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// Copyright 2014 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
import 'dart:convert';
import 'dart:io';
import 'package:dart_style/dart_style.dart';
import 'package:meta/meta.dart';
import 'package:path/path.dart' as path;
import 'configuration.dart';
void errorExit(String message) {
stderr.writeln(message);
exit(1);
}
// A Tuple containing the name and contents associated with a code block in a
// snippet.
class _ComponentTuple {
_ComponentTuple(this.name, this.contents, {String language}) : language = language ?? '';
final String name;
final List<String> contents;
final String language;
String get mergedContent => contents.join('\n').trim();
}
/// Generates the snippet HTML, as well as saving the output snippet main to
/// the output directory.
class SnippetGenerator {
SnippetGenerator({Configuration configuration})
: configuration = configuration ??
// Flutter's root is four directories up from this script.
Configuration(flutterRoot: Directory(Platform.environment['FLUTTER_ROOT']
?? path.canonicalize(path.join(path.dirname(path.fromUri(Platform.script)), '..', '..', '..')))) {
this.configuration.createOutputDirectory();
}
/// The configuration used to determine where to get/save data for the
/// snippet.
final Configuration configuration;
static const JsonEncoder jsonEncoder = JsonEncoder.withIndent(' ');
/// A Dart formatted used to format the snippet code and finished application
/// code.
static DartFormatter formatter = DartFormatter(pageWidth: 80, fixes: StyleFix.all);
/// This returns the output file for a given snippet ID. Only used for
/// [SnippetType.sample] snippets.
File getOutputFile(String id) => File(path.join(configuration.outputDirectory.path, '$id.dart'));
/// Gets the path to the template file requested.
File getTemplatePath(String templateName, {Directory templatesDir}) {
final Directory templateDir = templatesDir ?? configuration.templatesDirectory;
final File templateFile = File(path.join(templateDir.path, '$templateName.tmpl'));
return templateFile.existsSync() ? templateFile : null;
}
/// Injects the [injections] into the [template], and turning the
/// "description" injection into a comment. Only used for
/// [SnippetType.sample] snippets.
String interpolateTemplate(List<_ComponentTuple> injections, String template, Map<String, Object> metadata) {
final RegExp moustacheRegExp = RegExp('{{([^}]+)}}');
return template.replaceAllMapped(moustacheRegExp, (Match match) {
if (match[1] == 'description') {
// Place the description into a comment.
final List<String> description = injections
.firstWhere((_ComponentTuple tuple) => tuple.name == match[1])
.contents
.map<String>((String line) => '// $line')
.toList();
// Remove any leading/trailing empty comment lines.
// We don't want to remove ALL empty comment lines, only the ones at the
// beginning and the end.
while (description.isNotEmpty && description.last == '// ') {
description.removeLast();
}
while (description.isNotEmpty && description.first == '// ') {
description.removeAt(0);
}
return description.join('\n').trim();
} else {
// If the match isn't found in the injections, then just remove the
// mustache reference, since we want to allow the sections to be
// "optional" in the input: users shouldn't be forced to add an empty
// "```dart preamble" section if that section would be empty.
final _ComponentTuple result = injections
.firstWhere((_ComponentTuple tuple) => tuple.name == match[1], orElse: () => null);
return result?.mergedContent ?? (metadata[match[1]] ?? '').toString();
}
}).trim();
}
/// Interpolates the [injections] into an HTML skeleton file.
///
/// Similar to interpolateTemplate, but we are only looking for `code-`
/// components, and we care about the order of the injections.
///
/// Takes into account the [type] and doesn't substitute in the id and the app
/// if not a [SnippetType.sample] snippet.
String interpolateSkeleton(SnippetType type, List<_ComponentTuple> injections, String skeleton, Map<String, Object> metadata) {
final List<String> result = <String>[];
const HtmlEscape htmlEscape = HtmlEscape();
String language;
for (final _ComponentTuple injection in injections) {
if (!injection.name.startsWith('code')) {
continue;
}
result.addAll(injection.contents);
if (injection.language.isNotEmpty) {
language = injection.language;
}
result.addAll(<String>['', '// ...', '']);
}
if (result.length > 3) {
result.removeRange(result.length - 3, result.length);
}
// Only insert a div for the description if there actually is some text there.
// This means that the {{description}} marker in the skeleton needs to
// be inside of an {@inject-html} block.
String description = injections.firstWhere((_ComponentTuple tuple) => tuple.name == 'description').mergedContent;
description = description.trim().isNotEmpty
? '<div class="snippet-description">{@end-inject-html}$description{@inject-html}</div>'
: '';
// DartPad only supports stable or master as valid channels. Use master
// if not on stable so that local runs will work (although they will
// still take their sample code from the master docs server).
final String channel = metadata['channel'] == 'stable' ? 'stable' : 'master';
final Map<String, String> substitutions = <String, String>{
'description': description,
'code': htmlEscape.convert(result.join('\n')),
'language': language ?? 'dart',
'serial': '',
'id': metadata['id'] as String,
'channel': channel,
'element': metadata['element'] as String ?? '',
'app': '',
};
if (type == SnippetType.sample) {
substitutions
..['serial'] = metadata['serial']?.toString() ?? '0'
..['app'] = htmlEscape.convert(injections.firstWhere((_ComponentTuple tuple) => tuple.name == 'app').mergedContent);
}
return skeleton.replaceAllMapped(RegExp('{{(${substitutions.keys.join('|')})}}'), (Match match) {
return substitutions[match[1]];
});
}
/// Parses the input for the various code and description segments, and
/// returns them in the order found.
List<_ComponentTuple> parseInput(String input) {
bool inCodeBlock = false;
input = input.trim();
final List<String> description = <String>[];
final List<_ComponentTuple> components = <_ComponentTuple>[];
String language;
final RegExp codeStartEnd = RegExp(r'^\s*```([-\w]+|[-\w]+ ([-\w]+))?\s*$');
for (final String line in input.split('\n')) {
final Match match = codeStartEnd.firstMatch(line);
if (match != null) { // If we saw the start or end of a code block
inCodeBlock = !inCodeBlock;
if (match[1] != null) {
language = match[1];
if (match[2] != null) {
components.add(_ComponentTuple('code-${match[2]}', <String>[], language: language));
} else {
components.add(_ComponentTuple('code', <String>[], language: language));
}
} else {
language = null;
}
continue;
}
if (!inCodeBlock) {
description.add(line);
} else {
assert(language != null);
components.last.contents.add(line);
}
}
return <_ComponentTuple>[
_ComponentTuple('description', description),
...components,
];
}
String _loadFileAsUtf8(File file) {
return file.readAsStringSync(encoding: Encoding.getByName('utf-8'));
}
String _addLineNumbers(String app) {
final StringBuffer buffer = StringBuffer();
int count = 0;
for (final String line in app.split('\n')) {
count++;
buffer.writeln('${count.toString().padLeft(5, ' ')}: $line');
}
return buffer.toString();
}
/// The main routine for generating snippets.
///
/// The [input] is the file containing the dartdoc comments (minus the leading
/// comment markers).
///
/// The [type] is the type of snippet to create: either a
/// [SnippetType.sample] or a [SnippetType.snippet].
///
/// [showDartPad] indicates whether DartPad should be shown where possible.
/// Currently, this value only has an effect if [type] is
/// [SnippetType.sample], in which case an alternate skeleton file is
/// used to create the final HTML output.
///
/// The [template] must not be null if the [type] is
/// [SnippetType.sample], and specifies the name of the template to use
/// for the application code.
///
/// The [id] is a string ID to use for the output file, and to tell the user
/// about in the `flutter create` hint. It must not be null if the [type] is
/// [SnippetType.sample].
String generate(
File input,
SnippetType type, {
bool showDartPad = false,
String template,
File output,
@required Map<String, Object> metadata,
}) {
assert(template != null || type != SnippetType.sample);
assert(metadata != null && metadata['id'] != null);
assert(input != null);
assert(!showDartPad || type == SnippetType.sample, 'Only application samples work with dartpad.');
final List<_ComponentTuple> snippetData = parseInput(_loadFileAsUtf8(input));
switch (type) {
case SnippetType.sample:
final Directory templatesDir = configuration.templatesDirectory;
if (templatesDir == null) {
stderr.writeln('Unable to find the templates directory.');
exit(1);
}
final File templateFile = getTemplatePath(template, templatesDir: templatesDir);
if (templateFile == null) {
stderr.writeln(
'The template $template was not found in the templates directory ${templatesDir.path}');
exit(1);
}
final String templateContents = _loadFileAsUtf8(templateFile);
String app = interpolateTemplate(snippetData, templateContents, metadata);
try {
app = formatter.format(app);
} on FormatterException catch (exception) {
stderr.write('Code to format:\n${_addLineNumbers(app)}\n');
errorExit('Unable to format snippet app template: $exception');
}
snippetData.add(_ComponentTuple('app', app.split('\n')));
final File outputFile = output ?? getOutputFile(metadata['id'] as String);
stderr.writeln('Writing to ${outputFile.absolute.path}');
outputFile.writeAsStringSync(app);
final File metadataFile = File(path.join(path.dirname(outputFile.path),
'${path.basenameWithoutExtension(outputFile.path)}.json'));
stderr.writeln('Writing metadata to ${metadataFile.absolute.path}');
final _ComponentTuple description = snippetData.firstWhere(
(_ComponentTuple data) => data.name == 'description',
orElse: () => null,
);
metadata.addAll(<String, Object>{
'file': path.basename(outputFile.path),
'description': description?.mergedContent,
});
metadataFile.writeAsStringSync(jsonEncoder.convert(metadata));
break;
case SnippetType.snippet:
break;
}
final String skeleton =
_loadFileAsUtf8(configuration.getHtmlSkeletonFile(type, showDartPad: showDartPad));
return interpolateSkeleton(type, snippetData, skeleton, metadata);
}
}