125 lines
3.6 KiB
JavaScript
Executable File
125 lines
3.6 KiB
JavaScript
Executable File
module.exports = WktParser;
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var Types = require('./types');
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var Point = require('./point');
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function WktParser(value) {
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this.value = value;
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this.position = 0;
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}
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WktParser.prototype.match = function (tokens) {
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this.skipWhitespaces();
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for (var i = 0; i < tokens.length; i++) {
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if (this.value.substring(this.position).indexOf(tokens[i]) === 0) {
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this.position += tokens[i].length;
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return tokens[i];
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}
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}
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return null;
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};
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WktParser.prototype.matchRegex = function (tokens) {
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this.skipWhitespaces();
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for (var i = 0; i < tokens.length; i++) {
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var match = this.value.substring(this.position).match(tokens[i]);
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if (match) {
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this.position += match[0].length;
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return match;
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}
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}
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return null;
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};
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WktParser.prototype.isMatch = function (tokens) {
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this.skipWhitespaces();
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for (var i = 0; i < tokens.length; i++) {
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if (this.value.substring(this.position).indexOf(tokens[i]) === 0) {
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this.position += tokens[i].length;
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return true;
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}
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}
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return false;
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};
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WktParser.prototype.matchType = function () {
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var geometryType = this.match([Types.wkt.Point, Types.wkt.LineString, Types.wkt.Polygon, Types.wkt.MultiPoint,
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Types.wkt.MultiLineString, Types.wkt.MultiPolygon, Types.wkt.GeometryCollection]);
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if (!geometryType)
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throw new Error('Expected geometry type');
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return geometryType;
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};
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WktParser.prototype.matchDimension = function () {
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var dimension = this.match(['ZM', 'Z', 'M']);
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switch (dimension) {
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case 'ZM': return { hasZ: true, hasM: true };
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case 'Z': return { hasZ: true, hasM: false };
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case 'M': return { hasZ: false, hasM: true };
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default: return { hasZ: false, hasM: false };
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}
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};
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WktParser.prototype.expectGroupStart = function () {
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if (!this.isMatch(['(']))
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throw new Error('Expected group start');
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};
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WktParser.prototype.expectGroupEnd = function () {
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if (!this.isMatch([')']))
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throw new Error('Expected group end');
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};
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WktParser.prototype.matchCoordinate = function (options) {
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var match;
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if (options.hasZ && options.hasM)
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match = this.matchRegex([/^(\S*)\s+(\S*)\s+(\S*)\s+([^\s,)]*)/]);
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else if (options.hasZ || options.hasM)
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match = this.matchRegex([/^(\S*)\s+(\S*)\s+([^\s,)]*)/]);
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else
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match = this.matchRegex([/^(\S*)\s+([^\s,)]*)/]);
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if (!match)
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throw new Error('Expected coordinates');
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if (options.hasZ && options.hasM)
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return new Point(parseFloat(match[1]), parseFloat(match[2]), parseFloat(match[3]), parseFloat(match[4]));
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else if (options.hasZ)
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return new Point(parseFloat(match[1]), parseFloat(match[2]), parseFloat(match[3]));
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else if (options.hasM)
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return new Point(parseFloat(match[1]), parseFloat(match[2]), undefined, parseFloat(match[3]));
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else
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return new Point(parseFloat(match[1]), parseFloat(match[2]));
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};
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WktParser.prototype.matchCoordinates = function (options) {
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var coordinates = [];
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do {
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var startsWithBracket = this.isMatch(['(']);
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coordinates.push(this.matchCoordinate(options));
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if (startsWithBracket)
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this.expectGroupEnd();
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} while (this.isMatch([',']));
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return coordinates;
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};
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WktParser.prototype.skipWhitespaces = function () {
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while (this.position < this.value.length && this.value[this.position] === ' ')
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this.position++;
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};
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