ed

commit 47c37a24c3250598b8eb14fd586cd2cbd1c59a3f
parent b459d51057d6791a1cac2eaca0f471dc4b9e3ef1
Author: Byron Torres <b@torresjrjr.com>
Date:   Thu,  9 Sep 2021 08:33:52 +0100

Create data structures and example code

Diffstat:
M
ed.ha
 | 
87
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

1 file changed, 87 insertions(+), 0 deletions(-)
diff --git a/ed.ha b/ed.ha
@@ -1,3 +1,4 @@
+use bufio;
 use fmt;
 use fs;
 use getopt;
@@ -5,8 +6,26 @@ use io;
 use os;
 
 type filename = (str | void);
+
 type file = (io::file | void);
 
+type buffer = struct {
+	head: *line,
+	tail: *line,
+};
+
+type line = struct {
+	value: value,
+	prev: *line,
+	next: *line,
+};
+
+type value = (headtype | str | tailtype);
+
+type headtype = void;
+
+type tailtype = void;
+
 export fn main() void = {
 	const help: [_]getopt::help = [
 		"standard line editor",
@@ -48,6 +67,74 @@ export fn main() void = {
 			file: io::file => file,
 		},
 	};
+
+	const buf = new_buffer();
+
+	if (file is io::file) {
+		cmd_edit(file: io::file);
+	};
+};
+
+fn cmd_edit(file: io::file) void = {
+	print_buffer(read(&file));
+};
+
+// Initialises a new buffer.
+fn new_buffer() *buffer = {
+	const head = alloc(line { value = headtype, ... });
+	const tail = alloc(line { value = tailtype, prev = head });
+	head.next = tail;
+	return alloc(buffer {
+		head = head,
+		tail = tail,
+	});
+};
+
+// Reads text from source into a new buffer.
+fn read(source: *io::stream) *buffer = {
+	const buf = new_buffer();
+	let   localhead = buf.head;
+	const localtail = buf.tail;
+
+	for (true) {
+		const rawline = match (bufio::scanline(source)) {
+			err: io::error => abort("io::error"),
+			io::EOF => break,
+			rawline: []u8 => rawline,
+		};
+		//defer free(rawline);
+		const value = fmt::bsprint(rawline);
+
+		const line = alloc(line {
+			value = value,
+			prev = localhead,
+			next = localtail,
+		});
+
+		localhead.next = line;
+		localtail.prev = line;
+
+		localhead = line;
+	};
+
+	return buf;
+};
+
+// Sequencially prints lines of a buffer.
+fn print_buffer(buf: *buffer) void = {
+	let line = buf.head;
+	for (true) {
+		match (line.value) {
+			headtype => {
+				line = line.next;
+			},
+			s: str => {
+				fmt::println(s)?;
+				line = line.next;
+			},
+			tailtype => break
+		};
+	};
 };
 
 @noreturn fn exit_usage(help: []getopt::help) void = {