error_handling/
error_handling.rs

1//! Example demonstrating error handling.
2
3use dice_parser::{DiceExpr, DiceError};
4
5fn main() {
6    println!("=== Error Handling Examples ===\n");
7
8    // Parse error - invalid syntax
9    println!("1. Parse error (missing sides):");
10    match DiceExpr::parse("2d") {
11        Ok(_) => println!("  Unexpectedly succeeded!"),
12        Err(e) => println!("  Error: {}", e),
13    }
14    println!();
15
16    // Syntax error - negative dice count
17    println!("2. Syntax error (negative dice count):");
18    match DiceExpr::parse("-2d6") {
19        Ok(_) => println!("  Unexpectedly succeeded!"),
20        Err(e) => println!("  Error: {}", e),
21    }
22    println!();
23
24    // Trailing input error
25    println!("3. Trailing input error:");
26    match DiceExpr::parse("2d6 extra") {
27        Ok(_) => println!("  Unexpectedly succeeded!"),
28        Err(e) => println!("  Error: {}", e),
29    }
30    println!();
31
32    // Invalid spec error (keep more than rolled)
33    println!("4. Invalid roll specification:");
34    use dice_parser::{RollSpec, Keep};
35    let spec = RollSpec::new(2, 6, Some(Keep::Highest(5))); // Try to keep 5 dice when only rolling 2
36    let expr = DiceExpr::Roll(spec);
37    match expr.roll() {
38        Ok(_) => println!("  Unexpectedly succeeded!"),
39        Err(e) => println!("  Error: {}", e),
40    }
41    println!();
42
43    // Pattern matching on error types
44    println!("5. Pattern matching on DiceError:");
45    let result = DiceExpr::parse("abc");
46    match result {
47        Ok(_) => println!("  Unexpectedly succeeded!"),
48        Err(DiceError::ParseError { kind, input, start, stop: _ }) => {
49            println!("  Parse error at position {}: {:?}", start, kind);
50            println!("  Input: {}", input);
51        }
52        Err(e) => println!("  Other error: {}", e),
53    }
54}
error_handling/error_handling.rs

error_handling/
error_handling.rs
