Implement CLI

.github/workflows/node.js.yml

@@ -27,5 +27,6 @@ jobs:
         node-version: ${{ matrix.node-version }}
         cache: 'npm'
     - run: npm ci
-    - run: npm run build --if-present
+    - run: npm run lint
+    - run: npm run build
     - run: npm test

README.md

@@ -80,22 +80,47 @@ Wide-JSON:
 
 ## Rules for Compact Layout
 
-Wide-JSON will use the following rules in layout out JSON:
-
-- Maps (Objects) will always include the first property on the
-  same line as the opening '{'.
-- Subsequent properties will be included on the same line if they
-  will fit within the available width.
-- If a property will not fit in the available width, it will be
-  indented on a new line at the same indentation level as it's sibling
-  properties.
-
-- Arrays will always include the first value on the same line as the
-  opening '['.
-- Subsequent values will the included on the same line if they will fit
-  in the available width.
-- Additions array values will be "word-wrapped" to subsequent lines with
-  the same indentation as the first value of the array.
+Wide-JSON will use the following rules in layout out JSON
+Maps (Objects) and Arrays.
+
+- The first child (element or property) will appear
+  on the same line as the opening `{` or `[`.
+- Subsequent children will be included on the same line
+  if they will fit in the available width.
+- If a child will not fit in the available width, it will be
+  indented on a new line at the same indentation level as
+  the first child.
+- The closing `}` or `]` will always appear on the same
+  line as the last child.
+
+## Using the CLI
+
+Wide-JSON exports a command-line utility which reads
+a JSON file and outputs a reformatted version on the
+command line:
+
+```
+$ npx wide-json input.json > output.json
+
+$ npx wide-json --help
+
+Usage:
+  wide-json [options] filename.json > output.json
+  wide-json [options] < input.json > output.json
+
+Options:
+  --help       Show this help message.
+  --width=N    Set the target width of the output.
+               (default: 80)
+```
+
+## Using the Node Package
+
+```js
+const wideJSON = require('wide-json');
+
+console.log(wideJSON.stringify(myJSON));
+```
 
 ## Note about maximum line length
 

package.json

@@ -1,6 +1,6 @@
 {
   "name": "wide-json",
-  "version": "0.2.1",
+  "version": "0.3.0",
   "description": "JSON formatter - preferring wide layout to tall layout",
   "main": "dist/index.js",
   "bin": "dist/cli.js",

src/cli.ts

@@ -1,3 +1,66 @@
 #!/usr/bin/env node
 
-console.log("wide-json");
+import { exit } from "process";
+import { readFile } from 'fs/promises';
+import { stringify } from './index.js';
+
+async function main(args: string[]) {
+  let width = 80;
+  let useStdin = true;
+
+  for (const option of args) {
+    if (option.startsWith('--')) {
+      const [, name, value] = option.match(/^--([^=]+)=?(.*)$/) || [];
+      if (name === 'help') {
+        help();
+      } else if (name === 'width') {
+        width = parseInt(value, 10);
+        if (isNaN(width) || width < 0) {
+          help("width must be a positive number");
+        }
+      } else {
+        help(`Unknown option: ${option}`);
+      }
+    } else {
+      const fileName = option;
+      useStdin = false;
+
+      try {
+        const json = await readFile(fileName, 'utf8');
+        console.log(stringify(JSON.parse(json), width) + '\n');
+      } catch (e) {
+        help(`Could not read ${fileName}:\n${e}`);
+      }
+    }
+  }
+
+  if (!useStdin) {
+    return;
+  }
+
+  const json = await readFile('/dev/stdin', 'utf8');
+  console.log(stringify(JSON.parse(json), width) + '\n');
+}
+
+function help(msg?: string) {
+  if (msg) {
+    console.error(msg + '\n');
+  }
+
+  console.log(`
+Usage:
+  wide-json [options] filename.json > output.json
+  wide-json [options] < input.json > output.json
+
+Options:
+  --help       Show this help message.
+  --width=N    Set the target width of the output.
+               (default: 80)
+`);
+
+  exit(msg === undefined ? 0 : 1);
+}
+
+if (require.main === module) {
+  main(process.argv.slice(2));
+}