From 530b120014c0ae7fc2994b21fc388ea36ddb4ce8 Mon Sep 17 00:00:00 2001 From: Jesse Plamondon-Willard Date: Sun, 8 Jul 2018 15:48:32 -0400 Subject: [PATCH] rewrite TypeReference comparison to handle more edge cases, exit earlier if possible, and encapsulate a bit more --- .../ModLoading/TypeReferenceComparer.cs | 308 +++++++++--------- 1 file changed, 150 insertions(+), 158 deletions(-) diff --git a/src/SMAPI/Framework/ModLoading/TypeReferenceComparer.cs b/src/SMAPI/Framework/ModLoading/TypeReferenceComparer.cs index 8d128b37..f7497789 100644 --- a/src/SMAPI/Framework/ModLoading/TypeReferenceComparer.cs +++ b/src/SMAPI/Framework/ModLoading/TypeReferenceComparer.cs @@ -1,21 +1,23 @@ +using System; using System.Collections.Generic; -using System.Text.RegularExpressions; +using System.Linq; using Mono.Cecil; namespace StardewModdingAPI.Framework.ModLoading { /// Performs heuristic equality checks for instances. + /// + /// This implementation compares instances to see if they likely + /// refer to the same type. While the implementation is obvious for types like System.Bool, + /// this class mainly exists to handle cases like System.Collections.Generic.Dictionary`2<!0,Netcode.NetRoot`1<!1>> + /// and System.Collections.Generic.Dictionary`2<TKey,Netcode.NetRoot`1<TValue>> + /// which are compatible, but not directly comparable. It does this by splitting each type name + /// into its component token types, and performing placeholder substitution (e.g. !0 to + /// TKey in the above example). If all components are equal after substitution, and the + /// tokens can all be mapped to the same generic type, the types are considered equal. + /// internal class TypeReferenceComparer : IEqualityComparer { - /********* - ** Properties - *********/ - /// A pattern matching type name substrings to strip for display. - private readonly Regex StripTypeNamePattern = new Regex(@"`\d+(?=<)", RegexOptions.Compiled); - - private List symbolBoundaries = new List { '<', '>', ',' }; - - /********* ** Public methods *********/ @@ -24,25 +26,13 @@ namespace StardewModdingAPI.Framework.ModLoading /// The second object to compare. public bool Equals(TypeReference a, TypeReference b) { - string typeA = this.GetComparableTypeID(a); - string typeB = this.GetComparableTypeID(b); + if (a == null || b == null) + return a == b; - string placeholderType = "", actualType = ""; - - if (this.HasPlaceholder(typeA)) - { - placeholderType = typeA; - actualType = typeB; - } - else if (this.HasPlaceholder(typeB)) - { - placeholderType = typeB; - actualType = typeA; - } - else - return typeA == typeB; - - return this.PlaceholderTypeValidates(placeholderType, actualType); + return + a == b + || a.FullName == b.FullName + || this.HeuristicallyEquals(a, b); } /// Get a hash code for the specified object. @@ -57,153 +47,155 @@ namespace StardewModdingAPI.Framework.ModLoading /********* ** Private methods *********/ - /// Get a unique string representation of a type. - /// The type reference. - private string GetComparableTypeID(TypeReference type) + /// Get whether two types are heuristically equal based on generic type token substitution. + /// The first type to compare. + /// The second type to compare. + private bool HeuristicallyEquals(TypeReference typeA, TypeReference typeB) { - return this.StripTypeNamePattern.Replace(type.FullName, ""); - } - - /// Determine whether this type ID has a placeholder such as !0. - /// The type to check. - /// true if the type ID contains a placeholder, false if not. - private bool HasPlaceholder(string typeID) - { - return typeID.Contains("!0"); - } - - /// returns whether this type ID is a placeholder, i.e., it begins with "!". - /// The symbol to validate. - /// true if the symbol is a placeholder, false if not - private bool IsPlaceholder(string symbol) - { - return symbol.StartsWith("!"); - } - - /// Traverses and parses out symbols from a type which does not contain placeholder values. - /// The type to traverse. - /// A List in which to store the parsed symbols. - private void TraverseActualType(string type, List typeSymbols) - { - int depth = 0; - string symbol = ""; - - foreach (char c in type) + bool HeuristicallyEquals(string typeNameA, string typeNameB, IDictionary tokenMap) { - if (this.symbolBoundaries.Contains(c)) + // analyse type names + bool hasTokensA = typeNameA.Contains("!"); + bool hasTokensB = typeNameB.Contains("!"); + bool isTokenA = hasTokensA && typeNameA[0] == '!'; + bool isTokenB = hasTokensB && typeNameB[0] == '!'; + + // validate + if (!hasTokensA && !hasTokensB) + return typeNameA == typeNameB; // no substitution needed + if (hasTokensA && hasTokensB) + throw new InvalidOperationException("Can't compare two type names when both contain generic type tokens."); + + // perform substitution if applicable + if (isTokenA) + typeNameA = this.MapPlaceholder(placeholder: typeNameA, type: typeNameB, map: tokenMap); + if (isTokenB) + typeNameB = this.MapPlaceholder(placeholder: typeNameB, type: typeNameA, map: tokenMap); + + // compare inner tokens + string[] symbolsA = this.GetTypeSymbols(typeNameA).ToArray(); + string[] symbolsB = this.GetTypeSymbols(typeNameB).ToArray(); + if (symbolsA.Length != symbolsB.Length) + return false; + + for (int i = 0; i < symbolsA.Length; i++) { - typeSymbols.Add(new SymbolLocation(symbol, depth)); - symbol = ""; - switch (c) - { - case '<': - depth++; - break; - case '>': - depth--; - break; - default: - break; - } - } - else - symbol += c; - } - } - - /// Determines whether two symbols in a type ID match, accounting for placeholders such as !0. - /// A symbol in a typename which contains placeholders. - /// A symbol in a typename which does not contain placeholders. - /// A dictionary containing a mapping of placeholders to concrete types. - /// true if the symbols match, false if not. - private bool SymbolsMatch(SymbolLocation symbolA, SymbolLocation symbolB, Dictionary placeholderMap) - { - if (symbolA.depth != symbolB.depth) - return false; - - if (!this.IsPlaceholder(symbolA.symbol)) - { - return symbolA.symbol == symbolB.symbol; - } - - if (placeholderMap.ContainsKey(symbolA.symbol)) - { - return placeholderMap[symbolA.symbol] == symbolB.symbol; - } - - placeholderMap[symbolA.symbol] = symbolB.symbol; - - return true; - } - - /// Determines whether a type which has placeholders correctly resolves to the concrete type provided. - /// A type containing placeholders such as !0. - /// The list of symbols extracted from the concrete type. - /// true if the type resolves correctly, false if not. - private bool PlaceholderTypeResolvesToActualType(string type, List typeSymbols) - { - Dictionary placeholderMap = new Dictionary(); - - int depth = 0, symbolCount = 0; - string symbol = ""; - - foreach (char c in type) - { - if (this.symbolBoundaries.Contains(c)) - { - bool match = this.SymbolsMatch(new SymbolLocation(symbol, depth), typeSymbols[symbolCount], placeholderMap); - if (typeSymbols.Count <= symbolCount || - !match) + if (!HeuristicallyEquals(symbolsA[i], symbolsB[i], tokenMap)) return false; - - symbolCount++; - symbol = ""; - switch (c) - { - case '<': - depth++; - break; - case '>': - depth--; - break; - default: - break; - } } - else - symbol += c; + + return true; } - return true; + return HeuristicallyEquals(typeA.FullName, typeB.FullName, new Dictionary()); } - /// Determines whether a type with placeholders in it matches a type without placeholders. - /// The type with placeholders in it. - /// The type without placeholders. - /// true if the placeholder type can resolve to the actual type, false if not. - private bool PlaceholderTypeValidates(string placeholderType, string actualType) + /// Map a generic type placeholder (like !0) to its actual type. + /// The token placeholder. + /// The actual type. + /// The map of token to map substitutions. + /// Returns the previously-mapped type if applicable, else the . + private string MapPlaceholder(string placeholder, string type, IDictionary map) { - List typeSymbols = new List(); + if (map.TryGetValue(placeholder, out string result)) + return result; - this.TraverseActualType(actualType, typeSymbols); - return PlaceholderTypeResolvesToActualType(placeholderType, typeSymbols); + map[placeholder] = type; + return type; } - - - /********* - ** Inner classes - *********/ - protected class SymbolLocation + /// Get the top-level type symbols in a type name (e.g. List and NetRef<T> in List<NetRef<T>>) + /// The full type name. + private IEnumerable GetTypeSymbols(string typeName) { - public string symbol; - public int depth; + int openGenerics = 0; - public SymbolLocation(string symbol, int depth) + Queue queue = new Queue(typeName); + string symbol = ""; + while (queue.Any()) { - this.symbol = symbol; - this.depth = depth; + char ch = queue.Dequeue(); + switch (ch) + { + // skip `1 generic type identifiers + case '`': + while (int.TryParse(queue.Peek().ToString(), out int _)) + queue.Dequeue(); + break; + + // start generic args + case '<': + switch (openGenerics) + { + // start new generic symbol + case 0: + yield return symbol; + symbol = ""; + openGenerics++; + break; + + // continue accumulating nested type symbol + default: + symbol += ch; + openGenerics++; + break; + } + break; + + // generic args delimiter + case ',': + switch (openGenerics) + { + // invalid + case 0: + throw new InvalidOperationException($"Encountered unexpected comma in type name: {typeName}."); + + // start next generic symbol + case 1: + yield return symbol; + symbol = ""; + break; + + // continue accumulating nested type symbol + default: + symbol += ch; + break; + } + break; + + + // end generic args + case '>': + switch (openGenerics) + { + // invalid + case 0: + throw new InvalidOperationException($"Encountered unexpected closing generic in type name: {typeName}."); + + // end generic symbol + case 1: + yield return symbol; + symbol = ""; + openGenerics--; + break; + + // continue accumulating nested type symbol + default: + symbol += ch; + openGenerics--; + break; + } + break; + + // continue symbol + default: + symbol += ch; + break; + } } + + if (symbol != "") + yield return symbol; } } }