private int _ruleIdx; // 上述列表的索引
/// <summary>
/// <see cref="StackFrameFunction"/> 函数的参数
/// </summary>
/// <param name="startIdx">从token列表的哪个位置开始分析</param>
/// <param name="currentNonTerminal">当前使用的BNF产生式，将使用这个式子检查接下来的token</param>
/// <param name="tokens">Token列表</param>
/// <param name="bnfDefination">所有的BNF产生式</param>
/// <param name="backtracings">保存<see cref="Continuation"/>，用于回溯</param>
public ParserFunc(int startIdx, string currentNonTerminal, IList <Token> tokens,
BnfDefination bnfDefination, Stack <Continuation> backtracings)
: base(0)
{
_startIdx = startIdx;
_backtracings = backtracings;
_tokens = tokens;
_bnfDefination = bnfDefination;
_currentNonTerminal = currentNonTerminal;
}
/// <summary>
/// 对Token序列进行语法分析
/// </summary>
/// <param name="tokens">要分析的序列</param>
/// <param name="defination">用来分析的定义</param>
/// <param name="startSymbol">起始项，一个在defination中出现的非终结符，来表示分析的起点，也是根节点</param>
/// <param name="startIdx">从序列的哪个位置开始分析，默认是开头</param>
/// <returns>如果序列符合定义，返回语法分析树；否则返回 null</returns>
public static NonTerminalTree Parse(IList <Token> tokens, BnfDefination defination, string startSymbol,
int startIdx = 0)
{
var machine = new StackMachine.StackMachine();
var backtracing = new Stack <Continuation>();
var(tree, scannedLength) = ((NonTerminalTree, int))
machine.Run(new ParserFunc(startIdx, startSymbol, tokens, defination, backtracing));
while (tree == null && backtracing.Count > 0)
{
var cont = backtracing.Pop();
(tree, scannedLength) = ((NonTerminalTree, int))machine.RunWithContinuation(cont, true);
}
Assert(tree == null || scannedLength == tokens.Count, "在rule遍历时做了判断，这里一定相等");
return(tree);
}
private ParserFunc(ParserFunc that)
: base(that)
{
_startIdx = that._startIdx;
// 浅拷贝，因为必须在全局保持状态一致
_backtracings = that._backtracings;
// 浅拷贝，因为是不变量
_tokens = that._tokens;
_bnfDefination = that._bnfDefination;
_currentNonTerminal = that._currentNonTerminal;
_currentTokenIdx = that._currentTokenIdx;
_ruleItemIdx = that._ruleItemIdx;
// 浅拷贝，因为回溯会覆盖之前的结果，不会产生影响
_childs = that._childs;
// 浅拷贝，因为是不变量
_ruleList = that._ruleList;
_ruleIdx = that._ruleIdx;
}
public static LL1Table BuildAnalysisTable(BnfDefination defination)
{
throw new NotImplementedException();
}
