classConflictResolver

packages/sql-parser/src/Automaton/ConflictResolver.php:24

final class ConflictResolver

Restricted visibility: declared "@visibility root". Code outside that scope must not name this declaration.

Settles the conflicts of one state the way its generator would.

A shift/reduce conflict is decided by precedence when both the token and the rule are ranked: the higher rank wins, and equal ranks follow the token's associativity. Without ranks the shift wins and the conflict is counted. A reduce/reduce conflict goes to the earlier rule, except that Lemon lets a higher-ranked rule win first.

Methods§

public function __construct(private Grammar $grammar)

source §

Parameters

$grammar Grammar Grammar whose precedences decide

public function resolve(
    array<int, int> $shifts,
    array<int, array<int, int>> $lookaheads,
): ResolvedState

source §

Resolves the actions of one state.

Parameters

`$shifts`	`array<int, int>`	Target state by terminal
`$lookaheads`	`array<int, array<int, int>>`	Lookahead bitset by completed rule

Returns

ResolvedState The settled actions

Test cases 4

Called from 1

method-call SqlParser\Automaton\ParseTableBuilder::build() packages/sql-parser/src/Automaton/ParseTableBuilder.php:63

Calls 11

static-call ActionCode::shift() line 45
function-call ksort line 50
static-call Bitset::members() line 53
static-call ActionCode::reduce() line 56
static-call ActionCode::isShift() line 58
method-call ConflictResolver::shiftOrReduce() line 59
class-const ActionCode::ERROR() line 62
static-call ActionCode::isReduce() line 64
method-call ConflictResolver::reduceOrReduce() line 69
static-call ActionCode::rule() line 69
new ResolvedState line 81

public function shiftOrReduce(int $terminal, int $rule): int|null

source §

Decides a shift/reduce conflict on one terminal.

Parameters

`$terminal`	`int`	Terminal that can be shifted
`$rule`	`int`	Rule that can be reduced

Returns

int|null The winning action code, the error code when neither may win, or null when the conflict stays unresolved

Test cases 2

Called from 1

method-call SqlParser\Automaton\ConflictResolver::resolve() packages/sql-parser/src/Automaton/ConflictResolver.php:59

Calls 9

method-call Grammar::memberPrecedence() line 94
method-call Grammar::rulePrecedence() line 95
static-call ActionCode::shift() line 100
static-call ActionCode::reduce() line 100
class-const Associativity::Right() line 104
class-const Associativity::Left() line 105
class-const Associativity::NonAssoc() line 106
class-const ActionCode::ERROR() line 106
class-const Associativity::Precedence() line 107

public function reduceOrReduce(int $earlier, int $later): int|null

source §

Decides a reduce/reduce conflict between two rules that reduce on the same terminal.

Bison always keeps the earlier rule and counts the conflict. Lemon lets the higher-ranked rule win outright and counts the conflict only when the ranks are missing or equal, in which case the earlier rule wins.