public AstLambda(PegAstNode node)
: base(node)
{
CheckLabel(AstLabel.Lambda);
CheckChildCount(node, 2);
AstParam name = new AstParam(node.GetChild(0));
mIdentifiers.Add(name.ToString());
CatAstNode tmp = Create(node.GetChild(1));
// lambda nodes either contain quotes or other lambda nodes
if (!(tmp is AstQuote))
{
if (!(tmp is AstLambda))
{
throw new Exception("expected lambda expression or quotation");
}
AstLambda lambda = tmp as AstLambda;
mIdentifiers.AddRange(lambda.mIdentifiers);
// Take ownership of the terms from the child lambda expression
mTerms = lambda.mTerms;
}
else
{
AstQuote q = tmp as AstQuote;
// Take ownership of the terms from the quote
mTerms = q.mTerms;
}
}
public static void RenameFirstInstance(string sOld, string sNew, List <CatAstNode> terms)
{
for (int i = 0; i < terms.Count; ++i)
{
if (TermContains(terms[i], sOld))
{
if (terms[i] is AstLambda)
{
AstLambda l = terms[i] as AstLambda;
RenameFirstInstance(sOld, sNew, l.mTerms);
return;
}
else if (terms[i] is AstQuote)
{
AstQuote q = terms[i] as AstQuote;
RenameFirstInstance(sOld, sNew, q.mTerms);
return;
}
else
{
// Should never happen.
throw new Exception("expected either a lamda node or quote node");
}
}
else if (TermEquals(terms[i], sOld))
{
terms[i] = new AstName(sNew);
return;
}
}
throw new Exception(sOld + " was not found in the list of terms");
}
public static bool TermContains(CatAstNode term, string var)
{
if (term is AstQuote)
{
AstQuote q = term as AstQuote;
foreach (CatAstNode child in q.mTerms)
{
if (TermContainsOrEquals(child, var))
{
return(true);
}
}
return(false);
}
else if (term is AstLambda)
{
AstLambda l = term as AstLambda;
foreach (CatAstNode child in l.mTerms)
{
if (TermContainsOrEquals(child, var))
{
return(true);
}
}
return(false);
}
else
{
return(false);
}
}
public static int CountInstancesOf(string var, List <CatAstNode> terms)
{
int ret = 0;
foreach (CatAstNode term in terms)
{
if (term is AstQuote)
{
AstQuote q = term as AstQuote;
ret += CountInstancesOf(var, q.mTerms);
}
else if (term is AstLambda)
{
AstLambda l = term as AstLambda;
ret += CountInstancesOf(var, l.mTerms);
}
else
{
if (TermEquals(term, var))
{
ret += 1;
}
}
}
return(ret);
}
public Function LiteralToFunction(string name, AstLiteral literal)
{
switch (literal.GetLabel())
{
case AstLabel.Int: {
AstInt tmp = literal as AstInt;
return(new PushInt(tmp.GetValue()));
}
case AstLabel.Bin: {
AstBin tmp = literal as AstBin;
return(new PushInt(tmp.GetValue()));
}
case AstLabel.Char: {
AstChar tmp = literal as AstChar;
return(new PushValue <char>(tmp.GetValue()));
}
case AstLabel.String: {
AstString tmp = literal as AstString;
return(new PushValue <string>(tmp.GetValue()));
}
case AstLabel.Float: {
AstFloat tmp = literal as AstFloat;
return(new PushValue <double>(tmp.GetValue()));
}
case AstLabel.Hex: {
AstHex tmp = literal as AstHex;
return(new PushInt(tmp.GetValue()));
}
case AstLabel.Quote: {
AstQuote tmp = literal as AstQuote;
CatExpr fxns = NodesToFxns(name, tmp.GetTerms());
if (Config.gbOptimizeQuotations)
{
MetaCat.ApplyMacros(this, fxns);
}
return(new PushFunction(fxns));
}
case AstLabel.Lambda: {
AstLambda tmp = literal as AstLambda;
CatLambdaConverter.Convert(tmp);
CatExpr fxns = NodesToFxns(name, tmp.GetTerms());
if (Config.gbOptimizeLambdas)
{
MetaCat.ApplyMacros(this, fxns);
}
return(new PushFunction(fxns));
}
default:
throw new Exception("unhandled literal " + literal.ToString());
}
}
public static void Convert( AstLambda l ) {
ConvertTerms( l.mIdentifiers, l.mTerms );
// We won't be needing the identifiers anymore and I don't want
// to have the conversion algorithm get run potentially multiple
// times on each lambda term.
l.mIdentifiers.Clear();
}
public static void RemoveTerm( string var, List<CatAstNode> terms ) {
// Find the first term that either contains, or is equal to the
// free variable
int i = 0;
while (i < terms.Count) {
if (TermContainsOrEquals( terms[ i ], var ))
break;
++i;
}
if (i == terms.Count)
throw new Exception( "error in abstraction elimination algorithm" );
if (i > 0) {
AstQuote q = new AstQuote( terms.GetRange( 0, i ) );
terms.RemoveRange( 0, i );
terms.Insert( 0, q );
terms.Insert( 1, new AstName( "dip" ) );
i = 2;
} else {
i = 0;
}
if (TermEquals( terms[ i ], var )) {
terms[ i ] = new AstName( "id" );
return;
} else if (TermContains( terms[ i ], var )) {
if (terms[ i ] is AstQuote) {
AstQuote subExpr = terms[ i ] as AstQuote;
RemoveTerm( var, subExpr.mTerms );
} else if (TermContains( terms[ i ], var )) {
AstLambda subExpr = terms[ i ] as AstLambda;
RemoveTerm( var, subExpr.mTerms );
} else {
throw new Exception( "internal error: expected either a quotation or lambda term" );
}
terms.Insert( i + 1, new AstName( "papply" ) );
return;
} else {
throw new Exception( "error in abstraction elimination algorithm" );
}
}
public static void Convert(AstLambda l)
{
ConvertTerms(l.mIdentifiers, l.mTerms);
// We won't be needing the identifiers anymore and I don't want
// to have the conversion algorithm get run potentially multiple
// times on each lambda term.
l.mIdentifiers.Clear();
}
