parser: fix allocation of local variables

A 'New' instruction is added in VM to manage initialisation
of typed variables in the stack. The instantiated type symbols
are now added to global data. Accessing and setting values by
address is now working.

1 files changed, 14 insertions, 6 deletions

diff --git a/parser/decl.go b/parser/decl.go
index 782b57a..54a2989 100644
--- a/parser/decl.go
+++ b/parser/decl.go
@@ -4,12 +4,15 @@ import (
 	"errors"
 	"go/constant"
 	"go/token"
+	"reflect"
 	"strings"
 
 	"github.com/gnolang/parscan/lang"
 	"github.com/gnolang/parscan/scanner"
 )
 
+var nilValue = reflect.ValueOf(nil)
+
 func (p *Parser) ParseConst(in Tokens) (out Tokens, err error) {
 	if len(in) < 2 {
 		return out, errors.New("missing expression")
@@ -51,8 +54,8 @@ func (p *Parser) parseConstLine(in Tokens) (out Tokens, err error) {
 		if errors.Is(err, MissingTypeErr) {
 			for _, lt := range decl.Split(lang.Comma) {
 				vars = append(vars, lt[0].Str)
-				// TODO: compute type from rhs
-				p.addSym(unsetAddr, strings.TrimPrefix(p.scope+"/"+lt[0].Str, "/"), nil, symConst, nil, false)
+				name := strings.TrimPrefix(p.scope+"/"+lt[0].Str, "/")
+				p.addSym(unsetAddr, name, nilValue, symConst, nil, false)
 			}
 		} else {
 			return out, err
@@ -75,7 +78,7 @@ func (p *Parser) parseConstLine(in Tokens) (out Tokens, err error) {
 			kind:  symConst,
 			index: unsetAddr,
 			cval:  cval,
-			value: constValue(cval),
+			value: reflect.ValueOf(constValue(cval)),
 			local: p.funcScope != "",
 			used:  true,
 		}
@@ -222,7 +225,7 @@ func (p *Parser) parseTypeLine(in Tokens) (out Tokens, err error) {
 	if err != nil {
 		return out, err
 	}
-	p.addSym(unsetAddr, in[0].Str, nil, symType, typ, p.funcScope != "")
+	p.addSym(unsetAddr, in[0].Str, reflect.New(typ).Elem(), symType, typ, p.funcScope != "")
 	return out, err
 }
 
@@ -257,8 +260,13 @@ func (p *Parser) parseVarLine(in Tokens) (out Tokens, err error) {
 		if errors.Is(err, MissingTypeErr) {
 			for _, lt := range decl.Split(lang.Comma) {
 				vars = append(vars, lt[0].Str)
-				// TODO: compute type from rhs
-				p.addSym(unsetAddr, strings.TrimPrefix(p.scope+"/"+lt[0].Str, "/"), nil, symVar, nil, false)
+				name := strings.TrimPrefix(p.scope+"/"+lt[0].Str, "/")
+				if p.funcScope == "" {
+					p.addSym(unsetAddr, name, nilValue, symVar, nil, false)
+					continue
+				}
+				p.addSym(p.framelen[p.funcScope], name, nilValue, symVar, nil, false)
+				p.framelen[p.funcScope]++
 			}
 		} else {
 			return out, err