lib/src/code_generator/writer.dart

// 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/utils.dart';
import 'package:meta/meta.dart';

import 'binding_string.dart';

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

  final UniqueNamer uniqueNamer;

  String _ffiLibraryPrefix;
  String get ffiLibraryPrefix =>
      _ffiLibraryPrefix ??= uniqueNamer.makeUnique('ffi');

  String _dylibIdentifier;
  String get dylibIdentifier =>
      _dylibIdentifier ??= uniqueNamer.makeUnique('_dylib');

  String _arrayHelperClassPrefix;

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

  final List<BindingString> _bindings = [];

  /// [usedUpNames] should contain names of all the declarations which are
  /// already used. This is used to avoid name collisions.
  Writer({
    @required Set<String> usedUpNames,
    String initFunctionIdentifier = 'init',
    this.header,
  })  : uniqueNamer = UniqueNamer(usedUpNames),
        assert(initFunctionIdentifier != null) {
    _initFunctionIdentifier =
        uniqueNamer.makeUnique(initFunctionIdentifier);

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

    // Write file header (if any).
    if (header != null) {
      s.write(header);
      s.write('\n');
    } else {
      // Write default header, in case none was provided.
      s.write('''/// AUTO GENERATED FILE, DO NOT EDIT.
///
/// Generated by `package:ffigen`.
''');
    }

    // Write neccesary imports.
    s.write("import 'dart:ffi' as $ffiLibraryPrefix;\n");
    s.write('\n');

    // Write dylib.
    s.write('/// Holds the Dynamic library.\n');
    s.write('$ffiLibraryPrefix.DynamicLibrary ${dylibIdentifier};\n');
    s.write('\n');
    s.write('/// Initialises the Dynamic library.\n');
    s.write(
        'void $_initFunctionIdentifier($ffiLibraryPrefix.DynamicLibrary dynamicLibrary){\n');
    s.write('  ${dylibIdentifier} = dynamicLibrary;\n');
    s.write('}\n');

    // Write bindings.
    for (final bs in _bindings) {
      s.write(bs.string);
    }

    return s.toString();
  }

  void addBindingString(BindingString b) {
    _bindings.add(b);
  }
}