1 files changed, 64 insertions, 0 deletions
diff --git a/dev/lib/handlebars/scripts/print_ast.js b/dev/lib/handlebars/scripts/print_ast.js
new file mode 100755
index 00000000..b97fb5a6
--- /dev/null
+++ b/dev/lib/handlebars/scripts/print_ast.js
@@ -0,0 +1,64 @@
+#!/usr/bin/env node
+/*
+ * Elasticsearch B.V licenses this file to you under the MIT License.
+ * See `packages/kbn-handlebars/LICENSE` for more information.
+ */
+'use strict'; // eslint-disable-line strict
+
+const { relative } = require('path');
+const { inspect } = require('util');
+
+const { parse } = require('handlebars');
+const argv = require('minimist')(process.argv.slice(2));
+
+const DEFAULT_FILTER = 'loc,strip,openStrip,inverseStrip,closeStrip';
+
+const filter = argv['show-all'] ? [''] : (argv.filter || DEFAULT_FILTER).split(',');
+const hideEmpty = argv['hide-empty'] || false;
+const template = argv._[0];
+
+if (template === undefined) {
+  const script = relative(process.cwd(), process.argv[1]);
+  console.log(`Usage: ${script} [options] <template>`);
+  console.log();
+  console.log('Options:');
+  console.log('  --filter=...  A comma separated list of keys to filter from the output.');
+  console.log(`                Default: ${DEFAULT_FILTER}`);
+  console.log('  --hide-empty  Do not display empty properties.');
+  console.log('  --show-all    Do not filter out any properties. Equivalent to --filter="".');
+  console.log();
+  console.log('Example:');
+  console.log(`  ${script} --hide-empty -- 'hello {{name}}'`);
+  console.log();
+  process.exit(1);
+}
+
+console.log(inspect(reduce(parse(template, filter)), { colors: true, depth: null }));
+
+function reduce(ast) {
+  if (Array.isArray(ast)) {
+    for (let i = 0; i < ast.length; i++) {
+      ast[i] = reduce(ast[i]);
+    }
+  } else {
+    for (const k of filter) {
+      delete ast[k];
+    }
+
+    if (hideEmpty) {
+      for (const [k, v] of Object.entries(ast)) {
+        if (v === undefined || v === null || (Array.isArray(v) && v.length === 0)) {
+          delete ast[k];
+        }
+      }
+    }
+
+    for (const [k, v] of Object.entries(ast)) {
+      if (typeof v === 'object' && v !== null) {
+        ast[k] = reduce(v);
+      }
+    }
+  }
+
+  return ast;
+}