rewrite

Documentation

Index

• Variables
• func BottomUp(root ops.Operator, resolveID func(ops.Operator) semantics.TableSet, ...) (ops.Operator, error)
• func BottomUpAll(root ops.Operator, resolveID func(ops.Operator) semantics.TableSet, ...) (ops.Operator, error)
• func EnableDebugPrinting() (reset func())
• func FixedPointBottomUp(root ops.Operator, resolveID func(ops.Operator) semantics.TableSet, ...) (op ops.Operator, err error)
• func TopDown(root ops.Operator, resolveID func(ops.Operator) semantics.TableSet, ...) (op ops.Operator, err error)
• func Visit(root ops.Operator, visitor func(ops.Operator) error) error
• type ApplyResult
  • func NewTree(message string, op ops.Operator) *ApplyResult
  • func Swap(parent, child ops.Operator, message string) (ops.Operator, *ApplyResult, error)
  • func (ar *ApplyResult) Changed() bool
  • func (ar *ApplyResult) Merge(other *ApplyResult) *ApplyResult
• type Rewrite
• type ShouldVisit
• type VisitF
• type VisitRule

Variables

var DebugOperatorTree = false

Functions

func BottomUp

func BottomUp(
	root ops.Operator,
	resolveID func(ops.Operator) semantics.TableSet,
	visit VisitF,
	shouldVisit ShouldVisit,
) (ops.Operator, error)

BottomUp rewrites an operator tree from the bottom up. BottomUp applies a transformation function to the given operator tree from the bottom up. Each callback [f] returns a ApplyResult that is aggregated into a final output indicating whether the operator tree was changed.

func BottomUpAll

func BottomUpAll(
	root ops.Operator,
	resolveID func(ops.Operator) semantics.TableSet,
	visit VisitF,
) (ops.Operator, error)

BottomUpAll rewrites an operator tree from the bottom up. BottomUp applies a transformation function to the given operator tree from the bottom up. Each callback [f] returns a ApplyResult that is aggregated into a final output indicating whether the operator tree was changed.

func EnableDebugPrinting

func EnableDebugPrinting() (reset func())

func FixedPointBottomUp

func FixedPointBottomUp(
	root ops.Operator,
	resolveID func(ops.Operator) semantics.TableSet,
	visit VisitF,
	shouldVisit ShouldVisit,
) (op ops.Operator, err error)

FixedPointBottomUp rewrites an operator tree much like BottomUp does, but does the rewriting repeatedly, until a tree walk is done with no changes to the tree.

func TopDown

func TopDown(
	root ops.Operator,
	resolveID func(ops.Operator) semantics.TableSet,
	visit VisitF,
	shouldVisit ShouldVisit,
) (op ops.Operator, err error)

TopDown rewrites an operator tree from the bottom up. BottomUp applies a transformation function to the given operator tree from the bottom up. Each callback [f] returns a ApplyResult that is aggregated into a final output indicating whether the operator tree was changed.

Parameters: - root: The root operator of the tree to be traversed. - resolveID: A function to resolve the TableSet of an operator. - visit: The VisitF function to be called for each visited operator. - shouldVisit: The ShouldVisit function to control which nodes and ancestors to visit and which to skip.

Returns: - ops.Operator: The root of the (potentially) transformed operator tree. - error: An error if any occurred during the traversal.

func Visit

func Visit(root ops.Operator, visitor func(ops.Operator) error) error

Visit allows for the walking of the operator tree. If any error is returned, the walk is aborted

Types

type ApplyResult

type ApplyResult struct {
	Transformations []Rewrite
}

ApplyResult tracks modifications to node and expression trees. Only return SameTree when it is acceptable to return the original input and discard the returned result as a performance improvement.

var (
	SameTree *ApplyResult = nil
)

func NewTree

func NewTree(message string, op ops.Operator) *ApplyResult

func Swap

func Swap(parent, child ops.Operator, message string) (ops.Operator, *ApplyResult, error)

Swap takes a tree like a->b->c and swaps `a` and `b`, so we end up with b->a->c

func (*ApplyResult) Changed

func (ar *ApplyResult) Changed() bool

func (*ApplyResult) Merge

func (ar *ApplyResult) Merge(other *ApplyResult) *ApplyResult

type Rewrite

type Rewrite struct {
	Message string
	Op      ops.Operator
}

type ShouldVisit

type ShouldVisit func(ops.Operator) VisitRule

ShouldVisit is used when we want to control which nodes and ancestors to visit and which to skip

type VisitF

type VisitF func(
	op ops.Operator,
	lhsTables semantics.TableSet,
	isRoot bool,
) (ops.Operator, *ApplyResult, error)

VisitF is the visitor that walks an operator tree

type VisitRule

type VisitRule bool

VisitRule signals to the rewriter if the children of this operator should be visited or not

const (
	VisitChildren VisitRule = true
	SkipChildren  VisitRule = false
)