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#region Copyright notice and license
// Protocol Buffers - Google's data interchange format
// Copyright 2008 Google Inc. All rights reserved.
//
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file or at
// https://developers.google.com/open-source/licenses/bsd
#endregion
using System;
using System.Collections.Generic;
using System.Text;
namespace Google.Protobuf.Reflection
{
/// <summary>
/// Contains lookup tables containing all the descriptors defined in a particular file.
/// </summary>
internal sealed class DescriptorPool
{
private readonly IDictionary<string, IDescriptor> descriptorsByName =
new Dictionary<string, IDescriptor>();
private readonly IDictionary<ObjectIntPair<IDescriptor>, FieldDescriptor> fieldsByNumber =
new Dictionary<ObjectIntPair<IDescriptor>, FieldDescriptor>();
private readonly IDictionary<ObjectIntPair<IDescriptor>, EnumValueDescriptor> enumValuesByNumber =
new Dictionary<ObjectIntPair<IDescriptor>, EnumValueDescriptor>();
private readonly IDictionary<EnumValueByNameDescriptorKey, EnumValueDescriptor> enumValuesByName =
new Dictionary<EnumValueByNameDescriptorKey, EnumValueDescriptor>();
private readonly HashSet<FileDescriptor> dependencies = new HashSet<FileDescriptor>();
internal DescriptorPool(IEnumerable<FileDescriptor> dependencyFiles)
{
foreach (FileDescriptor dependencyFile in dependencyFiles)
{
dependencies.Add(dependencyFile);
ImportPublicDependencies(dependencyFile);
}
foreach (FileDescriptor dependency in dependencyFiles)
{
AddPackage(dependency.Package, dependency);
}
}
private void ImportPublicDependencies(FileDescriptor file)
{
foreach (FileDescriptor dependency in file.PublicDependencies)
{
if (dependencies.Add(dependency))
{
ImportPublicDependencies(dependency);
}
}
}
/// <summary>
/// Finds a symbol of the given name within the pool.
/// </summary>
/// <typeparam name="T">The type of symbol to look for</typeparam>
/// <param name="fullName">Fully-qualified name to look up</param>
/// <returns>The symbol with the given name and type,
/// or null if the symbol doesn't exist or has the wrong type</returns>
internal T FindSymbol<T>(string fullName) where T : class
{
descriptorsByName.TryGetValue(fullName, out IDescriptor result);
if (result is T descriptor)
{
return descriptor;
}
// dependencies contains direct dependencies and any *public* dependencies
// of those dependencies (transitively)... so we don't need to recurse here.
foreach (FileDescriptor dependency in dependencies)
{
dependency.DescriptorPool.descriptorsByName.TryGetValue(fullName, out result);
descriptor = result as T;
if (descriptor != null)
{
return descriptor;
}
}
return null;
}
/// <summary>
/// Adds a package to the symbol tables. If a package by the same name
/// already exists, that is fine, but if some other kind of symbol
/// exists under the same name, an exception is thrown. If the package
/// has multiple components, this also adds the parent package(s).
/// </summary>
internal void AddPackage(string fullName, FileDescriptor file)
{
int dotpos = fullName.LastIndexOf('.');
String name;
if (dotpos != -1)
{
AddPackage(fullName.Substring(0, dotpos), file);
name = fullName.Substring(dotpos + 1);
}
else
{
name = fullName;
}
if (descriptorsByName.TryGetValue(fullName, out IDescriptor old))
{
if (old is not PackageDescriptor)
{
throw new DescriptorValidationException(file,
"\"" + name +
"\" is already defined (as something other than a " +
"package) in file \"" + old.File.Name + "\".");
}
}
descriptorsByName[fullName] = new PackageDescriptor(name, fullName, file);
}
/// <summary>
/// Adds a symbol to the symbol table.
/// </summary>
/// <exception cref="DescriptorValidationException">The symbol already existed
/// in the symbol table.</exception>
internal void AddSymbol(IDescriptor descriptor)
{
ValidateSymbolName(descriptor);
string fullName = descriptor.FullName;
if (descriptorsByName.TryGetValue(fullName, out IDescriptor old))
{
throw new DescriptorValidationException(descriptor,
GetDescriptorAlreadyAddedExceptionMessage(descriptor, fullName, old));
}
descriptorsByName[fullName] = descriptor;
}
private static string GetDescriptorAlreadyAddedExceptionMessage(IDescriptor descriptor, string fullName, IDescriptor old)
{
int dotPos = fullName.LastIndexOf('.');
return descriptor.File != old.File ? $"\"{fullName}\" is already defined in file \"{old.File.Name}\"."
: dotPos == -1 ? $"{fullName} is already defined."
: $"\"{fullName.Substring(dotPos + 1)}\" is already defined in \"{fullName.Substring(0, dotPos)}\".";
}
/// <summary>
/// Verifies that the descriptor's name is valid (i.e. it contains
/// only letters, digits and underscores, and does not start with a digit).
/// </summary>
/// <param name="descriptor"></param>
private static void ValidateSymbolName(IDescriptor descriptor)
{
if (descriptor.Name.Length == 0)
{
throw new DescriptorValidationException(descriptor, "Missing name.");
}
// Symbol name must start with a letter or underscore, and it can contain letters,
// numbers and underscores.
string name = descriptor.Name;
if (!IsAsciiLetter(name[0]) && name[0] != '_')
{
ThrowInvalidSymbolNameException(descriptor);
}
for (int i = 1; i < name.Length; i++)
{
if (!IsAsciiLetter(name[i]) && !IsAsciiDigit(name[i]) && name[i] != '_')
{
ThrowInvalidSymbolNameException(descriptor);
}
}
static bool IsAsciiLetter(char c) => (uint)((c | 0x20) - 'a') <= 'z' - 'a';
static bool IsAsciiDigit(char c) => (uint)(c - '0') <= '9' - '0';
static void ThrowInvalidSymbolNameException(IDescriptor descriptor) =>
throw new DescriptorValidationException(
descriptor, "\"" + descriptor.Name + "\" is not a valid identifier.");
}
/// <summary>
/// Returns the field with the given number in the given descriptor,
/// or null if it can't be found.
/// </summary>
internal FieldDescriptor FindFieldByNumber(MessageDescriptor messageDescriptor, int number)
{
fieldsByNumber.TryGetValue(new ObjectIntPair<IDescriptor>(messageDescriptor, number), out FieldDescriptor ret);
return ret;
}
internal EnumValueDescriptor FindEnumValueByNumber(EnumDescriptor enumDescriptor, int number)
{
enumValuesByNumber.TryGetValue(new ObjectIntPair<IDescriptor>(enumDescriptor, number), out EnumValueDescriptor ret);
return ret;
}
internal EnumValueDescriptor FindEnumValueByName(EnumDescriptor enumDescriptor, string name)
{
enumValuesByName.TryGetValue(new EnumValueByNameDescriptorKey(enumDescriptor, name), out EnumValueDescriptor ret);
return ret;
}
/// <summary>
/// Adds a field to the fieldsByNumber table.
/// </summary>
/// <exception cref="DescriptorValidationException">A field with the same
/// containing type and number already exists.</exception>
internal void AddFieldByNumber(FieldDescriptor field)
{
// for extensions, we use the extended type, otherwise we use the containing type
ObjectIntPair<IDescriptor> key = new ObjectIntPair<IDescriptor>(field.Proto.HasExtendee ? field.ExtendeeType : field.ContainingType, field.FieldNumber);
if (fieldsByNumber.TryGetValue(key, out FieldDescriptor old))
{
throw new DescriptorValidationException(field, "Field number " + field.FieldNumber +
"has already been used in \"" +
field.ContainingType.FullName +
"\" by field \"" + old.Name + "\".");
}
fieldsByNumber[key] = field;
}
/// <summary>
/// Adds an enum value to the enumValuesByNumber and enumValuesByName tables. If an enum value
/// with the same type and number already exists, this method does nothing to enumValuesByNumber.
/// (This is allowed; the first value defined with the number takes precedence.) If an enum
/// value with the same name already exists, this method throws DescriptorValidationException.
/// (It is expected that this method is called after AddSymbol, which would already have thrown
/// an exception in this failure case.)
/// </summary>
internal void AddEnumValue(EnumValueDescriptor enumValue)
{
ObjectIntPair<IDescriptor> numberKey = new ObjectIntPair<IDescriptor>(enumValue.EnumDescriptor, enumValue.Number);
if (!enumValuesByNumber.ContainsKey(numberKey))
{
enumValuesByNumber[numberKey] = enumValue;
}
EnumValueByNameDescriptorKey nameKey = new EnumValueByNameDescriptorKey(enumValue.EnumDescriptor, enumValue.Name);
if (enumValuesByName.TryGetValue(nameKey, out EnumValueDescriptor old))
{
throw new DescriptorValidationException(enumValue,
GetDescriptorAlreadyAddedExceptionMessage(enumValue, enumValue.FullName, old));
}
enumValuesByName[nameKey] = enumValue;
}
/// <summary>
/// Looks up a descriptor by name, relative to some other descriptor.
/// The name may be fully-qualified (with a leading '.'), partially-qualified,
/// or unqualified. C++-like name lookup semantics are used to search for the
/// matching descriptor.
/// </summary>
/// <remarks>
/// This isn't heavily optimized, but it's only used during cross linking anyway.
/// If it starts being used more widely, we should look at performance more carefully.
/// </remarks>
internal IDescriptor LookupSymbol(string name, IDescriptor relativeTo)
{
IDescriptor result;
if (name.StartsWith("."))
{
// Fully-qualified name.
result = FindSymbol<IDescriptor>(name.Substring(1));
}
else
{
// If "name" is a compound identifier, we want to search for the
// first component of it, then search within it for the rest.
int firstPartLength = name.IndexOf('.');
string firstPart = firstPartLength == -1 ? name : name.Substring(0, firstPartLength);
// We will search each parent scope of "relativeTo" looking for the
// symbol.
StringBuilder scopeToTry = new StringBuilder(relativeTo.FullName);
while (true)
{
// Chop off the last component of the scope.
int dotpos = scopeToTry.ToString().LastIndexOf(".");
if (dotpos == -1)
{
result = FindSymbol<IDescriptor>(name);
break;
}
else
{
scopeToTry.Length = dotpos + 1;
// Append firstPart and try to find.
scopeToTry.Append(firstPart);
result = FindSymbol<IDescriptor>(scopeToTry.ToString());
if (result != null)
{
if (firstPartLength != -1)
{
// We only found the first part of the symbol. Now look for
// the whole thing. If this fails, we *don't* want to keep
// searching parent scopes.
scopeToTry.Length = dotpos + 1;
scopeToTry.Append(name);
result = FindSymbol<IDescriptor>(scopeToTry.ToString());
}
break;
}
// Not found. Remove the name so we can try again.
scopeToTry.Length = dotpos;
}
}
}
if (result == null)
{
throw new DescriptorValidationException(relativeTo, "\"" + name + "\" is not defined.");
}
else
{
return result;
}
}
/// <summary>
/// Struct used to hold the keys for the enumValuesByName table.
/// </summary>
private struct EnumValueByNameDescriptorKey : IEquatable<EnumValueByNameDescriptorKey>
{
private readonly string name;
private readonly IDescriptor descriptor;
internal EnumValueByNameDescriptorKey(EnumDescriptor descriptor, string valueName)
{
this.descriptor = descriptor;
this.name = valueName;
}
public bool Equals(EnumValueByNameDescriptorKey other) =>
descriptor == other.descriptor
&& name == other.name;
public override bool Equals(object obj) =>
obj is EnumValueByNameDescriptorKey pair && Equals(pair);
public override int GetHashCode()
{
unchecked
{
var hashCode = descriptor.GetHashCode();
hashCode = (hashCode * 397) ^ (name != null ? name.GetHashCode() : 0);
return hashCode;
}
}
}
}
}