1 files changed, 39 insertions, 15 deletions

diff --git a/src/parse.zig b/src/parse.zig
index 901ce0d..1dda517 100644
--- a/src/parse.zig
+++ b/src/parse.zig
@@ -5,6 +5,15 @@ const root = @import("root");
 const Lexer = root.Lexer;
 const Token = root.Lexer.Token;
 
+pub const Stmt = struct {
+    loc: Lexer.Location,
+    type: Type,
+
+    pub const Type = union(enum) {
+        expr: *const Expr,
+    };
+};
+
 pub const Expr = struct {
     loc: Lexer.Location,
     type: Type,
@@ -12,7 +21,6 @@ pub const Expr = struct {
     pub const Type = union(enum) {
         integer_literal,
         bin_op: BinOp,
-        invalid: Token,
         call: Call,
         identifier,
 
@@ -48,14 +56,30 @@ pub const Expr = struct {
         switch (self.type) {
             .integer_literal => try writer.print("<int>", .{}),
             .bin_op => |bin_op| try writer.print("({} {} {})", .{ bin_op.lhs, bin_op.op, bin_op.rhs }),
-            .invalid => try writer.print("<invalid>", .{}),
             .call => |call| try writer.print("({} {})", .{ call.proc, call.arg }),
             .identifier => try writer.print("<identifier>", .{}),
         }
     }
 };
 
-pub fn expression(allocator: Allocator, lexer: *Lexer) error{OutOfMemory}!*Expr {
+pub fn statements(allocator: Allocator, lexer: *Lexer) ![]Stmt {
+    var stmts: std.ArrayList(Stmt) = .init(allocator);
+    while (lexer.peek().type != .eof) {
+        try stmts.append(try statement(allocator, lexer));
+    }
+    return try stmts.toOwnedSlice();
+}
+
+pub fn statement(allocator: Allocator, lexer: *Lexer) !Stmt {
+    var expr = try expression(allocator, lexer);
+    const semicolon: Lexer.Token = if (lexer.peek().type == .semicolon) lexer.next() else return error.ExpectedSemicolon;
+    return .{
+        .loc = expr.loc.combine(semicolon.loc),
+        .type = .{ .expr = expr },
+    };
+}
+
+pub fn expression(allocator: Allocator, lexer: *Lexer) error{ OutOfMemory, ExpectedRightParen, UnexpectedToken }!*Expr {
     return addExpr(allocator, lexer);
 }
 
@@ -70,7 +94,7 @@ pub fn addExpr(allocator: Allocator, lexer: *Lexer) !*Expr {
         _ = lexer.next();
 
         const rhs = try callExpr(allocator, lexer);
-        lhs = try allocate(allocator, .{
+        lhs = try allocate(Expr, allocator, .{
             .loc = lhs.loc.combine(rhs.loc),
             .type = .{ .bin_op = .{ .lhs = lhs, .op = op, .rhs = rhs } },
         });
@@ -82,11 +106,11 @@ pub fn callExpr(allocator: Allocator, lexer: *Lexer) !*Expr {
     var proc = try primaryExpr(allocator, lexer);
     while (true) {
         switch (lexer.peek().type) {
-            .left_paren, .integer_literal => {},
+            .left_paren, .integer_literal, .identifier => {},
             else => break,
         }
         const arg = try primaryExpr(allocator, lexer);
-        proc = try allocate(allocator, .{
+        proc = try allocate(Expr, allocator, .{
             .loc = proc.loc.combine(arg.loc),
             .type = .{ .call = .{ .proc = proc, .arg = arg } },
         });
@@ -97,25 +121,25 @@ pub fn callExpr(allocator: Allocator, lexer: *Lexer) !*Expr {
 pub fn primaryExpr(allocator: Allocator, lexer: *Lexer) !*Expr {
     const token = lexer.next();
     // std.debug.print("term {}\n", .{token});
-    return allocate(allocator, switch (token.type) {
+    return allocate(Expr, allocator, switch (token.type) {
         .left_paren => {
             const res = expression(allocator, lexer);
             const right_paren = lexer.next();
             if (right_paren.type != .right_paren)
-                return allocate(allocator, .{
-                    .loc = right_paren.loc,
-                    .type = .{ .invalid = right_paren },
-                });
+                return error.ExpectedRightParen;
             return res;
         },
         .integer_literal => .{ .loc = token.loc, .type = .integer_literal },
         .identifier => .{ .loc = token.loc, .type = .identifier },
-        else => .{ .loc = token.loc, .type = .{ .invalid = token } },
+        else => |t| {
+            std.debug.print("Expected '(', integer literal, or identifier. Got {}\n", .{t});
+            return error.UnexpectedToken;
+        },
     });
 }
 
-fn allocate(allocator: Allocator, expr: Expr) !*Expr {
-    const res = try allocator.create(Expr);
-    res.* = expr;
+fn allocate(T: type, allocator: Allocator, t: T) !*T {
+    const res = try allocator.create(T);
+    res.* = t;
     return res;
 }