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const std = @import("std");
const Allocator = std.mem.Allocator;
const eql = std.mem.eql;
const unicode = std.unicode;
const lexed = @import("lexed.zig");
pub const Lexer = struct {
iter: unicode.Utf8Iterator,
force_lit: bool = false,
const Self = @This();
pub const Error = error{
InvalidUtf8,
} || Allocator.Error;
pub fn init(content: []const u8) Error!Lexer {
const view = try unicode.Utf8View.init(content);
return .{ .iter = view.iterator() };
}
pub fn next(self: *Self, alloc: Allocator) Error!?lexed.Lexed {
var acc = try std.ArrayList(u8).initCapacity(alloc, 2);
errdefer acc.deinit(alloc);
var current_kind: ?lexed.Kind = null;
while (self.iter.nextCodepointSlice()) |rune| {
if (eql(u8, rune, "\r")) continue;
var override_if: ?[]const u8 = null;
// escape chars
if (eql(u8, rune, "\\")) {
self.force_lit = true;
current_kind = .literal;
} else {
self.force_lit = false;
const res = self.getCurrentKind(current_kind, rune, acc.items);
current_kind = res.kind;
override_if = res.override_if;
try acc.appendSlice(alloc, rune);
}
// conds here to avoid creating complex condition in while
const next_rune = self.iter.peek(1);
if (next_rune.len > 0) {
if (self.getCurrentKind(current_kind, next_rune, acc.items).kind != current_kind.? and
(override_if == null or !eql(u8, override_if.?, next_rune)))
{
if (!requiresSpace(current_kind.?)) break;
if (eql(u8, next_rune, " ")) {
// consume next space
_ = self.iter.nextCodepoint();
break;
}
current_kind = .literal;
}
}
}
const kind = current_kind orelse {
acc.deinit(alloc);
return null;
};
return lexed.Lexed.init(alloc, kind, acc);
}
const kindRes = struct {
kind: lexed.Kind,
override_if: ?[]const u8 = null,
fn equals(self: @This(), v: @This()) bool {
if (self.kind != v.kind) return false;
if (self.override_if == null and v.override_if != null) return false;
if (self.override_if != null and v.override_if == null) return false;
if (self.override_if) |it| return eql(u8, it, v.override_if.?);
return true;
}
};
fn getCurrentKind(self: *Self, before: ?lexed.Kind, rune: []const u8, acc: []const u8) kindRes {
if (self.force_lit) return .{ .kind = .literal };
if (eql(u8, rune, "\n")) return .{ .kind = .delimiter };
if (eql(u8, rune, "*")) return .{ .kind = .bold };
if (eql(u8, rune, "_")) return .{ .kind = .italic };
if (eql(u8, rune, ">")) return .{ .kind = .quote };
if (eql(u8, rune, "-")) return .{ .kind = .list_unordored };
if (eql(u8, rune, ".")) return .{ .kind = .list_ordored };
if (eql(u8, rune, "!")) return .{ .kind = .image };
if (eql(u8, rune, "<")) return .{ .kind = .ref };
if (is('#', 6, rune, acc)) return .{ .kind = .title };
if (isIn(links, rune, acc, before, .link)) return .{ .kind = .link };
if (isOneOrThree(":", rune, acc, .ref, .callout)) |it| return it;
if (isOneOrThree("$", rune, acc, .math, .math)) |it| return it;
if (isOneOrThree("`", rune, acc, .code, .code)) |it| return it;
return .{ .kind = .literal };
}
};
fn is(v: u8, maxLen: usize, rune: []const u8, acc: []const u8) bool {
if (acc.len >= maxLen) return false;
for (0..acc.len) |i| if (acc[i] != v) return false;
return eql(u8, rune, &[_]u8{v});
}
const links = &[_][]const u8{ "[", "](", ")" };
fn isIn(ops: []const []const u8, rune: []const u8, p: []const u8, before: ?lexed.Kind, now: lexed.Kind) bool {
var acc = p;
if (before) |b| {
if (now != b) acc = &[_]u8{};
}
for (ops) |op| {
const ln = acc.len + rune.len;
if (op.len >= ln and eql(u8, acc, op[0..acc.len]) and eql(u8, rune, op[acc.len..ln]))
return true;
}
return false;
}
fn isOneOrThree(op: []const u8, rune: []const u8, p: []const u8, one: lexed.Kind, three: lexed.Kind) ?Lexer.kindRes {
if (!eql(u8, rune, op)) return null;
var acc = p;
if (acc.len < op.len or !eql(u8, acc[0..op.len], op)) acc = &[_]u8{};
var iter = (unicode.Utf8View.init(acc) catch unreachable).iterator();
var ln: usize = 1; // number of runes
while (iter.nextCodepointSlice()) |it| : (ln += 1) {
if (!eql(u8, it, op)) return null;
}
return switch (ln) {
1 => .{
.kind = one,
.override_if = op,
},
2 => .{
.kind = .literal,
.override_if = op,
},
3 => .{ .kind = three },
else => unreachable,
};
}
fn requiresSpace(k: lexed.Kind) bool {
return switch (k) {
.title => true,
.list_ordored => true,
.list_unordored => true,
else => false,
};
}
fn doTest(alloc: Allocator, l: *Lexer, k: lexed.Kind, v: []const u8) !void {
var first = (try l.next(alloc)).?;
defer first.deinit();
std.testing.expect(first.equals(k, v)) catch |err| {
std.debug.print("{}({s})\n", .{ first.kind, first.content.items });
return err;
};
}
test "one or three" {
const expect = std.testing.expect;
// valid
try expect(isOneOrThree(":", ":", "", .ref, .callout).?.equals(.{ .kind = .ref, .override_if = ":" }));
try expect(isOneOrThree(":", ":", ":", .ref, .callout).?.equals(.{ .kind = .literal, .override_if = ":" }));
try expect(isOneOrThree(":", ":", "::", .ref, .callout).?.equals(.{ .kind = .callout }));
try expect(isOneOrThree(":", ":", "a", .ref, .callout).?.equals(.{ .kind = .ref, .override_if = ":" }));
// invalid
try expect(isOneOrThree(":", "a", "", .ref, .callout) == null);
try expect(isOneOrThree(":", "a", "b", .ref, .callout) == null);
try expect(isOneOrThree(":", "a", ":", .ref, .callout) == null);
}
test "lexer common" {
const expect = std.testing.expect;
var arena = std.heap.DebugAllocator(.{}).init;
defer _ = arena.deinit();
const alloc = arena.allocator();
var l = try Lexer.init("# hello world :)");
try doTest(alloc, &l, .title, "#");
try doTest(alloc, &l, .literal, "hello world ");
try doTest(alloc, &l, .ref, ":");
try doTest(alloc, &l, .link, ")");
try expect(try l.next(alloc) == null);
}
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