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feature: Add a way to invoke a command specifying optional values by …
…name (#1123) * Add NamedArgumentTypeAttribute * Add NamedArgumentTypeReader * Fix superflous empty line. * Fix logic for quoted arguments * Throw an exception with a tailored message. * Add a catch to wrap parsing/input errors * Trim potential excess whitespace * Fix an off-by-one * Support to read an IEnumerable property * Add a doc * Add assertion for the collection test
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src/Discord.Net.Commands/Attributes/NamedArgumentTypeAttribute.cs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,11 @@ | ||
| using System; | ||
|
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| namespace Discord.Commands | ||
| { | ||
| /// <summary> | ||
| /// Instructs the command system to treat command paramters of this type | ||
| /// as a collection of named arguments matching to its properties. | ||
| /// </summary> | ||
| [AttributeUsage(AttributeTargets.Class, AllowMultiple = false, Inherited = true)] | ||
| public sealed class NamedArgumentTypeAttribute : Attribute { } | ||
| } |
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191 changes: 191 additions & 0 deletions
191
src/Discord.Net.Commands/Readers/NamedArgumentTypeReader.cs
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,191 @@ | ||
| using System; | ||
| using System.Collections; | ||
| using System.Collections.Generic; | ||
| using System.Collections.Immutable; | ||
| using System.Linq; | ||
| using System.Reflection; | ||
| using System.Threading.Tasks; | ||
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| namespace Discord.Commands | ||
| { | ||
| internal sealed class NamedArgumentTypeReader<T> : TypeReader | ||
| where T : class, new() | ||
| { | ||
| private static readonly IReadOnlyDictionary<string, PropertyInfo> _tProps = typeof(T).GetTypeInfo().DeclaredProperties | ||
| .Where(p => p.SetMethod != null && p.SetMethod.IsPublic && !p.SetMethod.IsStatic) | ||
| .ToImmutableDictionary(p => p.Name, StringComparer.OrdinalIgnoreCase); | ||
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| private readonly CommandService _commands; | ||
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| public NamedArgumentTypeReader(CommandService commands) | ||
| { | ||
| _commands = commands; | ||
| } | ||
|
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| public override async Task<TypeReaderResult> ReadAsync(ICommandContext context, string input, IServiceProvider services) | ||
| { | ||
| var result = new T(); | ||
| var state = ReadState.LookingForParameter; | ||
| int beginRead = 0, currentRead = 0; | ||
|
|
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| while (state != ReadState.End) | ||
| { | ||
| try | ||
| { | ||
| var prop = Read(out var arg); | ||
| var propVal = await ReadArgumentAsync(prop, arg).ConfigureAwait(false); | ||
| if (propVal != null) | ||
| prop.SetMethod.Invoke(result, new[] { propVal }); | ||
| else | ||
| return TypeReaderResult.FromError(CommandError.ParseFailed, $"Could not parse the argument for the parameter '{prop.Name}' as type '{prop.PropertyType}'."); | ||
| } | ||
| catch (Exception ex) | ||
| { | ||
| //TODO: use the Exception overload after a rebase on latest | ||
| return TypeReaderResult.FromError(CommandError.Exception, ex.Message); | ||
| } | ||
| } | ||
|
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| return TypeReaderResult.FromSuccess(result); | ||
|
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| PropertyInfo Read(out string arg) | ||
| { | ||
| string currentParam = null; | ||
| char match = '\0'; | ||
|
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| for (; currentRead < input.Length; currentRead++) | ||
| { | ||
| var currentChar = input[currentRead]; | ||
| switch (state) | ||
| { | ||
| case ReadState.LookingForParameter: | ||
| if (Char.IsWhiteSpace(currentChar)) | ||
| continue; | ||
| else | ||
| { | ||
| beginRead = currentRead; | ||
| state = ReadState.InParameter; | ||
| } | ||
| break; | ||
| case ReadState.InParameter: | ||
| if (currentChar != ':') | ||
| continue; | ||
| else | ||
| { | ||
| currentParam = input.Substring(beginRead, currentRead - beginRead); | ||
| state = ReadState.LookingForArgument; | ||
| } | ||
| break; | ||
| case ReadState.LookingForArgument: | ||
| if (Char.IsWhiteSpace(currentChar)) | ||
| continue; | ||
| else | ||
| { | ||
| beginRead = currentRead; | ||
| state = (QuotationAliasUtils.GetDefaultAliasMap.TryGetValue(currentChar, out match)) | ||
| ? ReadState.InQuotedArgument | ||
| : ReadState.InArgument; | ||
| } | ||
| break; | ||
| case ReadState.InArgument: | ||
| if (!Char.IsWhiteSpace(currentChar)) | ||
| continue; | ||
| else | ||
| return GetPropAndValue(out arg); | ||
| case ReadState.InQuotedArgument: | ||
| if (currentChar != match) | ||
| continue; | ||
| else | ||
| return GetPropAndValue(out arg); | ||
| } | ||
| } | ||
|
|
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| if (currentParam == null) | ||
| throw new InvalidOperationException("No parameter name was read."); | ||
|
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| return GetPropAndValue(out arg); | ||
|
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| PropertyInfo GetPropAndValue(out string argv) | ||
| { | ||
| bool quoted = state == ReadState.InQuotedArgument; | ||
| state = (currentRead == (quoted ? input.Length - 1 : input.Length)) | ||
| ? ReadState.End | ||
| : ReadState.LookingForParameter; | ||
|
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| if (quoted) | ||
| { | ||
| argv = input.Substring(beginRead + 1, currentRead - beginRead - 1).Trim(); | ||
| currentRead++; | ||
| } | ||
| else | ||
| argv = input.Substring(beginRead, currentRead - beginRead); | ||
|
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| return _tProps[currentParam]; | ||
| } | ||
| } | ||
|
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| async Task<object> ReadArgumentAsync(PropertyInfo prop, string arg) | ||
| { | ||
| var elemType = prop.PropertyType; | ||
| bool isCollection = false; | ||
| if (elemType.GetTypeInfo().IsGenericType && elemType.GetGenericTypeDefinition() == typeof(IEnumerable<>)) | ||
| { | ||
| elemType = prop.PropertyType.GenericTypeArguments[0]; | ||
| isCollection = true; | ||
| } | ||
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| var overridden = prop.GetCustomAttribute<OverrideTypeReaderAttribute>(); | ||
| var reader = (overridden != null) | ||
| ? ModuleClassBuilder.GetTypeReader(_commands, elemType, overridden.TypeReader, services) | ||
| : (_commands.GetDefaultTypeReader(elemType) | ||
| ?? _commands.GetTypeReaders(elemType).FirstOrDefault().Value); | ||
|
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| if (reader != null) | ||
| { | ||
| if (isCollection) | ||
| { | ||
| var method = _readMultipleMethod.MakeGenericMethod(elemType); | ||
| var task = (Task<IEnumerable>)method.Invoke(null, new object[] { reader, context, arg.Split(','), services }); | ||
| return await task.ConfigureAwait(false); | ||
| } | ||
| else | ||
| return await ReadSingle(reader, context, arg, services).ConfigureAwait(false); | ||
| } | ||
| return null; | ||
| } | ||
| } | ||
|
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| private static async Task<object> ReadSingle(TypeReader reader, ICommandContext context, string arg, IServiceProvider services) | ||
| { | ||
| var readResult = await reader.ReadAsync(context, arg, services).ConfigureAwait(false); | ||
| return (readResult.IsSuccess) | ||
| ? readResult.BestMatch | ||
| : null; | ||
| } | ||
| private static async Task<IEnumerable> ReadMultiple<TObj>(TypeReader reader, ICommandContext context, IEnumerable<string> args, IServiceProvider services) | ||
| { | ||
| var objs = new List<TObj>(); | ||
| foreach (var arg in args) | ||
| { | ||
| var read = await ReadSingle(reader, context, arg.Trim(), services).ConfigureAwait(false); | ||
| if (read != null) | ||
| objs.Add((TObj)read); | ||
| } | ||
| return objs.ToImmutableArray(); | ||
| } | ||
| private static readonly MethodInfo _readMultipleMethod = typeof(NamedArgumentTypeReader<T>) | ||
| .GetTypeInfo() | ||
| .DeclaredMethods | ||
| .Single(m => m.IsPrivate && m.IsStatic && m.Name == nameof(ReadMultiple)); | ||
|
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| private enum ReadState | ||
| { | ||
| LookingForParameter, | ||
| InParameter, | ||
| LookingForArgument, | ||
| InArgument, | ||
| InQuotedArgument, | ||
| End | ||
| } | ||
| } | ||
| } |
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