@sap/cds/lib/compile/for/assert.js

SAP Cloud Application Programming Model - CDS for Node.js

const $collected = Symbol.for('collected')

module.exports = function cds_compile_for_assert(csn) {
  function _asserts4element(element, name, base) {
    let xpr = element?.['@assert']?.xpr
    if (!xpr) return

    const inherited = base.elements[name]?.['@assert']?.xpr
    if (inherited) {
      // dedupe by splitting into "when ... then ..." blocks and filtering out own blocks already in @assert of projection target
      const _inherited = _extract_cases(inherited).map(c => JSON.stringify(c))
      const own = _extract_cases(xpr).filter(c => !_inherited.includes(JSON.stringify(c)))
      if (own.length)
        xpr = ['case', ...inherited.slice(1, -1), ...own.reduce((acc, cur) => (acc.push(...cur), acc), []), 'end']
    }

    return xpr
  }

  function _asserts4entity(entity) {
    if (entity[$collected]) return

    // buttom up collection of asserts -> process base entity first
    projection: if (entity.projection || entity.query) {
      // during compile for java, model is never linked -> no prototype chain
      let base = (entity.projection || entity.query.SELECT)?.from?.ref?.[0]
      if (!base) throw new Error(`Unable to determine base entity of ${entity.name}`)

      base = csn.definitions[base]

      // REVISIT: when compiling extensions, base may not be in the model -> OK to abort?
      if (!base) break projection

      _asserts4entity(base)

      for (const each in entity.elements) {
        const element = entity.elements[each]
        if (element['@assert']) {
          element['@assert']._xpr = element['@assert'].xpr
          element['@assert'].xpr = _asserts4element(element, each, base)
        }
      }
    }

    entity[$collected] = true
  }

  for (const each in csn.definitions) {
    const entity = csn.definitions[each]
    if (entity.kind !== 'entity') continue
    if (!entity.projection && !entity.query) continue

    _asserts4entity(entity)
  }
}

function _extract_cases(xpr) {
  const cases = []
  for (const each of xpr.slice(1, -1)) {
    if (each === 'when') cases.push([])
    cases.at(-1).push(each)
  }
  return cases
}