Inline Options & Safety Limits

In regex.zig, every configurable operation accepts its options as the final argument using Zig's anonymous struct literal syntax (.{}).

Omitted fields receive documented safe defaults through Zig struct field initializers.

---

Compilation Options (CompileOptions)

pub const CompileOptions = struct {
    /// Case-insensitive matching ('i' flag).
    caseInsensitive: bool = false,

    /// Multiline mode ('m' flag): '^' and '$' match at line boundaries ('\n').
    multiline: bool = false,

    /// Dot-all mode ('s' flag): '.' matches any character including newline '\n'.
    dotAll: bool = false,

    /// Inverts the greediness of quantifiers ('U' flag).
    ungreedy: bool = false,

    /// Restrict shorthand classes (\d, \w, \s) and boundaries to ASCII.
    ascii: bool = false,

    /// Safety and memory resource limits.
    limits: Limits = .{},
};

Usage Example

// Default options
var re = try regex.compile(allocator, "\\d+", .{});
defer re.deinit();

// Inline custom configuration
var custom_re = try regex.compile(allocator, "^[a-z]+$", .{
    .caseInsensitive = true,
    .multiline = true,
});
defer custom_re.deinit();

---

Safety Limits (Limits)

To protect server processes against memory exhaustion or malicious patterns, regex.zig enforces strict compile-time limits:

pub const Limits = struct {
    /// Maximum allowed pattern length in bytes (default: 65,536).
    maxPatternLength: usize = 65536,

    /// Maximum group/parenthesis nesting depth (default: 256).
    maxNestingDepth: usize = 256,

    /// Maximum compiled instruction count in the bytecode program (default: 65,536).
    maxProgramSize: usize = 65536,

    /// Maximum number of capturing groups allowed (default: 128).
    maxCaptures: usize = 128,

    /// Maximum repetition count in bounded repetitions {min,max} (default: 1,000).
    maxRepetition: usize = 1000,
};

Configuring Tight Limits

var restricted_re = try regex.compile(allocator, user_supplied_pattern, .{
    .limits = .{
        .maxPatternLength = 1024,
        .maxNestingDepth = 16,
        .maxRepetition = 100,
    },
});
defer restricted_re.deinit();

If user input exceeds any limit, compilation returns a typed error:

• error.PatternTooLong
• error.NestingTooDeep
• error.ProgramTooLarge
• error.TooManyCaptures
• error.RepetitionLimitExceeded

---

Execution Options

Operation	Option Type	Configurable Fields
isMatch, find, captures	MatchOptions	startOffset: usize = 0
findAll, capturesAll	FindAllOptions	startOffset: usize = 0, maxMatches: ?usize = null
replace	ReplaceOptions	startOffset: usize = 0
replaceAll	ReplaceAllOptions	startOffset: usize = 0, maxReplacements: ?usize = null
split	SplitOptions	startOffset: usize = 0, maxSplits: ?usize = null
count	CountOptions	startOffset: usize = 0, maxMatches: ?usize = null
iterator, capturesIterator	IterateOptions	startOffset: usize = 0