/// <summary>
/// Parses a simple expression (no function calls on top-level expression.
/// </summary>
public static bool AcceptAtom(string Text, int Start, out Expression Expression, out int LastChar)
{
// Procedure
if (AcceptString(Text, Start, "{", out LastChar))
{
ProcedureExpression procedure;
AcceptWhitespace(Text, LastChar, out LastChar);
AcceptProcedure(Text, LastChar, out procedure, out LastChar);
AcceptWhitespace(Text, LastChar, out LastChar);
if (AcceptString(Text, LastChar, "}", out LastChar))
{
Expression = procedure;
return true;
}
}
// Variable
Operator op;
string varname;
if (AcceptWord(Text, Start, out varname, out LastChar) && ValidVariable(varname) && !LookupOperator(varname, out op))
{
Expression = new VariableExpression(varname);
return true;
}
// Parentheses
if (AcceptString(Text, Start, "(", out LastChar))
{
// Operator
int nc = LastChar;
if (AcceptWord(Text, nc, out varname, out LastChar) && LookupOperator(varname, out op))
{
if (AcceptString(Text, LastChar, ")", out LastChar))
{
Expression = new VariableExpression(varname);
return true;
}
}
Expression exp;
AcceptWhitespace(Text, nc, out LastChar);
if (AcceptExpression(Text, LastChar, out exp, out LastChar))
{
AcceptWhitespace(Text, LastChar, out LastChar);
if (AcceptString(Text, LastChar, ")", out LastChar))
{
Expression = exp;
return true;
}
}
}
// Integer literal
long val;
if (AcceptIntegerLiteral(Text, Start, out val, out LastChar))
{
Expression = new IntegerLiteralExpression(val);
return true;
}
// Alternate lambda syntax
if (AcceptString(Text, Start, "function", out LastChar))
{
AcceptWhitespace(Text, LastChar, out LastChar);
if (AcceptString(Text, LastChar, "(", out LastChar))
{
AcceptWhitespace(Text, LastChar, out LastChar);
List<KeyValuePair<Expression, string>> arglist;
AcceptArgumentList(Text, LastChar, out arglist, out LastChar);
AcceptWhitespace(Text, LastChar, out LastChar);
if (AcceptString(Text, LastChar, ")", out LastChar))
{
AcceptWhitespace(Text, LastChar, out LastChar);
if (AcceptString(Text, LastChar, "{", out LastChar))
{
ProcedureExpression procedure;
AcceptWhitespace(Text, LastChar, out LastChar);
AcceptProcedure(Text, LastChar, out procedure, out LastChar);
AcceptWhitespace(Text, LastChar, out LastChar);
if (AcceptString(Text, LastChar, "}", out LastChar))
{
Expression = new FunctionDefineExpression(arglist, procedure);
return true;
}
}
}
}
}
// Function type
if (AcceptString(Text, Start, "<", out LastChar))
{
AcceptWhitespace(Text, LastChar, out LastChar);
List<KeyValuePair<Expression, string>> argtypelist;
AcceptArgumentList(Text, LastChar, out argtypelist, out LastChar);
AcceptWhitespace(Text, LastChar, out LastChar);
if (AcceptString(Text, LastChar, ">", out LastChar))
{
AcceptWhitespace(Text, LastChar, out LastChar);
Expression returntype;
if (AcceptTightExpression(Text, LastChar, out returntype, out LastChar))
{
Expression = new FunctionTypeExpression(argtypelist, returntype);
return true;
}
}
}
Expression = null;
return false;
}
public override void TypeCheck(
IVariableStack<Expression> TypeStack,
IVariableStack<Expression> Stack,
out Expression TypeSafeExpression, out Expression Type)
{
Expression sifunc;
Expression itype;
this.Function.TypeCheck(
TypeStack.Cut(this.ArgumentIndex).Append(new Expression[] { this.ArgumentType }),
Stack.Cut(this.ArgumentIndex).Append(new Expression[] { Expression.Variable(Stack.NextFreeIndex) }),
out sifunc, out itype);
Type = Expression.FunctionType(this.ArgumentIndex, this.ArgumentType, itype);
TypeSafeExpression = new FunctionDefineExpression(this.ArgumentIndex, this.ArgumentType, sifunc);
}
/// <summary>
/// Parses an expression that can not be broken apart with an operator.
/// </summary>
public static bool AcceptTightExpression(string Text, int Start, out Expression Expression, out int LastChar)
{
// Normal
if (AcceptAtom(Text, Start, out Expression, out LastChar))
{
int nc = 0;
while (true)
{
// Try to get a function
if (AcceptString(Text, LastChar, "(", out nc))
{
List<Expression> exps;
AcceptExpressions(Text, nc, out exps, out nc);
if (AcceptString(Text, nc, ")", out nc))
{
LastChar = nc;
Expression = new FunctionCallExpression(Expression, exps);
continue;
}
}
// Try to get an accessor
if (AcceptString(Text, LastChar, ".", out nc))
{
string accessname;
if (AcceptWord(Text, nc, out accessname, out nc))
{
LastChar = nc;
Expression = new AccessorExpression(Expression, accessname);
continue;
}
}
break;
}
return true;
}
// Lambda
if (AcceptString(Text, Start, "(", out LastChar))
{
AcceptWhitespace(Text, LastChar, out LastChar);
List<KeyValuePair<Expression, string>> arglist;
AcceptArgumentList(Text, LastChar, out arglist, out LastChar);
AcceptWhitespace(Text, LastChar, out LastChar);
if (AcceptString(Text, LastChar, ")", out LastChar))
{
AcceptWhitespace(Text, LastChar, out LastChar);
if (AcceptString(Text, LastChar, "=>", out LastChar))
{
AcceptWhitespace(Text, LastChar, out LastChar);
Expression def;
if (AcceptExpression(Text, LastChar, out def, out LastChar))
{
Expression = new FunctionDefineExpression(arglist, def);
return true;
}
}
}
}
Expression = null;
return false;
}
