Function try_parse_mir

src/expr-parser/src/parser.rs:30–50

Builds a [mz_expr::MirRelationExpr] from a string.

(catalog: &TestCatalog, s: &str)

/// Builds a [mz_expr::MirRelationExpr] from a string.
pub fn try_parse_mir(catalog: &TestCatalog, s: &str) -> Result<mz_expr::MirRelationExpr, String> {
    // Define a Parser that constructs a (read-only) parsing context `ctx` and
    // delegates to `relation::parse_expr` by passing a `ctx` as a shared ref.
    let parser = move |input: ParseStream| {
        let ctx = Ctx { catalog };
        relation::parse_expr(&ctx, input)
    };
    // Since the syn lexer doesn't parse comments, we replace all `// {`
    // occurrences in the input string with `:: {`.
    let s = s.replace("// {", ":: {");
    // Call the parser with the given input string.
    let mut expr = parser.parse_str(&s).map_err(|err| {
        let (line, column) = (err.span().start().line, err.span().start().column);
        format!("parse error at {line}:{column}:\n{err}\n")
    })?;
    // Fix the types of the local let bindings of the parsed expression in a
    // post-processing pass.
    relation::fix_types(&mut expr, &mut relation::FixTypesCtx::default())?;
    // Return the parsed, post-processed expression.
    Ok(expr)
}

/// Builds a source definition from a string.
pub fn try_parse_def(catalog: &TestCatalog, s: &str) -> Result<Def, String> {