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package scope
import (
"fmt"
"jinx/pkg/lang/vm/code"
)
type ScopeChain struct {
symbolScopes []SymbolScope // All other scopes are bound to this by ID.
functionScopes []FunctionScope
loopScopes []LoopScope
}
func NewScopeChain() ScopeChain {
symbolScopes := make([]SymbolScope, 1)
symbolScopes[0] = NewSymbolScope()
functionScopes := make([]FunctionScope, 1)
functionScopes[0] = NewFunctionScope(0, "") // Root function to house top-scope sub units
loopScopes := make([]LoopScope, 0)
return ScopeChain{
symbolScopes: symbolScopes,
functionScopes: functionScopes,
loopScopes: loopScopes,
}
}
func (sc *ScopeChain) CurrentScopeID() ScopeID {
return ScopeID(len(sc.symbolScopes) - 1)
}
func (sc *ScopeChain) IsRootScope() bool {
return sc.CurrentScopeID() == ScopeID(0)
}
func (sc *ScopeChain) Current() *SymbolScope {
if len(sc.functionScopes) == 0 {
panic("root scope is missing")
}
return &sc.symbolScopes[sc.CurrentScopeID()]
}
func (sc *ScopeChain) CurrentFunction() *FunctionScope {
if len(sc.functionScopes) == 0 {
panic("root function scope is missing")
}
return &sc.functionScopes[len(sc.functionScopes)-1]
}
func (sc *ScopeChain) CurrentLoop() *LoopScope {
if len(sc.loopScopes) == 0 {
return nil
}
return &sc.loopScopes[len(sc.loopScopes)-1]
}
func (sc *ScopeChain) CalculateTopLocalIndex() int {
topFunctionScope := sc.CurrentFunction()
sumLocals := 0
for scopeIndex := len(sc.symbolScopes) - 1; scopeIndex >= 0; scopeIndex-- {
scope := sc.symbolScopes[scopeIndex]
sumLocals += len(scope.variableSymbols)
// Function scope signifies start of stack boundry.
if ScopeID(scopeIndex) == topFunctionScope.id {
break
}
}
return sumLocals
}
func (sc *ScopeChain) CanSymbolBeDeclared(name string) bool {
topFunctionScope := sc.CurrentFunction()
for scopeIndex := len(sc.symbolScopes) - 1; scopeIndex >= 0; scopeIndex-- {
scope := sc.symbolScopes[scopeIndex]
if _, ok := scope.nameToSymbol[name]; ok {
return false
}
// Shadowing only allowed with at least one function scope in the chain.
if ScopeID(scopeIndex) == topFunctionScope.id {
return true
}
}
return true
}
func (sc *ScopeChain) Enter() {
sc.symbolScopes = append(sc.symbolScopes, NewSymbolScope())
}
func (sc *ScopeChain) EnterFunction(unit code.Marker) {
sc.Enter()
sc.functionScopes = append(sc.functionScopes, NewFunctionScope(sc.CurrentScopeID(), unit))
}
func (sc *ScopeChain) EnterConstructor(unit code.Marker, thisLocal int) {
sc.Enter()
sc.functionScopes = append(sc.functionScopes, NewMethodFunctionScope(sc.CurrentScopeID(), unit, thisLocal))
}
func (sc *ScopeChain) EnterMethod(unit code.Marker) {
sc.Enter()
sc.functionScopes = append(sc.functionScopes, NewMethodFunctionScope(sc.CurrentScopeID(), unit, -1))
}
func (sc *ScopeChain) EnterLoop() (code.Marker, code.Marker) {
parentMarker := sc.CreateAnonymousFunctionSubUnit()
breakMarker := parentMarker.SubMarker("end")
continueMarker := parentMarker.SubMarker("start")
sc.Enter()
sc.loopScopes = append(sc.loopScopes, NewLoopScope(sc.CurrentScopeID(), breakMarker, continueMarker))
return breakMarker, continueMarker
}
func (sc *ScopeChain) Exit() int {
if sc.CurrentScopeID() == 0 {
return 0
}
id := sc.CurrentScopeID()
stackSpace := len(sc.symbolScopes[id].variableSymbols)
sc.symbolScopes = sc.symbolScopes[:id]
if sc.CurrentLoop() != nil && sc.CurrentLoop().id == id {
sc.loopScopes = sc.loopScopes[:len(sc.loopScopes)-1]
}
if sc.CurrentFunction().id == id {
sc.functionScopes = sc.functionScopes[:len(sc.functionScopes)-1]
}
return stackSpace
}
func (sc *ScopeChain) Declare(name string) (int, bool) {
// Check whether the symbol is already declared in any of the scopes.
if !sc.CanSymbolBeDeclared(name) {
return 0, false
}
current := sc.Current()
indexInScope := len(current.variableSymbols)
symbolID := SymbolID{
symbolKind: SymbolKindVariable,
scopeID: sc.CurrentScopeID(),
indexInScope: indexInScope,
}
localIndex := sc.CalculateTopLocalIndex()
// Declare the symbol in the current scope.
current.variableSymbols = append(current.variableSymbols, Symbol[SymbolVariable]{
name: name,
data: SymbolVariable{
localIndex: localIndex,
},
})
current.nameToSymbol[name] = symbolID
return localIndex, true
}
func (sc *ScopeChain) DeclareAnonymous() int {
current := sc.Current()
localIndex := sc.CalculateTopLocalIndex()
current.variableSymbols = append(current.variableSymbols, Symbol[SymbolVariable]{
name: "", // An anonymous symbol has no name.
data: SymbolVariable{
localIndex: localIndex,
},
})
return localIndex
}
func (sc *ScopeChain) DeclareTemporary() int {
return sc.CalculateTopLocalIndex() // :)
}
func (sc *ScopeChain) DeclareGlobal(name, module, author string) bool {
if !sc.CanSymbolBeDeclared(name) {
return false
}
current := sc.Current()
indexInScope := len(current.globalSymbols)
symbolID := SymbolID{
symbolKind: SymbolKindGlobal,
scopeID: sc.CurrentScopeID(),
indexInScope: indexInScope,
}
globalID := fmt.Sprintf("%s:%s:%s", author, module, name)
// Declare the symbol in the current scope.
current.globalSymbols = append(current.globalSymbols, Symbol[SymbolGlobal]{
name: name,
data: SymbolGlobal{
id: globalID,
},
})
current.nameToSymbol[name] = symbolID
return true
}
func (sc *ScopeChain) CreateAnonymousFunctionSubUnit() code.Marker {
fnScope := sc.CurrentFunction()
index := fnScope.subUnitCount
fnScope.subUnitCount++
return sc.CreateFunctionSubUnit(fmt.Sprintf("anon_%d", index))
}
func (sc *ScopeChain) CreateFunctionSubUnit(subUnitName string) code.Marker {
fnScope := sc.CurrentFunction()
name := fnScope.unit
if name == "" {
name = code.Marker(subUnitName)
} else {
name = name.SubUnit(subUnitName)
}
return name
}
func (sc *ScopeChain) Lookup(name string) (SymbolID, bool) {
var id SymbolID
for scopeIndex := len(sc.symbolScopes) - 1; scopeIndex >= 0; scopeIndex-- {
scope := sc.symbolScopes[scopeIndex]
if foundID, ok := scope.nameToSymbol[name]; ok {
id = foundID
break
}
if scopeIndex == 0 {
return SymbolID{}, false
}
}
// Check whether the symbol is outside the current function scope.
fnScope := sc.CurrentFunction()
if id.scopeID < fnScope.id {
// Return env symbol instead of a local symbol.
return SymbolID{
symbolKind: SymbolKindEnv,
scopeID: id.scopeID,
indexInScope: id.indexInScope,
}, true
}
return id, true
}
func (sc *ScopeChain) GetVariable(id SymbolID) Symbol[SymbolVariable] {
if id.symbolKind != SymbolKindVariable {
panic("incorrect symbol id kind given")
}
return sc.symbolScopes[id.scopeID].variableSymbols[id.indexInScope]
}
func (sc *ScopeChain) GetEnv(id SymbolID) Symbol[SymbolEnv] {
if id.symbolKind != SymbolKindEnv {
panic("incorrect symbol id kind given")
}
symbol := sc.symbolScopes[id.scopeID].variableSymbols[id.indexInScope]
// Add the local to the function scope, if it is not already there.
fnScope := sc.CurrentFunction()
var indexInEnv int
alreadyUsed := false
for i, env := range fnScope.outsideSymbolsInEnv {
if env == id {
alreadyUsed = true
indexInEnv = i
break
}
}
if !alreadyUsed {
indexInEnv = len(fnScope.outsideSymbolsInEnv)
fnScope.outsideSymbolsInEnv = append(fnScope.outsideSymbolsInEnv, id)
}
return Symbol[SymbolEnv]{
name: symbol.name,
data: SymbolEnv{
indexInEnv: indexInEnv,
},
}
}
func (sc *ScopeChain) GetGlobal(id SymbolID) Symbol[SymbolGlobal] {
if id.symbolKind != SymbolKindGlobal {
panic("incorrect symbol id kind given")
}
return sc.symbolScopes[id.scopeID].globalSymbols[id.indexInScope]
}
|
