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Copy pathstack.go
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Copy pathstack.go
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488 lines (443 loc) · 12.1 KB
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package lua
import "log"
func (l *State) push(v value) {
l.stack[l.top] = v
l.top++
}
func (l *State) pop() value {
l.top--
return l.stack[l.top]
}
type upValue struct {
home interface{}
}
type closure interface {
upValue(i int) value
setUpValue(i int, v value)
upValueCount() int
}
type luaClosure struct {
prototype *prototype
upValues []*upValue
}
type goClosure struct {
function Function
upValues []value
}
// Function wrapper, to allow go functions as keys in maps. Explicitly not a closure.
type goFunction struct {
Function
}
func (c *luaClosure) upValue(i int) value {
uv := c.upValues[i]
if home, ok := uv.home.(stackLocation); ok {
return home.state.stack[home.index]
}
return uv.home
}
func (c *luaClosure) setUpValue(i int, v value) {
uv := c.upValues[i]
if home, ok := uv.home.(stackLocation); ok {
home.state.stack[home.index] = v
} else {
uv.home = v
}
}
func (c *luaClosure) upValueCount() int { return len(c.upValues) }
func (c *goClosure) upValue(i int) value { return c.upValues[i] }
func (c *goClosure) setUpValue(i int, v value) { c.upValues[i] = v }
func (c *goClosure) upValueCount() int { return len(c.upValues) }
func (l *State) newUpValue() *upValue { return &upValue{home: nil} }
func (uv *upValue) value() value {
if home, ok := uv.home.(stackLocation); ok {
return home.state.stack[home.index]
}
return uv.home
}
func (uv *upValue) close() {
if home, ok := uv.home.(stackLocation); ok {
uv.home = home.state.stack[home.index]
} else {
panic("attempt to close already-closed up value")
}
}
func (uv *upValue) isInStackAt(level int) bool {
if home, ok := uv.home.(stackLocation); ok {
return home.index == level
}
return false
}
func (uv *upValue) isInStackAbove(level int) bool {
if home, ok := uv.home.(stackLocation); ok {
return home.index >= level
}
return false
}
type openUpValue struct {
upValue *upValue
next *openUpValue
}
func (l *State) newUpValueAt(level int) *upValue {
uv := &upValue{home: stackLocation{state: l, index: level}}
l.upValues = &openUpValue{upValue: uv, next: l.upValues}
return uv
}
func (l *State) close(level int) {
// TODO this seems really inefficient - how can we terminate early?
var p *openUpValue
for e := l.upValues; e != nil; e, p = e.next, e {
if e.upValue.isInStackAbove(level) {
e.upValue.close()
if p != nil {
p.next = e.next
} else {
l.upValues = e.next
}
}
}
}
// information about a call
type callInfo struct {
function, top, resultCount int
previous, next *callInfo
callStatus callStatus
*luaCallInfo
*goCallInfo
}
type luaCallInfo struct {
frame []value
savedPC pc
code []instruction
}
type goCallInfo struct {
context, extra, oldErrorFunction int
continuation Function
oldAllowHook, shouldYield bool
error error
}
func (ci *callInfo) setCallStatus(flag callStatus) { ci.callStatus |= flag }
func (ci *callInfo) clearCallStatus(flag callStatus) { ci.callStatus &^= flag }
func (ci *callInfo) isCallStatus(flag callStatus) bool { return ci.callStatus&flag != 0 }
func (ci *callInfo) isLua() bool { return ci.luaCallInfo != nil }
func (ci *callInfo) stackIndex(slot int) int { return ci.top - len(ci.frame) + slot }
func (ci *callInfo) base() int { return ci.top - len(ci.frame) }
func (ci *callInfo) skip() { ci.savedPC++ }
func (ci *callInfo) jump(offset int) { ci.savedPC += pc(offset) }
func (ci *callInfo) setTop(top int) {
if ci.luaCallInfo != nil {
diff := top - ci.top
ci.frame = ci.frame[:len(ci.frame)+diff]
}
ci.top = top
}
func (ci *callInfo) frameIndex(stackSlot int) int {
if stackSlot < ci.top-len(ci.frame) || ci.top <= stackSlot {
panic("frameIndex called with out-of-range stackSlot")
}
return stackSlot - ci.top + len(ci.frame)
}
func (l *State) pushLuaFrame(function, base, resultCount int, p *prototype) *callInfo {
ci := l.callInfo.next
if ci == nil {
ci = &callInfo{previous: l.callInfo, luaCallInfo: &luaCallInfo{code: p.code}}
l.callInfo.next = ci
} else if ci.luaCallInfo == nil {
ci.goCallInfo = nil
ci.luaCallInfo = &luaCallInfo{code: p.code}
} else {
ci.savedPC = 0
ci.code = p.code
}
ci.function = function
ci.top = base + p.maxStackSize
// TODO l.assert(ci.top <= l.stackLast)
ci.resultCount = resultCount
ci.callStatus = callStatusLua
ci.frame = l.stack[base:ci.top]
l.callInfo = ci
l.top = ci.top
return ci
}
func (l *State) pushGoFrame(function, resultCount int) {
ci := l.callInfo.next
if ci == nil {
ci = &callInfo{previous: l.callInfo, goCallInfo: &goCallInfo{}}
l.callInfo.next = ci
} else if ci.goCallInfo == nil {
ci.goCallInfo = &goCallInfo{}
ci.luaCallInfo = nil
}
ci.function = function
ci.top = l.top + MinStack
// TODO l.assert(ci.top <= l.stackLast)
ci.resultCount = resultCount
ci.callStatus = 0
l.callInfo = ci
}
func (ci *luaCallInfo) step() instruction {
i := ci.code[ci.savedPC]
ci.savedPC++
return i
}
func (l *State) newLuaClosure(p *prototype) *luaClosure {
return &luaClosure{prototype: p, upValues: make([]*upValue, len(p.upValues))}
}
func (l *State) findUpValue(level int) *upValue {
for e := l.upValues; e != nil; e = e.next {
if e.upValue.isInStackAt(level) {
return e.upValue
}
}
return l.newUpValueAt(level)
}
func (l *State) newClosure(p *prototype, upValues []*upValue, base int) value {
c := l.newLuaClosure(p)
p.cache = c
for i, uv := range p.upValues {
if uv.isLocal { // upValue refers to local variable
c.upValues[i] = l.findUpValue(base + uv.index)
} else { // get upValue from enclosing function
c.upValues[i] = upValues[uv.index]
}
}
return c
}
func cached(p *prototype, upValues []*upValue, base int) *luaClosure {
c := p.cache
if c != nil {
for i, uv := range p.upValues {
if uv.isLocal && !c.upValues[i].isInStackAt(base+uv.index) {
return nil
} else if !uv.isLocal && c.upValues[i].home != upValues[uv.index].home {
return nil
}
}
}
return c
}
func (l *State) callGo(f value, function int, resultCount int) {
l.checkStack(MinStack)
l.pushGoFrame(function, resultCount)
if l.hookMask&MaskCall != 0 {
l.hook(HookCall, -1)
}
var n int
switch f := f.(type) {
case *goClosure:
n = f.function(l)
case *goFunction:
n = f.Function(l)
}
apiCheckStackSpace(l, n)
l.postCall(l.top - n)
}
func (l *State) preCall(function int, resultCount int) bool {
for {
switch f := l.stack[function].(type) {
case *goClosure:
l.callGo(f, function, resultCount)
return true
case *goFunction:
l.callGo(f, function, resultCount)
return true
case *luaClosure:
p := f.prototype
l.checkStack(p.maxStackSize)
argCount, parameterCount := l.top-function-1, p.parameterCount
if argCount < parameterCount {
extra := parameterCount - argCount
args := l.stack[l.top : l.top+extra]
for i := range args {
args[i] = nil
}
l.top += extra
argCount += extra
}
base := function + 1
if p.isVarArg {
base = l.adjustVarArgs(p, argCount)
}
ci := l.pushLuaFrame(function, base, resultCount, p)
if l.hookMask&MaskCall != 0 {
l.callHook(ci)
}
return false
default:
tm := l.tagMethodByObject(f, tmCall)
switch tm.(type) {
case closure:
case *goFunction:
default:
l.typeError(f, "call")
}
// Slide the args + function up 1 slot and poke in the tag method
for p := l.top; p > function; p-- {
l.stack[p] = l.stack[p-1]
}
l.top++
l.checkStack(0)
l.stack[function] = tm
}
}
}
func (l *State) callHook(ci *callInfo) {
ci.savedPC++ // hooks assume 'pc' is already incremented
if pci := ci.previous; pci.isLua() && pci.code[pci.savedPC-1].opCode() == opTailCall {
ci.setCallStatus(callStatusTail)
l.hook(HookTailCall, -1)
} else {
l.hook(HookCall, -1)
}
ci.savedPC-- // correct 'pc'
}
func (l *State) adjustVarArgs(p *prototype, argCount int) int {
fixedArgCount := p.parameterCount
l.assert(argCount >= fixedArgCount)
// move fixed parameters to final position
fixed := l.top - argCount // first fixed argument
base := l.top // final position of first argument
fixedArgs := l.stack[fixed : fixed+fixedArgCount]
copy(l.stack[base:base+fixedArgCount], fixedArgs)
for i := range fixedArgs {
fixedArgs[i] = nil
}
return base
}
func (l *State) postCall(firstResult int) bool {
ci := l.callInfo
if l.hookMask&MaskReturn != 0 {
l.hook(HookReturn, -1)
}
result, wanted, i := ci.function, ci.resultCount, 0
l.callInfo = ci.previous // back to caller
// TODO this is obscure - I don't fully understand the control flow, but it works
for i = wanted; i != 0 && firstResult < l.top; i-- {
l.stack[result] = l.stack[firstResult]
result++
firstResult++
}
for ; i > 0; i-- {
l.stack[result] = nil
result++
}
l.top = result
if l.hookMask&(MaskReturn|MaskLine) != 0 {
l.oldPC = l.callInfo.savedPC // oldPC for caller function
}
return wanted != MultipleReturns
}
// Call a Go or Lua function. The function to be called is at function.
// The arguments are on the stack, right after the function. On return, all the
// results are on the stack, starting at the original function position.
func (l *State) call(function int, resultCount int, allowYield bool) {
if l.nestedGoCallCount++; l.nestedGoCallCount == maxCallCount {
l.runtimeError("Go stack overflow")
} else if l.nestedGoCallCount >= maxCallCount+maxCallCount>>3 {
l.throw(ErrorError) // error while handling stack error
}
if !allowYield {
l.nonYieldableCallCount++
}
if !l.preCall(function, resultCount) { // is a Lua function?
l.execute() // call it
}
if !allowYield {
l.nonYieldableCallCount--
}
l.nestedGoCallCount--
}
func (l *State) throw(errorCode error) {
if l.protectFunction != nil {
panic(errorCode)
} else {
l.error = errorCode
if g := l.global.mainThread; g.protectFunction != nil {
g.push(l.stack[l.top-1])
g.throw(errorCode)
} else {
if l.global.panicFunction != nil {
l.global.panicFunction(l)
}
log.Panicf("Uncaught Lua error: %v", errorCode)
}
}
}
func (l *State) protect(f func()) (err error) {
nestedGoCallCount, protectFunction := l.nestedGoCallCount, l.protectFunction
l.protectFunction = func() {
if e := recover(); e != nil {
err = e.(error)
l.nestedGoCallCount, l.protectFunction = nestedGoCallCount, protectFunction
}
}
defer l.protectFunction()
f()
l.nestedGoCallCount, l.protectFunction = nestedGoCallCount, protectFunction
return err
}
func (l *State) hook(event, line int) {
if l.hooker == nil || !l.allowHook {
return
}
ci := l.callInfo
top := l.top
ciTop := ci.top
ar := Debug{Event: event, CurrentLine: line, callInfo: ci}
l.checkStack(MinStack)
ci.setTop(l.top + MinStack)
l.assert(ci.top <= l.stackLast)
l.allowHook = false // can't hook calls inside a hook
ci.setCallStatus(callStatusHooked)
l.hooker(l, ar)
l.assert(!l.allowHook)
l.allowHook = true
ci.setTop(ciTop)
l.top = top
ci.clearCallStatus(callStatusHooked)
}
func (l *State) initializeStack() {
l.stack = make([]value, basicStackSize)
l.stackLast = basicStackSize - extraStack
l.top++
l.baseCallInfo.luaCallInfo = &luaCallInfo{frame: l.stack[:0]}
l.baseCallInfo.setTop(l.top + MinStack)
l.callInfo = &l.baseCallInfo
}
func (l *State) checkStack(n int) {
if l.stackLast-l.top <= n {
l.growStack(n)
}
}
func (l *State) reallocStack(newSize int) {
l.assert(newSize <= maxStack || newSize == errorStackSize)
l.assert(l.stackLast == len(l.stack)-extraStack)
l.stack = append(l.stack, make([]value, newSize-len(l.stack))...)
l.stackLast = len(l.stack) - extraStack
l.callInfo.next = nil
for ci := l.callInfo; ci != nil; ci = ci.previous {
if ci.isLua() {
top := ci.top
ci.frame = l.stack[top-len(ci.frame) : top]
}
}
}
func (l *State) growStack(n int) {
if len(l.stack) > maxStack { // error after extra size?
l.throw(ErrorError)
} else {
needed := l.top + n + extraStack
newSize := 2 * len(l.stack)
if newSize > maxStack {
newSize = maxStack
}
if newSize < needed {
newSize = needed
}
if newSize > maxStack { // stack overflow?
l.reallocStack(errorStackSize)
l.runtimeError("stack overflow")
} else {
l.reallocStack(newSize)
}
}
}
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