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const std = @import("std");
const CharSet = @import("char-set.zig");
const Character = @import("character.zig").Character;
const Self = @This();
const Rhs = []Character;
name: u8,
rhs: std.ArrayList(Rhs),
first: CharSet,
follows: CharSet,
pub fn init(name: u8, allocator: std.mem.Allocator) Self {
return Self {
.name = name,
.rhs = std.ArrayList(Rhs).init(allocator),
.first = CharSet {},
.follows = CharSet {},
};
}
pub fn deinit(self: *Self, allocator: std.mem.Allocator) void {
for (self.rhs.items) |item| {
allocator.free(item);
}
self.rhs.deinit();
}
pub fn add_rule(self: *Self, rhs: Rhs) !void {
try self.rhs.append(rhs);
}
pub fn parse_rule(
buffer: []const u8,
allocator: std.mem.Allocator
) !struct { u8, Rhs } {
var rhs = std.ArrayList(Character).init(allocator);
errdefer rhs.deinit();
var tokens = std.mem.tokenizeAny(u8, buffer, &std.ascii.whitespace);
const lhs = tokens.next() orelse return error.MissingLhs;
if (lhs.len > 1) return error.InvalidLhs;
const arrow = tokens.next() orelse return error.MissingArrow;
if (!std.mem.eql(u8, arrow, "->")) return error.InvalidArrow;
while (tokens.next()) |token| {
if (token.len > 1) return error.InvalidCharacter;
try rhs.append(Character.from_u8(token[0]));
}
if (rhs.items.len == 0) {
return error.EmptyProduction;
}
return .{ lhs[0], try rhs.toOwnedSlice() };
}
pub inline fn is_empty(self: *const Self) bool {
return self.rhs.items.len == 0;
}
pub fn format(
self: *const Self,
comptime fmt: []const u8,
options: std.fmt.FormatOptions,
writer: anytype,
) !void {
_ = fmt;
_ = options;
try writer.print("[{c} -> ", .{ self.name });
if (self.rhs.items.len > 0) {
for (self.rhs.items[0]) |c| {
try writer.print("{}", .{c});
}
for (self.rhs.items[1..]) |r| {
try writer.print(" | ", .{});
for (r) |c| {
try writer.print("{}", .{c});
}
}
}
try writer.writeByte(']');
}
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