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// Gap buffer
// SPDX-FileCopyrightText: 2025 Nguyễn Gia Phong
// SPDX-License-Identifier: GPL-3.0-or-later
const assert = std.debug.assert;
const eql = std.meta.eql;
const std = @import("std");
const Input = tree_sitter.Input;
const Parser = tree_sitter.Parser;
const Point = tree_sitter.Point;
const Tree = tree_sitter.Tree;
const tree_sitter = @import("tree-sitter");
const Grapheme = Graphemes.Grapheme;
const Graphemes = vaxis.Graphemes;
const vaxis = @import("vaxis");
const janet = zsanett.janet;
const zsanett = @import("zsanett");
const Selection = @import("Selection.zig");
const languages = @import("languages");
const graphemes = &@import("main.zig").graphemes;
const initial_gap_size = std.atomic.cache_line;
const Buffer = @This();
/// File content with gap, owned by Janet runtime.
data: []u8,
gap_position: u32 = 0,
gap_size: u32 = initial_gap_size,
parser: *Parser,
tree: *Tree, // TODO: polyglot
scroll_row: u32 = 0,
selection: Selection,
paste_direction: enum { before, after } = .before,
fn read(payload: ?*anyopaque, byte_index: u32, _: Point,
bytes_read: *u32) callconv(.C) [*c]const u8 {
const buffer: *Buffer = @alignCast(@ptrCast(payload.?));
if (byte_index < buffer.gap_position) {
bytes_read.* = @intCast(buffer.gap_position - byte_index);
return buffer.data[byte_index..buffer.gap_position].ptr;
}
const index_with_gap = byte_index + buffer.gap_size;
if (index_with_gap < buffer.data.len) {
bytes_read.* = @intCast(buffer.data.len - index_with_gap);
return buffer.data[index_with_gap..].ptr;
} else {
bytes_read.* = 0;
return "";
}
}
pub fn open(text: []u8) !Buffer {
const data = gap: {
const n: i32 = @intCast(text.len);
const buffer = janet.pointerBufferUnsafe(@ptrCast(text.ptr), n, n);
const capacity: usize = @intCast(n + initial_gap_size);
if (janet.realloc(buffer.*.data, capacity)) |data| {
janet.gcpressure(initial_gap_size);
buffer.*.data = @ptrCast(data);
buffer.*.capacity = @intCast(capacity);
buffer.*.count = buffer.*.capacity;
// TODO: use @memmove in Zig 0.15
var i = capacity;
while (i >= initial_gap_size) : (i -= 1)
buffer.*.data[i] = buffer.*.data[i - initial_gap_size];
break :gap buffer.*.data[0..capacity];
} else return error.OutOfMemory;
};
const parser = Parser.create();
errdefer parser.destroy();
const language = languages.c();
errdefer language.destroy();
try parser.setLanguage(language);
var result = Buffer{
.data = data,
.parser = parser,
.tree = undefined,
.selection = undefined,
};
result.tree = parser.parse(.{
.payload = &result,
.read = Buffer.read,
}, null).?;
result.selection = .{
.head = .{ .node = result.tree.rootNode() },
.tail = .{ .node = result.tree.rootNode() },
};
return result;
}
pub fn close(buffer: Buffer) void {
buffer.tree.getLanguage().destroy();
buffer.tree.destroy();
buffer.parser.destroy();
}
fn skipLines(text: []const u8, from: u32, n: u32) union(enum) {
done: u32,
left: u32,
} {
assert(n > 0);
var lines: u32 = 0;
for (text[from..], 1..) |c, i|
if (c == '\n') {
lines += 1;
if (lines == n)
return .{ .done = @intCast(from + i) };
};
return .{ .left = n - lines };
}
pub fn iterate(buffer: Buffer) struct {
const Iterator = @This();
graphemes_iterator: Graphemes.Iterator,
data: []const u8,
offset: u32,
before_gap: bool,
gap_start: u32,
gap_end: u32,
pub fn next(iterator: *Iterator) ?Grapheme {
if (iterator.graphemes_iterator.next()) |grapheme| {
return .{
.offset = grapheme.offset + iterator.offset,
.len = grapheme.len,
};
} else if (iterator.before_gap) {
const buffer_after_gap = iterator.data[iterator.gap_end..];
iterator.graphemes_iterator = graphemes.iterator(buffer_after_gap);
iterator.offset = iterator.gap_start;
iterator.before_gap = false;
return iterator.next();
} else return null;
}
} {
const root_node = buffer.tree.rootNode();
const point = Point{ .row = buffer.scroll_row, .column = 0 };
const node = root_node.descendantForPointRange(point, point).?;
const start_point = node.startPoint();
assert(start_point.row < point.row or eql(start_point, point));
const start_byte = node.startByte();
const start = if (eql(start_point, point))
start_byte
else if (start_byte >= buffer.gap_position)
skipLines(buffer.data[buffer.gap_size..], start_byte,
point.row - start_point.row).done
else switch (skipLines(buffer.data[0..buffer.gap_position], start_byte,
point.row - start_point.row)) {
.done => |offset| offset,
.left => |left| skipLines(buffer.data[buffer.gap_size..],
buffer.gap_position, left).done,
};
if (start < buffer.gap_position) {
const buffer_before_gap = buffer.data[start..buffer.gap_position];
return .{
.graphemes_iterator = graphemes.iterator(buffer_before_gap),
.data = buffer.data,
.offset = start,
.before_gap = true,
.gap_start = buffer.gap_position,
.gap_end = buffer.gap_position + buffer.gap_size,
};
}
const offset = start + buffer.gap_size;
return .{
.graphemes_iterator = graphemes.iterator(buffer.data[offset..]),
.data = undefined,
.offset = start,
.before_gap = true,
.gap_start = undefined,
.gap_end = undefined,
};
}
pub fn bytes(buffer: Buffer, grapheme: Grapheme) []const u8 {
if (grapheme.offset < buffer.gap_position)
return grapheme.bytes(buffer.data);
const start = grapheme.offset + buffer.gap_size;
const end = start + grapheme.len;
return buffer.data[start..end];
}
pub fn selectedBytes(buffer: Buffer) []const u8 {
const start = buffer.selection.startByte();
const end = buffer.selection.endByte();
if (end <= buffer.gap_position)
return buffer.data[start..end];
if (start >= buffer.gap_position)
return buffer.data[buffer.gap_size..][start..end];
unreachable;
}
pub fn paste(buffer: Buffer, data: []const u8) Buffer {
_ = data;
return buffer;
}
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