lib/src/code_generator/struc.dart - ffigen - 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/typedef.dart';

 import 'binding.dart';
 import 'binding_string.dart';
 import 'type.dart';
 import 'utils.dart';
 import 'writer.dart';

 /// A binding for C Struct.
 ///
 /// For a C structure -
 /// ```c
 /// struct C {
 ///   int a;
 ///   double b;
 ///   int c;
 /// };
 /// ```
 /// The generated dart code is -
 /// ```dart
 /// class Struct extends ffi.Struct{
 ///  @ffi.Int32()
 ///  int a;
 ///
 ///  @ffi.Double()
 ///  double b;
 ///
 ///  @ffi.Uint8()
 ///  int c;
 ///
 /// }
 /// ```
 class Struc extends NoLookUpBinding {
   List<Member> members;

   Struc({
     String? usr,
     String? originalName,
     required String name,
     String? dartDoc,
     List<Member>? members,
   })  : members = members ?? [],
         super(
           usr: usr,
           originalName: originalName,
           name: name,
           dartDoc: dartDoc,
         );

   List<int> _getArrayDimensionLengths(Type type) {
     final array = <int>[];
     var startType = type;
     while (startType.broadType == BroadType.ConstantArray) {
       array.add(startType.length!);
       startType = startType.child!;
     }
     return array;
   }

   List<Typedef>? _typedefDependencies;
   @override
   List<Typedef> getTypedefDependencies(Writer w) {
     if (_typedefDependencies == null) {
       _typedefDependencies = <Typedef>[];

       // Write typedef's required by members and resolve name conflicts.
       for (final m in members) {
         final base = m.type.getBaseType();
         if (base.broadType == BroadType.NativeFunction) {
           _typedefDependencies!.addAll(base.nativeFunc!.getDependencies());
         }
       }
     }
     return _typedefDependencies ?? [];
   }

   @override
   BindingString toBindingString(Writer w) {
     final s = StringBuffer();
     final enclosingClassName = name;
     if (dartDoc != null) {
       s.write(makeDartDoc(dartDoc!));
     }

     final helpers = <ArrayHelper>[];

     final expandedArrayItemPrefix = getUniqueExpandedArrayItemPrefix();

     /// Adding [enclosingClassName] because dart doesn't allow class member
     /// to have the same name as the class.
     final localUniqueNamer = UniqueNamer({enclosingClassName});

     // Write class declaration.
     s.write(
         'class $enclosingClassName extends ${w.ffiLibraryPrefix}.Struct{\n');
     for (final m in members) {
       final memberName = localUniqueNamer.makeUnique(m.name);
       if (m.type.broadType == BroadType.ConstantArray) {
         // TODO(5): Remove array helpers when inline array support arives.
         final arrayHelper = ArrayHelper(
           helperClassGroupName:
               '${w.arrayHelperClassPrefix}_${enclosingClassName}_${memberName}',
           elementType: m.type.getBaseArrayType(),
           dimensions: _getArrayDimensionLengths(m.type),
           name: memberName,
           structName: enclosingClassName,
           elementNamePrefix: '${expandedArrayItemPrefix}${memberName}_item_',
         );
         s.write(arrayHelper.declarationString(w));
         helpers.add(arrayHelper);
       } else {
         const depth = '  ';
         if (m.dartDoc != null) {
           s.write(depth + '/// ');
           s.writeAll(m.dartDoc!.split('\n'), '\n' + depth + '/// ');
           s.write('\n');
         }
         if (m.type.isPrimitive) {
           s.write('$depth@${m.type.getCType(w)}()\n');
         }
         s.write('${depth}external ${m.type.getDartType(w)} ${memberName};\n\n');
       }
     }
     s.write('}\n\n');

     for (final helper in helpers) {
       s.write(helper.helperClassString(w));
     }

     return BindingString(type: BindingStringType.struc, string: s.toString());
   }

   /// Gets a unique prefix in local namespace for expanded array items.
   String getUniqueExpandedArrayItemPrefix() {
     final base = '_unique';
     var expandedArrayItemPrefix = base;
     var suffixInt = 0;
     for (var i = 0; i < members.length; i++) {
       if (members[i].name.startsWith(expandedArrayItemPrefix)) {
         // Not a unique prefix, start over with a new suffix.
         i = -1;
         suffixInt++;
         expandedArrayItemPrefix = '${base}${suffixInt}';
       }
     }
     return expandedArrayItemPrefix + '_';
   }
 }

 class Member {
   final String? dartDoc;
   final String originalName;
   final String name;
   final Type type;

   const Member({
     String? originalName,
     required this.name,
     required this.type,
     this.dartDoc,
   }) : originalName = originalName ?? name;
 }

 // Helper bindings for struct array.
 class ArrayHelper {
   final Type elementType;
   final List<int> dimensions;
   final String? structName;

   final String? name;
   final String helperClassGroupName;
   final String elementNamePrefix;

   int? _expandedArrayLength;
   int get expandedArrayLength {
     if (_expandedArrayLength != null) return _expandedArrayLength!;

     var arrayLength = 1;
     for (final i in dimensions) {
       arrayLength = arrayLength * i;
     }
     return arrayLength;
   }

   ArrayHelper({
     required this.elementType,
     required this.dimensions,
     required this.structName,
     required this.name,
     required this.helperClassGroupName,
     required this.elementNamePrefix,
   });

   /// Create declaration binding, added inside the struct binding.
   String declarationString(Writer w) {
     final s = StringBuffer();
     final arrayDartType = elementType.getDartType(w);
     final arrayCType = elementType.getCType(w);

     for (var i = 0; i < expandedArrayLength; i++) {
       if (elementType.isPrimitive) {
         s.write('  @${arrayCType}()\n');
       }
       s.write('  external ${arrayDartType} ${elementNamePrefix}$i;\n');
     }

     s.write('/// Helper for array `$name`.\n');
     s.write(
         '${helperClassGroupName}_level0 get $name => ${helperClassGroupName}_level0(this, $dimensions, 0, 0);\n');

     return s.toString();
   }

   String helperClassString(Writer w) {
     final s = StringBuffer();
     final arrayType = elementType.getDartType(w);
     for (var dim = 0; dim < dimensions.length; dim++) {
       final helperClassName = '${helperClassGroupName}_level${dim}';
       final structIdentifier = '_struct';
       final dimensionsIdentifier = 'dimensions';
       final levelIdentifier = 'level';
       final absoluteIndexIdentifier = '_absoluteIndex';
       final checkBoundsFunctionIdentifier = '_checkBounds';
       final legthIdentifier = 'length';

       s.write('/// Helper for array `$name` in struct `$structName`.\n');

       // Write class declaration.
       s.write('class ${helperClassName}{\n');
       s.write('final $structName $structIdentifier;\n');
       s.write('final List<int> $dimensionsIdentifier;\n');
       s.write('final int $levelIdentifier;\n');
       s.write('final int $absoluteIndexIdentifier;\n');
       s.write(
           'int get $legthIdentifier => $dimensionsIdentifier[$levelIdentifier];\n');

       // Write class constructor.
       s.write(
           '$helperClassName(this.$structIdentifier, this.$dimensionsIdentifier, this.$levelIdentifier, this.$absoluteIndexIdentifier);\n');

       // Write checkBoundsFunction.
       s.write('''
   void $checkBoundsFunctionIdentifier(int index) {
     if (index >= $legthIdentifier || index < 0) {
       throw RangeError('Dimension \$$levelIdentifier: index not in range 0..\${$legthIdentifier} exclusive.');
     }
   }
   ''');
       // If this isn't the last level.
       if (dim + 1 != dimensions.length) {
         // Override [] operator.
         s.write('''
   ${helperClassGroupName}_level${dim + 1} operator [](int index) {
     $checkBoundsFunctionIdentifier(index);
     var offset = index;
     for (var i = level + 1; i < $dimensionsIdentifier.length; i++) {
       offset *= $dimensionsIdentifier[i];
     }
     return ${helperClassGroupName}_level${dim + 1}(
         $structIdentifier, $dimensionsIdentifier, $levelIdentifier + 1, $absoluteIndexIdentifier + offset);
   }
 ''');
       } else {
         // This is the last level, add switching logic here.
         // Override [] operator.
         s.write('$arrayType operator[](int index){\n');
         s.write('$checkBoundsFunctionIdentifier(index);\n');
         s.write('switch($absoluteIndexIdentifier+index){\n');
         for (var i = 0; i < expandedArrayLength; i++) {
           s.write('case $i:\n');
           s.write('  return $structIdentifier.${elementNamePrefix}$i;\n');
         }
         s.write('default:\n');
         s.write("  throw Exception('Invalid Array Helper generated.');");
         s.write('}\n');
         s.write('}\n');

         // Override []= operator.
         s.write('void operator[]=(int index, $arrayType value){\n');
         s.write('$checkBoundsFunctionIdentifier(index);\n');
         s.write('switch($absoluteIndexIdentifier+index){\n');
         for (var i = 0; i < expandedArrayLength; i++) {
           s.write('case $i:\n');
           s.write('  $structIdentifier.${elementNamePrefix}$i = value;\n');
           s.write('  break;\n');
         }
         s.write('default:\n');
         s.write("  throw Exception('Invalid Array Helper generated.');\n");
         s.write('}\n');
         s.write('}\n');
       }
       s.write('}\n');
     }
     return s.toString();
   }
 }
	// 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/typedef.dart';

	import 'binding.dart';
	import 'binding_string.dart';
	import 'type.dart';
	import 'utils.dart';
	import 'writer.dart';

	/// A binding for C Struct.
	///
	/// For a C structure -
	/// ```c
	/// struct C {
	/// int a;
	/// double b;
	/// int c;
	/// };
	/// ```
	/// The generated dart code is -
	/// ```dart
	/// class Struct extends ffi.Struct{
	/// @ffi.Int32()
	/// int a;
	///
	/// @ffi.Double()
	/// double b;
	///
	/// @ffi.Uint8()
	/// int c;
	///
	/// }
	/// ```
	class Struc extends NoLookUpBinding {
	List<Member> members;

	Struc({
	String? usr,
	String? originalName,
	required String name,
	String? dartDoc,
	List<Member>? members,
	}) : members = members ?? [],
	super(
	usr: usr,
	originalName: originalName,
	name: name,
	dartDoc: dartDoc,
	);

	List<int> _getArrayDimensionLengths(Type type) {
	final array = <int>[];
	var startType = type;
	while (startType.broadType == BroadType.ConstantArray) {
	array.add(startType.length!);
	startType = startType.child!;
	}
	return array;
	}

	List<Typedef>? _typedefDependencies;
	@override
	List<Typedef> getTypedefDependencies(Writer w) {
	if (_typedefDependencies == null) {
	_typedefDependencies = <Typedef>[];

	// Write typedef's required by members and resolve name conflicts.
	for (final m in members) {
	final base = m.type.getBaseType();
	if (base.broadType == BroadType.NativeFunction) {
	_typedefDependencies!.addAll(base.nativeFunc!.getDependencies());
	}
	}
	}
	return _typedefDependencies ?? [];
	}

	@override
	BindingString toBindingString(Writer w) {
	final s = StringBuffer();
	final enclosingClassName = name;
	if (dartDoc != null) {
	s.write(makeDartDoc(dartDoc!));
	}

	final helpers = <ArrayHelper>[];

	final expandedArrayItemPrefix = getUniqueExpandedArrayItemPrefix();

	/// Adding [enclosingClassName] because dart doesn't allow class member
	/// to have the same name as the class.
	final localUniqueNamer = UniqueNamer({enclosingClassName});

	// Write class declaration.
	s.write(
	'class $enclosingClassName extends ${w.ffiLibraryPrefix}.Struct{\n');
	for (final m in members) {
	final memberName = localUniqueNamer.makeUnique(m.name);
	if (m.type.broadType == BroadType.ConstantArray) {
	// TODO(5): Remove array helpers when inline array support arives.
	final arrayHelper = ArrayHelper(
	helperClassGroupName:
	'${w.arrayHelperClassPrefix}_${enclosingClassName}_${memberName}',
	elementType: m.type.getBaseArrayType(),
	dimensions: _getArrayDimensionLengths(m.type),
	name: memberName,
	structName: enclosingClassName,
	elementNamePrefix: '${expandedArrayItemPrefix}${memberName}_item_',
	);
	s.write(arrayHelper.declarationString(w));
	helpers.add(arrayHelper);
	} else {
	const depth = ' ';
	if (m.dartDoc != null) {
	s.write(depth + '/// ');
	s.writeAll(m.dartDoc!.split('\n'), '\n' + depth + '/// ');
	s.write('\n');
	}
	if (m.type.isPrimitive) {
	s.write('$depth@${m.type.getCType(w)}()\n');
	}
	s.write('${depth}external ${m.type.getDartType(w)} ${memberName};\n\n');
	}
	}
	s.write('}\n\n');

	for (final helper in helpers) {
	s.write(helper.helperClassString(w));
	}

	return BindingString(type: BindingStringType.struc, string: s.toString());
	}

	/// Gets a unique prefix in local namespace for expanded array items.
	String getUniqueExpandedArrayItemPrefix() {
	final base = '_unique';
	var expandedArrayItemPrefix = base;
	var suffixInt = 0;
	for (var i = 0; i < members.length; i++) {
	if (members[i].name.startsWith(expandedArrayItemPrefix)) {
	// Not a unique prefix, start over with a new suffix.
	i = -1;
	suffixInt++;
	expandedArrayItemPrefix = '${base}${suffixInt}';
	}
	}
	return expandedArrayItemPrefix + '_';
	}
	}

	class Member {
	final String? dartDoc;
	final String originalName;
	final String name;
	final Type type;

	const Member({
	String? originalName,
	required this.name,
	required this.type,
	this.dartDoc,
	}) : originalName = originalName ?? name;
	}

	// Helper bindings for struct array.
	class ArrayHelper {
	final Type elementType;
	final List<int> dimensions;
	final String? structName;

	final String? name;
	final String helperClassGroupName;
	final String elementNamePrefix;

	int? _expandedArrayLength;
	int get expandedArrayLength {
	if (_expandedArrayLength != null) return _expandedArrayLength!;

	var arrayLength = 1;
	for (final i in dimensions) {
	arrayLength = arrayLength * i;
	}
	return arrayLength;
	}

	ArrayHelper({
	required this.elementType,
	required this.dimensions,
	required this.structName,
	required this.name,
	required this.helperClassGroupName,
	required this.elementNamePrefix,
	});

	/// Create declaration binding, added inside the struct binding.
	String declarationString(Writer w) {
	final s = StringBuffer();
	final arrayDartType = elementType.getDartType(w);
	final arrayCType = elementType.getCType(w);

	for (var i = 0; i < expandedArrayLength; i++) {
	if (elementType.isPrimitive) {
	s.write(' @${arrayCType}()\n');
	}
	s.write(' external ${arrayDartType} ${elementNamePrefix}$i;\n');
	}

	s.write('/// Helper for array `$name`.\n');
	s.write(
	'${helperClassGroupName}_level0 get $name => ${helperClassGroupName}_level0(this, $dimensions, 0, 0);\n');

	return s.toString();
	}

	String helperClassString(Writer w) {
	final s = StringBuffer();
	final arrayType = elementType.getDartType(w);
	for (var dim = 0; dim < dimensions.length; dim++) {
	final helperClassName = '${helperClassGroupName}_level${dim}';
	final structIdentifier = '_struct';
	final dimensionsIdentifier = 'dimensions';
	final levelIdentifier = 'level';
	final absoluteIndexIdentifier = '_absoluteIndex';
	final checkBoundsFunctionIdentifier = '_checkBounds';
	final legthIdentifier = 'length';

	s.write('/// Helper for array `$name` in struct `$structName`.\n');

	// Write class declaration.
	s.write('class ${helperClassName}{\n');
	s.write('final $structName $structIdentifier;\n');
	s.write('final List<int> $dimensionsIdentifier;\n');
	s.write('final int $levelIdentifier;\n');
	s.write('final int $absoluteIndexIdentifier;\n');
	s.write(
	'int get $legthIdentifier => $dimensionsIdentifier[$levelIdentifier];\n');

	// Write class constructor.
	s.write(
	'$helperClassName(this.$structIdentifier, this.$dimensionsIdentifier, this.$levelIdentifier, this.$absoluteIndexIdentifier);\n');

	// Write checkBoundsFunction.
	s.write('''
	void $checkBoundsFunctionIdentifier(int index) {
	if (index >= $legthIdentifier \|\| index < 0) {
	throw RangeError('Dimension \$$levelIdentifier: index not in range 0..\${$legthIdentifier} exclusive.');
	}
	}
	''');
	// If this isn't the last level.
	if (dim + 1 != dimensions.length) {
	// Override [] operator.
	s.write('''
	${helperClassGroupName}_level${dim + 1} operator [](int index) {
	$checkBoundsFunctionIdentifier(index);
	var offset = index;
	for (var i = level + 1; i < $dimensionsIdentifier.length; i++) {
	offset *= $dimensionsIdentifier[i];
	}
	return ${helperClassGroupName}_level${dim + 1}(
	$structIdentifier, $dimensionsIdentifier, $levelIdentifier + 1, $absoluteIndexIdentifier + offset);
	}
	''');
	} else {
	// This is the last level, add switching logic here.
	// Override [] operator.
	s.write('$arrayType operator[](int index){\n');
	s.write('$checkBoundsFunctionIdentifier(index);\n');
	s.write('switch($absoluteIndexIdentifier+index){\n');
	for (var i = 0; i < expandedArrayLength; i++) {
	s.write('case $i:\n');
	s.write(' return $structIdentifier.${elementNamePrefix}$i;\n');
	}
	s.write('default:\n');
	s.write(" throw Exception('Invalid Array Helper generated.');");
	s.write('}\n');
	s.write('}\n');

	// Override []= operator.
	s.write('void operator[]=(int index, $arrayType value){\n');
	s.write('$checkBoundsFunctionIdentifier(index);\n');
	s.write('switch($absoluteIndexIdentifier+index){\n');
	for (var i = 0; i < expandedArrayLength; i++) {
	s.write('case $i:\n');
	s.write(' $structIdentifier.${elementNamePrefix}$i = value;\n');
	s.write(' break;\n');
	}
	s.write('default:\n');
	s.write(" throw Exception('Invalid Array Helper generated.');\n");
	s.write('}\n');
	s.write('}\n');
	}
	s.write('}\n');
	}
	return s.toString();
	}
	}