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Copy pathast_rewrite_same_clauses.c
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373 lines (315 loc) · 11.9 KB
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/*
* Copyright (c) 2006-Present, Redis Ltd.
* All rights reserved.
*
* Licensed under your choice of the Redis Source Available License 2.0
* (RSALv2); or (b) the Server Side Public License v1 (SSPLv1); or (c) the
* GNU Affero General Public License v3 (AGPLv3).
*/
#include "ast.h"
#include "../util/arr.h"
#include "../query_ctx.h"
#include "../util/qsort.h"
#include "../util/sds/sds.h"
#include "../errors/errors.h"
#include "../procedures/procedure.h"
// forward declarations
static inline bool is_compressible(const cypher_astnode_t *clause,
cypher_astnode_type_t type);
static bool _compress_clauses(const cypher_astnode_t *node);
typedef void (*replace_func)(cypher_astnode_t *, cypher_astnode_t *, unsigned int, unsigned int);
typedef const cypher_astnode_t * (*get_clause_func)(const cypher_astnode_t *, unsigned int);
// compresses multiple consecutive CREATE clauses into a single CREATE clause
static void _replace_create_clause
(
cypher_astnode_t *root, // ast root
cypher_astnode_t **clauses, // clause being replaced
int scope_start, // beginning of scope
int scope_end, // ending of scope
replace_func replace // replace function pointer
) {
uint count = array_len(clauses);
struct cypher_input_range range = cypher_astnode_range(clauses[0]);
cypher_astnode_t **paths = array_new(cypher_astnode_t *, count);
// collect paths
for (uint i = 0; i < count; i++) {
const cypher_astnode_t *pattern =
cypher_ast_create_get_pattern(clauses[i]);
uint npaths = cypher_ast_pattern_npaths(pattern);
for (uint j = 0; j < npaths; j++) {
const cypher_astnode_t *path =
cypher_ast_pattern_get_path(pattern, j);
array_append(paths, cypher_ast_clone(path));
}
}
// build the replacement pattern
cypher_astnode_t *pattern = cypher_ast_pattern(paths, array_len(paths),
paths, array_len(paths), range);
// build the replacement clause
cypher_astnode_t *new_clause = cypher_ast_create(false, pattern, &pattern,
1, range);
// replace original clause with the new one
replace(root, new_clause, scope_start, scope_end);
array_free(paths);
}
// compresses multiple consecutive MATCH clauses into a single MATCH clause
static void _replace_match_clause
(
cypher_astnode_t *root, // ast root
cypher_astnode_t **clauses, // clause being replaced
int scope_start, // beginning of scope
int scope_end, // ending of scope
replace_func replace // replace function pointer
) {
uint count = array_len(clauses);
cypher_astnode_t *predicate = NULL;
struct cypher_input_range range = cypher_astnode_range(clauses[0]);
cypher_astnode_t **paths = array_new(cypher_astnode_t *, count);
// collect MATCH patterns and predicates
for (uint i = 0; i < count; i++) {
const cypher_astnode_t *pattern =
cypher_ast_match_get_pattern(clauses[i]);
uint npaths = cypher_ast_pattern_npaths(pattern);
for (uint j = 0; j < npaths; j++) {
const cypher_astnode_t *path =
cypher_ast_pattern_get_path(pattern, j);
array_append(paths, cypher_ast_clone(path));
}
// combine MATCH predicates into a single predicate using AND connectors
cypher_astnode_t *new_predicate =
(cypher_astnode_t *)cypher_ast_match_get_predicate(clauses[i]);
if(new_predicate != NULL) {
new_predicate = cypher_ast_clone(new_predicate);
if(predicate == NULL) {
predicate = new_predicate;
} else {
// concat using AND
cypher_astnode_t *children[] = {predicate, new_predicate};
predicate = cypher_ast_binary_operator(CYPHER_OP_AND, predicate,
new_predicate, children, 2, range);
}
}
}
// build the replacement pattern
cypher_astnode_t *pattern =
cypher_ast_pattern(paths, array_len(paths), paths, array_len(paths),
range);
// build the replacement clause
cypher_astnode_t *children[] = {pattern, predicate};
cypher_astnode_t *new_clause = cypher_ast_match(false, pattern, NULL, 0,
predicate, children, predicate == NULL ? 1 : 2, range);
// replace original clause with the new one
replace(root, new_clause, scope_start, scope_end);
array_free(paths);
}
// compresses multiple consecutive DELETE clauses into a single DELETE clause
static void _replace_delete_clause
(
cypher_astnode_t *root, // ast root
cypher_astnode_t **clauses, // clause being replaced
int scope_start, // beginning of scope
int scope_end, // ending of scope
replace_func replace // replace function pointer
) {
uint count = array_len(clauses);
struct cypher_input_range range = cypher_astnode_range(clauses[0]);
cypher_astnode_t **exps = array_new(cypher_astnode_t *, count);
rax *identifiers = raxNew();
// collect expressions
for (uint i = 0; i < count; i++) {
uint nexps = cypher_ast_delete_nexpressions(clauses[i]);
for(uint j = 0; j < nexps; j++) {
const cypher_astnode_t *exp =
cypher_ast_delete_get_expression(clauses[i], j);
// do not aggregate multiple appearances of an identifier
if(cypher_astnode_type(exp) == CYPHER_AST_IDENTIFIER) {
const char *identifier = cypher_ast_identifier_get_name(exp);
if(raxTryInsert(identifiers, (unsigned char *)identifier, strlen(identifier), NULL, NULL)) {
array_append(exps, cypher_ast_clone(exp));
}
} else {
// "MATCH p1=(n:N), p2=(m:M) DELETE nodes(p1)[0] DELETE nodes(p2)[0]"
array_append(exps, cypher_ast_clone(exp));
}
}
}
raxFree(identifiers);
// build the replacement clause
cypher_astnode_t *new_clause = cypher_ast_delete(false, exps,
array_len(exps), exps, array_len(exps), range);
// replace original clause with the new one
replace(root, new_clause, scope_start, scope_end);
array_free(exps);
}
// compresses multiple consecutive SET clauses into a single SET clause
static void _replace_set_clause
(
cypher_astnode_t *root, // ast root
cypher_astnode_t **clauses, // clause being replaced
int scope_start, // beginning of scope
int scope_end, // ending of scope
replace_func replace // replace function pointer
) {
uint count = array_len(clauses);
struct cypher_input_range range = cypher_astnode_range(clauses[0]);
cypher_astnode_t **items = array_new(cypher_astnode_t *, count);
for (uint i = 0; i < count; i++) {
uint nitems = cypher_ast_set_nitems(clauses[i]);
for(uint j = 0; j < nitems; j++) {
const cypher_astnode_t *item =
cypher_ast_set_get_item(clauses[i], j);
array_append(items, cypher_ast_clone(item));
}
}
// build the replacement clause
cypher_astnode_t *new_clause = cypher_ast_set(items, array_len(items),
items, array_len(items), range);
// replace original clause with the new one
replace(root, new_clause, scope_start, scope_end);
array_free(items);
}
// compresses multiple consecutive REMOVE clauses into a single REMOVE clause
static void _replace_remove_clause
(
cypher_astnode_t *root, // ast root
cypher_astnode_t **clauses, // clause being replaced
int scope_start, // beginning of scope
int scope_end, // ending of scope
replace_func replace // replace function pointer
) {
uint count = array_len(clauses);
struct cypher_input_range range = cypher_astnode_range(clauses[0]);
cypher_astnode_t **items = array_new(cypher_astnode_t *, count);
for (uint i = 0; i < count; i++) {
uint nitems = cypher_ast_remove_nitems(clauses[i]);
for(uint j = 0; j < nitems; j++) {
const cypher_astnode_t *item =
cypher_ast_remove_get_item(clauses[i], j);
array_append(items, cypher_ast_clone(item));
}
}
// build the replacement clause
cypher_astnode_t *new_clause =
cypher_ast_remove(items, array_len(items), items, array_len(items),
range);
// replace original clause with fully populated one
replace(root, new_clause, scope_start, scope_end);
array_free(items);
}
// tries to compress clauses of a query or a foreach clause
// returns true if a rewrite occurred
static bool _compress_clauses
(
const cypher_astnode_t *node // node containing clauses to compress
) {
bool rewritten = false;
cypher_astnode_type_t type = cypher_astnode_type(node);
ASSERT(type == CYPHER_AST_QUERY || type == CYPHER_AST_FOREACH);
cypher_astnode_t **clauses = array_new(cypher_astnode_t *, 0);
// is the node representing a FOREACH clause
uint clause_count = 0;
replace_func replace_func = NULL;
get_clause_func get_clause = NULL;
// use appropriate function to get a positioned clause
if(type == CYPHER_AST_FOREACH) {
get_clause = cypher_ast_foreach_get_clause;
clause_count = cypher_ast_foreach_nclauses(node);
replace_func = cypher_ast_foreach_replace_clauses;
} else {
get_clause = cypher_ast_query_get_clause;
replace_func = cypher_ast_query_replace_clauses;
clause_count = cypher_ast_query_nclauses(node);
}
for(uint i = 0; i < clause_count; i++) {
const cypher_astnode_t *clause = get_clause(node, i);
cypher_astnode_type_t t = cypher_astnode_type(clause);
// try compressing the inner-clauses of foreach clause and call subquery
if(t == CYPHER_AST_FOREACH) {
rewritten |= _compress_clauses(clause);
continue;
} else if(t == CYPHER_AST_CALL_SUBQUERY) {
rewritten |=
_compress_clauses(cypher_ast_call_subquery_get_query(clause));
continue;
}
// check compressibility, move on if not compressible
if(!is_compressible(clause, t)) {
continue;
}
//----------------------------------------------------------------------
// collect clauses of the same type as current clause
//----------------------------------------------------------------------
for (uint j = i; j < clause_count; j++) {
clause = get_clause(node, j);
cypher_astnode_type_t t2 = cypher_astnode_type(clause);
if(t2 != t || !is_compressible(clause, t2)) {
break;
}
array_append(clauses, (cypher_astnode_t *)clause);
}
//----------------------------------------------------------------------
// compress clauses
//----------------------------------------------------------------------
uint s = i;
uint e = s + array_len(clauses) - 1;
if(array_len(clauses) > 1) {
// multiple consecutive clauses of the same type
// compress them
if(t == CYPHER_AST_CREATE) {
_replace_create_clause((cypher_astnode_t *)node, clauses, s, e, replace_func);
} else if(t == CYPHER_AST_MATCH) {
_replace_match_clause((cypher_astnode_t *)node, clauses, s, e, replace_func);
} else if(t == CYPHER_AST_DELETE) {
_replace_delete_clause((cypher_astnode_t *)node, clauses, s, e, replace_func);
} else if(t == CYPHER_AST_SET) {
_replace_set_clause((cypher_astnode_t *)node, clauses, s, e, replace_func);
} else if(t == CYPHER_AST_REMOVE) {
_replace_remove_clause((cypher_astnode_t *)node, clauses, s, e, replace_func);
}
rewritten = true;
// update clause count, skip compressed clauses
clause_count -= array_len(clauses) - 1;
}
array_clear(clauses);
}
array_free(clauses);
return rewritten;
}
// returns true if AST clause type is compressible
static inline bool is_compressible
(
const cypher_astnode_t *clause, // clause to check
cypher_astnode_type_t type // type of clause
) {
// compressible clauses:
// 1. Non-OPTIONAL MATCH
// 2. CREATE
// 3. SET
// 4. DELETE
// 5. REMOVE
return ((type == CYPHER_AST_MATCH &&
!cypher_ast_match_is_optional(clause)) ||
type == CYPHER_AST_CREATE ||
type == CYPHER_AST_SET ||
type == CYPHER_AST_DELETE ||
type == CYPHER_AST_REMOVE);
}
// rewrite result by compressing consecutive clauses of the same type
// to a single clause, returning true if the rewrite has been performed
bool AST_RewriteSameClauses
(
const cypher_astnode_t *root // root of AST
) {
bool rewritten = false;
if(cypher_astnode_type(root) != CYPHER_AST_STATEMENT) {
return rewritten;
}
// retrieve the root's body
const cypher_astnode_t *body = cypher_ast_statement_get_body(root);
if(cypher_astnode_type(body) != CYPHER_AST_QUERY) {
return rewritten;
}
// traverse clauses
// compress consecutive clauses
return _compress_clauses(body);
}
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