Function replace_clause

src/ast/ast_rewrite_star_projections.c:21–221

replaces a `WITH` clause containing a star projection with explicit projections. if `identifiers` is NULL, it will be populated with all identifiers in scope

// projections.
// if `identifiers` is NULL, it will be populated with all identifiers in scope
static void replace_clause
(
	cypher_astnode_t *root,    // ast root
	cypher_astnode_t *clause,  // clause being replaced
	int scope_start,           // beginning of scope
	int scope_end,             // ending of scope
	rax *identifiers           // bound vars
) {
	cypher_astnode_type_t t = cypher_astnode_type(clause);

	//--------------------------------------------------------------------------
	// collect identifiers
	//--------------------------------------------------------------------------
	if(identifiers == NULL) {
		identifiers = raxNew();
		collect_aliases_in_scope(root, scope_start, scope_end, identifiers);
	}

	//--------------------------------------------------------------------------
	// determine number of projections
	//--------------------------------------------------------------------------

	// `existing_projections_count` refers to explicit projections
	// e.g.
	// RETURN *, x, 1+2
	// `x`, `1+2` are explicit projections
	uint existing_projections_count = (t == CYPHER_AST_WITH) ?
		cypher_ast_with_nprojections(clause) :
		cypher_ast_return_nprojections(clause);

	//--------------------------------------------------------------------------
	// remove explicit identifiers
	//--------------------------------------------------------------------------

	for(uint i = 0; i < existing_projections_count; i ++) {
		const cypher_astnode_t *projection = (t == CYPHER_AST_WITH) ?
			cypher_ast_with_get_projection(clause, i) :
			cypher_ast_return_get_projection(clause, i);
		// if the projection has an alias use it,
		// otherwise the expression is the alias
		const cypher_astnode_t *exp =
			cypher_ast_projection_get_alias(projection);
		exp = exp ? exp : cypher_ast_projection_get_expression(projection);
		ASSERT(cypher_astnode_type(exp) == CYPHER_AST_IDENTIFIER);

		const char *identifier = cypher_ast_identifier_get_name(exp);
		raxRemove(identifiers, (unsigned char *)identifier, strlen(identifier), NULL);
	}

	// compute identifiers_count after duplication removal
	uint identifiers_count = raxSize(identifiers);

	// require atleast 1 projection
	uint nprojections = identifiers_count + existing_projections_count;
	uint proj_idx = 0; // projections will be added to projections[proj_idx];
	cypher_astnode_t *projections[nprojections + 1];

	//--------------------------------------------------------------------------