Function parse_expression

crates/gitql-parser/src/parser.rs:1301–1360

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

}

pub(crate) fn parse_expression(
    context: &mut ParserContext,
    env: &mut Environment,
    tokens: &[Token],
    position: &mut usize,
) -> Result<Box<dyn Expr>, Box<Diagnostic>> {
    let aggregation_count_before = context.aggregations.len();
    let window_count_before = context.window_functions.len();
    let expression = parse_assignment_expression(context, env, tokens, position)?;

    if expression.kind() != ExprKind::Symbol {
        // This Expression contains aggregate function call or aggregate value
        if aggregation_count_before != context.aggregations.len() {
            let column_name = context.name_generator.generate_column_name();
            let expr_type = expression.expr_type();
            env.define(column_name.to_string(), expr_type.clone());

            // Register the new aggregation generated field if the this expression is after group by
            if context.has_group_by_statement && !context.hidden_selections.contains(&column_name) {
                context.hidden_selections.push(column_name.to_string());
            }

            context
                .aggregations
                .insert(column_name.clone(), AggregateValue::Expression(expression));

            return Ok(Box::new(SymbolExpr {
                value: column_name,
                expr_type,
                flag: SymbolFlag::None,
            }));
        }

        // This Expression contains window function call or window value
        if window_count_before != context.window_functions.len() {
            let column_name = context.name_generator.generate_column_name();
            let expr_type = expression.expr_type();
            env.define(column_name.to_string(), expr_type.clone());

            // Register the new window generated field if the this expression is after group by
            if context.has_group_by_statement && !context.hidden_selections.contains(&column_name) {
                context.hidden_selections.push(column_name.to_string());
            }

            context
                .window_functions
                .insert(column_name.clone(), WindowValue::Expression(expression));

            return Ok(Box::new(SymbolExpr {
                value: column_name,
                expr_type,
                flag: SymbolFlag::None,
            }));
        }

        return Ok(expression);
    }