Function AST_PrepareMergeOp

src/ast/ast_build_op_contexts.c:338–395

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

AST_MergeContext AST_PrepareMergeOp
(
	const cypher_astnode_t *merge_clause,
	GraphContext *gc,
	QueryGraph *qg,
	rax *bound_vars
) {
	AST_MergeContext merge_ctx = { .nodes_to_merge = NULL,
								   .edges_to_merge = NULL,
								   .on_match = NULL,
								   .on_create = NULL
								 };

	// Prepare all create contexts for nodes and edges on Merge path.
	rax *on_match_items = NULL;
	rax *on_create_items = NULL;
	NodeCreateCtx *nodes_to_merge = array_new(NodeCreateCtx, 1);
	EdgeCreateCtx *edges_to_merge = array_new(EdgeCreateCtx, 1);
	const cypher_astnode_t *path = cypher_ast_merge_get_pattern_path(merge_clause);

	// Shouldn't operate on the original bound variables map, as this function may insert aliases.
	rax *bound_and_introduced_entities = (bound_vars) ? raxClone(bound_vars) : raxNew();
	AST_PreparePathCreation(path, qg, bound_and_introduced_entities, &nodes_to_merge, &edges_to_merge);
	raxFree(bound_and_introduced_entities);


	// Convert any ON MATCH and ON CREATE directives.
	uint directive_count = cypher_ast_merge_nactions(merge_clause);

	for(uint i = 0; i < directive_count; i ++) {
		const cypher_astnode_t *directive = cypher_ast_merge_get_action(merge_clause, i);
		cypher_astnode_type_t type = cypher_astnode_type(directive);

		if(type == CYPHER_AST_ON_CREATE) {
			uint create_prop_count = cypher_ast_on_create_nitems(directive);
			if(on_create_items == NULL) on_create_items = raxNew();
			for(uint j = 0; j < create_prop_count; j ++) {
				const cypher_astnode_t *create_item = cypher_ast_on_create_get_item(directive, j);
				_ConvertUpdateItem(gc, on_create_items, create_item);
			}
		} else if(type == CYPHER_AST_ON_MATCH) {
			uint match_prop_count = cypher_ast_on_match_nitems(directive);
			if(on_match_items == NULL) on_match_items = raxNew();
			for(uint j = 0; j < match_prop_count; j ++) {
				const cypher_astnode_t *match_item = cypher_ast_on_match_get_item(directive, j);
				_ConvertUpdateItem(gc, on_match_items, match_item);
			}
		} else {
			ASSERT(false);
		}
	}

	merge_ctx.on_match = on_match_items;
	merge_ctx.on_create = on_create_items;
	merge_ctx.edges_to_merge = edges_to_merge;
	merge_ctx.nodes_to_merge = nodes_to_merge;
	return merge_ctx;
}