operations_parser

Links

• Documentation: Docs.rs
• Crate on crates.io: crates.io

Operations Parser is a Rust-based library that parses and evaluates arithmetic expressions.

Features

• Supports basic arithmetic operators: +, -, *, /, and ^
• Handles function calls like sqrt(16) and sin(pi)
• Can parse complex, nested expressions like 3 + sqrt(16) * (2^3)

Technical Overview

This parser uses the Pest grammar and parses expressions in multiple stages:

1. Expression: The top-level rule.
2. Sum: Handles addition and subtraction.
3. Product: Handles multiplication and division.
4. Power: Handles exponentiation.
5. Function Call: Parses functions with expressions as arguments.

Usage

To use the parser, run the following command in the terminal:

cargo run -- parse <file>

To get available commands, just type in the commang:

cargo run -- help

For parsing an expression right from the command run:

cargo run -- "3 + sqrt(16)"

To get credits use:

cargo run -- credits

Grammar Structure

The parser uses a PEG-based grammar defined in grammar.pest. Below are the rules that govern expression parsing.

• expression: Parses the entire arithmetic expression, starting with sum.
• sum: Handles addition and subtraction.
• product: Handles multiplication and division.
• power: Handles exponentiation with ^.
• unary: Handles unary operators (+ and -).
• primary: Recognizes numbers, function calls, and grouped expressions (parentheses).
• function_call: Matches function names followed by an argument in parentheses.
• ident: Matches alphabetic characters used for function names or constants.

Full Grammar

WHITESPACE = _{ " " | "\t" }
expression = _{ sum }
sum = { product ~ (add_op ~ product)* }
product = { power ~ (mul_op ~ power)* }
power = { unary ~ (exp_op ~ unary)* }
unary = { unary_op? ~ primary }
primary = { number | function_call | "(" ~ expression ~ ")" }
number = @{ "-"? ~ ASCII_DIGIT+ ~ ("." ~ ASCII_DIGIT+)? }
add_op = { "+" | "-" }
mul_op = { "*" | "/" }
exp_op = { "^" }
unary_op = { "+" | "-" }
function_call = { ident ~ "(" ~ expression ~ ")" }
ident = @{ ASCII_ALPHA+ }
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