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Add support for widget builders.
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@tugorez
tugorez committed Feb 21, 2024
1 parent 8f730b9 commit 42a83ca
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Showing 5 changed files with 825 additions and 82 deletions.
46 changes: 46 additions & 0 deletions packages/rfw/lib/src/dart/model.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -439,6 +439,26 @@ class ConstructorCall extends BlobNode {
String toString() => '$name($arguments)';
}

/// Representation of functions that return widgets in Remote Flutter library blobs.
class WidgetBuilderDeclaration extends BlobNode {
/// Creates a [WidgetBuilderDeclaration].
const WidgetBuilderDeclaration(this.argumentName, this.widget);

/// The name associated with the passed [DynamicMap].
final String argumentName;

/// The widget that will be returned when the builder is called.
///
/// This is usually a [ConstructorCall], but may be a [Switch] (so long as
/// that [Switch] resolves to a [ConstructorCall]. Other values (or a [Switch]
/// that does not resolve to a constructor call) will result in an
/// [ErrorWidget] being used.
final BlobNode widget;

@override
String toString() => '($argumentName) => $widget';
}

/// Base class for various kinds of references in the RFW data structures.
abstract class Reference extends BlobNode {
/// Abstract const constructor. This constructor enables subclasses to provide
Expand Down Expand Up @@ -534,6 +554,32 @@ class DataReference extends Reference {
String toString() => 'data.${parts.join(".")}';
}

/// Reference to the [DynamicMap] passed into the widget builder.
///
/// This class is used to represent references to a function argument.
/// In "(scope) => Container(width: scope.width)" this represents "scope.width".
///
/// See also:
///
/// * [WidgetBuilderDeclaration] which represents a widget builder definition.
class WidgetBuilderArgReference extends Reference {
/// Wraps the given [parts] associated to the [argumentName] as an [WidgetBuilderArgReference].
///
/// The parts must not be mutated after the object is created.
const WidgetBuilderArgReference(this.argumentName, super.parts);

/// References the function argument name.
final String argumentName;

WidgetBuilderArgReference constructReference(List<Object> moreParts) {
return WidgetBuilderArgReference(argumentName, parts + moreParts);
}

@override
String toString() => '$argumentName.${parts.join('.')}';
}


/// Unbound reference to a [Loop].
class LoopReference extends Reference {
/// Wraps the given [loop] and [parts] as a [LoopReference].
Expand Down
147 changes: 123 additions & 24 deletions packages/rfw/lib/src/dart/text.dart
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Original file line number Diff line number Diff line change
Expand Up @@ -272,8 +272,8 @@ DynamicMap parseDataFile(String file) {
/// declaration, along with its arguments. Arguments are a map of key-value
/// pairs, where the values can be any of the types in the data model defined
/// above plus any of the types defined below in this section, such as
/// references to arguments, the data model, loops, state, switches, or
/// event handlers.
/// references to arguments, the data model, widget builders, loops, state,
/// switches or event handlers.
///
/// In this example, several constructor calls are nested together:
///
Expand All @@ -283,6 +283,9 @@ DynamicMap parseDataFile(String file) {
/// Container(
/// child: Text(text: "Hello"),
/// ),
/// Builder(
/// builder: (scope) => Text(text: scope.world),
/// ),
/// ],
/// );
/// ```
Expand All @@ -293,6 +296,35 @@ DynamicMap parseDataFile(String file) {
/// constructor call also has only one argument, `child`, whose value, again, is
/// a constructor call, in this case creating a `Text` widget.
///
/// ### Widget Builders
///
/// Widget builders take a single argument and return a widget.
/// The [DynamicMap] argument consists of key-value pairs where values
/// can be of any types in the data model. Widget builders arguments are lexically
/// scoped so a given constructor call has access to any arguments where it is
/// defined plus arguments defined by its parents (if any).
///
/// In this example several widget builders are nested together:
///
/// ```
/// widget Foo {text: 'this is cool'} = Builder(
/// builder: (foo) => Builder(
/// builder: (bar) => Builder(
/// builder: (baz) => Text(
/// text: [
/// args.text,
/// state.text,
/// data.text,
/// foo.text,
/// bar.text,
/// baz.text,
/// ],
/// ),
/// ),
/// ),
/// );
/// ```
///
/// ### References
///
/// Remote widget libraries typically contain _references_, e.g. to the
Expand Down Expand Up @@ -610,6 +642,12 @@ const Set<String> _reservedWords = <String>{
'true',
};

void _checkIsNotReservedWord(String identifier, _Token identifierToken) {
if (_reservedWords.contains(identifier)) {
throw ParserException._fromToken('$identifier is a reserved word', identifierToken);
}
}

sealed class _Token {
_Token(this.line, this.column, this.start, this.end);
final int line;
Expand All @@ -630,6 +668,7 @@ class _SymbolToken extends _Token {
static const int colon = 0x3A; // U+003A COLON character (:)
static const int semicolon = 0x3B; // U+003B SEMICOLON character (;)
static const int equals = 0x3D; // U+003D EQUALS SIGN character (=)
static const int greatherThan = 0x3E; // U+003D GREATHER THAN character (>)
static const int openBracket = 0x5B; // U+005B LEFT SQUARE BRACKET character ([)
static const int closeBracket = 0x5D; // U+005D RIGHT SQUARE BRACKET character (])
static const int openBrace = 0x7B; // U+007B LEFT CURLY BRACKET character ({)
Expand Down Expand Up @@ -812,6 +851,7 @@ Iterable<_Token> _tokenize(String file) sync* {
case 0x3A: // U+003A COLON character (:)
case 0x3B: // U+003B SEMICOLON character (;)
case 0x3D: // U+003D EQUALS SIGN character (=)
case 0x3E: // U+003E GREATHER THAN SIGN character (>)
case 0x5B: // U+005B LEFT SQUARE BRACKET character ([)
case 0x5D: // U+005D RIGHT SQUARE BRACKET character (])
case 0x7B: // U+007B LEFT CURLY BRACKET character ({)
Expand Down Expand Up @@ -2132,22 +2172,35 @@ class _Parser {
return _readString();
}

DynamicMap _readMap({ required bool extended }) {
DynamicMap _readMap({
required bool extended,
List<String> widgetBuilderScope = const <String>[],
}) {
_expectSymbol(_SymbolToken.openBrace);
final DynamicMap results = _readMapBody(extended: extended);
final DynamicMap results = _readMapBody(
widgetBuilderScope: widgetBuilderScope,
extended: extended,
);
_expectSymbol(_SymbolToken.closeBrace);
return results;
}

DynamicMap _readMapBody({ required bool extended }) {
DynamicMap _readMapBody({
required bool extended,
List<String> widgetBuilderScope = const <String>[],
}) {
final DynamicMap results = DynamicMap(); // ignore: prefer_collection_literals
while (_source.current is! _SymbolToken) {
final String key = _readKey();
if (results.containsKey(key)) {
throw ParserException._fromToken('Duplicate key "$key" in map', _source.current);
}
_expectSymbol(_SymbolToken.colon);
final Object value = _readValue(extended: extended, nullOk: true);
final Object value = _readValue(
extended: extended,
nullOk: true,
widgetBuilderScope: widgetBuilderScope,
);
if (value != missing) {
results[key] = value;
}
Expand All @@ -2162,7 +2215,10 @@ class _Parser {

final List<String> _loopIdentifiers = <String>[];

DynamicList _readList({ required bool extended }) {
DynamicList _readList({
required bool extended,
List<String> widgetBuilderScope = const <String>[],
}) {
final DynamicList results = DynamicList.empty(growable: true);
_expectSymbol(_SymbolToken.openBracket);
while (!_foundSymbol(_SymbolToken.closeBracket)) {
Expand All @@ -2172,19 +2228,26 @@ class _Parser {
_expectIdentifier('for');
final _Token loopIdentifierToken = _source.current;
final String loopIdentifier = _readIdentifier();
if (_reservedWords.contains(loopIdentifier)) {
throw ParserException._fromToken('$loopIdentifier is a reserved word', loopIdentifierToken);
}
_checkIsNotReservedWord(loopIdentifier, loopIdentifierToken);
_expectIdentifier('in');
final Object collection = _readValue(extended: true);
final Object collection = _readValue(
widgetBuilderScope: widgetBuilderScope,
extended: true,
);
_expectSymbol(_SymbolToken.colon);
_loopIdentifiers.add(loopIdentifier);
final Object template = _readValue(extended: extended);
final Object template = _readValue(
widgetBuilderScope: widgetBuilderScope,
extended: extended,
);
assert(_loopIdentifiers.last == loopIdentifier);
_loopIdentifiers.removeLast();
results.add(_withSourceRange(Loop(collection, template), start));
} else {
final Object value = _readValue(extended: extended);
final Object value = _readValue(
widgetBuilderScope: widgetBuilderScope,
extended: extended,
);
results.add(value);
}
if (_foundSymbol(_SymbolToken.comma)) {
Expand All @@ -2197,8 +2260,10 @@ class _Parser {
return results;
}

Switch _readSwitch(SourceLocation? start) {
final Object value = _readValue(extended: true);
Switch _readSwitch(SourceLocation? start, {
List<String> widgetBuilderScope = const <String>[],
}) {
final Object value = _readValue(extended: true, widgetBuilderScope: widgetBuilderScope);
final Map<Object?, Object> cases = <Object?, Object>{};
_expectSymbol(_SymbolToken.openBrace);
while (_source.current is! _SymbolToken) {
Expand All @@ -2210,13 +2275,13 @@ class _Parser {
key = null;
_advance();
} else {
key = _readValue(extended: true);
key = _readValue(extended: true, widgetBuilderScope: widgetBuilderScope);
if (cases.containsKey(key)) {
throw ParserException._fromToken('Switch has duplicate cases for key $key', _source.current);
}
}
_expectSymbol(_SymbolToken.colon);
final Object value = _readValue(extended: true);
final Object value = _readValue(extended: true, widgetBuilderScope: widgetBuilderScope);
cases[key] = value;
if (_foundSymbol(_SymbolToken.comma)) {
_advance();
Expand Down Expand Up @@ -2249,13 +2314,19 @@ class _Parser {
return results;
}

Object _readValue({ required bool extended, bool nullOk = false }) {
Object _readValue({
required bool extended,
bool nullOk = false,
List<String> widgetBuilderScope = const <String>[],
}) {
if (_source.current is _SymbolToken) {
switch ((_source.current as _SymbolToken).symbol) {
case _SymbolToken.openBracket:
return _readList(extended: extended);
return _readList(widgetBuilderScope: widgetBuilderScope, extended: extended);
case _SymbolToken.openBrace:
return _readMap(extended: extended);
return _readMap(widgetBuilderScope: widgetBuilderScope, extended: extended);
case _SymbolToken.openParen:
return _readWidgetBuilderDeclaration(widgetBuilderScope: widgetBuilderScope);
}
} else if (_source.current is _IntegerToken) {
final Object result = (_source.current as _IntegerToken).value;
Expand Down Expand Up @@ -2306,10 +2377,15 @@ class _Parser {
_advance();
return _withSourceRange(StateReference(_readParts()), start);
}
if (widgetBuilderScope.contains(identifier)) {
final SourceLocation? start = _getSourceLocation();
_advance();
return _withSourceRange(WidgetBuilderArgReference(identifier, _readParts()), start);
}
if (identifier == 'switch') {
final SourceLocation? start = _getSourceLocation();
_advance();
return _readSwitch(start);
return _readSwitch(start, widgetBuilderScope: widgetBuilderScope);
}
if (identifier == 'set') {
final SourceLocation? start = _getSourceLocation();
Expand All @@ -2327,16 +2403,39 @@ class _Parser {
_advance();
return _withSourceRange(LoopReference(_loopIdentifiers.length - index, _readParts(optional: true)), start);
}
return _readConstructorCall();
return _readConstructorCall(widgetBuilderScope: widgetBuilderScope);
}
throw ParserException._unexpected(_source.current);
}

ConstructorCall _readConstructorCall() {
WidgetBuilderDeclaration _readWidgetBuilderDeclaration({
List<String> widgetBuilderScope = const <String>[],
}) {
_expectSymbol(_SymbolToken.openParen);
final _Token argumentNameToken = _source.current;
final String argumentName = _readIdentifier();
_checkIsNotReservedWord(argumentName, argumentNameToken);
_expectSymbol(_SymbolToken.closeParen);
_expectSymbol(_SymbolToken.equals);
_expectSymbol(_SymbolToken.greatherThan);
final Object widget = _readValue(
extended: true,
widgetBuilderScope: <String>[...widgetBuilderScope, argumentName],
);
assert(widget is ConstructorCall || widget is Switch);
return WidgetBuilderDeclaration(argumentName, widget as BlobNode);
}

ConstructorCall _readConstructorCall({
List<String> widgetBuilderScope = const <String>[],
}) {
final SourceLocation? start = _getSourceLocation();
final String name = _readIdentifier();
_expectSymbol(_SymbolToken.openParen);
final DynamicMap arguments = _readMapBody(extended: true);
final DynamicMap arguments = _readMapBody(
extended: true,
widgetBuilderScope: widgetBuilderScope,
);
_expectSymbol(_SymbolToken.closeParen);
return _withSourceRange(ConstructorCall(name, arguments), start);
}
Expand Down
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