Crate vector_expr

Vectorized math expression parser/evaluator.

Why?

Performance. Evaluation of math expressions involving many variables can incur significant overhead from traversing the expression tree or performing variable lookups. We amortize that cost by performing intermediate operations on vectors of input data at a time (with optional data parallelism via the rayon feature).

Example

use vector_expr::*;

fn binding_map(var_name: &str) -> BindingId {
    match var_name {
        "bar" => 0,
        "baz" => 1,
        "foo" => 2,
        _ => unreachable!(),
    }
}
let parsed = Expression::parse("2 * (foo + bar) * baz", binding_map).unwrap();
let real = parsed.unwrap_real();

let bar = [1.0, 2.0, 3.0];
let baz = [4.0, 5.0, 6.0];
let foo = [7.0, 8.0, 9.0];
let bindings: &[&[f64]] = &[&bar, &baz, &foo];
let mut registers = Registers::new(3);
let output = real.evaluate(bindings, &mut registers);
assert_eq!(&output, &[64.0, 100.0, 144.0]);

Modules

• grammar_doc
  Uses the pest parsing expression grammar language.

Structs

• Registers
  Scratch space for calculations. Can be reused across evaluations with the same data binding length.

Enums

• BoolExpression
  A bool-valued expression.
• Expression
  Top-level parseable calculation.
• RealExpression
  An f64-valued expression.
• StringExpression

Traits

• FloatExt

Functions

• empty_binding_map
  Pass to Expression::parse if the expression has no variables.

Type Aliases

• BindingId
  Index into the &[&[f64]] bindings passed to expression evaluation.
• ParseError
• StringId
  To speed up string comparisons, we use string interning.