Module validator 

Argument validation module

This module provides functions to validate parsed arguments against the rules defined in the configuration. It completes the parsing layer by ensuring values meet all specified constraints.

Overview

The validator module works with ValidationRule definitions from the configuration to validate parsed argument values. It supports:

• File validation: Existence checks and extension restrictions
• Range validation: Numeric bounds (min/max)
• Type-specific validation: Applied after type parsing

Architecture

Configuration (YAML/JSON)
    ↓
ValidationRule definitions
    ↓
Parsed arguments (HashMap<String, String>)
    ↓
Validators (this module)
    ↓
Validated values (Result<(), ValidationError>)

Submodules

• file_validator: File existence and extension validation
• range_validator: Numeric range validation

Usage Example

use dynamic_cli::validator::{file_validator, range_validator};
use dynamic_cli::config::schema::ValidationRule;
use std::path::Path;

// Validate file exists
let path = Path::new("config.yaml");
file_validator::validate_file_exists(path, "config")?;

// Validate file extension
file_validator::validate_file_extension(
    path,
    "config",
    &["yaml".to_string(), "yml".to_string()]
)?;

// Validate numeric range
range_validator::validate_range(75.0, "percentage", Some(0.0), Some(100.0))?;

Integration with Other Modules

With Parser Module

The validator works with values after they’ve been parsed:

User Input: "simulate input.dat --threshold 0.5"
    ↓ [parser]
HashMap { "input": "input.dat", "threshold": "0.5" }
    ↓ [validator]
Validated ✓

With Config Module

Validation rules come from the configuration:

arguments:
  - name: input
    arg_type: path
    validation:
      - must_exist: true
      - extensions: [dat, csv]
  - name: threshold
    arg_type: float
    validation:
      - min: 0.0
        max: 1.0

With Error Module

All validation errors use ValidationError:

• FileNotFound - File doesn’t exist
• InvalidExtension - Wrong file extension
• OutOfRange - Value outside min/max bounds
• CustomConstraint - Custom validation failed

Complete Workflow Example

use dynamic_cli::config::schema::{ArgumentDefinition, ArgumentType, ValidationRule};
use dynamic_cli::validator::{file_validator, validate_file_exists, validate_file_extension};
use std::collections::HashMap;
use std::path::Path;

// Define an argument with validation rules
let arg_def = ArgumentDefinition {
    name: "input_file".to_string(),
    arg_type: ArgumentType::Path,
    required: true,
    description: "Input data file".to_string(),
    validation: vec![
        ValidationRule::MustExist { must_exist: true },
        ValidationRule::Extensions {
            extensions: vec!["csv".to_string(), "tsv".to_string()],
        },
    ],
};

// Parse arguments
let mut args = HashMap::new();
args.insert("input_file".to_string(), "data.csv".to_string());

// Validate (would check if file exists in real scenario)
if let Some(value) = args.get(&arg_def.name) {
    let path = Path::new(value);
    for rule in &arg_def.validation {
        match rule {
            ValidationRule::MustExist { must_exist } if *must_exist => {
                validate_file_exists(path, &arg_def.name)?;
            },
            ValidationRule::Extensions { extensions } => {
                validate_file_extension(path, &arg_def.name, extensions)?;
            },
            _ => {}
        }
    }
}

Design Philosophy

Fail Fast

Validation happens early, before command execution, to catch errors as soon as possible. This prevents wasted computation and provides immediate feedback to users.

Clear Error Messages

All validation errors include:

• The argument name that failed
• The actual value provided
• The expected constraint
• Helpful context for fixing the issue

Type-Appropriate Validation

Validation rules are matched to argument types:

• Path arguments: file existence, extensions
• Integer/Float arguments: range constraints
• All types: custom constraints

No Side Effects

Validators only check values - they don’t modify files, create directories, or perform any side effects.

Re-exports

pub use file_validator::validate_file_exists;

pub use file_validator::validate_file_extension;

pub use range_validator::validate_range;

Modules

file_validator

File validation functions

range_validator

Numeric range validation functions