pkgs/ffigen/lib/src/code_generator/writer.dart - native - Git at Google

 // Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.

 import 'package:ffigen/src/code_generator.dart';
 import 'package:ffigen/src/code_generator/utils.dart';
 import 'package:logging/logging.dart';

 import '../strings.dart' as strings;

 final _logger = Logger('ffigen.code_generator.writer');

 /// To store generated String bindings.
 class Writer {
   final String? header;

   /// Holds bindings, which lookup symbols.
   final List<Binding> lookUpBindings;

   /// Holds bindings, which lookup symbols through `FfiNative`.
   final List<Binding> ffiNativeBindings;

   /// Holds bindings which don't lookup symbols.
   final List<Binding> noLookUpBindings;

   /// The default asset id to use for [ffiNativeBindings].
   final String? nativeAssetId;

   /// Manages the `_SymbolAddress` class.
   final symbolAddressWriter = SymbolAddressWriter();

   late String _className;
   String get className => _className;

   final String? classDocComment;

   String? _ffiLibraryPrefix;
   String get ffiLibraryPrefix {
     if (_ffiLibraryPrefix != null) {
       return _ffiLibraryPrefix!;
     }

     final import = _usedImports.firstWhere(
         (element) => element.name == ffiImport.name,
         orElse: () => ffiImport);
     _usedImports.add(import);
     return _ffiLibraryPrefix = import.prefix;
   }

   String? _ffiPkgLibraryPrefix;
   String get ffiPkgLibraryPrefix {
     if (_ffiPkgLibraryPrefix != null) {
       return _ffiPkgLibraryPrefix!;
     }

     final import = _usedImports.firstWhere(
         (element) => element.name == ffiPkgImport.name,
         orElse: () => ffiPkgImport);
     _usedImports.add(import);
     return _ffiPkgLibraryPrefix = import.prefix;
   }

   String? _objcPkgPrefix;
   String get objcPkgPrefix {
     if (_objcPkgPrefix != null) {
       return _objcPkgPrefix!;
     }

     final import = _usedImports.firstWhere(
         (element) => element.name == objcPkgImport.name,
         orElse: () => objcPkgImport);
     _usedImports.add(import);
     return _objcPkgPrefix = import.prefix;
   }

   late String selfImportPrefix = () {
     final import = _usedImports
         .firstWhere((element) => element.name == self.name, orElse: () => self);
     _usedImports.add(import);
     return import.prefix;
   }();

   final Set<LibraryImport> _usedImports = {};

   late String _lookupFuncIdentifier;
   String get lookupFuncIdentifier => _lookupFuncIdentifier;

   late String _symbolAddressClassName;
   late String _symbolAddressVariableName;
   late String _symbolAddressLibraryVarName;

   /// Initial namers set after running constructor. Namers are reset to this
   /// initial state everytime [generate] is called.
   late UniqueNamer _initialTopLevelUniqueNamer, _initialWrapperLevelUniqueNamer;

   /// Used by [Binding]s for generating required code.
   late UniqueNamer _topLevelUniqueNamer, _wrapperLevelUniqueNamer;
   UniqueNamer get topLevelUniqueNamer => _topLevelUniqueNamer;
   UniqueNamer get wrapperLevelUniqueNamer => _wrapperLevelUniqueNamer;

   late String _arrayHelperClassPrefix;

   /// Guaranteed to be a unique prefix.
   String get arrayHelperClassPrefix => _arrayHelperClassPrefix;

   /// Set true after calling [generate]. Indicates if
   /// [generateSymbolOutputYamlMap] can be called.
   bool get canGenerateSymbolOutput => _canGenerateSymbolOutput;
   bool _canGenerateSymbolOutput = false;

   /// [_usedUpNames] should contain names of all the declarations which are
   /// already used. This is used to avoid name collisions.
   Writer({
     required this.lookUpBindings,
     required this.ffiNativeBindings,
     required this.noLookUpBindings,
     required String className,
     required this.nativeAssetId,
     Set<LibraryImport>? additionalImports,
     this.classDocComment,
     this.header,
   }) {
     final globalLevelNameSet = noLookUpBindings.map((e) => e.name).toSet();
     final wrapperLevelNameSet = lookUpBindings.map((e) => e.name).toSet();
     final allNameSet = <String>{}
       ..addAll(globalLevelNameSet)
       ..addAll(wrapperLevelNameSet);

     _initialTopLevelUniqueNamer = UniqueNamer(globalLevelNameSet);
     _initialWrapperLevelUniqueNamer = UniqueNamer(wrapperLevelNameSet);
     final allLevelsUniqueNamer = UniqueNamer(allNameSet);

     /// Wrapper class name must be unique among all names.
     _className = _resolveNameConflict(
       name: className,
       makeUnique: allLevelsUniqueNamer,
       markUsed: [_initialWrapperLevelUniqueNamer, _initialTopLevelUniqueNamer],
     );

     /// Library imports prefix should be unique unique among all names.
     if (additionalImports != null) {
       for (final lib in additionalImports) {
         lib.prefix = _resolveNameConflict(
           name: lib.prefix,
           makeUnique: allLevelsUniqueNamer,
           markUsed: [
             _initialWrapperLevelUniqueNamer,
             _initialTopLevelUniqueNamer
           ],
         );
       }
     }

     /// [_lookupFuncIdentifier] should be unique in top level.
     _lookupFuncIdentifier = _resolveNameConflict(
       name: '_lookup',
       makeUnique: _initialTopLevelUniqueNamer,
       markUsed: [_initialTopLevelUniqueNamer],
     );

     /// Resolve name conflicts of identifiers used for SymbolAddresses.
     _symbolAddressClassName = _resolveNameConflict(
       name: '_SymbolAddresses',
       makeUnique: allLevelsUniqueNamer,
       markUsed: [_initialWrapperLevelUniqueNamer, _initialTopLevelUniqueNamer],
     );
     _symbolAddressVariableName = _resolveNameConflict(
       name: 'addresses',
       makeUnique: _initialWrapperLevelUniqueNamer,
       markUsed: [_initialWrapperLevelUniqueNamer],
     );
     _symbolAddressLibraryVarName = _resolveNameConflict(
       name: '_library',
       makeUnique: _initialWrapperLevelUniqueNamer,
       markUsed: [_initialWrapperLevelUniqueNamer],
     );

     /// Finding a unique prefix for Array Helper Classes and store into
     /// [_arrayHelperClassPrefix].
     final base = 'ArrayHelper';
     _arrayHelperClassPrefix = base;
     var suffixInt = 0;
     for (var i = 0; i < allNameSet.length; i++) {
       if (allNameSet.elementAt(i).startsWith(_arrayHelperClassPrefix)) {
         // Not a unique prefix, start over with a new suffix.
         i = -1;
         suffixInt++;
         _arrayHelperClassPrefix = '$base$suffixInt';
       }
     }

     _resetUniqueNamersNamers();
   }

   /// Resolved name conflict using [makeUnique] and marks the result as used in
   /// all [markUsed].
   String _resolveNameConflict({
     required String name,
     required UniqueNamer makeUnique,
     List<UniqueNamer> markUsed = const [],
   }) {
     final s = makeUnique.makeUnique(name);
     for (final un in markUsed) {
       un.markUsed(s);
     }
     return s;
   }

   /// Resets the namers to initial state. Namers are reset before generating.
   void _resetUniqueNamersNamers() {
     _topLevelUniqueNamer = _initialTopLevelUniqueNamer.clone();
     _wrapperLevelUniqueNamer = _initialWrapperLevelUniqueNamer.clone();
   }

   void markImportUsed(LibraryImport import) {
     _usedImports.add(import);
   }

   /// Writes all bindings to a String.
   String generate() {
     final s = StringBuffer();

     // We write the source first to determine which imports are actually
     // referenced. Headers and [s] are then combined into the final result.
     final result = StringBuffer();

     // Reset unique namers to initial state.
     _resetUniqueNamersNamers();

     // Write file header (if any).
     if (header != null) {
       result.writeln(header);
     }

     // Write auto generated declaration.
     result.write(makeDoc(
         'AUTO GENERATED FILE, DO NOT EDIT.\n\nGenerated by `package:ffigen`.'));

     // Write lint ignore if not specified by user already.
     if (!RegExp(r'ignore_for_file:\s*type\s*=\s*lint').hasMatch(header ?? '')) {
       result.write(makeDoc('ignore_for_file: type=lint'));
     }

     // If there are any @Native bindings, the file needs to have an
     // `@DefaultAsset` annotation for the symbols to resolve properly. This
     // avoids duplicating the asset on every element.
     // Since the annotation goes on a `library;` directive, it needs to appear
     // before other definitions in the file.
     if (ffiNativeBindings.isNotEmpty && nativeAssetId != null) {
       result
         ..writeln("@$ffiLibraryPrefix.DefaultAsset('$nativeAssetId')")
         ..writeln('library;\n');
     }

     /// Write [lookUpBindings].
     if (lookUpBindings.isNotEmpty) {
       // Write doc comment for wrapper class.
       if (classDocComment != null) {
         s.write(makeDartDoc(classDocComment!));
       }
       // Write wrapper classs.
       s.write('class $_className{\n');
       // Write dylib.
       s.write('/// Holds the symbol lookup function.\n');
       s.write(
           'final $ffiLibraryPrefix.Pointer<T> Function<T extends $ffiLibraryPrefix.NativeType>(String symbolName) $lookupFuncIdentifier;\n');
       s.write('\n');
       //Write doc comment for wrapper class constructor.
       s.write(makeDartDoc('The symbols are looked up in [dynamicLibrary].'));
       // Write wrapper class constructor.
       s.write(
           '$_className($ffiLibraryPrefix.DynamicLibrary dynamicLibrary): $lookupFuncIdentifier = dynamicLibrary.lookup;\n\n');
       //Write doc comment for wrapper class named constructor.
       s.write(makeDartDoc('The symbols are looked up with [lookup].'));
       // Write wrapper class named constructor.
       s.write(
           '$_className.fromLookup($ffiLibraryPrefix.Pointer<T> Function<T extends $ffiLibraryPrefix.NativeType>(String symbolName) lookup): $lookupFuncIdentifier = lookup;\n\n');
       for (final b in lookUpBindings) {
         s.write(b.toBindingString(this).string);
       }
       if (symbolAddressWriter.shouldGenerate) {
         s.write(symbolAddressWriter.writeObject(this));
       }

       s.write('}\n\n');
     }

     if (ffiNativeBindings.isNotEmpty) {
       for (final b in ffiNativeBindings) {
         s.write(b.toBindingString(this).string);
       }

       if (symbolAddressWriter.shouldGenerate) {
         s.write(symbolAddressWriter.writeObject(this));
       }
     }

     if (symbolAddressWriter.shouldGenerate) {
       s.write(symbolAddressWriter.writeClass(this));
     }

     /// Write [noLookUpBindings].
     for (final b in noLookUpBindings) {
       s.write(b.toBindingString(this).string);
     }

     // Write neccesary imports.
     for (final lib in _usedImports) {
       result
         ..write("import '${lib.importPath}' as ${lib.prefix};")
         ..write('\n');
     }
     result.write(s);

     _canGenerateSymbolOutput = true;
     return result.toString();
   }

   Map<String, dynamic> generateSymbolOutputYamlMap(String importFilePath) {
     final bindings = <Binding>[
       ...noLookUpBindings,
       ...ffiNativeBindings,
       ...lookUpBindings
     ];
     if (!canGenerateSymbolOutput) {
       throw Exception(
           "Invalid state: generateSymbolOutputYamlMap() called before generate()");
     }
     final result = <String, dynamic>{};

     result[strings.formatVersion] = strings.symbolFileFormatVersion;
     result[strings.files] = <String, dynamic>{};
     result[strings.files][importFilePath] = <String, dynamic>{};

     final fileConfig = result[strings.files][importFilePath];
     fileConfig[strings.usedConfig] = <String, dynamic>{};

     // Warn for macros.
     final hasMacroBindings = bindings.any(
         (element) => element is Constant && element.usr.contains('@macro@'));
     if (hasMacroBindings) {
       _logger.info(
           'Removing all Macros from symbol file since they cannot be cross referenced reliably.');
     }
     // Remove internal bindings and macros.
     bindings.removeWhere((element) {
       return element.isInternal ||
           (element is Constant && element.usr.contains('@macro@'));
     });
     // Sort bindings alphabetically by USR.
     bindings.sort((a, b) => a.usr.compareTo(b.usr));
     fileConfig[strings.usedConfig][strings.ffiNative] = bindings
         .whereType<Func>()
         .any((element) => element.ffiNativeConfig.enabled);
     fileConfig[strings.symbols] = <String, dynamic>{};
     final symbolConfig = fileConfig[strings.symbols];
     for (final binding in bindings) {
       symbolConfig[binding.usr] = {
         strings.name: binding.name,
       };
     }
     return result;
   }
 }

 /// Manages the generated `_SymbolAddress` class.
 class SymbolAddressWriter {
   final List<_SymbolAddressUnit> _addresses = [];

   /// Used to check if we need to generate `_SymbolAddress` class.
   bool get shouldGenerate => _addresses.isNotEmpty;

   bool get hasNonNativeAddress => _addresses.any((e) => !e.native);

   void addSymbol({
     required String type,
     required String name,
     required String ptrName,
   }) {
     _addresses.add(_SymbolAddressUnit(type, name, ptrName, false));
   }

   void addNativeSymbol({required String type, required String name}) {
     _addresses.add(_SymbolAddressUnit(type, name, '', true));
   }

   String writeObject(Writer w) {
     final className = w._symbolAddressClassName;
     final fieldName = w._symbolAddressVariableName;

     if (hasNonNativeAddress) {
       return 'late final $fieldName = $className(this);';
     } else {
       return 'const $fieldName = $className();';
     }
   }

   String writeClass(Writer w) {
     final sb = StringBuffer();
     sb.write('class ${w._symbolAddressClassName} {\n');

     if (hasNonNativeAddress) {
       // Write Library object.
       sb.write('final ${w._className} ${w._symbolAddressLibraryVarName};\n');
       // Write Constructor.
       sb.write(
           '${w._symbolAddressClassName}(this.${w._symbolAddressLibraryVarName});\n');
     } else {
       // Native bindings are top-level, so we don't need a field here.
       sb.write('const ${w._symbolAddressClassName}();');
     }

     for (final address in _addresses) {
       sb.write('${address.type} get ${address.name} => ');

       if (address.native) {
         // For native fields and functions, we can use Native.addressOf to look
         // up their address.
         // The name of address getter shadows the actual element in the library,
         // so we need to use a self-import.
         final arg = '${w.selfImportPrefix}.${address.name}';
         sb.writeln('${w.ffiLibraryPrefix}.Native.addressOf($arg);');
       } else {
         // For other elements, the generator will write a private field of type
         // Pointer which we can reference here.
         sb.writeln('${w._symbolAddressLibraryVarName}.${address.ptrName};');
       }
     }
     sb.write('}\n');
     return sb.toString();
   }
 }

 /// Holds the data for a single symbol address.
 class _SymbolAddressUnit {
   final String type, name, ptrName;

   /// Whether the symbol we're looking up has been declared with `@Native`.
   final bool native;

   _SymbolAddressUnit(this.type, this.name, this.ptrName, this.native);
 }
	// Copyright (c) 2020, the Dart project authors. Please see the AUTHORS file
	// for details. All rights reserved. Use of this source code is governed by a
	// BSD-style license that can be found in the LICENSE file.

	import 'package:ffigen/src/code_generator.dart';
	import 'package:ffigen/src/code_generator/utils.dart';
	import 'package:logging/logging.dart';

	import '../strings.dart' as strings;

	final _logger = Logger('ffigen.code_generator.writer');

	/// To store generated String bindings.
	class Writer {
	final String? header;

	/// Holds bindings, which lookup symbols.
	final List<Binding> lookUpBindings;

	/// Holds bindings, which lookup symbols through `FfiNative`.
	final List<Binding> ffiNativeBindings;

	/// Holds bindings which don't lookup symbols.
	final List<Binding> noLookUpBindings;

	/// The default asset id to use for [ffiNativeBindings].
	final String? nativeAssetId;

	/// Manages the `_SymbolAddress` class.
	final symbolAddressWriter = SymbolAddressWriter();

	late String _className;
	String get className => _className;

	final String? classDocComment;

	String? _ffiLibraryPrefix;
	String get ffiLibraryPrefix {
	if (_ffiLibraryPrefix != null) {
	return _ffiLibraryPrefix!;
	}

	final import = _usedImports.firstWhere(
	(element) => element.name == ffiImport.name,
	orElse: () => ffiImport);
	_usedImports.add(import);
	return _ffiLibraryPrefix = import.prefix;
	}

	String? _ffiPkgLibraryPrefix;
	String get ffiPkgLibraryPrefix {
	if (_ffiPkgLibraryPrefix != null) {
	return _ffiPkgLibraryPrefix!;
	}

	final import = _usedImports.firstWhere(
	(element) => element.name == ffiPkgImport.name,
	orElse: () => ffiPkgImport);
	_usedImports.add(import);
	return _ffiPkgLibraryPrefix = import.prefix;
	}

	String? _objcPkgPrefix;
	String get objcPkgPrefix {
	if (_objcPkgPrefix != null) {
	return _objcPkgPrefix!;
	}

	final import = _usedImports.firstWhere(
	(element) => element.name == objcPkgImport.name,
	orElse: () => objcPkgImport);
	_usedImports.add(import);
	return _objcPkgPrefix = import.prefix;
	}

	late String selfImportPrefix = () {
	final import = _usedImports
	.firstWhere((element) => element.name == self.name, orElse: () => self);
	_usedImports.add(import);
	return import.prefix;
	}();

	final Set<LibraryImport> _usedImports = {};

	late String _lookupFuncIdentifier;
	String get lookupFuncIdentifier => _lookupFuncIdentifier;

	late String _symbolAddressClassName;
	late String _symbolAddressVariableName;
	late String _symbolAddressLibraryVarName;

	/// Initial namers set after running constructor. Namers are reset to this
	/// initial state everytime [generate] is called.
	late UniqueNamer _initialTopLevelUniqueNamer, _initialWrapperLevelUniqueNamer;

	/// Used by [Binding]s for generating required code.
	late UniqueNamer _topLevelUniqueNamer, _wrapperLevelUniqueNamer;
	UniqueNamer get topLevelUniqueNamer => _topLevelUniqueNamer;
	UniqueNamer get wrapperLevelUniqueNamer => _wrapperLevelUniqueNamer;

	late String _arrayHelperClassPrefix;

	/// Guaranteed to be a unique prefix.
	String get arrayHelperClassPrefix => _arrayHelperClassPrefix;

	/// Set true after calling [generate]. Indicates if
	/// [generateSymbolOutputYamlMap] can be called.
	bool get canGenerateSymbolOutput => _canGenerateSymbolOutput;
	bool _canGenerateSymbolOutput = false;

	/// [_usedUpNames] should contain names of all the declarations which are
	/// already used. This is used to avoid name collisions.
	Writer({
	required this.lookUpBindings,
	required this.ffiNativeBindings,
	required this.noLookUpBindings,
	required String className,
	required this.nativeAssetId,
	Set<LibraryImport>? additionalImports,
	this.classDocComment,
	this.header,
	}) {
	final globalLevelNameSet = noLookUpBindings.map((e) => e.name).toSet();
	final wrapperLevelNameSet = lookUpBindings.map((e) => e.name).toSet();
	final allNameSet = <String>{}
	..addAll(globalLevelNameSet)
	..addAll(wrapperLevelNameSet);

	_initialTopLevelUniqueNamer = UniqueNamer(globalLevelNameSet);
	_initialWrapperLevelUniqueNamer = UniqueNamer(wrapperLevelNameSet);
	final allLevelsUniqueNamer = UniqueNamer(allNameSet);

	/// Wrapper class name must be unique among all names.
	_className = _resolveNameConflict(
	name: className,
	makeUnique: allLevelsUniqueNamer,
	markUsed: [_initialWrapperLevelUniqueNamer, _initialTopLevelUniqueNamer],
	);

	/// Library imports prefix should be unique unique among all names.
	if (additionalImports != null) {
	for (final lib in additionalImports) {
	lib.prefix = _resolveNameConflict(
	name: lib.prefix,
	makeUnique: allLevelsUniqueNamer,
	markUsed: [
	_initialWrapperLevelUniqueNamer,
	_initialTopLevelUniqueNamer
	],
	);
	}
	}

	/// [_lookupFuncIdentifier] should be unique in top level.
	_lookupFuncIdentifier = _resolveNameConflict(
	name: '_lookup',
	makeUnique: _initialTopLevelUniqueNamer,
	markUsed: [_initialTopLevelUniqueNamer],
	);

	/// Resolve name conflicts of identifiers used for SymbolAddresses.
	_symbolAddressClassName = _resolveNameConflict(
	name: '_SymbolAddresses',
	makeUnique: allLevelsUniqueNamer,
	markUsed: [_initialWrapperLevelUniqueNamer, _initialTopLevelUniqueNamer],
	);
	_symbolAddressVariableName = _resolveNameConflict(
	name: 'addresses',
	makeUnique: _initialWrapperLevelUniqueNamer,
	markUsed: [_initialWrapperLevelUniqueNamer],
	);
	_symbolAddressLibraryVarName = _resolveNameConflict(
	name: '_library',
	makeUnique: _initialWrapperLevelUniqueNamer,
	markUsed: [_initialWrapperLevelUniqueNamer],
	);

	/// Finding a unique prefix for Array Helper Classes and store into
	/// [_arrayHelperClassPrefix].
	final base = 'ArrayHelper';
	_arrayHelperClassPrefix = base;
	var suffixInt = 0;
	for (var i = 0; i < allNameSet.length; i++) {
	if (allNameSet.elementAt(i).startsWith(_arrayHelperClassPrefix)) {
	// Not a unique prefix, start over with a new suffix.
	i = -1;
	suffixInt++;
	_arrayHelperClassPrefix = '$base$suffixInt';
	}
	}

	_resetUniqueNamersNamers();
	}

	/// Resolved name conflict using [makeUnique] and marks the result as used in
	/// all [markUsed].
	String _resolveNameConflict({
	required String name,
	required UniqueNamer makeUnique,
	List<UniqueNamer> markUsed = const [],
	}) {
	final s = makeUnique.makeUnique(name);
	for (final un in markUsed) {
	un.markUsed(s);
	}
	return s;
	}

	/// Resets the namers to initial state. Namers are reset before generating.
	void _resetUniqueNamersNamers() {
	_topLevelUniqueNamer = _initialTopLevelUniqueNamer.clone();
	_wrapperLevelUniqueNamer = _initialWrapperLevelUniqueNamer.clone();
	}

	void markImportUsed(LibraryImport import) {
	_usedImports.add(import);
	}

	/// Writes all bindings to a String.
	String generate() {
	final s = StringBuffer();

	// We write the source first to determine which imports are actually
	// referenced. Headers and [s] are then combined into the final result.
	final result = StringBuffer();

	// Reset unique namers to initial state.
	_resetUniqueNamersNamers();

	// Write file header (if any).
	if (header != null) {
	result.writeln(header);
	}

	// Write auto generated declaration.
	result.write(makeDoc(
	'AUTO GENERATED FILE, DO NOT EDIT.\n\nGenerated by `package:ffigen`.'));

	// Write lint ignore if not specified by user already.
	if (!RegExp(r'ignore_for_file:\stype\s=\s*lint').hasMatch(header ?? '')) {
	result.write(makeDoc('ignore_for_file: type=lint'));
	}

	// If there are any @Native bindings, the file needs to have an
	// `@DefaultAsset` annotation for the symbols to resolve properly. This
	// avoids duplicating the asset on every element.
	// Since the annotation goes on a `library;` directive, it needs to appear
	// before other definitions in the file.
	if (ffiNativeBindings.isNotEmpty && nativeAssetId != null) {
	result
	..writeln("@$ffiLibraryPrefix.DefaultAsset('$nativeAssetId')")
	..writeln('library;\n');
	}

	/// Write [lookUpBindings].
	if (lookUpBindings.isNotEmpty) {
	// Write doc comment for wrapper class.
	if (classDocComment != null) {
	s.write(makeDartDoc(classDocComment!));
	}
	// Write wrapper classs.
	s.write('class $_className{\n');
	// Write dylib.
	s.write('/// Holds the symbol lookup function.\n');
	s.write(
	'final $ffiLibraryPrefix.Pointer<T> Function<T extends $ffiLibraryPrefix.NativeType>(String symbolName) $lookupFuncIdentifier;\n');
	s.write('\n');
	//Write doc comment for wrapper class constructor.
	s.write(makeDartDoc('The symbols are looked up in [dynamicLibrary].'));
	// Write wrapper class constructor.
	s.write(
	'$_className($ffiLibraryPrefix.DynamicLibrary dynamicLibrary): $lookupFuncIdentifier = dynamicLibrary.lookup;\n\n');
	//Write doc comment for wrapper class named constructor.
	s.write(makeDartDoc('The symbols are looked up with [lookup].'));
	// Write wrapper class named constructor.
	s.write(
	'$_className.fromLookup($ffiLibraryPrefix.Pointer<T> Function<T extends $ffiLibraryPrefix.NativeType>(String symbolName) lookup): $lookupFuncIdentifier = lookup;\n\n');
	for (final b in lookUpBindings) {
	s.write(b.toBindingString(this).string);
	}
	if (symbolAddressWriter.shouldGenerate) {
	s.write(symbolAddressWriter.writeObject(this));
	}

	s.write('}\n\n');
	}

	if (ffiNativeBindings.isNotEmpty) {
	for (final b in ffiNativeBindings) {
	s.write(b.toBindingString(this).string);
	}

	if (symbolAddressWriter.shouldGenerate) {
	s.write(symbolAddressWriter.writeObject(this));
	}
	}

	if (symbolAddressWriter.shouldGenerate) {
	s.write(symbolAddressWriter.writeClass(this));
	}

	/// Write [noLookUpBindings].
	for (final b in noLookUpBindings) {
	s.write(b.toBindingString(this).string);
	}

	// Write neccesary imports.
	for (final lib in _usedImports) {
	result
	..write("import '${lib.importPath}' as ${lib.prefix};")
	..write('\n');
	}
	result.write(s);

	_canGenerateSymbolOutput = true;
	return result.toString();
	}

	Map<String, dynamic> generateSymbolOutputYamlMap(String importFilePath) {
	final bindings = <Binding>[
	...noLookUpBindings,
	...ffiNativeBindings,
	...lookUpBindings
	];
	if (!canGenerateSymbolOutput) {
	throw Exception(
	"Invalid state: generateSymbolOutputYamlMap() called before generate()");
	}
	final result = <String, dynamic>{};

	result[strings.formatVersion] = strings.symbolFileFormatVersion;
	result[strings.files] = <String, dynamic>{};
	result[strings.files][importFilePath] = <String, dynamic>{};

	final fileConfig = result[strings.files][importFilePath];
	fileConfig[strings.usedConfig] = <String, dynamic>{};

	// Warn for macros.
	final hasMacroBindings = bindings.any(
	(element) => element is Constant && element.usr.contains('@macro@'));
	if (hasMacroBindings) {
	_logger.info(
	'Removing all Macros from symbol file since they cannot be cross referenced reliably.');
	}
	// Remove internal bindings and macros.
	bindings.removeWhere((element) {
	return element.isInternal \|\|
	(element is Constant && element.usr.contains('@macro@'));
	});
	// Sort bindings alphabetically by USR.
	bindings.sort((a, b) => a.usr.compareTo(b.usr));
	fileConfig[strings.usedConfig][strings.ffiNative] = bindings
	.whereType<Func>()
	.any((element) => element.ffiNativeConfig.enabled);
	fileConfig[strings.symbols] = <String, dynamic>{};
	final symbolConfig = fileConfig[strings.symbols];
	for (final binding in bindings) {
	symbolConfig[binding.usr] = {
	strings.name: binding.name,
	};
	}
	return result;
	}
	}

	/// Manages the generated `_SymbolAddress` class.
	class SymbolAddressWriter {
	final List<_SymbolAddressUnit> _addresses = [];

	/// Used to check if we need to generate `_SymbolAddress` class.
	bool get shouldGenerate => _addresses.isNotEmpty;

	bool get hasNonNativeAddress => _addresses.any((e) => !e.native);

	void addSymbol({
	required String type,
	required String name,
	required String ptrName,
	}) {
	_addresses.add(_SymbolAddressUnit(type, name, ptrName, false));
	}

	void addNativeSymbol({required String type, required String name}) {
	_addresses.add(_SymbolAddressUnit(type, name, '', true));
	}

	String writeObject(Writer w) {
	final className = w._symbolAddressClassName;
	final fieldName = w._symbolAddressVariableName;

	if (hasNonNativeAddress) {
	return 'late final $fieldName = $className(this);';
	} else {
	return 'const $fieldName = $className();';
	}
	}

	String writeClass(Writer w) {
	final sb = StringBuffer();
	sb.write('class ${w._symbolAddressClassName} {\n');

	if (hasNonNativeAddress) {
	// Write Library object.
	sb.write('final ${w._className} ${w._symbolAddressLibraryVarName};\n');
	// Write Constructor.
	sb.write(
	'${w._symbolAddressClassName}(this.${w._symbolAddressLibraryVarName});\n');
	} else {
	// Native bindings are top-level, so we don't need a field here.
	sb.write('const ${w._symbolAddressClassName}();');
	}

	for (final address in _addresses) {
	sb.write('${address.type} get ${address.name} => ');

	if (address.native) {
	// For native fields and functions, we can use Native.addressOf to look
	// up their address.
	// The name of address getter shadows the actual element in the library,
	// so we need to use a self-import.
	final arg = '${w.selfImportPrefix}.${address.name}';
	sb.writeln('${w.ffiLibraryPrefix}.Native.addressOf($arg);');
	} else {
	// For other elements, the generator will write a private field of type
	// Pointer which we can reference here.
	sb.writeln('${w._symbolAddressLibraryVarName}.${address.ptrName};');
	}
	}
	sb.write('}\n');
	return sb.toString();
	}
	}

	/// Holds the data for a single symbol address.
	class _SymbolAddressUnit {
	final String type, name, ptrName;

	/// Whether the symbol we're looking up has been declared with `@Native`.
	final bool native;

	_SymbolAddressUnit(this.type, this.name, this.ptrName, this.native);
	}