Merge pull request #34 from proj4js/wkt2-projjson

Add support for WKT2 and PROJJSON

Author: ahocevar

PROJJSONBuilder2015.js

@@ -0,0 +1,19 @@
+import PROJJSONBuilderBase from './PROJJSONBuilderBase.js';
+
+class PROJJSONBuilder2015 extends PROJJSONBuilderBase {
+  static convert(node, result = {}) {
+    super.convert(node, result);
+
+    // Skip `CS` and `USAGE` nodes for WKT2-2015
+    if (result.coordinate_system?.subtype === "Cartesian") {
+      delete result.coordinate_system;
+    }
+    if (result.usage) {
+      delete result.usage;
+    }
+
+    return result;
+  }
+}
+
+export default PROJJSONBuilder2015;

PROJJSONBuilder2019.js

@@ -0,0 +1,30 @@
+import PROJJSONBuilderBase from './PROJJSONBuilderBase.js';
+
+class PROJJSONBuilder2019 extends PROJJSONBuilderBase {
+  static convert(node, result = {}) {
+    super.convert(node, result);
+
+    // Handle `CS` node for WKT2-2019
+    const csNode = node.find((child) => Array.isArray(child) && child[0] === "CS");
+    if (csNode) {
+      result.coordinate_system = {
+        subtype: csNode[1],
+        axis: this.extractAxes(node),
+      };
+    }
+
+    // Handle `USAGE` node for WKT2-2019
+    const usageNode = node.find((child) => Array.isArray(child) && child[0] === "USAGE");
+    if (usageNode) {
+      result.usage = {
+        scope: usageNode.find((child) => Array.isArray(child) && child[0] === "SCOPE")?.[1],
+        area: usageNode.find((child) => Array.isArray(child) && child[0] === "AREA")?.[1],
+        bbox: usageNode.find((child) => Array.isArray(child) && child[0] === "BBOX")?.slice(1),
+      };
+    }
+
+    return result;
+  }
+}
+
+export default PROJJSONBuilder2019;

PROJJSONBuilderBase.js

@@ -0,0 +1,317 @@
+class PROJJSONBuilderBase {
+  static getId(node) {
+    const idNode = node.find((child) => Array.isArray(child) && child[0] === "ID");
+    if (idNode && idNode.length >= 3) {
+      return {
+        authority: idNode[1],
+        code: parseInt(idNode[2], 10),
+      };
+    }
+    return null;
+  }
+
+  static convertUnit(node, type = "unit") {
+    if (!node || node.length < 3) {
+      return { type, name: "unknown", conversion_factor: null };
+    }
+
+    const name = node[1];
+    const conversionFactor = parseFloat(node[2]) || null;
+
+    const idNode = node.find((child) => Array.isArray(child) && child[0] === "ID");
+    const id = idNode
+      ? {
+          authority: idNode[1],
+          code: parseInt(idNode[2], 10),
+        }
+      : null;
+
+    return {
+      type,
+      name,
+      conversion_factor: conversionFactor,
+      id,
+    };
+  }
+
+  static convertAxis(node) {
+    const name = node[1] || "Unknown";
+
+    // Determine the direction
+    let direction;
+    const abbreviationMatch = name.match(/^\((.)\)$/); // Match abbreviations like "(E)" or "(N)"
+    if (abbreviationMatch) {
+      // Use the abbreviation to determine the direction
+      const abbreviation = abbreviationMatch[1].toUpperCase();
+      if (abbreviation === 'E') direction = 'east';
+      else if (abbreviation === 'N') direction = 'north';
+      else if (abbreviation === 'U') direction = 'up';
+      else throw new Error(`Unknown axis abbreviation: ${abbreviation}`);
+    } else {
+      // Use the explicit direction provided in the AXIS node
+      direction = node[2]?.toLowerCase() || "unknown";
+    }
+
+    const orderNode = node.find((child) => Array.isArray(child) && child[0] === "ORDER");
+    const order = orderNode ? parseInt(orderNode[1], 10) : null;
+
+    const unitNode = node.find(
+      (child) =>
+        Array.isArray(child) &&
+        (child[0] === "LENGTHUNIT" || child[0] === "ANGLEUNIT" || child[0] === "SCALEUNIT")
+    );
+    const unit = this.convertUnit(unitNode);
+
+    return {
+      name,
+      direction, // Use the valid PROJJSON direction value
+      unit,
+      order,
+    };
+  }
+
+  static extractAxes(node) {
+    return node
+      .filter((child) => Array.isArray(child) && child[0] === "AXIS")
+      .map((axis) => this.convertAxis(axis))
+      .sort((a, b) => (a.order || 0) - (b.order || 0)); // Sort by the "order" property
+  }
+
+  static convert(node, result = {}) {
+
+    switch (node[0]) {
+      case "PROJCRS":
+        result.type = "ProjectedCRS";
+        result.name = node[1];
+        result.base_crs = node.find((child) => Array.isArray(child) && child[0] === "BASEGEOGCRS")
+          ? this.convert(node.find((child) => Array.isArray(child) && child[0] === "BASEGEOGCRS"))
+          : null;
+        result.conversion = node.find((child) => Array.isArray(child) && child[0] === "CONVERSION")
+          ? this.convert(node.find((child) => Array.isArray(child) && child[0] === "CONVERSION"))
+          : null;
+
+        const csNode = node.find((child) => Array.isArray(child) && child[0] === "CS");
+        if (csNode) {
+          result.coordinate_system = {
+            type: csNode[1],
+            axis: this.extractAxes(node),
+          };
+        }
+
+        const lengthUnitNode = node.find((child) => Array.isArray(child) && child[0] === "LENGTHUNIT");
+        if (lengthUnitNode) {
+          const unit = this.convertUnit(lengthUnitNode);
+          result.coordinate_system.unit = unit; // Add unit to coordinate_system
+        }
+
+        result.id = this.getId(node);
+        break;
+
+      case "BASEGEOGCRS":
+      case "GEOGCRS":
+        result.type = "GeographicCRS";
+        result.name = node[1];
+      
+        // Handle DATUM or ENSEMBLE
+        const datumOrEnsembleNode = node.find(
+          (child) => Array.isArray(child) && (child[0] === "DATUM" || child[0] === "ENSEMBLE")
+        );
+        if (datumOrEnsembleNode) {
+          const datumOrEnsemble = this.convert(datumOrEnsembleNode);
+          if (datumOrEnsembleNode[0] === "ENSEMBLE") {
+            result.datum_ensemble = datumOrEnsemble;
+          } else {
+            result.datum = datumOrEnsemble;
+          }
+          const primem = node.find((child) => Array.isArray(child) && child[0] === "PRIMEM");
+          if (primem && primem[1] !== 'Greenwich') {
+            datumOrEnsemble.prime_meridian = {
+              name: primem[1],
+              longitude: parseFloat(primem[2]),
+            }
+          }
+        }
+      
+        result.coordinate_system = {
+          type: "ellipsoidal",
+          axis: this.extractAxes(node),
+        };
+      
+        result.id = this.getId(node);
+        break;
+
+      case "DATUM":
+        result.type = "GeodeticReferenceFrame";
+        result.name = node[1];
+        result.ellipsoid = node.find((child) => Array.isArray(child) && child[0] === "ELLIPSOID")
+          ? this.convert(node.find((child) => Array.isArray(child) && child[0] === "ELLIPSOID"))
+          : null;
+        break;
+      
+      case "ENSEMBLE":
+        result.type = "DatumEnsemble";
+        result.name = node[1];
+      
+        // Extract ensemble members
+        result.members = node
+          .filter((child) => Array.isArray(child) && child[0] === "MEMBER")
+          .map((member) => ({
+            type: "DatumEnsembleMember",
+            name: member[1],
+            id: this.getId(member), // Extract ID as { authority, code }
+          }));
+      
+        // Extract accuracy
+        const accuracyNode = node.find((child) => Array.isArray(child) && child[0] === "ENSEMBLEACCURACY");
+        if (accuracyNode) {
+          result.accuracy = parseFloat(accuracyNode[1]);
+        }
+      
+        // Extract ellipsoid
+        const ellipsoidNode = node.find((child) => Array.isArray(child) && child[0] === "ELLIPSOID");
+        if (ellipsoidNode) {
+          result.ellipsoid = this.convert(ellipsoidNode); // Convert the ellipsoid node
+        }
+      
+        // Extract identifier for the ensemble
+        result.id = this.getId(node);
+        break;
+
+      case "ELLIPSOID":
+        result.type = "Ellipsoid";
+        result.name = node[1];
+        result.semi_major_axis = parseFloat(node[2]);
+        result.inverse_flattening = parseFloat(node[3]);
+        const units = node.find((child) => Array.isArray(child) && child[0] === "LENGTHUNIT")
+          ? this.convert(node.find((child) => Array.isArray(child) && child[0] === "LENGTHUNIT"), result)
+          : null;
+        break;
+
+      case "CONVERSION":
+        result.type = "Conversion";
+        result.name = node[1];
+        result.method = node.find((child) => Array.isArray(child) && child[0] === "METHOD")
+          ? this.convert(node.find((child) => Array.isArray(child) && child[0] === "METHOD"))
+          : null;
+        result.parameters = node
+          .filter((child) => Array.isArray(child) && child[0] === "PARAMETER")
+          .map((param) => this.convert(param));
+        break;
+
+      case "METHOD":
+        result.type = "Method";
+        result.name = node[1];
+        result.id = this.getId(node);
+        break;
+
+      case "PARAMETER":
+        result.type = "Parameter";
+        result.name = node[1];
+        result.value = parseFloat(node[2]);
+        result.unit = this.convertUnit(
+          node.find(
+            (child) =>
+              Array.isArray(child) &&
+              (child[0] === "LENGTHUNIT" || child[0] === "ANGLEUNIT" || child[0] === "SCALEUNIT")
+          )
+        );
+        result.id = this.getId(node);
+        break;
+
+      case "BOUNDCRS":
+        result.type = "BoundCRS";
+
+        // Process SOURCECRS
+        const sourceCrsNode = node.find((child) => Array.isArray(child) && child[0] === "SOURCECRS");
+        if (sourceCrsNode) {
+          const sourceCrsContent = sourceCrsNode.find((child) => Array.isArray(child));
+          result.source_crs = sourceCrsContent ? this.convert(sourceCrsContent) : null;
+        }
+
+        // Process TARGETCRS
+        const targetCrsNode = node.find((child) => Array.isArray(child) && child[0] === "TARGETCRS");
+        if (targetCrsNode) {
+          const targetCrsContent = targetCrsNode.find((child) => Array.isArray(child));
+          result.target_crs = targetCrsContent ? this.convert(targetCrsContent) : null;
+        }
+
+        // Process ABRIDGEDTRANSFORMATION
+        const transformationNode = node.find((child) => Array.isArray(child) && child[0] === "ABRIDGEDTRANSFORMATION");
+        if (transformationNode) {
+          result.transformation = this.convert(transformationNode);
+        } else {
+          result.transformation = null;
+        }
+        break;
+
+      case "ABRIDGEDTRANSFORMATION":
+        result.type = "Transformation";
+        result.name = node[1];
+        result.method = node.find((child) => Array.isArray(child) && child[0] === "METHOD")
+          ? this.convert(node.find((child) => Array.isArray(child) && child[0] === "METHOD"))
+          : null;
+
+        result.parameters = node
+          .filter((child) => Array.isArray(child) && (child[0] === "PARAMETER" || child[0] === "PARAMETERFILE"))
+          .map((param) => {
+            if (param[0] === "PARAMETER") {
+              return this.convert(param);
+            } else if (param[0] === "PARAMETERFILE") {
+              return {
+                name: param[1],
+                value: param[2],
+                id: {
+                  "authority": "EPSG",
+                  "code": 8656
+                }
+              };
+            }
+          });
+
+        // Adjust the Scale difference parameter if present
+        if (result.parameters.length === 7) {
+          const scaleDifference = result.parameters[6];
+          if (scaleDifference.name === "Scale difference") {
+            scaleDifference.value = Math.round((scaleDifference.value - 1) * 1e12) / 1e6;
+          }
+        }
+
+        result.id = this.getId(node);
+        break;
+      
+      case "AXIS":
+        if (!result.coordinate_system) {
+          result.coordinate_system = { type: "unspecified", axis: [] };
+        }
+        result.coordinate_system.axis.push(this.convertAxis(node));
+        break;
+      
+      case "LENGTHUNIT":
+        const unit = this.convertUnit(node, 'LinearUnit');
+        if (result.coordinate_system && result.coordinate_system.axis) {
+          result.coordinate_system.axis.forEach((axis) => {
+            if (!axis.unit) {
+              axis.unit = unit;
+            }
+          });
+        }
+        if (unit.conversion_factor && unit.conversion_factor !== 1) {
+          if (result.semi_major_axis) {
+            result.semi_major_axis = {
+              value: result.semi_major_axis,
+              unit,
+            }
+          }
+        }
+        break;
+
+      default:
+        result.keyword = node[0];
+        break;
+    }
+
+    return result;
+  }
+}
+
+export default PROJJSONBuilderBase;

README.md

@@ -1,7 +1,5 @@
 # wkt-parser
 
-The wkt parser pulled out of proj4 so it can be hacked on.
+The wkt parser pulled out of proj4 so it can be hacked on. Supports WKT1, WKT2 and PROJJSON.
 
-The parser currently only supports wkt strings of [version 1](https://docs.ogc.org/is/18-010r7/18-010r7.html#196) (earlier than 2015).
-
-It does not support geocentric currently (`GEOCCS`).
+It does not support geocentric currently (`GEOCCS`/`). `COMPOUNDCS` is only supported for WKT1.