go6502/asm/context/context.go

package context

import "fmt"

type Context interface {
	Set(name string, value uint16)
	Get(name string) (uint16, bool)
	SetAddr(uint16)
	GetAddr() (uint16, bool)
	DivZero() (uint16, error)
	RemoveChanged()
	Clear()
	SettingOn(name string) error
	SettingOff(name string) error
	Setting(name string) bool
	HasSetting(name string) bool
	AddMacroName(name string)
	HasMacroName(name string) bool
	PushMacroCall(name string, number int, locals map[string]bool)
	PopMacroCall() bool
	GetMacroCall() (string, int, map[string]bool)

	LastLabel() string
	SetLastLabel(label string)
}

type macroCall struct {
	name   string
	number int
	locals map[string]bool
}

type SimpleContext struct {
	symbols       map[string]symbolValue
	addr          int32
	lastLabel     string
	highbit       byte // OR-mask for ASCII high bit
	onOff         map[string]bool
	onOffDefaults map[string]bool
	macroNames    map[string]bool
	macroCalls    []macroCall
}

type symbolValue struct {
	v       uint16
	changed bool // Did the value ever change?
}

func (sc *SimpleContext) fix() {
	if sc.symbols == nil {
		sc.symbols = make(map[string]symbolValue)
	}
}

func (sc *SimpleContext) DivZero() (uint16, error) {
	return 0, fmt.Errorf("Not implemented: context.SimpleContext.DivZero()")
}

func (sc *SimpleContext) Get(name string) (uint16, bool) {
	if name == "*" {
		return sc.GetAddr()
	}
	sc.fix()
	s, found := sc.symbols[name]
	return s.v, found
}

func (sc *SimpleContext) SetAddr(addr uint16) {
	sc.addr = int32(addr)
}

func (sc *SimpleContext) GetAddr() (uint16, bool) {
	if sc.addr == -1 {
		return 0, false
	}
	return uint16(sc.addr), true
}

func (sc *SimpleContext) Set(name string, value uint16) {
	sc.fix()
	s, found := sc.symbols[name]
	if found && s.v != value {
		s.changed = true
	}
	s.v = value
	sc.symbols[name] = s
}

func (sc *SimpleContext) RemoveChanged() {
	sc.fix()
	for n, s := range sc.symbols {
		if s.changed {
			delete(sc.symbols, n)
		}
	}
}

func (sc *SimpleContext) Clear() {
	sc.symbols = make(map[string]symbolValue)
	sc.highbit = 0x00
	sc.macroNames = nil
	sc.resetOnOff()
}

func (sc *SimpleContext) SettingOn(name string) error {
	if !sc.HasSetting(name) {
		return fmt.Errorf("no settable variable named '%s'", name)
	}
	if sc.onOff == nil {
		sc.onOff = map[string]bool{name: true}
	} else {
		sc.onOff[name] = true
	}
	return nil
}

func (sc *SimpleContext) SettingOff(name string) error {
	if !sc.HasSetting(name) {
		return fmt.Errorf("no settable variable named '%s'", name)
	}
	if sc.onOff == nil {
		sc.onOff = map[string]bool{name: false}
	} else {
		sc.onOff[name] = false
	}
	return nil
}

func (sc *SimpleContext) Setting(name string) bool {
	return sc.onOff[name]
}

func (sc *SimpleContext) HasSetting(name string) bool {
	_, ok := sc.onOff[name]
	return ok
}

func (sc *SimpleContext) AddMacroName(name string) {
	if sc.macroNames == nil {
		sc.macroNames = make(map[string]bool)
	}
	sc.macroNames[name] = true
}

func (sc *SimpleContext) HasMacroName(name string) bool {
	return sc.macroNames[name]
}

func (sc *SimpleContext) resetOnOff() {
	sc.onOff = make(map[string]bool)
	for k, v := range sc.onOffDefaults {
		sc.onOff[k] = v
	}
}

func (sc *SimpleContext) SetOnOffDefaults(defaults map[string]bool) {
	sc.onOffDefaults = defaults
	sc.resetOnOff()
}

func (sc *SimpleContext) PushMacroCall(name string, number int, locals map[string]bool) {
	sc.macroCalls = append(sc.macroCalls, macroCall{name, number, locals})
}

func (sc *SimpleContext) PopMacroCall() bool {
	if len(sc.macroCalls) == 0 {
		return false
	}
	sc.macroCalls = sc.macroCalls[0 : len(sc.macroCalls)-1]
	return true
}

func (sc *SimpleContext) GetMacroCall() (string, int, map[string]bool) {
	if len(sc.macroCalls) == 0 {
		return "", 0, nil
	}
	mc := sc.macroCalls[len(sc.macroCalls)-1]
	return mc.name, mc.number, mc.locals
}

func (sc *SimpleContext) LastLabel() string {
	return sc.lastLabel
}

func (sc *SimpleContext) SetLastLabel(l string) {
	sc.lastLabel = l
}