expression stack based on THECO's ArithmeticStack

1 files changed, 184 insertions, 0 deletions

diff --git a/expressions.cpp b/expressions.cpp
new file mode 100644
index 0000000..1e48d3e
--- /dev/null
+++ b/expressions.cpp
@@ -0,0 +1,184 @@
+#include <glib.h>
+
+#include "sciteco.h"
+#include "undo.h"
+#include "expressions.h"
+
+Expressions expressions;
+
+void
+Expressions::set_num_sign(gint sign)
+{
+	undo.push_var<gint>(num_sign);
+	num_sign = sign;
+}
+
+void
+Expressions::set_radix(gint r)
+{
+	undo.push_var<gint>(radix);
+	radix = r;
+}
+
+gint64
+Expressions::push(gint64 number)
+{
+	while (numbers.peek() == G_MAXINT64)
+		pop_num();
+
+	push(OP_NUMBER);
+
+	undo.push(new UndoTokenPop<gint64>(numbers));
+	return numbers.push(number);
+}
+
+gint64
+Expressions::pop_num(int index)
+{
+	gint64 n = G_MAXINT64;
+
+	pop_op();
+	if (numbers.items() > 0) {
+		n = numbers.pop(index);
+		undo.push(new UndoTokenPush<gint64>(numbers, n, index));
+	}
+
+	return n;
+}
+
+gint64
+Expressions::pop_num_calc(int index, gint64 imply)
+{
+	gint64 n = G_MAXINT64;
+
+	eval();
+	if (args() > 0)
+		n = pop_num(index);
+	if (n == G_MAXINT64)
+		n = imply;
+
+	if (num_sign < 0)
+		set_num_sign(1);
+
+	return n;
+}
+
+gint64
+Expressions::add_digit(gchar digit)
+{
+	gint64 n = 0;
+
+	if (args() > 0) {
+		n = pop_num();
+		if (n == G_MAXINT64)
+			n = 0;
+	}
+
+	return push(n*radix + num_sign*(digit - '0'));
+}
+
+Expressions::Operator
+Expressions::push(Expressions::Operator op)
+{
+	undo.push(new UndoTokenPop<Operator>(operators));
+	return operators.push(op);
+}
+
+Expressions::Operator
+Expressions::push_calc(Expressions::Operator op)
+{
+	/* calculate if op has lower precedence than op on stack */
+	if (operators.peek(first_op()) <= op)
+		calc();
+
+	return push(op);
+}
+
+Expressions::Operator
+Expressions::pop_op(int index)
+{
+	Operator op = OP_NIL;
+
+	if (operators.items() > 0) {
+		op = operators.pop(index);
+		undo.push(new UndoTokenPush<Operator>(operators, op, index));
+	}
+
+	return op;
+}
+
+void
+Expressions::calc(void)
+{
+	gint64 result;
+
+	gint64 vright = pop_num();
+	Operator op = pop_op();
+	gint64 vleft = pop_num();
+
+	switch (op) {
+	case OP_POW:
+		result = 1;
+		while (vright--)
+			result *= vleft;
+		break;
+	case OP_MUL: result = vleft * vright; break;
+	case OP_DIV: result = vleft / vright; break;
+	case OP_MOD: result = vleft % vright; break;
+	case OP_ADD: result = vleft + vright; break;
+	case OP_SUB: result = vleft - vright; break;
+	case OP_AND: result = vleft & vright; break;
+	case OP_OR:  result = vleft | vright; break;
+	default:
+		/* shouldn't happen */
+		g_assert(false);
+	}
+
+	push(result);
+}
+
+void
+Expressions::eval(bool pop_brace)
+{
+	if (numbers.items() < 2)
+		return;
+
+	for (;;) {
+		gint n = first_op();
+		Operator op;
+
+		if (!n)
+			break;
+
+		op = operators.peek(n);
+		if (op == OP_LOOP)
+			break;
+		if (op == OP_BRACE) {
+			if (pop_brace)
+				pop_op(n);
+			break;
+		}
+
+		calc();
+	}
+}
+
+int
+Expressions::args(void)
+{
+	int n = 0;
+	int items = operators.items();
+
+	while (n < items && operators.peek(n+1) == OP_NUMBER)
+		n++;
+
+	return n;
+}
+
+void
+Expressions::discard_args(void)
+{
+	eval();
+	for (int i = args(); i; i--)
+		pop_num_calc();
+}