From a3da295cdab55466e9f0586c2dfc2ccad8b8472b Mon Sep 17 00:00:00 2001
From: Hidetatz Yaginuma <hidetatz@gmail.com>
Date: Wed, 6 Sep 2023 10:34:22 +0900
Subject: [PATCH] wip support struct field selection

---
 process.go      | 34 +++++++++++++++++++++++-----------
 tests/struct.sb |  3 ++-
 2 files changed, 25 insertions(+), 12 deletions(-)

diff --git a/process.go b/process.go
index afa1bcb..2c60efa 100644
--- a/process.go
+++ b/process.go
@@ -656,22 +656,34 @@ func procSelector(mod *module, n *ndSelector) (procResult, shibaErr) {
 		return nil, err
 	}
 
-	// currently selector typ must be mod.
-	// In the future this should support struct/field.
-	if selector.typ != tMod {
-		return nil, &errSimple{msg: fmt.Sprintf("selector %s is not a module", selector), l: n.token().loc}
-	}
+	if selector.typ == tMod {
+		target, err := procAsObj(selector.mod, n.target)
+		if err != nil {
+			return nil, err
+		}
 
-	target, err := procAsObj(selector.mod, n.target)
-	if err != nil {
-		return nil, err
+		if target != nil {
+			return &prObj{o: target}, nil
+		}
+
+		return nil, nil
 	}
 
-	if target != nil {
-		return &prObj{o: target}, nil
+	if selector.typ == tStruct {
+		field, ok := n.target.(*ndIdent)
+		if !ok {
+			return nil, &errSimple{msg: fmt.Sprintf("%s must be an identifier", n.target), l: n.token().loc}
+		}
+
+		f, ok := selector.fields[field.ident]
+		if !ok {
+			return nil, &errSimple{msg: fmt.Sprintf("unknown field name %s in %s", field.ident, selector), l: n.token().loc}
+		}
+
+		return &prObj{o: f}, nil
 	}
 
-	return nil, nil
+	return nil, &errSimple{msg: fmt.Sprintf("selector %s is not a module", selector), l: n.token().loc}
 }
 
 func procFuncall(mod *module, n *ndFuncall) (procResult, shibaErr) {
diff --git a/tests/struct.sb b/tests/struct.sb
index cb62bd4..7e742e0 100644
--- a/tests/struct.sb
+++ b/tests/struct.sb
@@ -20,6 +20,7 @@ struct person{
 }
 
 p = person{name: "alice", age: 3}
-print(p)
+as("alice", p.name)
+as(3, p.age)
 
 print("struct test succeeded")