expr_solver/
number.rs

1//! Numeric type abstraction for the expression solver.
2//!
3//! This module provides a type alias `Number` that resolves to either `f64` or `Decimal`
4//! depending on the enabled feature flag. This allows the library to be used with either
5//! standard floating-point arithmetic (faster, simpler) or high-precision decimal arithmetic.
6//!
7//! ## Features
8//!
9//! - **`f64-floats`** (default): Standard f64 floating-point arithmetic
10//!   - Fast and efficient for general-purpose math
11//!   - Allows `Inf` and `NaN` results
12//!   - Minimal error checking (only prevents panics)
13//!
14//! - **`decimal-precision`**: 128-bit Decimal for high precision
15//!   - Exact decimal representation
16//!   - Checked arithmetic with overflow/underflow detection
17//!   - Domain validation for all operations
18//!   - Ideal for financial calculations
19//!
20//! ## Type Alias
21//!
22//! The `Number` type alias resolves to:
23//! - `f64` when `f64-floats` feature is enabled
24//! - `rust_decimal::Decimal` when `decimal-precision` feature is enabled
25//!
26//! ## Internal Constants
27//!
28//! The `consts` module is internal and provides basic numeric constants (`ZERO`, `ONE`)
29//! used by the VM. Mathematical constants (pi, e, etc.) are provided through the
30//! type-specific symbol table implementations in `symbol/f64.rs` and `symbol/decimal.rs`.
31
32#[cfg(feature = "decimal-precision")]
33pub use rust_decimal::Decimal as Number;
34
35#[cfg(feature = "f64-floats")]
36pub type Number = f64;
37
38// Ensure exactly one feature is enabled
39#[cfg(all(feature = "f64-floats", feature = "decimal-precision"))]
40compile_error!("Cannot enable both 'f64-floats' and 'decimal-precision' features");
41
42#[cfg(not(any(feature = "f64-floats", feature = "decimal-precision")))]
43compile_error!("Must enable either 'f64-floats' or 'decimal-precision' feature");
44
45/// Internal numeric constants used by the VM.
46/// Mathematical constants like PI, E, etc. are provided through the symbol table.
47pub(crate) mod consts {
48    use super::Number;
49
50    #[cfg(feature = "decimal-precision")]
51    pub use rust_decimal::Decimal;
52
53    /// Zero constant
54    #[cfg(feature = "decimal-precision")]
55    pub const ZERO: Number = Decimal::ZERO;
56
57    #[cfg(feature = "f64-floats")]
58    pub const ZERO: Number = 0.0;
59
60    /// One constant
61    #[cfg(feature = "decimal-precision")]
62    pub const ONE: Number = Decimal::ONE;
63
64    #[cfg(feature = "f64-floats")]
65    pub const ONE: Number = 1.0;
66}
67
68/// Helper trait for parsing numbers from strings.
69pub trait ParseNumber: Sized {
70    /// Parse a number from a string.
71    fn parse_number(s: &str) -> Result<Self, String>;
72}
73
74#[cfg(feature = "decimal-precision")]
75impl ParseNumber for Number {
76    fn parse_number(s: &str) -> Result<Self, String> {
77        use rust_decimal::prelude::FromStr;
78        Number::from_str(s).map_err(|e| e.to_string())
79    }
80}
81
82#[cfg(feature = "f64-floats")]
83impl ParseNumber for Number {
84    fn parse_number(s: &str) -> Result<Self, String> {
85        s.parse::<f64>().map_err(|e| e.to_string())
86    }
87}
88
89/// Macro for creating numeric literals in a type-neutral way.
90///
91/// # Examples
92///
93/// ```
94/// use expr_solver::num;
95///
96/// let x = num!(42);
97/// let y = num!(3.14159);
98/// let z = num!(2.5);
99/// ```
100///
101/// This macro resolves to:
102/// - `$val as f64` when `f64-floats` is enabled
103/// - `dec!($val)` when `decimal-precision` is enabled
104#[macro_export]
105#[cfg(feature = "decimal-precision")]
106macro_rules! num {
107    ($val:expr) => {
108        rust_decimal_macros::dec!($val)
109    };
110}
111
112/// Macro for creating numeric literals in a type-neutral way.
113///
114/// # Examples
115///
116/// ```
117/// use expr_solver::num;
118///
119/// let x = num!(42);
120/// let y = num!(3.14159);
121/// let z = num!(2.5);
122/// ```
123///
124/// This macro resolves to:
125/// - `$val as f64` when `f64-floats` is enabled
126/// - `dec!($val)` when `decimal-precision` is enabled
127#[macro_export]
128#[cfg(feature = "f64-floats")]
129macro_rules! num {
130    ($val:expr) => {
131        $val as f64
132    };
133}
expr_solver/number.rs

expr_solver/
number.rs
