Add functions to push clause to query

lib/src/ast_call_subquery.c

@@ -99,6 +99,23 @@ void cypher_ast_call_subquery_replace_query
     node->query = query;
 }
 
+void cypher_ast_call_subquery_push_clause(
+    cypher_astnode_t *astnode,
+    cypher_astnode_t *clause,
+    unsigned int index
+) {
+    REQUIRE_TYPE(astnode, CYPHER_AST_CALL_SUBQUERY, NULL);
+    struct call_subquery *subquery_node =
+            container_of(astnode, struct call_subquery, _astnode);
+
+    cypher_astnode_t *new_query =
+        cypher_ast_query_push_clause(subquery_node->query, clause, index);
+
+    cypher_astnode_free(subquery_node->query);
+    astnode->children[0] = new_query;
+    subquery_node->query = new_query;
+}
+
 cypher_astnode_t *clone(const cypher_astnode_t *self,
         cypher_astnode_t **children)
 {

lib/src/ast_query.c

@@ -205,6 +205,48 @@ void cypher_ast_query_replace_clauses(
     astnode->nchildren -= end_index - start_index;
 }
 
+cypher_astnode_t *cypher_ast_query_push_clause(
+    cypher_astnode_t *astnode,
+    cypher_astnode_t *clause,
+    unsigned int index
+)
+{
+    REQUIRE_TYPE(astnode, CYPHER_AST_QUERY, NULL);
+    REQUIRE_TYPE(clause, CYPHER_AST_QUERY_CLAUSE, NULL);
+    struct query *query = container_of(astnode, struct query, _astnode);
+
+    unsigned int nchildren = astnode->nchildren + 1;
+    unsigned int nclauses = query->nclauses + 1;
+
+    cypher_astnode_t **clauses = calloc(nclauses, sizeof(cypher_astnode_t *));
+    if (clauses == NULL) {
+        return NULL;
+    }
+
+    cypher_astnode_t **children = calloc(nchildren, sizeof(cypher_astnode_t *));
+    if (children == NULL) {
+        return NULL;
+    }
+
+    //insert new clause
+    for(uint i = 0; i < index; i++) {
+        clauses[i] = query->clauses[i];
+        children[i] = query->clauses[i];
+    }
+    clauses[index] = clause;
+    children[index] = clause;
+    for(uint i = index + 1; i < nclauses; i++) {
+        clauses[i] = query->clauses[i - 1];
+        children[i] = query->clauses[i - 1];
+    }
+
+    cypher_astnode_t *new_query = cypher_ast_query(NULL, 0, clauses, nclauses,
+        children, nchildren, astnode->range);
+    free(clauses);
+    free(children);
+
+    return new_query;
+}
 
 ssize_t detailstr(const cypher_astnode_t *self, char *str, size_t size)
 {

lib/src/ast_statement.c

@@ -92,6 +92,26 @@ void cypher_ast_statement_replace_body
 }
 
 
+void cypher_ast_statement_push_clause
+(
+    cypher_astnode_t *astnode,
+    cypher_astnode_t *clause,
+    unsigned int index
+)
+{
+    REQUIRE_TYPE(astnode, CYPHER_AST_STATEMENT, NULL);
+    REQUIRE_TYPE(clause, CYPHER_AST_QUERY_CLAUSE, NULL);
+    struct statement *node = container_of(astnode, struct statement, _astnode);
+
+    cypher_astnode_t *body =
+        cypher_ast_query_push_clause(node->body, clause, index);
+
+    astnode->children[child_index(astnode, node->body)] = body;
+    cypher_astnode_free(node->body);
+    node->body = body;
+}
+
+
 cypher_astnode_t *clone(const cypher_astnode_t *self,
         cypher_astnode_t **children)
 {

lib/src/cypher-parser.h.in

@@ -550,6 +550,26 @@ cypher_astnode_t *cypher_ast_statement(cypher_astnode_t * const *options,
 void cypher_ast_statement_replace_body(cypher_astnode_t *astnode,
         const cypher_astnode_t *body);
 
+/**
+ * Insert clause at position `index` of a `CYPHER_AST_STATEMENT` node.
+ *
+ * If the node is not an instance of `CYPHER_AST_STATEMENT` then the result will
+ * be undefined.
+ *
+ * If the clause is not an instance of `CYPHER_AST_QUERY_CLAUSE` then the result
+ * will be undefined.
+ *
+ * @param [node] The AST node.
+ * @param [clause] The AST clause node.
+ * @param [index] The index of the new clause.
+ */
+void cypher_ast_statement_push_clause
+(
+    cypher_astnode_t *astnode,
+    cypher_astnode_t *clause,
+    unsigned int index
+);
+
 /**
  * Get the number of options in a `CYPHER_AST_STATEMENT` node.
  *
@@ -1328,6 +1348,26 @@ void cypher_ast_query_set_clause(
 void cypher_ast_query_replace_clauses(
         cypher_astnode_t *astnode, cypher_astnode_t *clause, unsigned int start_index, unsigned int end_index);
 
+/**
+ * Insert clause at position `index` of a `CYPHER_AST_QUERY` node.
+ *
+ * If the node is not an instance of `CYPHER_AST_QUERY` then the result will
+ * be undefined.
+ *
+ * If the clause is not an instance of `CYPHER_AST_QUERY_CLAUSE` then the result
+ * will be undefined.
+ *
+ * @param [node] The AST node.
+ * @param [clause] The AST clause node.
+ * @param [index] The index of the new clause.
+ * @return The query, or NULL if an error occurs.
+ */
+cypher_astnode_t *cypher_ast_query_push_clause(
+    cypher_astnode_t *astnode,
+    cypher_astnode_t *clause,
+    unsigned int index
+);
+
 /**
  * Replace the clauses of a `CYPHER_AST_FOREACH` node.
  *
@@ -3130,6 +3170,22 @@ void cypher_ast_call_subquery_replace_query
     cypher_astnode_t *query
 );
 
+/**
+ * Insert a new clause at position `index` of a `CYPHER_AST_CALL_SUBQUERY` node.
+ *
+ * If the node is not an instance of `CYPHER_AST_CALL_SUBQUERY` then the
+ * result will be undefined.
+ *
+ * @param [astnode] The AST node.
+ * @param [query] The query to replace the existing query with.
+ * @param [index] Position of the new clause
+ */
+void cypher_ast_call_subquery_push_clause(
+    cypher_astnode_t *astnode,
+    cypher_astnode_t *clause,
+    unsigned int index
+);
+
 /**
  * Get the proc name of a `CYPHER_AST_CALL` node.
  *