private void ParseFunctionDecl(SymTable symTable)
{
var c = Current;
SymTable procSymTable = new SymTable {
Parent = symTable
};
var h = ParseFunctionHeading(procSymTable);
Require(Semicolon);
if (symTable.Contains(h.Name))
{
throw new ParserException("Duplicate identifier {h.Name}", c.Line, c.Position);
}
var f = new FunctionSymbol
{
Name = h.Name,
Parameters = h.Parameters,
ReturnType = h.ReturnType
};
symTable.Add(h.Name, f);
var backup = CurrentReturnType;
CurrentReturnType = f.ReturnType;
var b = ParseBlock(procSymTable);
CurrentReturnType = backup;
Require(Semicolon);
f.Block = b;
}
private void ParseFieldDecl(SymTable parentSymTable, SymTable recSymTable)
{
var c = Current;
Require(Identifier);
List <string> idents = new List <string> {
c.Value.ToString()
};
var t = Current;
while (t.SubType == Comma)
{
Next();
t = Current;
Require(Identifier);
idents.Add(t.Value.ToString());
}
Require(Colon);
var tp = ParseType(parentSymTable);
foreach (var i in idents)
{
if (recSymTable.Contains(i))
{
throw new ParserException($"Field {i} already declared", c.Line, c.Position);
}
recSymTable.Add(i, new VarSymbol {
Name = i, Type = tp, Value = null
});
}
}
private void ParseProcedureDecl(SymTable symTable)
{
var c = Current;
SymTable procSymTable = new SymTable {
Parent = symTable
};
var h = ParseProcedureHeading(procSymTable);
Require(Semicolon);
if (symTable.Contains(h.Name))
{
throw new ParserException($"Duplicate identifier {h.Name}", c.Line, c.Position);
}
var p = new ProcedureSymbol {
Name = h.Name, Parameters = h.Parameters
};
symTable.Add(h.Name, p);
var backup = CurrentReturnType;
CurrentReturnType = null;
var b = ParseBlock(procSymTable);
CurrentReturnType = backup;
p.Block = b;
Require(Semicolon);
}
private void ParseConstantDecl(SymTable symTable)
{
var c = Current;
Next();
if (Current.SubType == Equal)
{
Next();
var ce = ParseConstExpr(symTable);
if (symTable.Contains(c.Value.ToString()))
{
throw new ParserException($"Duplicate identifier {c.Value}", c.Line, c.Position);
}
symTable.Add(c.Value.ToString(),
new ConstSymbol
{
Name = c.Value.ToString(),
Type = ce.Type,
Value = new SimpleConstant {
Type = ce.Type, Value = ce.Value
}
});
return;
}
if (Current.SubType != Colon)
{
throw new ParserException($"Expected '=' or ':', got {Current.SubType}.", Current.Line,
Current.Position);
}
Next();
var t = ParseType(symTable);
Require(Equal);
var tc = ParseTypedConstant(symTable, t);
CheckImplicitTypeCompatibility(tc.Type, t);
symTable.Add(c.Value.ToString(),
new TypedConstSymbol
{
Name = c.Value.ToString(),
Type = t,
Value = new SimpleConstant {
Type = t, Value = tc
}
});
}