[mustache_template] add example app and migrate README to excerpts

script/configs/temp_exclude_excerpt.yaml

@@ -7,6 +7,5 @@
 # https://github.com/flutter/flutter/issues/102679
 - espresso
 - in_app_purchase/in_app_purchase
-- mustache_template
 - pointer_interceptor
 - quick_actions/quick_actions

third_party/packages/mustache_template/CHANGELOG.md

@@ -1,5 +1,7 @@
 ## 2.0.4
 
+* Adds an example package with runnable samples and tests.
+* Migrates README.md to use code excerpts from the new example.
 * Fixes a broken README link to the Mustache manual.
 
 ## 2.0.3

third_party/packages/mustache_template/README.md

@@ -1,3 +1,5 @@
+<?code-excerpt path-base="example/lib"?>
+
 # Mustache templates
 
 A Dart library to parse and render [mustache templates](https://mustache.github.io/).
@@ -7,29 +9,25 @@ See the [mustache manual](https://mustache.github.io/mustache.5.html) for detail
 This library passes all [mustache specification](https://github.com/mustache/spec/tree/master/specs) tests.
 
 ## Example usage
+<?code-excerpt "readme_excerpts.dart (BasicRender)"?>
 ```dart
-import 'package:mustache_template/mustache_template.dart';
-
-main() {
-	var source = '''
-	  {{# names }}
-            <div>{{ lastname }}, {{ firstname }}</div>
-	  {{/ names }}
-	  {{^ names }}
-	    <div>No names.</div>
-	  {{/ names }}
-	  {{! I am a comment. }}
-	''';
-
-	var template = Template(source, name: 'template-filename.html');
-
-	var output = template.renderString({'names': [
-		{'firstname': 'Greg', 'lastname': 'Lowe'},
-		{'firstname': 'Bob', 'lastname': 'Johnson'}
-	]});
-
-	print(output);
-}
+  var source = '''
+{{# names }}
+<div>{{ lastname }}, {{ firstname }}</div>
+{{/ names }}
+{{^ names }}
+<div>No names.</div>
+{{/ names }}
+{{! I am a comment. }}
+''';
+
+  var template = Template(source, name: 'names-template');
+  var output = template.renderString(<String, Object>{
+    'names': <Map<String, String>>[
+      <String, String>{'firstname': 'Greg', 'lastname': 'Lowe'},
+      <String, String>{'firstname': 'Bob', 'lastname': 'Johnson'},
+    ],
+  });
 ```
 
 A template is parsed when it is created, after parsing it can be rendered any number of times with different values. A TemplateException is thrown if there is a problem parsing or rendering the template.
@@ -46,72 +44,46 @@ By default all output from `{{variable}}` tags is html escaped, this behaviour c
 
 * During rendering, if no map key or object member which matches the tag name is found, then a TemplateException will be thrown.
 
+<?code-excerpt "readme_excerpts.dart (StrictMode)"?>
+```dart
+late String result;
+try {
+  Template('{{missing}}').renderString({});
+  result = 'No exception thrown (unexpected)';
+} on TemplateException catch (e) {
+  // Strict mode (default): missing keys throw when rendering.
+  result = 'Strict mode exception: ${e.runtimeType}';
+}
+```
+
 ### Lenient mode
 
 * Tag names may use any characters.
 * During rendering, if no map key or object member which matches the tag name is found, then silently ignore and output nothing.
 
-## Nested paths
-
+<?code-excerpt "readme_excerpts.dart (LenientMode)"?>
 ```dart
-  var t = Template('{{ author.name }}');
-  var output = template.renderString({'author': {'name': 'Greg Lowe'}});
+final t = Template('{{missing}}', lenient: true);
+final String output = t.renderString({}); // ''
 ```
 
-## Partials - example usage
+## Partials
 
+<?code-excerpt "readme_excerpts.dart (Partials)"?>
 ```dart
-
 var partial = Template('{{ foo }}', name: 'partial');
-
-var resolver = (String name) {
-   if (name == 'partial-name') { // Name of partial tag.
-     return partial;
-   }
-};
+Template resolver(String name) {
+  if (name == 'partial-name') {
+    return partial;
+  }
+  throw StateError('Unknown partial: $name');
+}
 
 var t = Template('{{> partial-name }}', partialResolver: resolver);
-
 var output = t.renderString({'foo': 'bar'}); // bar
-
-```
-
-## Lambdas - example usage
-
-```dart
-var t = Template('{{# foo }}');
-var lambda = (_) => 'bar';
-t.renderString({'foo': lambda}); // bar
-```
-
-```dart
-var t = Template('{{# foo }}hidden{{/ foo }}');
-var lambda = (_) => 'shown';
-t.renderString('foo': lambda); // shown
 ```
 
-```dart
-var t = Template('{{# foo }}oi{{/ foo }}');
-var lambda = (LambdaContext ctx) => '<b>${ctx.renderString().toUpperCase()}</b>';
-t.renderString({'foo': lambda}); // <b>OI</b>
-```
+## More examples
 
-```dart
-var t = Template('{{# foo }}{{bar}}{{/ foo }}');
-var lambda = (LambdaContext ctx) => '<b>${ctx.renderString().toUpperCase()}</b>';
-t.renderString({'foo': lambda, 'bar': 'pub'}); // <b>PUB</b>
-```
-
-```dart
-var t = Template('{{# foo }}{{bar}}{{/ foo }}');
-var lambda = (LambdaContext ctx) => '<b>${ctx.renderString().toUpperCase()}</b>';
-t.renderString({'foo': lambda, 'bar': 'pub'}); // <b>PUB</b>
-```
-
-In the following example `LambdaContext.renderSource(source)` re-parses the source string in the current context, this is the default behaviour in many mustache implementations. Since re-parsing the content is slow, and often not required, this library makes this step optional.
-
-```dart
-var t = Template('{{# foo }}{{bar}}{{/ foo }}');
-var lambda = (LambdaContext ctx) => ctx.renderSource(ctx.source + ' {{cmd}}');
-t.renderString({'foo': lambda, 'bar': 'pub', 'cmd': 'build'}); // pub build
-```
+For additional usage including nested paths, lambdas, and
+`LambdaContext.renderSource`, see the [example app](example/).

third_party/packages/mustache_template/example/lib/readme_excerpts.dart

@@ -0,0 +1,135 @@
+// This file hosts README code excerpts (see README.md) and is imported by the
+// example runner and excerpt tests.
+
+// ignore_for_file: public_member_api_docs, specify_nonobvious_local_variable_types, prefer_function_declarations_over_variables
+
+import 'package:mustache_template/mustache_template.dart';
+
+String basicRenderExample() {
+  // #docregion BasicRender
+  const source = '''
+{{# names }}
+<div>{{ lastname }}, {{ firstname }}</div>
+{{/ names }}
+{{^ names }}
+<div>No names.</div>
+{{/ names }}
+{{! I am a comment. }}
+''';
+
+  final template = Template(source, name: 'names-template');
+  final output = template.renderString(<String, Object>{
+    'names': <Map<String, String>>[
+      <String, String>{'firstname': 'Greg', 'lastname': 'Lowe'},
+      <String, String>{'firstname': 'Bob', 'lastname': 'Johnson'},
+    ],
+  });
+  // #enddocregion BasicRender
+  return output;
+}
+
+String nestedPathsExample() {
+  // #docregion NestedPaths
+  final t = Template('{{ author.name }}');
+  final output = t.renderString(<String, Object>{
+    'author': {'name': 'Greg Lowe'},
+  });
+  // #enddocregion NestedPaths
+  return output;
+}
+
+String partialsExample() {
+  // #docregion Partials
+  final partial = Template('{{ foo }}', name: 'partial');
+  Template resolver(String name) {
+    if (name == 'partial-name') {
+      return partial;
+    }
+    throw StateError('Unknown partial: $name');
+  }
+
+  final t = Template('{{> partial-name }}', partialResolver: resolver);
+  var output = t.renderString({'foo': 'bar'}); // bar
+  // #enddocregion Partials
+  return output;
+}
+
+String lambdaSimpleExample() {
+  // #docregion LambdaSimpleValue
+  final t = Template('{{ foo }}');
+
+  final lambda = (_) => 'bar';
+
+  final output = t.renderString({'foo': lambda}); // bar
+  // #enddocregion LambdaSimpleValue
+  return output;
+}
+
+String lambdaShownExample() {
+  // #docregion LambdaSectionReplacement
+  final t = Template('{{# foo }}hidden{{/ foo }}');
+  final lambda = (_) => 'shown';
+
+  final output = t.renderString({'foo': lambda}); // shown
+  // #enddocregion LambdaSectionReplacement
+  return output;
+}
+
+String lambdaUppercaseOibExample() {
+  // #docregion LambdaUppercaseOib
+  final t = Template('{{# foo }}oi{{/ foo }}');
+  final lambda = (LambdaContext ctx) =>
+      '<b>${ctx.renderString().toUpperCase()}</b>';
+
+  final output = t.renderString({'foo': lambda}); // <b>OI</b>
+  // #enddocregion LambdaUppercaseOib
+  return output;
+}
+
+String lambdaRenderExample() {
+  // #docregion LambdaRenderString
+  final t = Template('{{# foo }}{{bar}}{{/ foo }}');
+  final lambda = (LambdaContext context) =>
+      '<b>${context.renderString().toUpperCase()}</b>';
+
+  final output = t.renderString({'foo': lambda, 'bar': 'pub'}); // <b>PUB</b>
+  // #enddocregion LambdaRenderString
+  return output;
+}
+
+String lambdaRenderSourceExample() {
+  // #docregion LambdaRenderSource
+  final t = Template('{{# foo }}{{bar}}{{/ foo }}');
+  final lambda = (LambdaContext ctx) =>
+      ctx.renderSource(ctx.source + ' {{cmd}}');
+
+  final output = t.renderString({
+    'foo': lambda,
+    'bar': 'pub',
+    'cmd': 'build',
+  }); // pub build
+  // #enddocregion LambdaRenderSource
+  return output;
+}
+
+String strictModeBehaviorExample() {
+  // #docregion StrictMode
+  late String result;
+  try {
+    Template('{{missing}}').renderString({});
+    result = 'No exception thrown (unexpected)';
+  } on TemplateException catch (e) {
+    // Strict mode (default): missing keys throw when rendering.
+    result = 'Strict mode exception: ${e.runtimeType}';
+  }
+  // #enddocregion StrictMode
+  return result;
+}
+
+String lenientModeBehaviorExample() {
+  // #docregion LenientMode
+  final t = Template('{{missing}}', lenient: true);
+  final String output = t.renderString({}); // ''
+  // #enddocregion LenientMode
+  return output;
+}

third_party/packages/mustache_template/example/main.dart

@@ -0,0 +1,16 @@
+// ignore_for_file: avoid_print
+
+import 'package:mustache_template_example/readme_excerpts.dart';
+
+void main() {
+  print(basicRenderExample());
+  print(nestedPathsExample());
+  print(partialsExample());
+  print(lambdaSimpleExample());
+  print(lambdaShownExample());
+  print(lambdaUppercaseOibExample());
+  print(lambdaRenderExample());
+  print(lambdaRenderSourceExample());
+  print(strictModeBehaviorExample());
+  print(lenientModeBehaviorExample());
+}

third_party/packages/mustache_template/example/pubspec.yaml

@@ -0,0 +1,12 @@
+name: mustache_template_example
+publish_to: none
+
+environment:
+  sdk: ^3.9.0
+
+dependencies:
+  mustache_template:
+    path: ../
+
+dev_dependencies:
+  test: ^1.16.5