Function _Validate_FOREACH_Clause

src/ast/ast_validations.c:1631–1699

validate a FOREACH clause MATCH (n) FOREACH(x in [1,2,3] | CREATE (n)-[:R]->({v:x}))

// validate a FOREACH clause
// MATCH (n) FOREACH(x in [1,2,3] | CREATE (n)-[:R]->({v:x}))
static VISITOR_STRATEGY _Validate_FOREACH_Clause
(
	const cypher_astnode_t *n,  // ast-node
	bool start,                 // first traversal
	ast_visitor *visitor        // visitor
) {
	validations_ctx *vctx = visitor->ctx;

	// we enter ONLY when start=true, so no check is needed

	// build a new environment of bounded vars from the current one to be
	// used in the traversal of the visitor in the clauses of the FOREACH
	// clause - as they are local to the FOREACH clause
	rax *orig_env = vctx->defined_identifiers;
	rax *scoped_env = raxClone(orig_env);
	vctx->defined_identifiers = scoped_env;

	// set the clause of the context
	vctx->clause = CYPHER_AST_FOREACH;

	// visit FOREACH array expression
	const cypher_astnode_t *list_node =
		cypher_ast_foreach_get_expression(n);
	AST_Visitor_visit(list_node, visitor);

	// introduce loop variable to bound vars
	const cypher_astnode_t *identifier_node =
		cypher_ast_foreach_get_identifier(n);

	const char *identifier =
		cypher_ast_identifier_get_name(identifier_node);

	raxInsert(vctx->defined_identifiers, (unsigned char *) identifier,
				strlen(identifier), NULL, NULL);

	// visit FOREACH loop body clauses
	uint nclauses = cypher_ast_foreach_nclauses(n);
	for(uint i = 0; i < nclauses; i++) {
		const cypher_astnode_t *clause = cypher_ast_foreach_get_clause(n, i);
		// make sure it is an updating clause
		cypher_astnode_type_t child_clause_type =
			cypher_astnode_type(clause);
		if(child_clause_type != CYPHER_AST_CREATE  &&
			child_clause_type != CYPHER_AST_SET     &&
			child_clause_type != CYPHER_AST_REMOVE  &&
			child_clause_type != CYPHER_AST_MERGE   &&
			child_clause_type != CYPHER_AST_DELETE  &&
			child_clause_type != CYPHER_AST_FOREACH
		) {
			ErrorCtx_SetError("Error: Only updating clauses may reside in FOREACH");
			break;
		}

		// visit the clause
		AST_Visitor_visit(clause, visitor);
	}

	// restore original environment of bounded vars