> Regex Patterns_

Predefined regex patterns for common validation scenarios.

Regex Dependency

Regex validation requires PCRE2. If compiled without regex support (-Dregex=false), these patterns return stub implementations that report "Regex support disabled".

// Usage

#include "argus/regex.h"

OPTION_STRING('e', "email", HELP("Email address"),
              VALIDATOR(V_REGEX(ARGUS_RE_EMAIL)))

// Network Patterns

IP Addresses

Pattern	Validates	Example
ARGUS_RE_IPV4	IPv4 addresses	192.168.1.1
ARGUS_RE_IPV6	IPv6 addresses	2001:db8::1

OPTION_STRING('i', "ip", HELP("Server IP address"),
              VALIDATOR(V_REGEX(ARGUS_RE_IPV4)))

Network Infrastructure

Pattern	Validates	Example
ARGUS_RE_DOMAIN	Domain names (FQDN)	example.com
ARGUS_RE_PORT	Port numbers (1-65535)	8080

OPTION_STRING('d', "domain", HELP("Domain name"),
              VALIDATOR(V_REGEX(ARGUS_RE_DOMAIN)))

URLs

Pattern	Validates	Example
ARGUS_RE_URL	Any protocol URL	https://example.com/path
ARGUS_RE_HTTP	HTTP(S) URLs only	http://example.com

OPTION_STRING('u', "url", HELP("Website URL"),
              VALIDATOR(V_REGEX(ARGUS_RE_URL)))

OPTION_STRING('a', "api", HELP("API endpoint"),
              VALIDATOR(V_REGEX(ARGUS_RE_HTTP)))

// Communication Patterns

Email

Pattern	Validates	Example
ARGUS_RE_EMAIL	Basic email format	user@example.com
ARGUS_RE_EMAIL_STRICT	RFC-compliant email	user.name+tag@example.com

OPTION_STRING('e', "email", HELP("Email address"),
              VALIDATOR(V_REGEX(ARGUS_RE_EMAIL)))

OPTION_STRING('c', "contact", HELP("Contact email (strict)"),
              VALIDATOR(V_REGEX(ARGUS_RE_EMAIL_STRICT)))

// Date and Time Patterns

Pattern	Validates	Example
ARGUS_RE_ISO_DATE	ISO date (YYYY-MM-DD)	2024-03-15
ARGUS_RE_ISOTIME	ISO datetime	2024-03-15T14:30:00

OPTION_STRING('d', "date", HELP("Date (YYYY-MM-DD)"),
              VALIDATOR(V_REGEX(ARGUS_RE_ISO_DATE)))

OPTION_STRING('t', "datetime", HELP("DateTime (ISO format)"),
              VALIDATOR(V_REGEX(ARGUS_RE_ISOTIME)))

// Security Patterns

Pattern	Validates	Example
ARGUS_RE_USER	Username (3-20 chars)	user_123
ARGUS_RE_PASSWD	Basic password	password123
ARGUS_RE_UUID	UUID v4 format	550e8400-e29b-41d4-a716-446655440000

OPTION_STRING('u', "username", HELP("Username"),
              VALIDATOR(V_REGEX(ARGUS_RE_USER)))

OPTION_STRING('p', "password", HELP("Password"),
              VALIDATOR(V_REGEX(ARGUS_RE_PASSWD)))

// File System Patterns

Pattern	Validates	Example
ARGUS_RE_UNIX_PATH	Unix absolute paths	/path/to/file
ARGUS_RE_FILENAME	Filename with extension	document.pdf

OPTION_STRING('f', "file", HELP("File path"),
              VALIDATOR(V_REGEX(ARGUS_RE_UNIX_PATH)))

OPTION_STRING('n', "name", HELP("Filename"),
              VALIDATOR(V_REGEX(ARGUS_RE_FILENAME)))

// Numbers and Formats

Pattern	Validates	Example
ARGUS_RE_SEMVER	Semantic version	1.2.3 or 1.0.0-beta+build
ARGUS_RE_POS_INT	Positive integers	123
ARGUS_RE_NEG_INT	Negative integers	-123
ARGUS_RE_FLOAT	Decimal numbers	3.14 or -2.7
ARGUS_RE_HEX	Hex numbers	0x1A3F

OPTION_STRING('v', "version", HELP("Semantic version"),
              VALIDATOR(V_REGEX(ARGUS_RE_SEMVER)))

OPTION_STRING('h', "hex", HELP("Hex number"),
              VALIDATOR(V_REGEX(ARGUS_RE_HEX)))

// Custom Patterns

Define your own patterns using MAKE_REGEX:

// Define at file scope
#define RE_PRODUCT_ID MAKE_REGEX("^[A-Z]{2}\\d{4}-[A-Z0-9]{6}$", "Format: XX0000-XXXXXX")
#define RE_LICENSE_KEY MAKE_REGEX("^[A-Z0-9]{4}-[A-Z0-9]{4}-[A-Z0-9]{4}$", "Format: XXXX-XXXX-XXXX")

ARGUS_OPTIONS(options,
    OPTION_STRING('p', "product", HELP("Product ID"),
                  VALIDATOR(V_REGEX(RE_PRODUCT_ID))),
    
    OPTION_STRING('k', "key", HELP("License key"),
                  VALIDATOR(V_REGEX(RE_LICENSE_KEY)))
)

// Pattern Testing

Test patterns before use:

# Valid examples
./app --email user@example.com          # ✅ Matches ARGUS_RE_EMAIL
./app --ip 192.168.1.1                  # ✅ Matches ARGUS_RE_IPV4  
./app --date 2024-03-15                  # ✅ Matches ARGUS_RE_ISO_DATE

# Invalid examples  
./app --email invalid-email             # ❌ Error: Invalid value 'invalid-email': Enter email: user@example.com
./app --ip 999.999.999.999              # ❌ Error: Invalid value '999.999.999.999': Enter valid IPv4: 192.168.1.1
./app --date 03-15-2024                  # ❌ Error: Invalid value '03-15-2024': Enter date: YYYY-MM-DD

// Error Messages

Each pattern includes helpful error hints:

• ARGUS_RE_EMAIL: "Enter email: user@example.com"
• ARGUS_RE_IPV4: "Enter valid IPv4: 192.168.1.1"
• ARGUS_RE_ISO_DATE: "Enter date: YYYY-MM-DD"

Custom patterns should include similar hints:

#define RE_CUSTOM MAKE_REGEX("pattern", "Clear format description")

// Performance Notes

• Patterns are compiled once at first use
• Complex patterns (like IPv6) may impact startup time
• Use simpler validation when regex isn't needed

// What's Next?

• Custom Validators - Create domain-specific validation
• Validation - Combine regex with other validators
• Examples - See patterns in real applications