--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/dmd/expression/Equal.d	Sat Oct 24 08:42:06 2009 +0400
@@ -0,0 +1,209 @@
+module dmd.expression.Equal;
+
+import dmd.Expression;
+import dmd.Type;
+import dmd.TOK;
+import dmd.Loc;
+import dmd.StringExp;
+import dmd.GlobalExpressions;
+import dmd.ArrayLiteralExp;
+import dmd.StructLiteralExp;
+import dmd.Global;
+import dmd.IntegerExp;
+
+import core.stdc.string;
+
+/* Also returns EXP_CANT_INTERPRET if cannot be computed.
+ */
+Expression Equal(TOK op, Type type, Expression e1, Expression e2)
+{   
+	Expression e;
+    Loc loc = e1.loc;
+    bool cmp;
+    real r1;
+    real r2;
+
+    //printf("Equal(e1 = %s, e2 = %s)\n", e1.toChars(), e2.toChars());
+
+    assert(op == TOK.TOKequal || op == TOK.TOKnotequal);
+
+    if (e1.op == TOK.TOKnull)
+    {
+		if (e2.op == TOK.TOKnull)
+			cmp = true;
+		else if (e2.op == TOK.TOKstring)
+		{   StringExp es2 = cast(StringExp)e2;
+			cmp = (0 == es2.len);
+		}
+		else if (e2.op == TOK.TOKarrayliteral)
+		{   
+			ArrayLiteralExp es2 = cast(ArrayLiteralExp)e2;
+			cmp = !es2.elements || (0 == es2.elements.dim);
+		}
+		else
+			return EXP_CANT_INTERPRET;
+    }
+    else if (e2.op == TOK.TOKnull)
+    {
+		if (e1.op == TOK.TOKstring)
+		{   
+			StringExp es1 = cast(StringExp)e1;
+			cmp = (0 == es1.len);
+		}
+		else if (e1.op == TOK.TOKarrayliteral)
+		{   
+			ArrayLiteralExp es1 = cast(ArrayLiteralExp)e1;
+			cmp = !es1.elements || (0 == es1.elements.dim);
+		}
+		else
+			return EXP_CANT_INTERPRET;
+    }
+    else if (e1.op == TOK.TOKstring && e2.op == TOK.TOKstring)
+    {	
+		StringExp es1 = cast(StringExp)e1;
+		StringExp es2 = cast(StringExp)e2;
+
+		if (es1.sz != es2.sz)
+		{
+			assert(global.errors);
+			return EXP_CANT_INTERPRET;
+		}
+		if (es1.len == es2.len && memcmp(es1.string_, es2.string_, es1.sz * es1.len) == 0)
+			cmp = true;
+		else
+			cmp = false;
+    }
+    else if (e1.op == TOK.TOKarrayliteral && e2.op == TOK.TOKarrayliteral)
+    {   
+		ArrayLiteralExp es1 = cast(ArrayLiteralExp)e1;
+		ArrayLiteralExp es2 = cast(ArrayLiteralExp)e2;
+
+		if ((!es1.elements || !es1.elements.dim) && (!es2.elements || !es2.elements.dim))
+			cmp = true;		// both arrays are empty
+		else if (!es1.elements || !es2.elements)
+			cmp = false;
+		else if (es1.elements.dim != es2.elements.dim)
+			cmp = false;
+		else
+		{
+			for (size_t i = 0; i < es1.elements.dim; i++)
+			{   
+				Expression ee1 = cast(Expression)es1.elements.data[i];
+				Expression ee2 = cast(Expression)es2.elements.data[i];
+
+				Expression v = Equal(TOK.TOKequal, Type.tint32, ee1, ee2);
+				if (v == EXP_CANT_INTERPRET)
+					return EXP_CANT_INTERPRET;
+				long tmp = v.toInteger();
+				cmp = (tmp != 0);
+				if (!cmp)
+					break;
+			}
+		}
+    }
+    else if (e1.op == TOK.TOKarrayliteral && e2.op == TOK.TOKstring)
+    {	
+		// Swap operands and use common code
+		Expression ee = e1;
+		e1 = e2;
+		e2 = ee;
+		goto Lsa;
+    }
+    else if (e1.op == TOK.TOKstring && e2.op == TOK.TOKarrayliteral)
+    {
+     Lsa:
+		StringExp es1 = cast(StringExp)e1;
+		ArrayLiteralExp es2 = cast(ArrayLiteralExp)e2;
+		size_t dim1 = es1.len;
+		size_t dim2 = es2.elements ? es2.elements.dim : 0;
+		if (dim1 != dim2)
+			cmp = false;
+		else
+		{
+			for (size_t i = 0; i < dim1; i++)
+			{
+				ulong c = es1.charAt(i);
+				Expression ee2 = cast(Expression)es2.elements.data[i];
+				if (ee2.isConst() != 1)
+					return EXP_CANT_INTERPRET;
+				cmp = (c == ee2.toInteger());
+				if (!cmp)
+					break;
+			}
+		}
+    }
+    else if (e1.op == TOK.TOKstructliteral && e2.op == TOK.TOKstructliteral)
+    {   
+		StructLiteralExp es1 = cast(StructLiteralExp)e1;
+		StructLiteralExp es2 = cast(StructLiteralExp)e2;
+
+		if (es1.sd != es2.sd)
+			cmp = false;
+		else if ((!es1.elements || !es1.elements.dim) && (!es2.elements || !es2.elements.dim))
+			cmp = true;		// both arrays are empty
+		else if (!es1.elements || !es2.elements)
+			cmp = false;
+		else if (es1.elements.dim != es2.elements.dim)
+			cmp = false;
+		else
+		{
+			cmp = true;
+			for (size_t i = 0; i < es1.elements.dim; i++)
+			{   
+				Expression ee1 = cast(Expression)es1.elements.data[i];
+				Expression ee2 = cast(Expression)es2.elements.data[i];
+
+				if (ee1 == ee2)
+					continue;
+				if (!ee1 || !ee2)
+				{   
+					cmp = false;
+					break;
+				}
+				Expression v = Equal(TOK.TOKequal, Type.tint32, ee1, ee2);
+				if (v == EXP_CANT_INTERPRET)
+					return EXP_CANT_INTERPRET;
+				long tmp = v.toInteger();
+				cmp = (tmp != 0);
+				if (!cmp)
+					break;
+			}
+		}
+    }
+///static if (false) {
+///    else if (e1.op == TOKarrayliteral && e2.op == TOKstring)
+///    {
+///    }
+///}
+    else if (e1.isConst() != 1 || e2.isConst() != 1)
+		return EXP_CANT_INTERPRET;
+    else if (e1.type.isreal())
+    {
+		r1 = e1.toReal();
+		r2 = e2.toReal();
+		goto L1;
+    }
+    else if (e1.type.isimaginary())
+    {
+		r1 = e1.toImaginary();
+		r2 = e2.toImaginary();
+	L1:
+		cmp = (r1 == r2);
+    }
+    else if (e1.type.iscomplex())
+    {
+		cmp = (e1.toComplex() == e2.toComplex());
+    }
+    else if (e1.type.isintegral())
+    {
+		cmp = (e1.toInteger() == e2.toInteger());
+    }
+    else
+		return EXP_CANT_INTERPRET;
+    if (op == TOK.TOKnotequal)
+		cmp = !cmp;
+
+    e = new IntegerExp(loc, cmp, type);
+
+    return e;
+}
\ No newline at end of file