deinit existing_cmds (not long lived)

closes #7

src/lang.zig

@@ -140,6 +140,7 @@ pub const ArgList = std.ArrayList([]const u8);
 
 pub const KeywordMap = std.StringHashMap(CommandType);
 
+/// A parser.
 pub const Lang = struct {
     allocator: *std.mem.Allocator,
     keywords: KeywordMap,

src/main.zig

@@ -25,29 +25,59 @@ fn wrapInCmdList(allocator: *std.mem.Allocator, cmd: langs.Command) !langs.Comma
 pub fn doRepl(allocator: *std.mem.Allocator, args_it: var) !void {
     var stdout_file = try std.io.getStdOut();
     const stdout = &stdout_file.outStream().stream;
-
     const scri_path = try (args_it.next(allocator) orelse @panic("expected scri path"));
 
+    var file_read = try std.fs.File.openRead(scri_path);
+    const total_bytes = try file_read.getEndPos();
+
+    var cmds = langs.CommandList.init(allocator);
+    defer cmds.deinit();
+
+    var lang = langs.Lang.init(allocator);
+    defer lang.deinit();
+
+    if (total_bytes > 0) {
+        // this MUST BE long lived (a reference to it is kept inside
+        // existing_cmds, and then passed along to cmds),
+        // we can't defer them here
+        var scri_existing = try allocator.alloc(u8, total_bytes);
+        _ = try file_read.read(scri_existing);
+
+        // we can defer this because we copy the Command structs back to cmds
+        var existing_cmds = try lang.parse(scri_existing);
+        defer existing_cmds.deinit();
+
+        // copy the existing command list into the repl's command list
+        var it = existing_cmds.iterator();
+        while (it.next()) |existing_cmd| {
+            try cmds.append(existing_cmd);
+        }
+    } else {
+        // if there isn't any commands on the file, we load our default
+        // 'load :1' command
+
+        // TODO load should +1 the index if its on repl
+        var loadargs = langs.ArgList.init(allocator);
+        try loadargs.append(":1");
+
+        try cmds.append(langs.Command{
+            .command = .Load,
+            .args = loadargs,
+        });
+    }
+
+    file_read.close();
+
     var file = try std.fs.File.openWrite(scri_path);
     defer file.close();
 
     var out = file.outStream();
     var stream = &out.stream;
 
-    // the thing here is that 'load :0' would load the scri_path, since we
-    // now have a 'repl' argument right before it. to counteract that, the
-    // initial repl buffer contains 'load :1' instead.
-
-    var loadargs = langs.ArgList.init(allocator);
-    defer loadargs.deinit();
-    try loadargs.append(":1");
-
-    var cmds = try wrapInCmdList(allocator, langs.Command{
-        .command = .Load,
-        .args = loadargs,
-    });
-
-    defer cmds.deinit();
+    // since we opened the file for writing, it becomes empty, so, to ensure
+    // we don't fuck up later on, we print cmds before starting the repl
+    try printer.printList(cmds, stdout);
+    try printer.printList(cmds, stream);
 
     // we keep
     //  - a CommandList with the full commands we have right now
@@ -58,9 +88,6 @@ pub fn doRepl(allocator: *std.mem.Allocator, args_it: var) !void {
     //  - one runner that gets copied from the original on every new
     //    command the user issues
 
-    var lang = langs.Lang.init(allocator);
-    defer lang.deinit();
-
     var current: langs.Command = undefined;
 
     var runner = runners.Runner.init(allocator);
@@ -99,6 +126,8 @@ pub fn doRepl(allocator: *std.mem.Allocator, args_it: var) !void {
             try printer.printList(cmds, stdout);
             continue;
         } else if (std.mem.eql(u8, line, "save")) {
+            // seek to 0 instead of appending the new command
+            // NOTE appending single command might be faster
             try file.seekTo(0);
             try printer.printList(cmds, stream);
             continue;