internal int Add(Token item)
{
return this.m_Array.Add(item);
}
private ParseResult ParseLALR(ref Token nextToken)
{
// This function analyzes a token and either:
// 1. Makes a SINGLE reduction and pushes a complete Reduction object on the m_Stack
// 2. Accepts the token and shifts
// 3. Errors and places the expected symbol indexes in the Tokens list
// The Token is assumed to be valid and WILL be checked
// If an action is performed that requires controlt to be returned to the user, the function returns true.
// The Message parameter is then set to the type of action.
var result = default(ParseResult);
var parseAction = this.m_LRStates[this.m_CurrentLALR][nextToken.Parent];
// Work - shift or reduce
if (parseAction != null)
{
this.m_HaveReduction = false;
// Will be set true if a reduction is made
// 'Debug.WriteLine("Action: " & ParseAction.Text)
switch (parseAction.Type)
{
case LRActionType.Accept:
this.m_HaveReduction = true;
result = ParseResult.Accept;
break;
case LRActionType.Shift:
this.m_CurrentLALR = parseAction.Value;
nextToken.State = (short)this.m_CurrentLALR;
this.m_Stack.Push(ref nextToken);
result = ParseResult.Shift;
break;
case LRActionType.Reduce:
// Produce a reduction - remove as many tokens as members in the rule & push a nonterminal token
var prod = this.m_ProductionTable[parseAction.Value];
// ======== Create Reduction
Token head;
short n;
if (this.m_TrimReductions && prod.ContainsOneNonTerminal())
{
// The current rule only consists of a single nonterminal and can be trimmed from the
// parse tree. Usually we create a new Reduction, assign it to the Data property
// of Head and push it on the m_Stack. However, in this case, the Data property of the
// Head will be assigned the Data property of the reduced token (i.e. the only one
// on the m_Stack).
// In this case, to save code, the value popped of the m_Stack is changed into the head.
head = this.m_Stack.Pop();
head.Parent = prod.Head();
result = ParseResult.ReduceEliminated;
// Build a Reduction
}
else
{
this.m_HaveReduction = true;
var newReduction = new Reduction(prod.Handle().Count());
var with2 = newReduction;
with2.Parent = prod;
for (n = (short)(prod.Handle().Count() - 1); n >= 0; n += -1)
{
with2[n] = this.m_Stack.Pop();
}
head = new Token(prod.Head(), newReduction);
result = ParseResult.ReduceNormal;
}
// ========== Goto
var index = this.m_Stack.Top().State;
// ========= If n is -1 here, then we have an Internal Table Error!!!!
n = this.m_LRStates[index].IndexOf(prod.Head());
if (n != -1)
{
this.m_CurrentLALR = this.m_LRStates[index][n].Value;
head.State = (short)this.m_CurrentLALR;
this.m_Stack.Push(ref head);
}
else
{
result = ParseResult.InternalError;
}
break;
}
}
else
{
// === Syntax Error! Fill Expected Tokens
this.m_ExpectedSymbols.Clear();
// .Count - 1
foreach (LRAction action in this.m_LRStates[this.m_CurrentLALR])
{
switch (action.Symbol.Type)
{
case SymbolType.Content:
case SymbolType.End:
case SymbolType.GroupStart:
case SymbolType.GroupEnd:
this.m_ExpectedSymbols.Add(action.Symbol);
break;
}
}
result = ParseResult.SyntaxError;
}
return result;
// Very important
}
private Token LookaheadDFA()
{
// This function implements the DFA for th parser's lexer.
// It generates a token which is used by the LALR state
// machine.
var target = 0;
var result = new Token();
// ===================================================
// Match DFA token
// ===================================================
var done = false;
int currentDFA = this.m_DFA.InitialState;
var currentPosition = 1;
// Next byte in the input Stream
var lastAcceptState = -1;
// We have not yet accepted a character string
var lastAcceptPosition = -1;
var ch = this.Lookahead(1);
// NO MORE DATA
// ReSharper disable once PossibleNullReferenceException
if (!(string.IsNullOrEmpty(ch) | ch[0] == 65535))
{
while (!done)
{
// This code searches all the branches of the current DFA state
// for the next character in the input Stream. If found the
// target state is returned.
ch = this.Lookahead(currentPosition);
// End reached, do not match
bool found;
if (string.IsNullOrEmpty(ch))
{
found = false;
}
else
{
var n = 0;
found = false;
while (n < this.m_DFA[currentDFA].Edges.Count & !found)
{
var edge = this.m_DFA[currentDFA].Edges[n];
// ==== Look for character in the Character Set Table
if (edge.Characters.Contains(ch[0]))
{
found = true;
target = edge.Target;
// .TableIndex
}
n += 1;
}
}
// This block-if statement checks whether an edge was found from the current state. If so, the state and current
// position advance. Otherwise it is time to exit the main loop and report the token found (if there was one).
// If the LastAcceptState is -1, then we never found a match and the Error Token is created. Otherwise, a new
// token is created using the Symbol in the Accept State and all the characters that comprise it.
if (found)
{
// This code checks whether the target state accepts a token.
// If so, it sets the appropiate variables so when the
// algorithm in done, it can return the proper token and
// number of characters.
// NOT is very important!
if (this.m_DFA[target].Accept != null)
{
lastAcceptState = target;
lastAcceptPosition = currentPosition;
}
currentDFA = target;
currentPosition += 1;
// No edge found
}
else
{
done = true;
// Lexer cannot recognize symbol
if (lastAcceptState == -1)
{
result.Parent = this.m_SymbolTable.GetFirstOfType(SymbolType.Error);
result.Data = this.LookaheadBuffer(1);
// Create Token, read characters
}
else
{
result.Parent = this.m_DFA[lastAcceptState].Accept;
result.Data = this.LookaheadBuffer(lastAcceptPosition);
// Data contains the total number of accept characters
}
}
// DoEvents
}
}
else
{
// End of file reached, create End Token
result.Data = string.Empty;
result.Parent = this.m_SymbolTable.GetFirstOfType(SymbolType.End);
}
// ===================================================
// Set the new token's position information
// ===================================================
// Notice, this is a copy, not a linking of an instance. We don't want the user
// to be able to alter the main value indirectly.
result.Position().Copy(this.m_SysPosition);
return result;
}
public void PushInput(ref Token theToken)
{
this.m_InputTokens.Push(theToken);
}
public bool Open(TextReader reader)
{
var start = new Token();
this.Restart();
this.m_Source = reader;
// === Create stack top item. Only needs state
start.State = this.m_LRStates.InitialState;
this.m_Stack.Push(ref start);
return true;
}
public void EnqueueInput(ref Token theToken)
{
this.m_InputTokens.Enqueue(ref theToken);
}