expr/operator-bool.go

// Copyright (c) 2024 Celestino Amoroso (celestino.amoroso@gmail.com).
// All rights reserved.

// operator-bool.go
package expr

import "fmt"

//-------- NOT term

func newNotTerm(tk *Token) (inst *term) {
	return &term{
		tk:       *tk,
		children: make([]*term, 0, 1),
		position: posPrefix,
		priority: priNot,
		evalFunc: evalNot,
	}
}

func evalNot(ctx ExprContext, opTerm *term) (v any, err error) {
	var rightValue any

	if rightValue, err = opTerm.evalPrefix(ctx); err != nil {
		return
	}

	if b, ok := ToBool(rightValue); ok {
		v = !b
	} else {
		err = opTerm.errIncompatibleType(rightValue)
	}
	return
}

//-------- AND term

func newAndTerm(tk *Token) (inst *term) {
	return &term{
		tk:       *tk,
		children: make([]*term, 0, 2),
		position: posInfix,
		priority: priAnd,
		evalFunc: evalAnd,
	}
}

func evalAnd(ctx ExprContext, self *term) (v any, err error) {
	if CtrlIsEnabled(ctx, ControlBoolShortcut) {
		v, err = evalAndWithShortcut(ctx, self)
	} else {
		v, err = evalAndWithoutShortcut(ctx, self)
	}
	return
}

func evalAndWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
	var leftValue, rightValue any
	var leftBool, rightBool bool
	var lok, rok bool

	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
		return
	}

	leftBool, lok = ToBool(leftValue)
	rightBool, rok = ToBool(rightValue)

	if lok && rok {
		v = leftBool && rightBool
	} else {
		err = self.errIncompatibleTypes(leftValue, rightValue)
	}
	return
}

func evalAndWithShortcut(ctx ExprContext, self *term) (v any, err error) {
	var leftValue, rightValue any

	if err = self.checkOperands(); err != nil {
		return
	}

	if leftValue, err = self.children[0].compute(ctx); err != nil {
		return
	}

	if leftBool, lok := ToBool(leftValue); !lok {
		err = fmt.Errorf("got %s as left operand type of 'AND' operator, it must be bool", TypeName(leftValue))
		return
	} else if !leftBool {
		v = false
	} else if rightValue, err = self.children[1].compute(ctx); err == nil {
		if rightBool, rok := ToBool(rightValue); rok {
			v = rightBool
		} else {
			err = self.errIncompatibleTypes(leftValue, rightValue)
		}
	}
	return
}

//-------- OR term

func newOrTerm(tk *Token) (inst *term) {
	return &term{
		tk:       *tk,
		children: make([]*term, 0, 2),
		position: posInfix,
		priority: priOr,
		evalFunc: evalOr,
	}
}

func evalOr(ctx ExprContext, self *term) (v any, err error) {
	if CtrlIsEnabled(ctx, ControlBoolShortcut) {
		v, err = evalOrWithShortcut(ctx, self)
	} else {
		v, err = evalOrWithoutShortcut(ctx, self)
	}
	return
}

func evalOrWithoutShortcut(ctx ExprContext, self *term) (v any, err error) {
	var leftValue, rightValue any
	var leftBool, rightBool bool
	var lok, rok bool

	if leftValue, rightValue, err = self.evalInfix(ctx); err != nil {
		return
	}

	leftBool, lok = ToBool(leftValue)
	rightBool, rok = ToBool(rightValue)

	if lok && rok {
		v = leftBool || rightBool
	} else {
		err = self.errIncompatibleTypes(leftValue, rightValue)
	}
	return
}

func evalOrWithShortcut(ctx ExprContext, self *term) (v any, err error) {
	var leftValue, rightValue any

	if err = self.checkOperands(); err != nil {
		return
	}

	if leftValue, err = self.children[0].compute(ctx); err != nil {
		return
	}

	if leftBool, lok := ToBool(leftValue); !lok {
		err = fmt.Errorf("got %s as left operand type of 'OR' operator, it must be bool", TypeName(leftValue))
		return
	} else if leftBool {
		v = true
	} else if rightValue, err = self.children[1].compute(ctx); err == nil {
		if rightBool, rok := ToBool(rightValue); rok {
			v = rightBool
		} else {
			err = self.errIncompatibleTypes(leftValue, rightValue)
		}
	}
	return
}

// init
func init() {
	registerTermConstructor(SymNot, newNotTerm)
	registerTermConstructor(SymAnd, newAndTerm)
	registerTermConstructor(SymOr, newOrTerm)
}