use super::{
automatic_view_layer, has_instead_of_trigger, BTreeSet, SQLError, TriggerEvent,
ViewRewriteContext,
};
use crate::ast::RuleEvent;
pub struct RuleInputRequirements {
pub columns: BTreeSet<String>,
pub requires_rows: bool,
}
pub fn rule_input_requirements(
services: ViewRewriteContext<'_>,
table: &str,
event: RuleEvent,
) -> Result<Option<RuleInputRequirements>, SQLError> {
collect_requirements(services, table, event, &mut BTreeSet::new())
}
fn collect_requirements(
services: ViewRewriteContext<'_>,
table: &str,
event: RuleEvent,
visited: &mut BTreeSet<String>,
) -> Result<Option<RuleInputRequirements>, SQLError> {
if !visited.insert(table.to_string()) {
return Err(SQLError::Internal(format!(
"cycle while resolving rewrite-rule inputs for `{table}`"
)));
}
let rules = services.catalog.rules_for(table, event)?;
let suppresses = rules
.iter()
.any(|rule| rule.definition.instead && rule.definition.condition.is_none());
let mut required = RuleInputRequirements {
columns: BTreeSet::new(),
requires_rows: rules
.iter()
.any(|rule| rule.definition.condition.is_some() || !rule.definition.actions.is_empty()),
};
for rule in &rules {
let Some(columns) = services.catalog.rule_new_row_columns(rule)? else {
return Ok(None);
};
required.columns.extend(columns);
}
if suppresses {
return Ok(Some(required));
}
let trigger = match event {
RuleEvent::Insert => TriggerEvent::Insert,
RuleEvent::Update => TriggerEvent::Update,
RuleEvent::Delete => TriggerEvent::Delete,
RuleEvent::Select => return Ok(None),
};
if has_instead_of_trigger(services, table, trigger)? {
return Ok(None);
}
let Some(layer) = automatic_view_layer(services, table)? else {
return Ok(None);
};
let Some(source) = collect_requirements(services, &layer.source_name, event, visited)? else {
return Ok(None);
};
required.requires_rows |= source.requires_rows;
for column in layer.columns {
if column
.writable_source_column
.as_ref()
.is_some_and(|name| source.columns.contains(name))
{
required.columns.insert(column.name);
}
}
Ok(Some(required))
}