katex-parser 0.1.0

A port of the KaTeX parser: lexing and parsing LaTeX math expressions with macro expansion into a typed AST, plus a Unicode rendering backend
Documentation 
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use crate::ast::ParseNode;
use crate::error::ParseError;

pub(crate) fn require_function_arg(
    args: &[ParseNode],
    index: usize,
    func_name: &str,
) -> Result<ParseNode, ParseError> {
    args.get(index).cloned().ok_or_else(|| ParseError::InternalInvariant {
        message: format!("Missing argument {index} for {func_name}"),
    })
}

pub(crate) fn ord_argument(arg: ParseNode) -> Vec<ParseNode> {
    if let ParseNode::OrdGroup { body, .. } = arg {
        body
    } else {
        vec![arg]
    }
}

pub(crate) fn normalize_argument(arg: ParseNode) -> ParseNode {
    if let ParseNode::OrdGroup { body, .. } = &arg
        && body.len() == 1 {
            return body[0].clone();
        }
    arg
}