Function parse_select_statement

crates/gitql-parser/src/parser.rs:536–641

(
    context: &mut ParserContext,
    env: &mut Environment,
    tokens: &[Token],
    position: &mut usize,
)

}

fn parse_select_statement(
    context: &mut ParserContext,
    env: &mut Environment,
    tokens: &[Token],
    position: &mut usize,
) -> Result<Statement, Box<Diagnostic>> {
    // Consume `SELECT` keyword
    *position += 1;

    if *position >= tokens.len() {
        return Err(Diagnostic::error("Incomplete input for select statement")
            .add_help("Try select one or more values in the `SELECT` statement")
            .add_note("Select statements requires at least selecting one value")
            .with_location(calculate_safe_location(tokens, *position - 1))
            .as_boxed());
    }

    // Parse `DISTINCT` or `DISTINCT ON(...)`
    let distinct = parse_select_distinct_option(context, tokens, position)?;

    // Parse `*` or `expressions`
    let mut fields_names: Vec<String> = vec![];
    let mut selected_expr_titles: Vec<String> = vec![];
    let mut selected_expr: Vec<Box<dyn Expr>> = vec![];
    let mut is_select_all = false;

    context.inside_selections = true;
    parse_select_all_or_expressions(
        context,
        env,
        tokens,
        position,
        &mut fields_names,
        &mut selected_expr_titles,
        &mut selected_expr,
        &mut is_select_all,
    )?;
    context.inside_selections = false;

    // Parse optional `FROM` with one or more tables and joins
    let mut joins: Vec<Join> = vec![];
    let mut tables_to_select_from: Vec<String> = vec![];
    parse_from_option(
        context,
        env,
        &mut tables_to_select_from,
        &mut joins,
        tokens,
        position,
    )?;

    // Make sure Aggregated functions are used with tables only
    if tables_to_select_from.is_empty() && !context.aggregations.is_empty() {
        return Err(
            Diagnostic::error("Aggregations functions should be used only with tables")
                .add_note("Try to select from one of the available tables in current schema")
                .with_location(calculate_safe_location(tokens, *position))
                .as_boxed(),