This project uses a nondeterministic FA to create the regex, and then converts it into a deterministic one.
Here's an example of how to use the regex structure:
const std = @import("std");
const regex = @import("regex");
pub fn main() !void {
var buf: [131072]u8 = undefined;
var alloc = std.heap.FixedBufferAllocator.init(&buf);
var allocator = alloc.allocator();
var x: [24]u8 = "0x(0|1|2|3|4|5|6|7|8|8)+".*;
var y: [6]u8 = "0x1223".*;
var w: [4]u8 = "1223".*;
var re = regex.Regex.new(allocator);
std.debug.print("\n{s}\n", .{try re.infixToPostfix(&x)});
try re.compile(&x);
std.debug.print("Match {s}: {}\n", .{ y, re.match(&y) });
std.debug.print("Match {s}: {}\n", .{ w, re.match(&w) });
std.debug.print("Total states: {}\n", .{re.autom.?.states.items.len});
for (0.., re.autom.?.states.items) |item, state| {
std.debug.print(
"Item #{} transitions (start = {}, finish = {}):\n",
.{ item, state.start, state.finish },
);
for (state.transitions.items) |trans| {
std.debug.print(
" - From: {} to {}, symbol = {s}\n",
.{ item, trans.dest, [1]u8{trans.symbol orelse 121} },
);
}
std.debug.print("\n", .{});
}
}And here's wat the program will output:
0x.01|2|3|4|5|6|7|8|8|+.
Match 0x1223: true
Match 1223: false
Total states: 4
Item #0 transitions (start = true, finish = false):
- From: 0 to 1, symbol = 0
Item #1 transitions (start = false, finish = false):
- From: 1 to 2, symbol = x
Item #2 transitions (start = false, finish = false):
- From: 2 to 3, symbol = 0
- From: 2 to 3, symbol = 7
- From: 2 to 3, symbol = 6
- From: 2 to 3, symbol = 5
- From: 2 to 3, symbol = 4
- From: 2 to 3, symbol = 3
- From: 2 to 3, symbol = 2
- From: 2 to 3, symbol = 1
- From: 2 to 3, symbol = 8
Item #3 transitions (start = false, finish = true):
- From: 3 to 3, symbol = 0
- From: 3 to 3, symbol = 7
- From: 3 to 3, symbol = 6
- From: 3 to 3, symbol = 5
- From: 3 to 3, symbol = 4
- From: 3 to 3, symbol = 3
- From: 3 to 3, symbol = 2
- From: 3 to 3, symbol = 1
- From: 3 to 3, symbol = 8
It even works with most unicode strings (though this was accidental)
const std = @import("std");
const regex = @import("regex");
pub fn main() !void {
var buf: [131072]u8 = undefined;
var alloc = std.heap.FixedBufferAllocator.init(&buf);
var allocator = alloc.allocator();
var x = "ä(bc|d)+".*;
var y = "äbcbcd".*;
var w: [4]u8 = "1223".*;
var re = regex.Regex.new(allocator);
std.debug.print("\n{s}\n", .{try re.infixToPostfix(&x)});
try re.compile(&x);
std.debug.print("Match {s}: {}\n", .{ y, re.match(&y) });
std.debug.print("Match {s}: {}\n", .{ w, re.match(&w) });
}ä.bc.d|+.
Match äbcbcd: true
Match 1223: false