private static Model.ValueNode FromMapOrArrayValue(Symbol val)
{
Model.ValueNode node;
string typeName;
switch (val.Type)
{
case SymbolType.TypedMapValue:
case SymbolType.TypedArrayValue:
typeName = GetTypeName(val.Children[0]);
node = FromMapOrArrayValue(val.Children[1]);
node.TypeName = typeName;
return(node);
case SymbolType.MapValue:
var map = new Model.MapValue();
if (val.Children.Length > 2)
{
PopulateMap(map, val.Children[1]);
}
return(map);
case SymbolType.ArrayValue:
var arr = new Model.ArrayValue();
if (val.Children.Length > 2)
{
PopulateArray(arr, val.Children[1]);
}
return(arr);
}
return(null);
}
private static void PopulateArray(Model.ArrayValue arr, Symbol arraySeq)
{
// Verify
if (arraySeq.Type != SymbolType.ArraySeq)
{
throw new InvalidOperationException($"Trying to populate array from invalid symbol '{arraySeq.Type}'");
}
if (arraySeq.Children[0].Type == SymbolType.ArraySeq)
{
PopulateArray(arr, arraySeq.Children[0]);
}
var valueNode = CreateValueNode(arraySeq.Children[arraySeq.Children.Length - 1]);
arr.Add(valueNode);
}
public Model.Node Parse(TokenStream strm)
{
// Sanity check
if (strm.EoS)
{
return(null);
}
// Initialise parse state
Stack <Symbol> parseStack = new Stack <Symbol>();
parseStack.Push(Symbol.ParseState(0));
Symbol lookahead = strm.Read();
// Loop until we're done
bool done = false;
while (!done)
{
// Read current parse state
Symbol parseState = parseStack.Peek();
if (!parseState.IsParseState)
{
throw new InvalidOperationException();
}
StateDefinition state = parseStates[parseState.State];
// Select next action
int terminalIndex = lookahead != null ? lookahead.TerminalIndex : SYMCNT_TERMINAL - 1;
var rule = state.LookaheadTable[terminalIndex];
switch (rule.Action)
{
case ParserAction.Shift:
parseStack.Push(lookahead);
lookahead = strm.Read();
parseStack.Push(Symbol.ParseState(rule.Arg));
break;
case ParserAction.Reduce:
GrammarRule grammarRule = grammarRules[rule.Arg];
int toRemove = grammarRule.MatchSymbols.Length;
Symbol[] children = new Symbol[toRemove];
while (toRemove > 0)
{
Symbol s = parseStack.Pop();
if (!s.IsParseState)
{
children[toRemove - 1] = s;
toRemove--;
}
}
Symbol newSymbol = new Symbol(grammarRule.OutputSymbol, children);
Symbol priorState = parseStack.Peek();
if (!priorState.IsParseState)
{
throw new InvalidOperationException();
}
StateDefinition priorStateDef = parseStates[priorState.State];
int nextState = priorStateDef.GotoTable[SymbolTypeToCol(grammarRule.OutputSymbol, true)];
parseStack.Push(newSymbol);
parseStack.Push(Symbol.ParseState(nextState));
break;
case ParserAction.Done:
done = true;
break;
case ParserAction.Error:
if (lookahead != null)
{
throw new InvalidOperationException($"Unexpected symbol '{lookahead.Value}' (line {lookahead.Position.Line}, col {lookahead.Position.Column})");
}
else
{
throw new InvalidOperationException($"Unexpected end of stream");
}
}
}
// Locate the parse tree
Symbol parseTree = null;
while (parseStack.Count > 0)
{
Symbol sym = parseStack.Pop();
if (!sym.IsParseState)
{
if (parseTree != null)
{
throw new InvalidOperationException($"Multiple parse trees generated (got '{sym.Type}', already had '{parseTree.Type}')");
}
else
{
parseTree = sym;
}
}
}
if (parseTree == null)
{
throw new InvalidOperationException($"Parse tree not generated");
}
// Identify it
switch (parseTree.Type)
{
case SymbolType.KeyValueSeq:
// We're going to emit a map
var map = new Model.MapValue();
PopulateMap(map, parseTree);
return(map);
case SymbolType.ArraySeq:
// We're going to emit an array
var arr = new Model.ArrayValue();
PopulateArray(arr, parseTree);
return(arr);
default:
throw new InvalidOperationException($"Unexpected root symbol '{parseTree.Type}'");
}
}