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|
const std = @import("std");
const Grammar = @import("grammar.zig");
const NonTerminal = @import("non-terminal.zig");
const Character = @import("character.zig").Character;
const Generator = @import("generator.zig").Generator;
const gss = @import("gss.zig");
const State = struct {
const Self = @This();
id: usize,
rule_index: usize,
inner_position: usize,
input_position: usize,
pub fn format(
self: *const Self,
comptime fmt: []const u8,
options: std.fmt.FormatOptions,
writer: anytype,
) !void {
_ = fmt;
_ = options;
try writer.print("[ {}, {}, {}, {} ]", .{
self.id,
self.rule_index,
self.inner_position,
self.input_position,
});
}
pub fn debug(self: *const Self, grammar: *Grammar, input: []const u8) void {
const rule = grammar.non_terminal_by_id(self.id).rules()[self.rule_index];
std.debug.print("input ({s}○{s}) state (", .{
input[0..self.input_position],
input[self.input_position..],
});
for (rule, 0..) |char, index| {
if (index == self.inner_position) {
std.debug.print("○", .{});
}
std.debug.print("{}", .{char});
}
if (rule.len == self.inner_position) {
std.debug.print("○", .{});
}
std.debug.print(")\n", .{});
}
};
pub fn check(grammar: *Grammar, input: []const u8, inner_allocator: std.mem.Allocator) !bool {
var arena = std.heap.ArenaAllocator.init(inner_allocator);
defer arena.deinit();
const allocator = arena.allocator();
const entry = grammar.entry_point();
var queues = [2]std.ArrayList(*gss.Node(State)) {
std.ArrayList(*gss.Node(State)).init(allocator),
std.ArrayList(*gss.Node(State)).init(allocator),
};
defer for (queues) |queue| queue.deinit();
var processing_queue = &queues[0];
for (0..entry.rules().len) |index| {
const node = try allocator.create(gss.Node(State));
node.* = gss.Node(State).init(State {
.id = entry.id,
.rule_index = index,
.inner_position = 0,
.input_position = 0,
});
try processing_queue.append(node);
}
var next_processing_queue = &queues[1];
while (processing_queue.items.len > 0) {
for (processing_queue.items) |node| {
const rule = grammar.non_terminal_by_id(node.state.id).rules()[node.state.rule_index];
if (node.state.inner_position == rule.len) {
if (
node.parent == null and
node.state.id == entry.id and
node.state.input_position == input.len
) {
return true;
}
const old_state, const parent_node = node.pop(allocator);
if (parent_node) |parent| {
const sibling = try parent.clone(State {
.id = parent.state.id,
.rule_index = parent.state.rule_index,
.inner_position = parent.state.inner_position + 1,
.input_position = old_state.input_position,
}, allocator);
try next_processing_queue.append(sibling);
}
} else {
const epsilon_only = node.state.input_position == input.len;
switch (rule[node.state.inner_position]) {
.terminal => |t| {
if (!epsilon_only and input[node.state.input_position] == t) {
const sibling = try node.clone(State {
.id = node.state.id,
.rule_index = node.state.rule_index,
.inner_position = node.state.inner_position + 1,
.input_position = node.state.input_position + 1,
}, allocator);
try next_processing_queue.append(sibling);
}
},
.non_terminal => |n| {
const non_terminal = grammar.non_terminal_by_id(n);
if (!epsilon_only and non_terminal.first.is_set(input[node.state.input_position])) {
for (0..non_terminal.rules().len) |index| {
const child = try node.push(State {
.id = non_terminal.id,
.rule_index = index,
.inner_position = 0,
.input_position = node.state.input_position,
}, allocator);
try next_processing_queue.append(child);
}
}
if (non_terminal.first.is_set(Character.EPSILON)) {
const sibling = try node.clone(State {
.id = node.state.id,
.rule_index = node.state.rule_index,
.inner_position = node.state.inner_position + 1,
.input_position = node.state.input_position
}, allocator);
try next_processing_queue.append(sibling);
}
},
.epsilon => {
const sibling = try node.clone(State {
.id = node.state.id,
.rule_index = node.state.rule_index,
.inner_position = node.state.inner_position + 1,
.input_position = node.state.input_position
}, allocator);
try next_processing_queue.append(sibling);
},
}
}
}
const swap = processing_queue;
processing_queue = next_processing_queue;
next_processing_queue = swap;
next_processing_queue.clearRetainingCapacity();
}
return false;
}
test "expr" {
const text =
\\S -> B A
\\A -> '+' B A
\\A -> ''
\\B -> D C
\\C -> '*' D C
\\C -> ''
\\D -> '(' S ')'
\\D -> 'a'
\\D -> 'b'
;
const input = "b+a*b";
const allocator = std.testing.allocator;
var grammar = try Grammar.parse("S", text, allocator);
defer grammar.deinit();
try std.testing.expect(try check(&grammar, input, allocator));
}
test "simple 0 - success" {
const text =
\\S -> A S 'd'
\\S -> B S
\\S -> ''
\\A -> 'a'
\\A -> 'c'
\\B -> 'a'
\\B -> 'b'
;
const input = "aad";
const allocator = std.testing.allocator;
var grammar = try Grammar.parse("S", text, allocator);
defer grammar.deinit();
try std.testing.expect(try check(&grammar, input, allocator));
}
test "simple 0 - fail" {
const text =
\\S -> A S 'd'
\\S -> B S
\\S -> ''
\\A -> 'a'
\\A -> 'c'
\\B -> 'a'
\\B -> 'b'
;
const input = "accd";
const allocator = std.testing.allocator;
var grammar = try Grammar.parse("S", text, allocator);
defer grammar.deinit();
try std.testing.expect(!try check(&grammar, input, allocator));
}
test "simple 0 - fuzzy" {
const text =
\\S -> A S 'd'
\\S -> B S
\\S -> ''
\\A -> 'a'
\\A -> 'c'
\\B -> 'a'
\\B -> 'b'
;
const allocator = std.testing.allocator;
var grammar = try Grammar.parse("S", text, allocator);
defer grammar.deinit();
var generator = Generator(struct {
const Self = @This();
pub fn next(_: *Self, n: usize) usize {
return std.crypto.random.uintLessThan(usize, n);
}
}){};
for (0..100) |_| {
const input = try generator.sentential_from_grammar(&grammar, 1000, allocator);
defer allocator.free(input);
try std.testing.expect(try check(&grammar, input, allocator));
}
}
|
