Crate expr

Example:

use expr::{Context, Parser};

let mut p = Parser::new();

let mut ctx = Context::default();
ctx.insert("two".to_string(), 2);

let three: i64 = p.eval("1 + two", &ctx).unwrap().as_number().unwrap();
assert_eq!(three, 3);

p.add_function("add", |c| {
  let mut sum = 0;
  for arg in c.args {
    sum += arg.as_number().unwrap();
  }
  Ok(sum.into())
});

let six: i64 = p.eval("add(1, two, 3)", &ctx).unwrap().as_number().unwrap();
assert_eq!(six, 6);

Macros

bail

value

Construct an expr::Value from a json-like literal.

Structs

Context

Environment

Struct containing custom environment setup for expr evaluation (e.g. custom function definitions)

ParserDeprecated

Main struct for parsing and evaluating expr programs

Program

A parsed expr program that can be run

Enums

Error

An error that can occur when parsing or evaluating an expr program

Rule

Value

Represents a data value as input or output to an expr program

Functions

compile

Parse an expr program to be run later

eval

Compile and run an expr program in one step, using the default environment.

run

Run a compiled expr program, using the default environment

Type Aliases

Result