From ae58deb5da1fa2ae5e461783ce592a9b962da778 Mon Sep 17 00:00:00 2001
From: Marc Vertes <mvertes@free.fr>
Date: Mon, 20 Nov 2023 19:28:31 +0100
Subject: parser: add pointer support (work in progress)

This is incomplete because the scalar variables are not addressable
right now. To be addressable they must be represented as reflect
values, not interfaces.
---
 parser/compiler.go         | 6 ++++++
 parser/expr.go             | 2 +-
 parser/interpreter_test.go | 7 +++++++
 parser/type.go             | 9 ++++++++-
 4 files changed, 22 insertions(+), 2 deletions(-)

diff --git a/parser/compiler.go b/parser/compiler.go
index bdf801b..36aa9d8 100644
--- a/parser/compiler.go
+++ b/parser/compiler.go
@@ -87,6 +87,12 @@ func (c *Compiler) Codegen(tokens Tokens) (err error) {
 		case lang.Plus:
 			// Nothing to do.
 
+		case lang.Address:
+			emit(int64(t.Pos), vm.Address)
+
+		case lang.Deref:
+			emit(int64(t.Pos), vm.Deref)
+
 		case lang.Index:
 			emit(int64(t.Pos), vm.Index)
 
diff --git a/parser/expr.go b/parser/expr.go
index 207f38b..806fd75 100644
--- a/parser/expr.go
+++ b/parser/expr.go
@@ -42,7 +42,7 @@ func (p *Parser) ParseExpr(in Tokens) (out Tokens, err error) {
 		case lang.Int, lang.String:
 			out = append(out, t)
 			vl++
-		case lang.Define, lang.Add, lang.Sub, lang.Assign, lang.Equal, lang.Greater, lang.Less, lang.Mul, lang.Land, lang.Lor, lang.Shl, lang.Shr, lang.Not:
+		case lang.Define, lang.Add, lang.Sub, lang.Assign, lang.Equal, lang.Greater, lang.Less, lang.Mul, lang.Land, lang.Lor, lang.Shl, lang.Shr, lang.Not, lang.And:
 			if i == 0 || in[i-1].Id.IsOperator() {
 				// An operator preceded by an operator or no token is unary.
 				t.Id = lang.UnaryOp[t.Id]
diff --git a/parser/interpreter_test.go b/parser/interpreter_test.go
index db9b916..9555475 100644
--- a/parser/interpreter_test.go
+++ b/parser/interpreter_test.go
@@ -192,6 +192,13 @@ func TestArray(t *testing.T) {
 	})
 }
 
+func TestPointer(t *testing.T) {
+	run(t, []etest{
+		{src: "var a *int; a", res: "<nil>"},
+		//{src: "var a int = 2; var b *int = &a; b", res: "2"},
+	})
+}
+
 func TestStruct(t *testing.T) {
 	run(t, []etest{
 		{src: "type T struct {a string; b, c int}; var t T; t", res: "{ 0 0}"},
diff --git a/parser/type.go b/parser/type.go
index 573ae6f..31af1e3 100644
--- a/parser/type.go
+++ b/parser/type.go
@@ -51,6 +51,13 @@ func (p *Parser) ParseTypeExpr(in Tokens) (typ reflect.Type, err error) {
 		}
 		return reflect.SliceOf(typ), nil
 
+	case lang.Mul:
+		typ, err := p.ParseTypeExpr(in[1:])
+		if err != nil {
+			return nil, err
+		}
+		return reflect.PointerTo(typ), nil
+
 	case lang.Func:
 		// Get argument and return token positions depending on function pattern:
 		// method with receiver, named function or anonymous closure.
@@ -165,7 +172,7 @@ func (p *Parser) parseParamTypes(in Tokens, flag typeFlag) (types []reflect.Type
 func (p *Parser) addSymVar(index int, name string, typ reflect.Type, flag typeFlag, local bool) {
 	var zv any = reflect.New(typ).Elem()
 	switch typ.Kind() {
-	case reflect.Struct, reflect.Array, reflect.Slice:
+	case reflect.Struct, reflect.Array, reflect.Slice, reflect.Pointer:
 	default:
 		zv = zv.(reflect.Value).Interface()
 	}
-- 
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