Added all source files

operator-sign.go

@@ -0,0 +1,61 @@
+// operator-sign.go
+package expr
+
+//-------- plus sign term
+
+func newPlusSignTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		class:    classOperator,
+		kind:     kindUnknown,
+		children: make([]*term, 0, 1),
+		position: posPrefix,
+		priority: priSign,
+		evalFunc: evalSign,
+	}
+}
+
+func newMinusSignTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		class:    classOperator,
+		kind:     kindUnknown,
+		children: make([]*term, 0, 1),
+		position: posPrefix,
+		priority: priSign,
+		evalFunc: evalSign,
+	}
+}
+
+func evalSign(ctx exprContext, self *term) (v any, err error) {
+	var rightValue any
+
+	if rightValue, err = self.evalPrefix(ctx); err != nil {
+		return
+	}
+
+	if isFloat(rightValue) {
+		if self.tk.Sym == SymChangeSign {
+			f, _ := rightValue.(float64)
+			v = -f
+		} else {
+			v = rightValue
+		}
+	} else if isInteger(rightValue) {
+		if self.tk.Sym == SymChangeSign {
+			i, _ := rightValue.(int64)
+			v = -i
+		} else {
+			v = rightValue
+		}
+	} else {
+		err = self.errIncompatibleType(rightValue)
+	}
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymUnchangeSign, newPlusSignTerm)
+	registerTermConstructor(SymChangeSign, newMinusSignTerm)
+}