Canon/Canon.Core/SemanticParser/SymbolTable.cs

127 lines
3.1 KiB
C#

using System.Diagnostics.CodeAnalysis;
namespace Canon.Core.SemanticParser;
/// <summary>
///符号表类
/// </summary>
public class SymbolTable
{
/// <summary>
/// 符号表
/// </summary>
private readonly Dictionary<string, Symbol> _symbols = [];
/// <summary>
/// 类型表
/// </summary>
private readonly TypeTable _typeTable = new();
/// <summary>
/// 父符号表
/// </summary>
private readonly SymbolTable? _parent;
/// <summary>
/// 获得当前符号表的所有父符号表
/// </summary>
public IEnumerable<SymbolTable> ParentTables => GetParents();
public SymbolTable() {}
private SymbolTable(SymbolTable parent)
{
_parent = parent;
}
public SymbolTable CreateChildTable()
{
return new SymbolTable(this);
}
/// <summary>
/// 尝试向符号表中添加符号
/// </summary>
/// <param name="symbol">欲添加的符号</param>
/// <returns>是否添加成功</returns>
public bool TryAddSymbol(Symbol symbol) => _symbols.TryAdd(symbol.SymbolName, symbol);
/// <summary>
/// 尝试从符号表极其父符号表查找符号
/// </summary>
/// <param name="name">需要查找的符号名称</param>
/// <param name="symbol">查找到的符号</param>
/// <returns>是否查找到符号</returns>
public bool TryGetSymbol(string name, [NotNullWhen(true)] out Symbol? symbol)
{
if (_symbols.TryGetValue(name, out symbol))
{
return true;
}
foreach (SymbolTable table in ParentTables)
{
if (table._symbols.TryGetValue(name, out symbol))
{
return true;
}
}
symbol = null;
return false;
}
/// <summary>
/// 从符号表极其父表的类型表中查找类型
/// </summary>
/// <param name="typeName">欲查找的类型名称</param>
/// <param name="type">查找到的类型</param>
/// <returns>是否查找到类型</returns>
public bool TryGetType(string typeName, [NotNullWhen(true)] out PascalType? type)
{
if (_typeTable.TryGetType(typeName, out type))
{
return true;
}
foreach (SymbolTable parent in ParentTables)
{
if (parent._typeTable.TryGetType(typeName, out type))
{
return true;
}
}
type = null;
return false;
}
/// <summary>
/// 尝试获得父符号表
/// </summary>
/// <param name="parent">获得的父符号表</param>
/// <returns>是否存在父符号表</returns>
public bool TryGetParent([NotNullWhen(true)] out SymbolTable? parent)
{
if (_parent is null)
{
parent = null;
return false;
}
parent = _parent;
return true;
}
private IEnumerable<SymbolTable> GetParents()
{
SymbolTable? now = _parent;
while (now is not null)
{
yield return now;
now = now._parent;
}
}
}