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package parser
import (
"fmt"
"go/constant"
"strings"
"github.com/mvertes/parscan/vm"
)
// SymKind represents the symbol kind.
type SymKind int
// Symbol kinds.
const (
SymValue SymKind = iota // a value defined in the runtime
SymType // a type
SymLabel // a label indication a position in the VM code
SymConst // a constant
SymVar // a variable, located in the VM memory
SymFunc // a function, located in the VM code
SymPkg // a package
)
//go:generate stringer -type=SymKind
// UnsetAddr denotes an unset symbol index (vs 0).
const UnsetAddr = -65535
// Symbol structure used in parser and compiler.
type Symbol struct {
Kind SymKind
Index int // address of symbol in frame
PkgPath string //
Type *vm.Type //
Value vm.Value //
Cval constant.Value //
Local bool // if true address is relative to local frame, otherwise global
Used bool //
}
// SymbolType returns the VM type of a symbol.
func SymbolType(s *Symbol) *vm.Type {
if s.Type != nil {
return s.Type
}
return vm.TypeOf(s.Value)
}
// AddSymbol adds a new named value at memory position i in the parser symbol table.
func (p *Parser) AddSymbol(i int, name string, v vm.Value, k SymKind, t *vm.Type, local bool) {
name = strings.TrimPrefix(name, "/")
p.Symbols[name] = &Symbol{Kind: k, Index: i, Local: local, Value: v, Type: t}
}
// GetSym searches for an existing symbol starting from the deepest scope.
func (p *Parser) GetSym(name, scope string) (sym *Symbol, sc string, ok bool) {
for {
if sym, ok = p.Symbols[scope+"/"+name]; ok {
return sym, scope, ok
}
i := strings.LastIndex(scope, "/")
if i == -1 {
i = 0
}
if scope = scope[:i]; scope == "" {
break
}
}
sym, ok = p.Symbols[name]
return sym, scope, ok
}
func initUniverse() map[string]*Symbol {
return map[string]*Symbol{
"any": {Kind: SymType, Index: UnsetAddr, Type: vm.TypeOf((*any)(nil)).Elem()},
"bool": {Kind: SymType, Index: UnsetAddr, Type: vm.TypeOf((*bool)(nil)).Elem()},
"error": {Kind: SymType, Index: UnsetAddr, Type: vm.TypeOf((*error)(nil)).Elem()},
"int": {Kind: SymType, Index: UnsetAddr, Type: vm.TypeOf((*int)(nil)).Elem()},
"string": {Kind: SymType, Index: UnsetAddr, Type: vm.TypeOf((*string)(nil)).Elem()},
"nil": {Index: UnsetAddr},
"iota": {Kind: SymConst, Index: UnsetAddr},
"true": {Index: UnsetAddr, Value: vm.ValueOf(true), Type: vm.TypeOf(true)},
"false": {Index: UnsetAddr, Value: vm.ValueOf(false), Type: vm.TypeOf(false)},
"println": {Index: UnsetAddr, Value: vm.ValueOf(func(v ...any) { fmt.Println(v...) })},
}
}
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