Added all source files

operator-sum.go

@@ -0,0 +1,84 @@
+// operator-sum.go
+package expr
+
+import (
+	"fmt"
+)
+
+//-------- plus term
+
+func newPlusTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		class:    classOperator,
+		kind:     kindUnknown,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priSum,
+		evalFunc: evalPlus,
+	}
+}
+
+func evalPlus(ctx exprContext, self *term) (v any, err error) {
+	var leftValue, rightValue any
+
+	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
+		return
+	}
+
+	if (isString(leftValue) && isNumberString(rightValue)) || (isString(rightValue) && isNumberString(leftValue)) {
+		v = fmt.Sprintf("%v%v", leftValue, rightValue)
+	} else if isNumber(leftValue) && isNumber(rightValue) {
+		if isFloat(leftValue) || isFloat(rightValue) {
+			v = numAsFloat(leftValue) + numAsFloat(rightValue)
+		} else {
+			leftInt, _ := leftValue.(int64)
+			rightInt, _ := rightValue.(int64)
+			v = leftInt + rightInt
+		}
+	} else {
+		err = self.errIncompatibleTypes(leftValue, rightValue)
+	}
+	return
+}
+
+//-------- minus term
+
+func newMinusTerm(tk *Token) (inst *term) {
+	return &term{
+		tk:       *tk,
+		class:    classOperator,
+		kind:     kindUnknown,
+		children: make([]*term, 0, 2),
+		position: posInfix,
+		priority: priSum,
+		evalFunc: evalMinus,
+	}
+}
+
+func evalMinus(ctx exprContext, self *term) (v any, err error) {
+	var leftValue, rightValue any
+
+	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
+		return
+	}
+
+	if isNumber(leftValue) && isNumber(rightValue) {
+		if isFloat(leftValue) || isFloat(rightValue) {
+			v = numAsFloat(leftValue) - numAsFloat(rightValue)
+		} else {
+			leftInt, _ := leftValue.(int64)
+			rightInt, _ := rightValue.(int64)
+			v = leftInt - rightInt
+		}
+	} else {
+		err = self.errIncompatibleTypes(leftValue, rightValue)
+	}
+	return
+}
+
+// init
+func init() {
+	registerTermConstructor(SymPlus, newPlusTerm)
+	registerTermConstructor(SymMinus, newMinusTerm)
+}