoList() const;
 
-    // non-standard
+    /** Unit information */
+    struct UnitInfo {
+        /** Authority name */
+        std::string authName;
+        /** Code */
+        std::string code;
+        /** Name */
+        std::string name;
+        /** Category: one of "linear", "linear_per_time", "angular",
+         * "angular_per_time", "scale", "scale_per_time" or "time" */
+        std::string category;
+        /** Conversion factor to the SI unit.
+         * It might be 0 in some cases to indicate no known conversion factor.
+         */
+        double convFactor;
+        /** PROJ short name (may be empty) */
+        std::string projShortName;
+        /** Whether the object is deprecated */
+        bool deprecated;
+
+        //! @cond Doxygen_Suppress
+        UnitInfo();
+        //! @endcond
+    };
+
+    PROJ_DLL std::list<UnitInfo> getUnitList() const;
+
     PROJ_DLL static AuthorityFactoryNNPtr
     create(const DatabaseContextNNPtr &context,
            const std::string &authorityName);

scripts/build_db.py

@@ -68,7 +68,7 @@ def ingest_epsg():
 
 def fill_unit_of_measure(proj_db_cursor):
     proj_db_cursor.execute(
-        "INSERT INTO unit_of_measure SELECT ?, uom_code, unit_of_meas_name, unit_of_meas_type, factor_b / factor_c, deprecated FROM epsg.epsg_unitofmeasure", (EPSG_AUTHORITY,))
+        "INSERT INTO unit_of_measure SELECT ?, uom_code, unit_of_meas_name, unit_of_meas_type, factor_b / factor_c, NULL, deprecated FROM epsg.epsg_unitofmeasure", (EPSG_AUTHORITY,))
 
 
 def fill_ellipsoid(proj_db_cursor):

src/iso19111/c_api.cpp

@@ -662,7 +662,8 @@ PJ *proj_create_from_database(PJ_CONTEXT *ctx, const char *auth_name,
 // ---------------------------------------------------------------------------
 
 //! @cond Doxygen_Suppress
-static const char *get_unit_category(UnitOfMeasure::Type type) {
+static const char *get_unit_category(const std::string &unit_name,
+                                     UnitOfMeasure::Type type) {
     const char *ret = nullptr;
     switch (type) {
     case UnitOfMeasure::Type::UNKNOWN:
@@ -672,19 +673,26 @@ static const char *get_unit_category(UnitOfMeasure::Type type) {
         ret = "none";
         break;
     case UnitOfMeasure::Type::ANGULAR:
-        ret = "angular";
+        ret = unit_name.find(" per ") != std::string::npos ? "angular_per_time"
+                                                           : "angular";
         break;
     case UnitOfMeasure::Type::LINEAR:
-        ret = "linear";
+        ret = unit_name.find(" per ") != std::string::npos ? "linear_per_time"
+                                                           : "linear";
         break;
     case UnitOfMeasure::Type::SCALE:
-        ret = "scale";
+        ret = unit_name.find(" per year") != std::string::npos ||
+                      unit_name.find(" per second") != std::string::npos
+                  ? "scale_per_time"
+                  : "scale";
         break;
     case UnitOfMeasure::Type::TIME:
         ret = "time";
         break;
     case UnitOfMeasure::Type::PARAMETRIC:
-        ret = "parametric";
+        ret = unit_name.find(" per ") != std::string::npos
+                  ? "parametric_per_time"
+                  : "parametric";
         break;
     }
     return ret;
@@ -704,8 +712,9 @@ static const char *get_unit_category(UnitOfMeasure::Type type) {
  * @param out_conv_factor Pointer to a value to store the conversion
  * factor of the prime meridian longitude unit to radian. or NULL
  * @param out_category Pointer to a string value to store the parameter name. or
- * NULL. This value might be "unknown", "none", "linear", "angular", "scale",
- * "time" or "parametric";
+ * NULL. This value might be "unknown", "none", "linear", "linear_per_time",
+ * "angular", "angular_per_time", "scale", "scale_per_time", "time",
+ * "parametric" or "parametric_per_time"
  * @return TRUE in case of success
  */
 int proj_uom_get_info_from_database(PJ_CONTEXT *ctx, const char *auth_name,
@@ -726,7 +735,7 @@ int proj_uom_get_info_from_database(PJ_CONTEXT *ctx, const char *auth_name,
             *out_conv_factor = obj->conversionToSI();
         }
         if (out_category) {
-            *out_category = get_unit_category(obj->type());
+            *out_category = get_unit_category(obj->name(), obj->type());
         }
         ctx->cpp_context->autoCloseDbIfNeeded();
         return true;
@@ -2585,6 +2594,100 @@ void proj_crs_info_list_destroy(PROJ_CRS_INFO **list) {
 
 // ---------------------------------------------------------------------------
 
+/** \brief Enumerate units from the database, taking into account various
+ * criteria.
+ *
+ * The returned object is an array of PROJ_UNIT_INFO* pointers, whose last
+ * entry is NULL. This array should be freed with proj_unit_list_destroy()
+ *
+ * @param ctx PROJ context, or NULL for default context
+ * @param auth_name Authority name, used to restrict the search.
+ * Or NULL for all authorities.
+ * @param category Filter by category, if this parameter is not NULL. Category
+ * is one of "linear", "linear_per_time", "angular", "angular_per_time",
+ * "scale", "scale_per_time" or "time"
+ * @param allow_deprecated whether we should return deprecated objects as well.
+ * @param out_result_count Output parameter pointing to an integer to receive
+ * the size of the result list. Might be NULL
+ * @return an array of PROJ_UNIT_INFO* pointers to be freed with
+ * proj_unit_list_destroy(), or NULL in case of error.
+ *
+ * @since 7.1
+ */
+PROJ_UNIT_INFO **proj_get_units_from_database(PJ_CONTEXT *ctx,
+                                              const char *auth_name,
+                                              const char *category,
+                                              int allow_deprecated,
+                                              int *out_result_count) {
+    SANITIZE_CTX(ctx);
+    PROJ_UNIT_INFO **ret = nullptr;
+    int i = 0;
+    try {
+        auto factory = AuthorityFactory::create(getDBcontext(ctx),
+                                                auth_name ? auth_name : "");
+        auto list = factory->getUnitList();
+        ret = new PROJ_UNIT_INFO *[list.size() + 1];
+        for (const auto &info : list) {
+            if (category && info.category != category) {
+                continue;
+            }
+            if (!allow_deprecated && info.deprecated) {
+                continue;
+            }
+            ret[i] = new PROJ_UNIT_INFO;
+            ret[i]->auth_name = pj_strdup(info.authName.c_str());
+            ret[i]->code = pj_strdup(info.code.c_str());
+            ret[i]->name = pj_strdup(info.name.c_str());
+            ret[i]->category = pj_strdup(info.category.c_str());
+            ret[i]->conv_factor = info.convFactor;
+            ret[i]->proj_short_name =
+                info.projShortName.empty()
+                    ? nullptr
+                    : pj_strdup(info.projShortName.c_str());
+            ret[i]->deprecated = info.deprecated;
+            i++;
+        }
+        ret[i] = nullptr;
+        if (out_result_count)
+            *out_result_count = i;
+        ctx->cpp_context->autoCloseDbIfNeeded();
+        return ret;
+    } catch (const std::exception &e) {
+        proj_log_error(ctx, __FUNCTION__, e.what());
+        if (ret) {
+            ret[i + 1] = nullptr;
+            proj_unit_list_destroy(ret);
+        }
+        if (out_result_count)
+            *out_result_count = 0;
+    }
+    ctx->cpp_context->autoCloseDbIfNeeded();
+    return nullptr;
+}
+
+// ---------------------------------------------------------------------------
+
+/** \brief Destroy the result returned by
+ * proj_get_units_from_database().
+ *
+ * @since 7.1
+ */
+void proj_unit_list_destroy(PROJ_UNIT_INFO **list) {
+    if (list) {
+        for (int i = 0; list[i] != nullptr; i++) {
+            pj_dalloc(list[i]->auth_name);
+            pj_dalloc(list[i]->code);
+            pj_dalloc(list[i]->name);
+            pj_dalloc(list[i]->category);
+            pj_dalloc(list[i]->proj_short_name);
+            delete list[i];
+        }
+        delete[] list;
+    }
+}
+
+// ---------------------------------------------------------------------------
+
 /** \brief Return the Conversion of a DerivedCRS (such as a ProjectedCRS),
  * or the Transformation from the baseCRS to the hubCRS of a BoundCRS
  *
@@ -6749,8 +6852,9 @@ int proj_coordoperation_get_param_index(PJ_CONTEXT *ctx,
  * unit code. or NULL
  * @param out_unit_category Pointer to a string value to store the parameter
  * name. or
- * NULL. This value might be "unknown", "none", "linear", "angular", "scale",
- * "time" or "parametric";
+ * NULL. This value might be "unknown", "none", "linear", "linear_per_time",
+ * "angular", "angular_per_time", "scale", "scale_per_time", "time",
+ * "parametric" or "parametric_per_time"
  * @return TRUE in case of success.
  */
 
@@ -6852,7 +6956,8 @@ int proj_coordoperation_get_param(
                 *out_unit_code = unit.code().c_str();
             }
             if (out_unit_category) {
-                *out_unit_category = get_unit_category(unit.type());
+                *out_unit_category =
+                    get_unit_category(unit.name(), unit.type());
             }
         }
     }

src/iso19111/factory.cpp

@@ -5214,6 +5214,64 @@ std::list<AuthorityFactory::CRSInfo> AuthorityFactory::getCRSInfoList() const {
 
 // ---------------------------------------------------------------------------
 
+//! @cond Doxygen_Suppress
+AuthorityFactory::UnitInfo::UnitInfo()
+    : authName{}, code{}, name{}, category{}, convFactor{}, projShortName{},
+      deprecated{} {}
+//! @endcond
+
+// ---------------------------------------------------------------------------
+
+/** \brief Return the list of units.
+ * @throw FactoryException
+ *
+ * @since 7.1
+ */
+std::list<AuthorityFactory::UnitInfo> AuthorityFactory::getUnitList() const {
+    std::string sql = "SELECT auth_name, code, name, type, conv_factor, "
+                      "proj_short_name, deprecated FROM unit_of_measure";
+    ListOfParams params;
+    if (d->hasAuthorityRestriction()) {
+        sql += " WHERE auth_name = ?";
+        params.emplace_back(d->authority());
+    }
+    sql += " ORDER BY auth_name, code";
+
+    auto sqlRes = d->run(sql, params);
+    std::list<AuthorityFactory::UnitInfo> res;
+    for (const auto &row : sqlRes) {
+        AuthorityFactory::UnitInfo info;
+        info.authName = row[0];
+        info.code = row[1];
+        info.name = row[2];
+        const std::string &raw_category(row[3]);
+        if (raw_category == "length") {
+            info.category = info.name.find(" per ") != std::string::npos
+                                ? "linear_per_time"
+                                : "linear";
+        } else if (raw_category == "angle") {
+            info.category = info.name.find(" per ") != std::string::npos
+                                ? "angular_per_time"
+                                : "angular";
+        } else if (raw_category == "scale") {
+            info.category =
+                info.name.find(" per year") != std::string::npos ||
+                        info.name.find(" per second") != std::string::npos
+                    ? "scale_per_time"
+                    : "scale";
+        } else {
+            info.category = raw_category;
+        }
+        info.convFactor = row[4].empty() ? 0 : c_locale_stod(row[4]);
+        info.projShortName = row[5];
+        info.deprecated = row[6] == "1";
+        res.emplace_back(info);
+    }
+    return res;
+}
+
+// ---------------------------------------------------------------------------
+
 /** \brief Gets the official name from a possibly alias name.
  *
  * @param aliasedName Alias name.