New, more flexible, parser context datatype that includes and extends

the previous flags allowForest and allowVarRef.
Added binary operator (work in progress).
Better implementation of +=,-=,*=, and /= (new) operators.

operator-binary.go

@@ -0,0 +1,104 @@
+// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
+// All rights reserved.
+
+// operator-binary.go
+package expr
+
+//-------- NOT term
+
+func newBinNotTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 1),
+		position: posPrefix,
+		priority: priNot,
+		evalFunc: evalBinaryNot,
+	}
+}
+
+func evalBinaryNot(ctx ExprContext, opTerm *term) (v any, err error) {
+	var value any
+
+	if value, err = opTerm.evalPrefix(ctx); err != nil {
+		return
+	}
+
+	if IsInteger(value) {
+		i, _ := value.(int64)
+		v = ^i
+	} else {
+		err = opTerm.errIncompatibleType(value)
+	}
+	return
+}
+
+//-------- Binary AND term
+
+func newBinAndTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priAnd,
+		evalFunc: evalBinaryAnd,
+	}
+}
+
+func evalBinaryAnd(ctx ExprContext, self *term) (v any, err error) {
+	var leftValue, rightValue any
+	var leftInt, rightInt int64
+	var lok, rok bool
+
+	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
+		return
+	}
+
+	leftInt, lok = leftValue.(int64)
+	rightInt, rok = rightValue.(int64)
+
+	if lok && rok {
+		v = leftInt & rightInt
+	} else {
+		err = self.errIncompatibleTypes(leftValue, rightValue)
+	}
+	return
+}
+
+//-------- Binary OR term
+
+func newBinOrTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priOr,
+		evalFunc: evalBinaryOr,
+	}
+}
+
+func evalBinaryOr(ctx ExprContext, self *term) (v any, err error) {
+	var leftValue, rightValue any
+	var leftInt, rightInt int64
+	var lok, rok bool
+
+	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
+		return
+	}
+
+	leftInt, lok = leftValue.(int64)
+	rightInt, rok = rightValue.(int64)
+
+	if lok && rok {
+		v = leftInt | rightInt
+	} else {
+		err = self.errIncompatibleTypes(leftValue, rightValue)
+	}
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymTilde, newBinNotTerm)
+	registerTermConstructor(SymAmpersand, newBinAndTerm)
+	// registerTermConstructor(SymVertBar, newBinOrTerm)
+}