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const std = @import("std");
const CharSet = @import("char-set.zig");
const Character = @import("character.zig").Character;
const string = @import("string.zig");
const Rule = @import("rule.zig");
const Self = @This();
id: usize,
name: []const u8,
rule_list: std.ArrayList(Rule),
first: CharSet = CharSet {},
follows: CharSet = CharSet {},
allocator: std.mem.Allocator,
pub fn init(name: []const u8, id: usize, allocator: std.mem.Allocator) !Self {
const target = try allocator.alloc(u8, name.len);
@memcpy(target, name);
return Self {
.name = target,
.id = id,
.rule_list = std.ArrayList(Rule).init(allocator),
.allocator = allocator,
};
}
pub fn deinit(self: *Self) void {
for (self.rules()) |rule| {
self.allocator.free(rule.items);
}
self.rule_list.deinit();
self.allocator.free(self.name);
}
pub inline fn rules(self: *Self) []Rule {
return self.rule_list.items;
}
pub fn add_rule(self: *Self, rule: Rule) !void {
try self.rule_list.append(rule);
}
pub fn parse_name(buffer: []const u8) ![]const u8 {
const arrow_start = std.mem.indexOf(u8, buffer, "->") orelse return error.MissingArrow;
if (arrow_start == 0) {
return error.MissingRuleName;
}
return std.mem.trim(u8, buffer[0..arrow_start], &std.ascii.whitespace);
}
pub fn parse_and_add_variants(
self: *Self,
buffer: []const u8,
names: *const std.StringHashMap(usize),
) !void {
const arrow_start = std.mem.indexOf(u8, buffer, "->") orelse return error.MissingArrow;
var head: []const u8 = buffer[arrow_start + 2..];
if (std.mem.trimLeft(u8, head, &std.ascii.whitespace).len == 0) {
return error.MissingBody;
}
var rule = std.ArrayList(Character).init(self.allocator);
errdefer rule.deinit();
head = std.mem.trimLeft(u8, head, &std.ascii.whitespace);
while (head.len > 0) {
if (head[0] == '|') {
try self.rule_list.append(Rule { .items = try rule.toOwnedSlice() });
rule = std.ArrayList(Character).init(self.allocator);
head = head[1..];
} else if (head[0] == '\'') {
head = head[1..];
if (head.len > 0 and head[0] == '\'') {
try rule.append(Character { .epsilon = void{} });
}
while (head.len > 0 and head[0] != '\'') {
const char, head = try string.read_first_from_literal(head);
try rule.append(Character { .terminal = char });
}
if (head.len == 0) {
return error.UnterminatedString;
}
head = head[1..];
} else {
const child_name, head = string.read_name(head);
if (child_name.len == 0) {
return error.EmptyVariant;
}
try rule.append(Character {
.non_terminal = names.get(child_name) orelse {
return error.MissingRule;
}
});
}
head = std.mem.trimLeft(u8, head, &std.ascii.whitespace);
}
if (rule.items.len == 0) {
return error.EmptyVariant;
}
try self.rule_list.append(Rule { .items = try rule.toOwnedSlice() });
}
pub inline fn is_empty(self: *const Self) bool {
return self.rules().len == 0;
}
pub fn format(
self: *const Self,
comptime fmt: []const u8,
options: std.fmt.FormatOptions,
writer: anytype,
) !void {
_ = fmt;
_ = options;
try writer.print("{s} ->", .{ self.name });
if (self.rule_list.items.len > 0) {
for (self.rule_list.items[0].items) |c| {
try writer.print(" {}", .{c});
}
for (self.rule_list.items[1..]) |r| {
try writer.print(" |", .{});
for (r.items) |c| {
try writer.print(" {}", .{c});
}
}
}
}
test "single-non-terminal" {
const allocator = std.testing.allocator;
var non_terminal = try Self.init("main", 0, allocator);
defer non_terminal.deinit();
var names = std.StringHashMap(usize).init(allocator);
defer names.deinit();
try names.put("main", 0);
try names.put("one", 1);
try non_terminal.parse_and_add_variants("main -> one", &names);
try std.testing.expectEqualDeep(&[_][]const Character{
&[_] Character { Character { .non_terminal = 1 } }
}, non_terminal.rules());
}
test "multiple-non-terminal" {
const allocator = std.testing.allocator;
var non_terminal = try Self.init("main", 0, allocator);
defer non_terminal.deinit();
var names = std.StringHashMap(usize).init(allocator);
defer names.deinit();
try names.put("main", 0);
try names.put("one", 1);
try names.put("two", 2);
try names.put("three", 3);
try non_terminal.parse_and_add_variants("main -> one | two | three", &names);
try std.testing.expectEqualDeep(&[_][]const Character{
&[_] Character { Character { .non_terminal = 1 } },
&[_] Character { Character { .non_terminal = 2 } },
&[_] Character { Character { .non_terminal = 3 } },
}, non_terminal.rules());
}
test "multiple-non-terminal-sequence" {
const allocator = std.testing.allocator;
var non_terminal = try Self.init("main", 0, allocator);
defer non_terminal.deinit();
var names = std.StringHashMap(usize).init(allocator);
defer names.deinit();
try names.put("main", 0);
try names.put("one", 1);
try names.put("two", 2);
try names.put("three", 3);
try non_terminal.parse_and_add_variants("main -> one two | two | three", &names);
try std.testing.expectEqualDeep(&[_][]const Character{
&[_] Character { Character { .non_terminal = 1 }, Character { .non_terminal = 2 }, },
&[_] Character { Character { .non_terminal = 2 } },
&[_] Character { Character { .non_terminal = 3 } },
}, non_terminal.rules());
}
test "single-terminal" {
const allocator = std.testing.allocator;
var non_terminal = try Self.init("main", 0, allocator);
defer non_terminal.deinit();
var names = std.StringHashMap(usize).init(allocator);
defer names.deinit();
try names.put("main", 0);
try names.put("one", 1);
try non_terminal.parse_and_add_variants("main -> 'one'", &names);
try std.testing.expectEqualDeep(&[_][]const Character{
&[_] Character {
Character { .terminal = 'o' },
Character { .terminal = 'n' },
Character { .terminal = 'e' }
},
}, non_terminal.rules());
}
test "single-terminal-with-escapes" {
const allocator = std.testing.allocator;
var non_terminal = try Self.init("main", 0, allocator);
defer non_terminal.deinit();
var names = std.StringHashMap(usize).init(allocator);
defer names.deinit();
try names.put("main", 0);
try non_terminal.parse_and_add_variants("main -> 'o\\r\\nn\\'e\\\\'", &names);
try std.testing.expectEqualDeep(&[_][]const Character{
&[_] Character {
Character { .terminal = 'o' },
Character { .terminal = '\r' },
Character { .terminal = '\n' },
Character { .terminal = 'n' },
Character { .terminal = '\'' },
Character { .terminal = 'e' },
Character { .terminal = '\\' },
},
}, non_terminal.rules());
}
test "mix" {
const allocator = std.testing.allocator;
var non_terminal = try Self.init("main", 0, allocator);
defer non_terminal.deinit();
var names = std.StringHashMap(usize).init(allocator);
defer names.deinit();
try names.put("main", 0);
try names.put("other", 1);
try names.put("some", 2);
try non_terminal.parse_and_add_variants("main -> 'ab' other | other some 'a' | main", &names);
try std.testing.expectEqualDeep(&[_][]const Character{
&[_] Character {
Character { .terminal = 'a' },
Character { .terminal = 'b' },
Character { .non_terminal = 1 },
},
&[_] Character {
Character { .non_terminal = 1 },
Character { .non_terminal = 2 },
Character { .terminal = 'a' },
},
&[_] Character {
Character { .non_terminal = 0 },
},
}, non_terminal.rules());
}
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