pub fn parse_expression(input: &str) -> AgResult<Vec<Token>>Expand description
Parse arithmetic and one-based band references (b1, b2, …) into RPN.
Supports parentheses, unary minus and +, -, *, /. Invalid syntax,
excessive nesting, more than 4096 input bytes or 256 lexical tokens returns
AgError::Query. Band availability is checked separately by the caller.