Add (untested!) identify subcommand

src/Subcommands/identify/index.mjs

@@ -0,0 +1,96 @@
+"use strict";
+
+import fs from 'fs';
+
+import a from '../../Helpers/Ansi.mjs';
+import Terrain50 from 'terrain50';
+
+function summarise_obj(obj) {
+	console.log(`Format: ASC`);
+	console.log(`Claimed size: ${obj.meta.ncols}x${obj.meta.nrows}`);
+	console.log(`Actual size: ${obj.data.length}x${obj.data[0].length}`);
+	console.log(`Lower-left corner: (${obj.meta.xllcorner}, ${obj.meta.yllcorner})`);
+	console.log(`Cell size: ${obj.meta.cellsize}`);
+	if(typeof obj.meta.NODATA_value !== "undefined")
+		console.log(`NODATA value: ${obj.meta.NODATA_value}`);
+	console.log(`Metadata keys: ${Object.keys(obj.meta).join(", ")}`);
+}
+
+export default async function(settings) {
+	
+	
+	let iterator = null;
+	switch(settings.cli.mode) {
+		case "single":
+			let obj = Terrain50.Parse(
+				fs.promises.readFile(settings.cli.input == "-" ? 0 : settings.cli.input, "utf-8")
+			);
+			summarise_obj(obj);
+			break;
+		
+		case "stream":
+			let stream = process.stdin;
+			if(settings.cli.input !== "-")
+				stream = fs.createReadStream(settings.cli.input, "utf-8");
+			
+			let i = 0;
+			for await(let next of Terrain50.ParseStream(stream)) {
+				console.log(`>>>>> Item ${i} <<<<<`);
+				summarise_obj(next);
+				
+				i++;
+			}
+	}
+	
+	
+	switch(settings.cli.mode) {
+		case "validate":
+			// Read stdin into a string - ref https://stackoverflow.com/a/56012724/1460422
+			let source = fs.readFileSync(0, 'utf-8');
+			
+			let errors = Terrain50.Validate(source);
+			display_errors(errors);
+			break;
+		
+		case "stream":
+			let i = 0;
+			for await (let next of Terrain50.ParseStream(process.stdin)) {
+				console.log(`>>> Item ${i} <<<`);
+				display_errors(next.validate());
+				i++;
+			}
+			break;
+		
+		default:
+			console.error(`${a.fred}${a.hicol}Error: Mode '${settings.cli.mode}' was not recognised. Possible modes: validate (the default), stream.${a.reset}`);
+			process.exit(1);
+	}
+}
+
+/**
+ * Displays the errors returned by a Terrain50 validation function.
+ * (e.g. `Terrain50.Validate(str)`, or `obj.validate()`)
+ * @param  {[type]} errors [description]
+ * @return {[type]}        [description]
+ */
+function display_errors(errors) {
+	if(errors.length > 0) {
+		for(let error of errors) {
+			switch(error.level) {
+				case "warning":
+					console.log(`${a.fyellow}${a.hicol}${error}${a.reset}`);
+					break;
+				case "error":
+					console.log(`${a.fred}${a.hicol}${error}${a.reset}`);
+					break;
+				default:
+					console.log(error);
+					break;
+			}
+		}
+		process.exit(1);
+	}
+	else {
+		console.log(`${a.fgreen}Validation completed successfully - no issues detected :D${a.reset}`);
+	}
+}

src/Subcommands/identify/meta.toml

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+description = "Summarise the specified Terrain50 file"
+
+[[arguments]]
+name = "input"
+description = "The filename to operate on (a dash - means read from stdin)"
+default_value = "-"
+type = "string"
+
+[[arguments]]
+name = "mode"
+description = "The mode to operate in. Possible values: single (default), stream. If stream, then the input will be parsed as a stream (otherwise everything is read into a string and parsed as a single entity)"
+default_value = "single"
+type = "string"