From 0ecfb750817b153a53c7297e366505fe2f1178f8 Mon Sep 17 00:00:00 2001
From: Luna <git@l4.pm>
Date: Mon, 26 Aug 2019 13:15:08 -0300
Subject: [PATCH] add struct field getting

---
 examples/hello.v    | 12 ++++++------
 src/ast.zig         |  7 +++++++
 src/ast_printer.zig |  8 ++++++++
 src/parser.zig      | 29 ++++++++++++++++++++++++++---
 4 files changed, 47 insertions(+), 9 deletions(-)

diff --git a/examples/hello.v b/examples/hello.v
index af539b5..74308b6 100644
--- a/examples/hello.v
+++ b/examples/hello.v
@@ -5,6 +5,11 @@ const (
 	Businesses = 4
 )
 
+struct Point {
+	x int
+	y int 
+} 
+
 fn main(a int) int {
 	1 + 2 + 3 + 4
 	1 + 1 * 1
@@ -41,10 +46,5 @@ fn main(a int) int {
 		y: 20 
 	} 
 
-	//println(p.x) 
+	println(p.x) 
 }
-
-struct Point {
-	x int
-	y int 
-} 
diff --git a/src/ast.zig b/src/ast.zig
index c031733..acce1d1 100644
--- a/src/ast.zig
+++ b/src/ast.zig
@@ -80,6 +80,7 @@ pub const ExprType = enum {
     Struct,
 
     Grouping,
+    Get,
 };
 
 pub const VarDecl = struct {
@@ -105,6 +106,11 @@ pub const StructExpr = struct {
     inits: StructInitList,
 };
 
+pub const GetExpr = struct {
+    struc: *Expr,
+    name: Token,
+};
+
 pub const Expr = union(ExprType) {
     Assign: AssignExpr,
     VarDecl: VarDecl,
@@ -118,6 +124,7 @@ pub const Expr = union(ExprType) {
     Variable: Token,
     Grouping: *Expr,
     Call: CallExpr,
+    Get: GetExpr,
 };
 
 pub const Block = std.ArrayList(*Stmt);
diff --git a/src/ast_printer.zig b/src/ast_printer.zig
index a44aa33..1574a5b 100644
--- a/src/ast_printer.zig
+++ b/src/ast_printer.zig
@@ -4,6 +4,8 @@ const Token = tokens.Token;
 
 usingnamespace @import("ast.zig");
 
+const warn = std.debug.warn;
+
 fn printIdent(ident: usize) void {
     var i: usize = 0;
     while (i < ident) : (i += 1) {
@@ -177,6 +179,12 @@ pub fn printExpr(expr: *Expr) void {
             std.debug.warn("))");
         },
 
+        .Get => |get| {
+            warn("(");
+            printExpr(get.struc);
+            warn(".{})", get.name.lexeme);
+        },
+
         else => std.debug.warn("UnknownExpr-{}", @tagName(expr.*)),
     }
 }
diff --git a/src/parser.zig b/src/parser.zig
index f300ddc..21b761b 100644
--- a/src/parser.zig
+++ b/src/parser.zig
@@ -89,7 +89,11 @@ pub const Parser = struct {
     }
 
     fn consume(self: *Parser, ttype: TokenType, comptime msg: []const u8) !Token {
-        if (self.check(ttype)) return try self.nextToken();
+        if (self.check(ttype)) {
+            var tok = self.peek();
+            _ = try self.nextToken();
+            return tok;
+        }
 
         try self.tokenError(self.peek(), msg);
         return Result.CompileError;
@@ -271,6 +275,18 @@ pub const Parser = struct {
         return expr;
     }
 
+    fn mkGet(self: *@This(), struc: *Expr, name: Token) !*Expr {
+        var expr = try self.allocator.create(Expr);
+        expr.* = Expr{
+            .Get = ast.GetExpr{
+                .struc = struc,
+                .name = name,
+            },
+        };
+
+        return expr;
+    }
+
     fn mkBool(self: *Parser, val: bool) !*ast.Expr {
         var expr = try self.allocator.create(Expr);
         expr.* = Expr{
@@ -724,8 +740,14 @@ pub const Parser = struct {
                 expr = try self.finishCall(expr);
             } else if (self.check(.Dot)) {
                 _ = try self.consumeSingle(.Dot);
-                _ = try self.consumeSingle(.LeftBrace);
-                expr = try self.finishStructVal(expr);
+
+                if (self.check(.LeftBrace)) {
+                    _ = try self.consumeSingle(.LeftBrace);
+                    expr = try self.finishStructVal(expr);
+                } else {
+                    var name = try self.consume(.Identifier, "Expect property name after '.'");
+                    expr = try self.mkGet(expr, name);
+                }
             } else {
                 break;
             }
@@ -752,6 +774,7 @@ pub const Parser = struct {
             }
         }
 
+        // TODO shouldnt consume() return the current token, not nextToken?
         var paren = try self.consume(.RightParen, "Expected ')' after arguments");
 
         return self.mkCall(callee, paren, args);